The Department of Pesticide Regulation and
For additional copies, contact the Pesticide Consultation and Analysis Unit of the California Department of Food and Agriculture at 1220 N Street, Room 108, Sacramento, California 98514, or (916) 654-1765.
TABLE OF CONTENTS EXECUTIVE SUMMARY. . . . . . . . . . . . . . . . . . . .3 INTRODUCTION 6 SUMMARIES OF SUBGROUPS' REPORTS SOIL FUMIGATION SUBGROUP REPORT . . . . . . . . . . .9 NURSERY SUBGROUP REPORT . . . . . . . . . . . . . . .11 COMMODITY/STRUCTURAL SUBGROUP REPORT. . . . . . . . .12 Commodity - Dried Fruit and Tree Nuts. . . . . .13 Commodity - Fresh Fruit and Vegetables . . . . .14 Structural . . . . . . . . . . . . . . . . . . .15 GOALS 17 RECOMMENDATIONS. . . . . . . . . . . . . . . . . . . . .18 A ROLE FOR CALIFORNIA. . . . . . . . . . . . . . . . . .19 REPORTS OF SUBGROUPS SOIL FUMIGATION SUBGROUP. . . . . . . . . . . . . . .21 Attachment A-1 Research Needs Identified by USDA Conference - Short- and Long-Term Priorities .24 Attachment A-2 Effectiveness of Other Chemical Fumigants Compared to Methyl Bromide . . . . . . . . . .28 Attachment A-3 Summary of Strawberry Production in Selected Locations Around the World . . . . . . . . . .29 NURSERY SUBGROUP. . . . . . . . . . . . . . . . . . .39 COMMODITY/STRUCTURAL SUBGROUP . . . . . . . . . . . .43 Dried Fruits and Tree Nuts . . . . . . . . . . .44 Fresh Fruit and Vegetables . . . . . . . . . . .55 Structural: Facilities and Residences . . . . .59 APPENDIX LIST OF TASK FORCE MEMBERS. . . . . . . . . . . . . .75
California is one of the largest users of methyl bromide in the United States. For a variety of crops, methyl bromide is currently the chemical of choice for preplant soil fumigation, commodity, and quarantine treatment requirements. Under the Clean Air Act, methyl bromide was declared an ozone depleting compound in 1993, and its production and importation will be phased out by 2001. The extent to which methyl bromide will be phased out internationally under the Montreal Protocol will be established in 1995. For many uses of methyl bromide, there are no alternatives or alternative strategies are not well studied for applicability.
In order to anticipate the impacts of methyl bromide phaseout and identify research needs for California, the Department of Pesticide Regulation (DPR) and the Department of Food and Agriculture (CDFA) convened the Methyl Bromide Research Task Force in 1993. The membership of the Task Force represents commodity groups, applicators, academic researchers, government agencies, and environmental advocates. The charge of the Task Force was to evaluate the research plan of the U.S. Department of Agriculture (USDA) for its adequacy to meet California's needs. The Task Force met periodically to discuss ongoing alternatives research, funding strategies for research, and developments under the Montreal Protocol.
Objective, Scope, Methodology of the Study
The Task Force was divided into three subgroups (soil, nursery, and commodity/structural) to review a key document, USDA's "Alternatives to Methyl Bromide: Assessment of Research Needs and Priorities". This document is the proceedings from a workshop held in 1993 where participants evaluated the status of existing and potential alternatives to methyl bromide, and identified and prioritized research needs for potential federal funding. The Task Force considered this document to be USDA's research plan.
Each of the Task Force's subgroups reviewed this report to determine whether California's needs would be met. The subgroups prepared reports addressing their areas of responsibility. The Task Force report combines the findings of the subgroups, and proposes goals and a role for California in the national effort to find feasible alternatives to methyl bromide.
Summary of Results
The Task Force found that many of California's research needs are addressed by the USDA research plan, but the plan lacks a comprehensive vision and specifics on delivery of results. Each subgroup identified strengths and weaknesses in the USDA approach for their specific area, as related to California agriculture. The Soil Fumigation Subgroup focused on research needs to replace preplant soil fumigation. The Subgroup supported the need for research outlined in the USDA report, but found the treatment of non-chemical or integration of chemical and non-chemical controls less thorough than for chemical controls. There was not sufficient emphasis on understanding soil microbiology as a basis for pest control decisions, nor did the report discuss the mechanisms for transfer of research results to growers. Overall, the report lacked a comprehensive vision of a research program to examine alternatives.
The Nursery Subgroup found that the USDA report adequately addresses California's needs for alternatives research on field crop production. This emphasis, however, overlooks the fact that sound field crop production systems start with healthy planting material produced from pest and disease free nurseries. Separate from the USDA research agenda is this Subgroup's concern about the availability of alternative treatments for nursery stock to meet California regulatory certification requirements for nematode-free nursery stock.
The Commodity/Structural Subgroup addressed alternative needs for dried fruits and nuts, fresh fruits and vegetables, and treatment of food processing facilities and transportation vehicles. This group found that, overall, the USDA plan addresses California's need for replacement technologies. In addition to reviewing the USDA report on methyl bromide alternatives, the Subgroup also reviewed research needs to reduce or eliminate methyl bromide emissions, and analyzed alternatives for residential fumigations. For dried fruits and nuts, replacement technologies need to address control of insects during storage and prior to shipment, as well as quarantine treatments. For fresh fruits and vegetables, replacement technologies for quarantine treatments are the sole and very significant postharvest need. The Subgroup emphasized the need for USDA to meet immediately with U.S. trading partners to establish acceptable alternatives to quarantine treatments with methyl bromide, and to coordinate such negotiations with research efforts.
While not all members of the Task Force agree with each subgroup report, there was support for the following goals and recommendations. The Task Force developed these recommendations from their review, and articulated a role for California. In developing goals, the Task Force emphasized a research orientation that includes grower/packer involvement in priority setting, interdisciplinary approaches, compatibility with integrated pest management approaches, and appropriate scaling of research to address field production and fumigation/storage facilities. Key goals of the Task Force can be summarized as follows:
*develop a more comprehensive understanding of pests and commodities, including the niche of pathogens in soil microbial ecology; monitoring and pest identification techniques; and pest and commodity responses to various treatment regimes
*develop comprehensive databases on existing and proposed chemical alternatives and application technologies, and on non-chemical alternatives research to facilitate coordination of research efforts and distribution of results
*develop and test pest/pathogen-resistant cultivars, production methods for pathogen-free propagation materials, and uses of beneficial microorganisms
*develop new culture/crop production systems to maximize non-chemical control strategies and chemical efficacy, and collect data on economic and environmental impacts of alternative strategies
The Task Force recommends a collaborative process to develop a strategic plan, involving a wide range of stakeholders, that would establish research goals, timetables, priorities, funding, and implementation of results. Further, the Task Force recommends an independent oversight panel, with broad representation, to allocate research funding, and provide research and adoption oversight.
The Task Force recommends that pilot demonstration projects in different regions of the State be used to speed adoption of innovative pest management and production systems.
The Task Force finds that California will play a critical role in the search for alternatives to methyl bromide because of its cropping diversity, long growing season, strong university and federal research programs, and stringent oversight of pesticide use. The State's farmers and pest control advisors lead the nation in exploring transitional pest management systems that reduce pesticide use. These factors make California the ideal location for testing the viability of alternative systems to methyl bromide.
California is one of the largest users of methyl bromide in the United States and will sustain major impact when the product is phased out in 2001 under the Clean Air Act. California is the nation's leader in the production of many fresh fruits, vegetables, dried fruits and nuts, as well as many field crops. For a variety of crops, methyl bromide is currently the chemical of choice for preplant soil fumigation, commodity, and quarantine treatment requirements.
Unless viable alternatives are found, the loss of methyl bromide will have a severe impact on California's ability to meet the requirements of a number of importing countries. The same is true for domestic quarantines. A good example of the State's need for methyl bromide is the continuing threat from the Mediterranean fruit fly (Medfly). Without methyl bromide or suitable substitutes, both domestic and foreign markets could be closed to California agricultural products.
In order to anticipate those impacts and identify research needs, the Department of Pesticide Regulation (DPR) and the California Department of Food and Agriculture (CDFA) convened a committee called the Methyl Bromide Research Task Force representing commodity groups, applicators, academics, government agencies, and environmental advocates.
The Task Force divided into three subgroups (soil, nursery, and commodity/structural) to review a key document, the U.S. Department of Agriculture's (USDA) "Alternatives to Methyl Bromide: Assessment of Research Needs and Priorities". This document is the proceedings from a three day workshop in which participants from USDA's Agricultural Research Services (ARS) and Animal and Plant Health Inspection Services (APHIS), the U.S. Environmental Protection Agency (U.S. EPA), State agencies, universities, and private institutions evaluated the status of existing and potential alternatives to methyl bromide for management of soil-borne, postharvest, structural, and quarantine pests. They also identified and prioritized research needs for potential federal funding.
Members of the California Task Force reviewed the completeness of this report in order to determine whether California's needs would be met. With the exception of residential structural alternatives, which were not in the purview of the USDA conference, the document makes an excellent start at identifying potential alternatives, many of which apply to California agricultural needs. However, some groups identified some significant gaps in the USDA proposal, particularly in the area of oversight and coordination of proposed research.
Further, while not all Task Force members are in agreement with all of the material in each subgroup report, Task Force members proposed goals, recommendations, and a role for California in the national effort to find feasible alternatives to methyl bromide. This report includes a summary of the conclusions reached by each subgroup, with the complete reports of the subgroups included at the end of this report.
The Task Force was well aware of the potential effects the loss of methyl bromide will have on California agriculture. Few of the alternatives identified in this report have been adequately tested on a large scale. Some of the alternatives identified in this report are in limited use in some crops and commodities in California; others are in the research phase or exist as ideas which may have potential. Further research on all alternatives is needed to assess applicability and cost effectiveness when extended to a broader range of crops and conditions throughout the State.
The loss of methyl bromide will have a profound impact on California agriculture, with potential yield losses in some crops. However, the loss also presents an opportunity to move away from a dependence on a single product that has discouraged an in-depth understanding of the soil dynamics of various crop systems. A recent report on research needs from the Crop Protection Coalition states,
If that restructuring includes (1) a broader understanding of soil-borne pest complexes, (2) development of effective, economical pest management systems, and (3) analysis of the means of transferring new information and technical advances to methyl bromide users, it will constitute a model with broad applications for the future.
The Soil Fumigation Subgroup strongly supported the need for research as outlined by
participants to the USDA conference in 1993. However, the following weaknesses were
noted in the report.
As mentioned, the USDA report does an excellent job of cataloguing the chemical pesticide alternatives that may provide the most immediate relief to impacts of the loss of methyl bromide. However, the synthetic pesticides are under review by State and federal regulatory agencies and their continued availability is unknown. We know some of the components of the soil-borne pest complex but others may become evident if the broad spectrum biocidal properties of methyl bromide are not available. The etiology and epidemiology of new pests may require years of additional research for control. If sufficient resources are available for research, then the use of non-chemical methods alone or in combination with chemical fumigants may achieve adequate pest control. These alternatives may require 5 to 7 years of field scale testing for implementation, because of annual variation in environmental conditions and pest levels.
While the USDA report also briefly considers cultural and biological controls, heat
treatment, genetic resistance, mulches, and other non-chemical soil treatments,
members of the Subgroup felt a more detailed description of non-chemical soil
treatments practiced on both conventional and organic farms would give a better idea
of the potential and range of non-chemical options (Attachment A-3 of the soil
fumigation report). This attachment also includes case histories of current
strawberry production systems that do not use methyl bromide. A thorough discussion
of methyl bromide alternatives, including the status of pesticide registrations,
also has been prepared by DPR.
The overall research needs outlined in the USDA program fall into five basic categories: soil/crop ecology, etiology, and epidemiology; crop production systems; plant breeding and integrated pest management; technology transfer; and identification and quantification of regulatory impacts. Significantly absent from this discussion of individual commodity needs is an overall research agenda that cuts across commodity groups. Further, it lacks a mechanism for identifying ongoing research and promising strategies so that research efforts can be focused and coordinated. Finally, there is no provision for oversight of research funds so that resources can be directed quickly to research that growers can implement with their existing technology.
2. U.S. Department of Agriculture. Alternatives to Methyl Bromide: Assessment of Research Needs and Priorities. Workshop, Arlington, VA, June 29-July 1, 1993, p.47.
3. Braun, A. L. and D.M. Supkoff. 1994. Options to Methyl Bromide for the Control of Soil-Borne Diseases and Pests. Pest Management Analysis and Planning Program. California Department of Pesticide Regulation. Sacramento.
4. Liebman, J. 1994. Alternatives to Methyl Bromide in California Strawberry Production. The IPM Practitioner 15(7);1-12.
Nursery plants are California's fourth largest crop, accounting for $6.5 billion in sales each year. Use of methyl bromide is crucial to the nursery industry. Since nursery stock is a high cash value crop, a small decrease in yield can have significant economic impact. The use of pathogen and pest-free planting stock is the basis of any farming system. Methyl bromide is used to produce disease and pest-free planting material and to comply with regulatory requirements in California and foreign countries. In general, infested or diseased nursery stock will not be accepted by buyers. Methyl bromide soil fumigation in the field or greenhouse is particularly important to eliminate volunteer crops and host weeds that can act as a source of disease or infestation. Only methyl bromide has shown the ability to penetrate dense tissue such as bulbs to assure effective control of soil-borne diseases and pests.
While there was considerable overlap between the scope of this group's effort and that of the Soil Fumigation Subgroup, the Nursery Subgroup had a wide diversity of commodities to consider, as well as two distinct growing environments: greenhouse and field grown crops. In evaluating the USDA report, the Nursery Subgroup found that the needs of California were adequately addressed, although the focus was largely on production crops rather than on greenhouse and nursery stock. This overlooks the fact that sound field crop production systems start with healthy planting material produced from pest and disease free nurseries.
California nursery operators are currently exploring available technologies, such as steam sterilization, that need additional engineering research to improve their economic viability as an alternative for methyl bromide in certain uses. Further review and prioritization of specific needs for nursery and greenhouse research is ongoing.
A pressing need outside the scope of the USDA report has been identified. California law currently requires that certain nursery stock be grown on soil treated in an approved manner to eliminate pest nematodes. The only feasible and approved treatment for these fields is methyl bromide fumigation, since soil sampling and steam treatment are not currently economical. Therefore, alternative treatments which will meet pest-free cleanliness standards for regulatory and export purposes or certification procedures should be explored.
The commodities principally addressed in this section are included in two groups, dried fruits and tree nuts and fresh fruits and vegetables. Both groups have diverse physical and chemical characteristics. For dried fruits and tree nuts, methyl bromide is used for insect control during storage, for quarantine treatments, and as a preshipment treatment to control insects during transit. For fresh fruits and vegetables, quarantine treatments comprise the sole postharvest use of methyl bromide. Many fumigations are conducted preshipment, but often methyl bromide fumigation occurs when insect pests are found at the port of entry.
Without feasible alternatives for these uses of methyl bromide, considerable loss of stored products will occur. Additionally, export markets would be lost to most of California's currently exported commodities.
Methyl bromide also has been used historically for structural insect control; however, its use has been declining in recent years as alternatives became available. The exception is powderpost beetle eggs, where methyl bromide is still the most cost-effective means of control.
The Structural/Commodity Subgroup evaluated whether the USDA research plan
adequately addresses California's needs for research on replacements for methyl
bromide for commodity fumigation and fumigation of food/grain facilities. In
addition, the group addressed research needs to retain methyl bromide but reduce or
eliminate its emissions, an option included in an earlier USDA report, "Methyl
Bromide Substitutes and Alternatives: A Research Agenda for the 1990's".
Overall, the USDA plan addresses California's needs for replacement technologies. Because of the diversity of affected commodities and sites, the Subgroup recommends that USDA establish mechanisms to:
1. Prioritize the research needs for different commodities and facilities.
2. Coordinate efforts with State, university, and private researchers.
3. Report to the user and research community on the progress of obtaining funding to support the research program.
4. Report to the user and research community on the progress and outcomes of the research effort.
While the Subgroup recognizes that negotiating with other countries on quarantine commodity treatments was not within the scope of USDA's research plan, the Subgroup recommends that USDA begin to meet immediately with U.S. trading partners to establish acceptable alternatives to methyl bromide fumigation. If no alternative treatments are negotiated, current foreign customers that buy California and other U.S. commodities will seek other trading partners. Close communication and collaboration between the different offices of USDA will be required in order to coordinate quarantine negotiations with research efforts.
Commodity - Dried Fruit and Tree Nuts
The specific research needs for dried fruit and tree nuts fall into two categories. The first is research needed for alternative treatments. Second, there is a significant amount of research that is required for reducing or eliminating methyl bromide emissions from existing types of treatment.
The Subgroup identified the following general areas with regard to research needs for alternative treatments:
1. Develop information, including basic biology and physiology of insects, to improve and expand integrated pest management systems that could provide long-term control.
2. Develop the engineering components that support priority research, with special emphasis on problems associated with scale of use, integration of alternatives, and specific design of facilities specifically to implement alternatives.
3. Improve the feasibility and economic viability of controlled atmosphere, hot and cold treatments, and other physical control techniques.
4. Research biological and microbial control agents and delivery systems for use as stand alone treatments or as part of an integrated pest management program.
5. Develop packaging and containerization technologies; identify practical volumes for storage and transportation for use in conjunction with alternative treatments.
With regard to research needs for reducing or eliminating methyl bromide emissions, the Subgroup identified:
1. Increase knowledge concerning the fate of applied methyl bromide on a commodity-by- commodity basis.
2. Develop large scale systems that trap and/or recycle methyl bromide, including evaluation of hazardous waste generation and the concomitant regulatory implications.
3. Review current recommendations for application rates to assess how increasing load factors, decreasing head space, tightening chambers, and various combination treatments with inert gasses could reduce application rates.
4. Evaluate existing technology and applications for upgrading and sealing fumigation chambers and continue research on reduced permeability of film for use on tarpaulin commodity fumigations.
Commodity - Fresh Fruit and Vegetables
Methyl bromide fumigation is the most commonly used insect quarantine treatment for fresh fruits and vegetables. Methyl bromide fumigation is required for export of many California crops and is required for import of many agricultural commodities to protect California agriculture from potential infestations. Methyl bromide has become the primary quarantine treatment because it is effective against a wide range of insect pests, is tolerated by most commodities, and is inexpensive and easy to apply. Considerable loss in export dollars will occur if suitable alternatives to methyl bromide are not developed and accepted by 2001.
California is unique in the volume and range of fresh commodities produced. If Medfly were to become established in the State, alternative treatments would be needed to maintain product flow to market. Alternative treatments would have to be rapid to prevent disruption of that flow. Cold treatment for Medfly, while available for several commodities, takes too long to prevent disruption of product flow.
Considerable research effort is needed to develop alternatives for methyl bromide. There do not appear to be new fumigants under development. New treatments will need to be developed on a pest/commodity basis. The potential alternative treatments include cold treatment, heat treatment, controlled atmospheres, irradiation, biocides, pest-free zones, host suitability, and systems approaches (see Commodity/Structural Subgroup - B. Fresh Fruits and Vegetables Report for details). For each pest/commodity combination, one or two alternatives may hold the most potential for development of a feasible treatment. A feasible treatment would result in desired insect control in a timely and economical manner without commodity injury.
Because negotiations on new quarantine treatments can take years, research funding should focus on treatments with potential for success in the short term. Negotiations with importing nations should begin as soon as feasible to explore potentially acceptable treatment alternatives to methyl bromide.
For postharvest treatments, there is considerable potential to develop recapture/recovery systems for methyl bromide which could eliminate or substantially reduce release of methyl bromide into the atmosphere. These systems should be further researched.
The amount of methyl bromide used in structural fumigations in California has steadily decreased over the past few years from over 5 million pounds in 1990 to less than one million in 1992, due to the availability of alternative chemicals and technologies. With the exception of powderpost beetle eggs, methyl bromide is no longer critical to structural fumigation, however, pressing research needs in this area are as follows:
1. Research needed on reducing dosage of methyl bromide, phosphine, and other alternative chemical treatments through the addition of synergists or displaced fumigation techniques.
2. Data needed on effective dosage for alternative chemical and non-chemical techniques for many pest systems.
3. Research needed on accurate in situ pest detection methods.
4. Large-scale field testing of alternative chemicals and non-chemical techniques.
5. Research needed on the effects of alternative chemical and non-chemical techniques on structural materials, commodities treated, occupants, and applicators.
The Clean Air Act requires phase-out of methyl bromide by the year 2001. Therefore, an accelerated research effort must be made to assist growers and packers to make the transition to alternative management practices.
To be effective, this research process must be designed to achieve practical results in a short time frame, and to generate sufficient grower confidence for rapid adoption of promising alternative methods. Priority should be given to alternatives that are environmentally safe. These objectives suggest the following research orientation:
1. Identify current methyl bromide alternative research efforts and develop a comprehensive research data base including government, academic, and private research efforts. Develop a mechanism to ensure distribution and coordination of existing research efforts. Document existing systems that maximize pest management through integrated pest management.
2. Improve methods to monitor population dynamics of soil-borne pests and pathogens. Develop a more comprehensive understanding of microbial ecology in the soil, including pest identification techniques, microbial interactions, and other ecological impacts of soil-borne plant pests.
3. Develop a current and comprehensive database on existing and proposed chemical alternatives and the most effective application technology. The emphasis in the short term should include timing of application, determination of minimum efficacious rates, reduction of emissions, and how to integrate existing alternatives into a pest management strategy for each commodity.
4. Develop new culture/crop production systems designed to maximize non-chemical control strategies and maximize the efficacy of the required crop protection chemicals.
5. Develop and test cultivars with resistance or tolerance to the known major soil-borne pathogens and pests. Research should include development of methods to produce pathogen-free propagation materials, and propagation materials inoculated with beneficial microorganisms.
6. Develop a more comprehensive understanding of the response of insect pests and commodities to various postharvest treatment alternatives through study of the biochemical and physiological response to those treatments.
7. Develop and coordinate collection of data on economic and environmental impacts as alternatives are identified and crop production systems are modified.
8. Identify regulatory impediments to the adoption of alternatives.
B. Independent Research Allocation and Oversight Panel. A panel comprised of growers, pest control advisors, researchers, cooperative extension, regulatory personnel, commodity representatives, and non-profit organizations be established to receive proposals, allocate any funds received, and provide oversight of the research process, results, and adoption by users.
C. Pilot Demonstration Programs. In order to speed adoption of innovative pest management and production systems, pilot on-site demonstration programs be established in different regions of the State. These pilot programs using alternatives to methyl bromide would (1) bring greater visibility to successful methods; (2) provide researchers with sites to evaluate the alternative methods; (3) transfer promising alternatives from research trials to complex conditions on farms and other sites of application, and fine-tune them.
Agriculture in California is unique in the number of specialty crops raised (e.g.,
lettuce, tomatoes, broccoli, grapes, nuts, strawberries, stone and pome fruits),
diversity of cropping systems, and a climate that allows 2-3 crop cycles per growing
season. This State supplies a major portion of the fresh fruits and vegetables for
the U.S. The technologies developed in California to accomplish this have been
adopted by other states and by many countries.
The usual 5 to 7 year time frame required for testing and implementation of a
promising alternative into an integrated farming system forces a focused research
effort to meet the 2001 phase out date for methyl bromide. California has a critical
role in the search for alternatives due to its crop diversity, long growing season,
strong university and federal research programs, and stringent oversight of
pesticide use. California is ahead of the nation in adopting non-chemical approaches
and has many farmers, cooperative extension farm advisors, and pest control advisors
exploring transitional pest management systems that reduce pesticide use. It is an
ideal location for testing the viability of alternative systems to methyl bromide.
The usual 5 to 7 year time frame required for testing and implementation of a promising alternative into an integrated farming system forces a focused research effort to meet the 2001 phase out date for methyl bromide. California has a critical role in the search for alternatives due to its crop diversity, long growing season, strong university and federal research programs, and stringent oversight of pesticide use. California is ahead of the nation in adopting non-chemical approaches and has many farmers, cooperative extension farm advisors, and pest control advisors exploring transitional pest management systems that reduce pesticide use. It is an ideal location for testing the viability of alternative systems to methyl bromide.
California is one of the largest users of methyl bromide for preplant soil fumigation in the United States and will sustain major impacts when the product is phased out in 2001 under the 1990 Clean Air Act. Methyl bromide is currently the chemical of choice for preplant soil fumigation because of its wide spectrum of biocidal activity with consistent performance. Unless viable alternatives are found there will be potential losses in yield for a wide range of crops, but this threat provides an opportunity to move away from a dependence on a single product that has discouraged an in-depth understanding of the soil dynamics of various crop systems. A recent report on research needs from the Crop Protection Coalition states:
The Soil Fumigation Subgroup strongly supported the need for research as outlined by
the participants to the USDA conference in 1993.
As mentioned, the USDA report does an excellent job of cataloguing the chemical
pesticide alternatives that may provide the most immediate relief to the impacts of
the loss of methyl bromide. (Tables comparing these alternatives are provided in
Attachment A-2.) However, the synthetic pesticides (including fumigants) are under
review by State and federal regulatory agencies and their continued availability is
unknown. An exceptionally thorough discussion of methyl bromide alternatives,
including the status of pesticide registration, has been prepared by DPR.
We know some of the components of the soil-borne pest complex but others may become evident if the broad spectrum biocidal properties of methyl bromide are not available. The etiology and epidemiology of new pests may require years of additional research for control. If sufficient resources are available for research, then the use of non-chemical methods alone or in combination with chemical fumigants may achieve adequate pest control. These alternatives may require 5 to 7 years of field scale testing for implementation, because of annual variation in environmental conditions and pest levels.
While the USDA report also briefly considers cultural and biological controls, heat
treatment, genetic resistance, mulches, and other non-chemical soil treatment
methods, members of the Subgroup felt a more detailed description of non-chemical
soil treatments practiced by farmers would give a more comprehensive overview of the
potential and range of non-chemical options. Farmers in California use some of these
options in combination with methyl bromide treatments. Case histories are offered as
examples of farming systems currently in use that may provide insight for identifying
potential research areas (Attachment A-3). A thorough discussion of methyl bromide
alternatives (chemical and non-chemical) in California strawberry production
systems, that have application for other crops, has been published in "The IPM
The overall research needs outlined in the USDA program fall into five basic categories: soil/crop ecology, etiology, and epidemiology; crop production systems; plant breeding and integrated pest management; technology transfer; and identification and quantification of regulatory impacts.
Significantly absent from this discussion of individual commodity needs is an overall research agenda that cuts across commodity groups. Further, the research agenda needs a mechanism for identifying ongoing research and promising strategies for oversight of research funds so that resources can be directed quickly to research that growers can implement with their existing technology.
7. U.S. Department of Agriculture. Alternatives to Methyl Bromide: Assessment of Research Needs and Priorities. Workshop, Arlington, VA, June 29 - July 1, 1993. 47 p.
8. Braun, A.L., and D.M. Supkoff. 1994. Options to Methyl Bromide for the Control of Soil-Borne Diseases and Pests. Pest Management Analysis and Planning Program. California Department of Pesticide Regulation. Sacramento.
9. Liebman, Jamie. 1994. Alternatives to Methyl Bromide in California Strawberry Production. The IPM Practitioner. Vol. XVI, No. 7. July, 1994.
|Priority||Strawberries||Tree Fruits, Nuts, Small Fruit & Misc.||Solanaceous Crops||Forestry, Nursery, & Ornamental Crops||Leafy & Other Vegetables|
|High||1) Develop database on likely alternatives to methyl bromide in order to develop predictable systems for soil-borne pest management.||1) Improve methods of risk assessments, including soil-borne plant pests (pathogens, insects and weed seeds) detection and development of action thresholds.||1) Improve methodologies to monitor population dynamics and understand microbial ecology in the soil, including pest identification techniques, microbial interactions, and other microorganism activities, of soil-borne plant pests.||1) Develop integrated pest management systems that make maximum use of existing chemical, cultural, physical, and biological control practices.||1) Develop integrated pest management systems that make maximum use of existing chemical, cultural, physical, and biological control practices.|
| ||2) Develop existing alternative chemical fumigant and application technology.||2) Evaluate existing (registered and non-registered) chemicals and develop improved application technology for soil-borne plant pest management.||2) Extensively evaluate alternative chemicals alone and in combinations, including chloropicrin, 1-3 Dichloropropene, metham-sodium, and other herbicides.||2) Develop new chemicals and chemical application technology. The emphasis in the short term should include timing of application, determining rates, and how best to apply and utilize other existing pesticides (including alternative soil fumigants). An emphasis should also be placed on minimizing pesticide use by maximizing understanding of when, how, and at what rates to use pesticides.||2) Evaluate existing vegetables germplasm for resistance major soil-borne pests.|
|3) Develop and evaluate alternative non-fumigant chemicals for weed control.||3) Evaluate existing germplasm for resistance and tolerance to specific soil-borne plant insects and pathogens, including plant parasites nematodes.||3) Reevaluate existing solanaceous germplasm for resistance/tolerance to the major soil-borne plant pests.||3) Develop new culture/crop production systems. Improve the efficacy of currently available cultural control systems. Test locally effective methods on a broader basis. Conduct research to better understand the basis for their effectiveness.||3) Develop vegetable cropping systems and cultural practices based on basic understanding of the biological and ecological characteristics of soil-borne plant pests to expand integrated pest management options.|
|4) Develop and evaluate genetically resistant/tolerant germplasm.||4) Develop improved technology for soil solarization of deep-rooted tree and vine crops under various climatic conditions.||4) Accelerate evaluation of existing and new chemicals and expansion of available pesticide labels, for management of soil-borne pests of minor vegetable crops.|
|5) Develop pathogen-free planting material programs.||5) Develop systems to produce high quality vegetable transplants inoculated with beneficial microorganisms to assure early season plant health in field plantings.|
|6) Develop effective soil-borne plant pest management based cultural practices.||6) Develop and evaluate soil pasteurization techniques for crop production beds and fields, such as soil solarization, electronic heat (microwave) and steam.|
|Medium||1) Evaluate irrigation systems for delivery of chemical pesticides and biological control agents to manage soil-borne plant pathogen and insect pests.||1) Develop physical pest management systems.|
|2) Evaluate new methods of heat treatment methods (radio frequency power) to effectively manage soil-borne plant pathogen and insect pests. Develop appropriate application technology.||2) Develop biological pest control practices, including the development of basic knowledge and a fundamental understanding of biological pest control.|
|Low||1) Develop pest-resistant hosts by breeding and biotechnology approaches|
|Priority||Strawberry||Tree Fruits, Nuts, Small Fruit & Misc||Solanaceous Crops||Forestry, Nursery, & Ornamental Crops||Leafy & Other Vegetables|
|High||1) Same as short term priority #4.||1) Develop and evaluate integrated, multi-component systems for soil-bornesoil-borne plant pest management.||1) Develop and evaluate improved soil-borne plant resistant/tolerant solanaceous crop germplasm with horticulturally or agronomically acceptable traits using both conventional and molecular techniques.||1) Develop new culture/crop production systems and integrate appropriate existing cultural practices. Conduct research that develops a fundamental knowledge of cultural control practices and use this knowledge to develop new and improved systems.||1) Develop bio-intensive integrated pest management systems using biological control agents for soil-borne pests in conjunction with application of soil amendments and timely application of chemicals|
|2) Same as short term priority #5.||2) Develop new, horticulturally desirable/acceptable rootstocks and cultivars with multiple soil-borne plant pathogen resistance, using traditional and novel breeding techniques.||2) Develop integrated pest management systems, including evaluation of combinations of chemicals and non-chemical approaches for effective management of soil-borne plant pests of solanaceous crops.||2) Develop biologically-based environmentally-sound integrated pest management systems that place increasing emphasis on the integration and use of cultural, physical, and biological control practices. Integration of plant resistant hosts into these systems should be emphasized only where applicable and economically feasible. Emphasis should be placed on the use of safer chemicals that specifically affect the target organisms.||2) Identify and develop pest resistant/tolerant crop germplasm and varieties utilizing conventional and biotechnological techniques.|
|3) Same as short term priority #3 except - develop biological control agent and integrate into effective soil-borne plant pest management system.||3) Identify, evaluate, and develop potential biological control agents and/or natural products to effectively manage soil-borne plant pests of solanaceous crops. This should include development of appropriate delivery and application methods, as well as development of strategies that enhance activities of biocontrol agents under natural conditions in solanaceous crop production systems.||3) Develop physical pest management treatment and integrate crop production systems. Increase research on soil solarization, pasteurization, and heat treatment methodologies||3) Develop soil-borne pest control systems utilizing nemato- and entomopathogens, plant growth and health promoting rhizobacteria, induce resistance, predatory parasites, parasitoids, microbial herbicides, and fungal pathogen antagonists.|
|4) Same as short term priority #6.||4) Develop and improve crop rotation systems that most effectively suppress the activities of soil-borne plant pests of solanaceous crops.||4) Develop methods to detect pest population levels and accurately forecast their impact.||4) Develop suppressive soils for management of soil-borne plant pests in vegetable production systems.|
|5) Develop enhanced technology transfer through training of extension personnel, scouts, and consultants in biointensive integrated pest management for vegetables.|
|Medium||1) Same as short term high priority #6.||1) Develop improved cultural practices for management of soil-borne plant pathogens and insect pests, including cover crops, crop rotational schemes and soil water management.||1) Same as short term priority #1. Develop new chemicals and chemical application technology.|
|2) Develop effective soil pasteurization technology including soil solarization, electronic heating, and steam.||2) Develop and evaluate environmentally safe broad spectrum chemical biocides/pesticides including synthetic chemicals, naturally occurring chemicals, and biorational products|
|3) Identify biocontrol agents and develop appropriate formulations and delivery systems applicable to commercial tree fruit, tree nut, and small fruit crop production.|
|Low||1) Evaluate soil amendments for suppression of soil-borne plant pathogens and pests of tree and vine crops.||1) Develop pest-resistant hosts by breeding/technology|
SOURCE: METHYL BROMIDE SUBSTITUTES AND ALTERNATIVES REPORT JAN. 1993
United States Department of Agriculture
Table B Effectiveness of Other Chemical Fumigants Compared to Methyl Bromide
A wide range of organic materials have been tested and used as soil amendments to suppress nematodes, pathogens, and weeds. These include livestock and poultry manures, tree bark, oil cakes, shellfish, and many other materials. Commercially available products include Clandosan , a product formulated from shells that controls nematodes by destroying their chitin, and potting soils such as ProGrow that contain beneficial fungi that suppress plant pathogens.
Neem oilcake is the residue remaining after pesticidal neem oil has been pressed out of the seeds of the neem tree, Azadirachta indica. When incorporated into soil, the oilcake suppresses root-knot nematodes in tomato crops as well or better than carbofuran. When mixed with sawdust and incorporated into soil, neem oilcake can also suppress plant parasitic fungi, possibly due to fungitoxic degradation products (Singh, S.A. et al. 1985. Changes in the phenobolic contents, related rhizophere mycoflora and nematode population in tomato inculcated with Meloidogyne incognita as a result of soil amendment with organic matter).
Plant Growth Promoting Rhizobacteria. Control of soil pests around the roots of plants using bacteria (rhizobacteria) antagonistic to the soil pests has been investigated but there are no useful repeatable greenhouse or field tests. Rhizobacteria products on the market have not been consistent or reliable under field conditions. More research is needed in this area.
Beneficial Soil Microorganisms. Use of beneficial fungi and bacteria antagonists to suppress soil pathogens such as fungi in the genera Fusarium, Phytophthora, Pythium, and Rhizoctonia is a subject under intense study. A number of soil amendments and other products containing antagonistic fungi such as Trichoderma, Gliocladium, or bacteria such as fluorescent pseudomonads are commercially available. In the Ohio nursery industry, use of such products has virtually replaced methyl bromide for soil fumigation.
Hoitink, H.A. 1994. Ohio State University, Wooster, OH 44691, USA. Personal communication.
Hoitink, H.A.J., and GA Kuter. 1985. Effects of compost in container media on diseases caused by soil-borne plant pathogens. Acta Horticulturae 172:191-197.
Moore, L.W. 1983. Composted bark, chrysanthemums, and Christmas trees. Plant Disease 67(6):706.
1. Crop Rotations. This historic method avoids soil pest problems by removing susceptible plants for periods of time, thus preventing buildup of soil pests. For example, tomato, cabbage, onion, pepper, sweet potato, corn, and snapbeans rotated with "Coastal" Bermuda grass, Cynodon dactylon, produce competitive yields without nematicides to control root-knot nematodes [Burton, G.W. and A.W. Johnson. 1987. Coastal Bermuda grass rotations for control of root-knot nematodes. Journal of Nematology 19(1):138-140]. Peach orchards rotated with "Stacy" wheat avoid damage by ring nematodes [Stanley, D. 1993. Preserving Georgia's peach pride. Agricultural Research 41(5):10-15].
2. Time of planting. Understanding of the epidemiology and the etiology may allow the planting of the crop when the populations of the soil pests are at a very low level.
3. Deep ploughing. Reduce inoculum by burial of the reproductive structures and by microbial decomposition.
4. Flooding. Flooding the soil for periods of time controls soil-borne pests. Flooding is particularly effective when organic matter is incorporated into the soil prior to addition of water, producing anaerobic microbial byproducts that suppress pathogens and nematodes. Flooding requires access to adequate supplies of water. It is currently used to control Verticillium and Fusarium wilts in cotton in China, Fusarium wilts of banana in Central America, and has been tried successfully in experimental trials on cotton in the San Joaquin Valley. In the former Soviet Union, grape phylloxera, an insect that attacks roots of grape vines, can be controlled by flooding vineyards for 10-15 days in fall or winter (Abramov, V. 1988, Culture of own-rooted grapevines. Sadovodstvo i Vinogradarstvo 9:23-24).
5. Fallowing. Taking land out of production reduces habitat and food sources supporting pests associated with a specific crop. For example, many growers of processing tomatoes in California include a fallow period in their rotations to prevent buildup of nematodes.
6. Cover Cropping. This usually consists of planting a non-cash crop between periods when the cash crop is grown. Many cover crops are legumes such as clovers, vetches, alfalfa, etc., that improve both the fertility and tilth of soil by increasing organic matter. Leguminous cover crops (also called "green manures") are increasingly used in orchards and vineyards to suppress weeds, and improve habitats for natural enemies of soil-borne and foliar pests.
7. Intercropping. This technique involves planting two or more crops simultaneously, usually in strips wide enough to permit independent cultivation, but narrow enough for the crops to interact agronomically. For example, alfalfa and cotton have been successfully strip intercropped in California. The alfalfa suppresses weeds and attracts beneficial insects to control foliar pests (Stern, V.M. 1969. Interplanting alfalfa in cotton to control lygus bugs and other insect pests. Proceedings of the Tall Timbers Conference on Ecological Animal Control by Habitat Management. Tallahassee, FL. Feb. 27-28. pp 55-69).
8. Replanting Strategies. Some decline or dieback of young vines or trees occurs in most vineyards or orchards whether or not treated with methyl bromide. The causes of decline range from abiotic (weather, climate) to biotic (pathogens, nematodes, etc.). California vineyards fumigated with methyl bromide commonly sustain 2 percent losses of vines to a variety of causes within the first 2 years (Smith et al. 1992). Almond growers replant an average of 1/tree/acre/year in orchards with 75 trees/acre, despite fumigation with methyl bromide (Asai et al. 1992). Losses such as these lead many growers to fumigate soil "for insurance" even though such treatments may be ineffective. A number of innovative replanting techniques may reduce costs of replanting and reduce real or perceived need for fumigation prior to replanting. For example, in South Africa, new vines are planted into plastic bags 1 year prior to bagged vines being transplanted into the vineyard. This approach minimizes disturbance to roots. The new vines are interplanted between old vines. After new vines are established (1-2 years), the old vines are cut off at the trunk and removed. This interplanting approach minimizes replanting production losses (Merwe 1989). Laser planting machines being tested in Europe (Tiezzi 1990) promise a 50 percent reduction in current replanting costs using conventional replanting methods.
Asai, W. et al. 1992. Sample costs to establish and produce almonds in the Northern San Joaquin Valley. University of California Cooperative Extension Service. 16 pp.
Merwe, G.G. van der. 1989. Interplanting of table grapes as method of re-establishment can it work? Deciduous Fruit Grower 39(8):264-267.
Smith, R. et al. 1992. Sample costs to establish a vineyard and produce wine grapes in Sonoma County in 1992. University of California Cooperative Extension Service. 19 pp.
Tiezzi, E. 1990. First Italian experiments with a laser planting machine. Prime esperienze italiane con la macchina a laser per l'impianto. Vignevine 17(10):37-40.
1. Solarization. Soil is pasteurized by placing transparent plastic tarps over moist soil. Solar energy from the sun is trapped under the tarp, raising soil temperatures to 160 degrees Fahrenheit (71 degrees Celsius) or higher. This pasturizes the soil, killing many soil pathogens, weed seeds, and nematodes, but allowing many heat-tolerant beneficial microorganisms to survive. These beneficials can attack or outcompete many soil pathogens seeking to recolonize solarized soil. Solarization can be used when annual or perennial crops are in the field, so there is no break in production. The impact of solarization can be enhanced by combining it with other pest suppressants such as cole crop residues, biological control organisms, or reduced application rates of fumigants such as metam sodium. In California, solarization would be useful on strawberries grown in the San Joaquin Valley, or in coastal Southern California near Irvine, where temperatures are sufficiently hot for it to be effective. Solarization is also currently used in some vineyards and orchards in the Central Valley in place of methyl bromide. Solarization has been successfully used to reduce soil pathogens in avocado orchards in South Africa by removing infested trees, tarping the planting hole to kill pathogens, then replanting new trees in the solarized hole (Kotze, J.M and J.M. Darvas. 1983. Integrated control of avocado root rot. California Avocado Society Yearbook 67:83-86). Even sublethal heating of infested roots via solarization can impact important pathogens such as oak root fungus, Armillaria mellea, that attacks roots of grapevines and certain fruit and nut trees. Sublethal heating can weaken the Armillaria pathogen enough to allow biocontrol by more heat-resistant beneficial microbes such as Trichoderma viride.
Ashworth, L.J., Jr. and S.A. Gaona. 1982. Evaluation of clear polyethylene mulch for controlling Verticillium wilt in established pistachio nut groves. Phytopathol. 72:243-246.
Chellemi, D. 1994. Integrated pest management for soil-borne pests of tomato. Presented at the Methyl Bromide Alternatives Outreach/USDA/USEPA, Annual International Conference on Methyl Bromide Alternatives and Emissions Reductions, 13-16 November 1994, Kissimmee, FL. Pp. 25-1-25-2.
Gamliel, A. and J. Katan. 1993. Suppression of major and minor pathogens by fluorescent pseudomonads in solarized and non-solarized soil. Phytophathol. 83:68-75.
Gamliel, A. and J. J. Stapleton. 1993a. Characterization of antifungal volatile compounds evolved from solarized soil amended with cabbage residues. Phytopathol. 83:899-905.
Gamliel, A. and J.J. Stapleton. 1993b. Effect of chicken compost or ammonium phosphate and solarization on pathogen control, rhizosphere microorganisms, and lettuce growth. Plant Dis. 77:886-891.
Hartz, T.K., J.E. DeVay and C.L. Elmore. 1993. Solarization is an effective soil disinfestation technique for strawberry production. HortScience 28(2):104-106.
Morgan, D.P. J.A. Liebman, L. Epstein, and M.J. Jimenez. 1991. Solarizing soil planted with cherry tomatoes vs. solarizing fallow ground for control of Verticillium wilt. Plant Dis. 75:148-151.
Munnecke, D.E. et al. 1976. Effect of heating and drying on Armillaria mellea or Trichoderma viride and the relation to survival of A. mellea in soil. Phytopathology. 66:1363-1368.
Ramirez-Villapudua, J. and D.E. Munnecke. 1988. Effect of solar heating and soil amendments of cruciferous residues on Fusarium oxysporum f. sp. conglutinans and other organisms. Phytopathology 28:289-295.
Ristaino, J.B., K.B. Perry and R.D. Lumsden. 1991. Effect of solarization and Gliocladium virens on sclerotia of Sclerotium rolfsii, soil microbiota, and the incidence of southern blight of tomato. Phytopathology 81:1117-1124.
2. Steam. Infested soil can be pasturized with steam at temperatures of 158-176 degrees Fahrenheit (70-80 degrees Celsius). This method is as effective as methyl bromide in suppressing soil pests. In the past, steam pasturization was common practice in greenhouses. Recent improvements in steam technology by incorporating negative pressure systems to increase soil penetration have revived use of steam. This method has been adopted widely in the Netherlands where methyl bromide has been phased out of greenhouse culture largely by use of steam. Since 1991, the Netherlands has eliminated the use of methyl bromide for soil fumigation.
3. Hot Water Dips. Rooted cuttings of grapes and other plants infested with insects or pathogens can be disinfested by dipping the roots in hot water. A study in Japan on grapevine stocks infested with root attacking Phylloxera sp. insects found treatments with methyl bromide (3 hours) versus hot water (20 minutes) produced comparable results (Sakai, et al. 1985. Methyl bromide fumigation and hot water treatment of grapevine stocks against the grape phylloxera, Viteus vitifolia Fitch. Research Bulletin of the Plant Protection Service, Japan 21:67-69).
4. Plastic Barriers. Polyethylene sleeves can protect young vines and trees from root-attacking insects such as grape phylloxera. In the former Soviet Union, rooted grapevine cuttings grown in 50 cm-long polyethylene sleeves and planted in the fall prevented infestation by phylloxera on grafted rootstocks, and delayed infestation on ungrafted vines for up to 9 years after planting (Goldriga et al. 1973. A new method of planting grated and non-grated grapevines. Vinodelie i Vinogradarstvo SSSR 1:28-30).
5. Wave-Length Selective Plastic Mulches. By excluding photosynthesizing light waves from reaching the soil, these mulches heat the soil but prevent weed growth. They are also used as a barrier to adult insects that lay eggs in soil (Purser, J. 1991. Producing vegetables using infrared transmitting plastic mulch and perforated row covers. 1991 Demonstration and Research Report. Univ. of Alaska Fairbanks Cooperative Extension Service).
6. Superheated Water. Commercial machines are available from New Zealand and the U.S. that heat water to 302 degrees Fahrenheit (150 degrees Celsius) to kill weeds. By applying water under high pressure through shanks, the hot water is claimed to penetrate 1 to 2 meters in the soil.
7. Flaming/Infrared Technology. Hand-held and tractor-driven flamers, fueled by propane or other fuels, are used to control weeds in orchards, cotton, vegetables, and many other crops. Flaming equipment is available in many countries [Daar, S. 1987. Flame weeding on European farms. The IPM Practitioner. 9(3):1-4].
8. Radio-frequency (Microwave) Heating. This technology was developed for the space program. Tests are underway in the U.S. to test a portion of the electromagnetic spectrum as a pest control tool against grape phylloxera and other pest insects and pathogens (Lagunas-Solar, M.C., J.D. MacDonald and J. Granett. 1993. Control of pests and pathogens in agricultural soils with radio frequency power: A proposal for defense technology conversion, reinvestment, and transition assistance program. SoilPro. 49 pp).
Strawberries are grown in many parts of the world without using methyl bromide (Table 1). In some cases, the yields are not as high as in California, but this may be offset by lower cost of production or higher returns or both. In all these cases the crop is considered profitable.
Case Study #1: Organic Production in California
Many small growers and some large growers have tried organic strawberry production. State regulations prohibit the use of methyl bromide in organic production. The California Certified Organic Farmers list 22 farms currently producing organic strawberries in California. In addition, several large growers produced strawberries organically for several years but at present are using only conventional production systems. Yields in organic production are about 65 percent that of conventional production. However, organic fruit obtains a higher price at the supermarket, and this partly offsets the lower yield. Fruit quality is considered quite good, although organic fruit may be slightly smaller. The lower yields obtained by organic growers have several causes. First is the lack of the non-specific yield increase that results from fumigation with methyl bromide. Second, some organic growers plant the cultivar "Chandler", which is known for its excellent flavor, higher plant vigor, and slightly lower yields in certain locations. Third, organic producers cannot use synthetic pesticides and fertilizers; this sometimes leads to increased pest problems, especially mites and lygus bugs, and difficulty regulating the timing of nitrogen applications. Conventional (non-organic) growers, of course, will be able to use synthetic fertilizers even after methyl bromide is banned, and so will not have the problems with nitrogen management and foliar pests faced by organic growers. Fourth, organic fruit often is slightly smaller than conventional, and this raises the picking costs. Finally, crop rotations are longer; growing crops less valuable than strawberries reduces the value of the rotation cycle as a whole. Research efforts could be expected to increase yields from most of these causes. However, there has been little research targeted specifically to small, organic growers. An additional problem faced by smaller organic growers is their limited access to shelf space at retail stores. Most, if not all, of these small organic growers consider marketing more of a problem than the actual production.
Case Study #2: Conventional Production in Oregon
Oregon produces strawberries on about 7,000 acres, and is a major supplier of processing strawberries. Only about 10 percent of the Oregon strawberry land is fumigated with methyl bromide. Yields are lower, and the processing crop is not as valuable on a per pound basis as the California fresh market crop. However, unlike California, the crop is grown as a perennial, i.e., the plants are left in the ground for 3-5 years at a time, and this greatly reduces production costs.
Case Study #3: Conventional Production in Germany
Germany and Switzerland have essentially banned methyl bromide over concerns about bromine residue in food and groundwater. Bans were phased in starting in the late 1970s. Both countries still grow strawberries. Strawberry production is typified by:
- perennial culture, with plants left in the ground for 3-5 years.
- rotations: 3 to 5 years recommended, although some growers use only 1-2 years. In Germany, the largest grower uses 15 year rotations.
- disease resistant varieties.
- mixed plantings of several strawberry varieties in the same field, to assure at least one variety does well under the unpredictable conditions of environment and disease and pest pressure.
- yields of about 5 tons per acre.
- individual growers marketing both fruit and daughter plants for transplanting.
Case Study #4: Conventional Production in Greenhouses in The Netherlands
The Netherlands was formerly one of Europe's largest users of methyl bromide for soil fumigation. During the 1980s, methyl bromide was phased out. Nevertheless, production of crops formerly dependent on methyl bromide has increased. The following description of strawberry production was extracted from reference 5, Attachment A-3 (page 38).
The Netherlands has developed glasshouse strawberry production systems with many economic and environmental advantages. Plants are grown on artificial substrate shelves in greenhouses or on raised shelves outdoors. The roots and runners do not contact the soil and thus soil-borne diseases and pests are reduced. Water and nutrients are pumped to the plants with a regulated trickle irrigation system. Drip irrigation reduces plant wetness and related foliage pest problems. The nutrients and water which drain from the roots may be recycled to reduce waste and environmental contamination. Growers sterilize the recycled nutrient water by heating to about 194 degrees Fahrenheit (90 degrees Celsius).
Plants are propagated by harvesting and rooting runners. Young plantlets are exposed to short-day lighting to stimulate bud formation, and then stored for up to eight months at 28 degrees Fahrenheit (-2 degrees Celsius) in a dormant state poised for flower development. Once removed from storage, plants are placed in substrates either indoors or outdoors and allowed to fruit. In warm conditions, these plants will bear fruit within 60 days.
Since this cropping technique requires only four months for the final growing and harvesting state, strawberries can be grown in soil without the use of methyl bromide or other fumigants, if pests are not too aggressive. Where soil-borne pests are more severe, plants can be grown on sterile peat sacks. Planting densities in glasshouses are doubled by hanging each tightly-spaced row from cables attached to winches. Alternated rows are then raised and lowered to gain access for tending or harvesting.
The shortness of the final cropping period allows growers to quickly change production to take advantage of market conditions. For example, growers can increase or decrease production depending on prices, or select alternative crops if strawberry prices are not favorable.
These systems are expensive. A glasshouse typically costs the U.S. $1.3-2.0 million per hectare. However, yields are greater than 44 tons/ha (18 tons/acre) and harvest cycle, and growers can produce 2 to 3 crops per year. One grower with a state-of-the-art system estimated an annual rate of return of up to 40 percent with a recovery of investment within three years. Normal payback periods for these systems is 10 to 15 years.
Table I. Summary of Strawberry Production in Selected Locations Around the World.
1. Cochran, J. 1994. Swanton Berry Farms, Davenport, CA 95017. Pers. comm.
2. Finn, C. 1994. USDA Corvallis, OR. Pers. comm.
3. Gliessman, S.R., S.L. Swezey, J. Allison, J. Cochran, J. Farrell, R. Dluson, F. Rosado-May, and M. Werner. 1990. Strawberry production systems during conversion to organic management. California Agriculture 44(4):4-7.
4. Ketzis, J.K. 1992. Case studies of the virtual elimination of methyl bromide soil fumigation in Germany and Switzerland and the alternatives employed. Presented at the Workshop on Alternatives to Methyl Bromide, Rome, Italy, October 21-23.
5. United Nations Environment Programme 1992. Methyl Bromide. Executive Summary of the International Workshops on Alternatives to Methyl Bromide for Soil Fumigation. Rotterdam, The Netherlands, 19-21
October 1992 and Rome, Italy, 22-23 October 1992. 32 pp.
6. University of California Statewide Integrated Pest Management Project. 1994. Integrated Pest Management for Strawberries. Publication 3351. Division of Agriculture and Natural Resources, Oakland, California. 142 pp.
7. Webb, R. 1994. Driscoll Strawberry Research, Watsonville, CA. Pers comm.
8. Welch, N. C., and J. A. Beutel 1990. Strawberry Production and Costs in the Central Coast of California. Agricultural Extension, University of California. 8 pp.
Methyl bromide is used in the nursery industry primarily as a preplant application for many cut flower, cut green crops, rose bush production, grapevine, fruit tree and nut tree nursery stock, strawberry plant production, turf sod production, container ornamental soil media sterilization, some vegetable transplant production, citrus and avocado plant production, seed bed and forestry field sterilization, and occasional fumigation of cuttings or live plants and seed.
The pests involved are nematodes, various pathogenic fungi [phytophthora (several strains), pythium, rhizoctonia, verticillium and others], pathogenic bacteria, crown gall, oak root fungus, other fungi, insects, and weeds.
The main acreage treated is in the San Joaquin and Sacramento valleys where the grapevines, fruit tree, nut tree, strawberry plants, and rose bushes use about 3,000 acres per year of methyl bromide-treated nursery land. The other nursery uses are scattered throughout the State with substantial use along the coast in cut flower and cut green production.
4. Alternatives to Methyl Bromide
Ideally, an alternative treatment would cost the same or less than methyl bromide, control the most serious pests, be safer to use, and not have an adverse impact on soil, water, air, or non-target organisms. The alternatives should not require a much longer treatment time than methyl bromide.
Research is currently being conducted on solarization, Basamid, composting, and for a method of applying Vapam for consistent results. For the major acreage needing treatment, none of these alternatives has been proven to work except Telone.
2. Potentially, a suitable application method for Vapam could make its use practical. Development of microwave frequencies currently reserved for use by the U.S. military might work but needs research. Ultra violet laser pulse technologies might be developed with suitable research to kill pathogens in soil. Marigolds can kill nematodes in some manner and other plants are toxic to some pests. Research might find the lethal ingredient in these plants and then synthesize this product for commercial use.
Since the nursery industry in California uses 2.5 million pounds annually of methyl bromide, it is important that every possible alternative be explored. Some of the uses did not appear to have a known, satisfactory alternative at this time.
Other Alternatives Discussed
1. Change crop to one not requiring methyl bromide treatment.
2. Change to resistant varieties and develop more resistant varieties in order to obviate the need for methyl bromide treatment.
3. Rotate crops over long enough period for pest control without methyl bromide use.
4. Cultural practice techniques that avoid methyl bromide use, such as other weed control methods.
5. Use of several specific action chemicals to replace the broad spectrum methyl bromide control.
6. Development and use of biological control organisms such as parasitic nematodes.
7. Use of non-chemical sterilants such as steam.
8. Use of ultra violet laser pulse technologies to kill pathogens in some nursery irrigation water, especially recycled irrigation water.
9. Research underway on pulse technology for electric heat treatment of field soils.
10. Super heat treatment for petroleum clean-up of contaminated soils that might have some adaptation to field soil treatment.
11. Development of new fumigants that are more benign than methyl bromide.
12. Adaptation of other fumigant materials for efficient uses in nurseries which currently do not work well, Vapam and some others.
13. Growing all field crop nursery stock in containers above ground to avoid the need to sterilize with methyl bromide. This can be done both in greenhouses as well as outdoors.
14. Live with pests and accept lower quality product and less productivity.
15. Grow more nursery crops by hydroponics.
16. Solarization of some nursery use soils.
NOTE: While the Subgroup discussed all the above ideas, it is important to note that many of the ideas have potential economic, worker safety, or environmentally harmful impacts that might be worse than those posed by methyl bromide. Also, some possibilities are ideas only and would require substantial research before practical use could be achieved.
The tree nut category includes almonds, pecans, and walnuts while the dried fruit category includes raisins, prunes, pears, apples, apricots, dates, figs, peaches, and tomatoes. Each category possesses diverse physical and chemical characteristics.
Tree nuts are subject to infestation by a wide range of insects. These include rusty grain beetle, red flour beetle, confused flour beetle, cigarette beetle, khapra beetle, drugstore beetle, saw toothed grain beetle, Indian meal moth, navel orange worm, almond moth, warehouse moth, raisin moth, and exotic fruit flies.
Dried fruits are also subject to infestation by a wide range of insects. These include khapra beetle, saw toothed grain beetle, merchant grain beetle, dried fruit beetle, confused flour beetle, cigarette beetle, vinegar flies, earwigs, dried fruit mite, common grain mite, almond moth, Indian meal moth, raisin moth, and dried fruit moth.
The scope of problems presented by these pests is large. The pests may be found at any time in nuts and dried fruit from the time they are harvested until they reach the consumer. Steps along the way include protection of the unprocessed product, product storage, shipping, and marketing of finished product. Product is subject to reinfestation in storage (domestic and foreign), during shipment within marketing channels, and consumer storage. Product intended for both domestic and foreign markets is also subject to mandatory quarantine treatments for control of pests.
California's total production of dried fruit and tree nuts (1.24 million tons) is treated at least once with methyl bromide or, in some cases, phosphine for pest control. The number of treatments is dependent upon the time interval for storage prior to processing as well as the duration of storage of finished product prior to shipment.
The loss of methyl bromide will have a severe adverse impact on the industry's current insect control practices during the storage, handling, and processing of commodity in domestic and foreign markets. No single alternative can provide the high levels of mortality required for quarantine for such a broad spectrum of pests. Alternatives will generally require extended times for application and treatment because of reduced efficacy. This suggests that several treatments will be needed to provide the security which methyl bromide provides. Developing quarantine treatment replacements will require long-term research efforts for data and for gaining regulatory acceptance. Because of this dilemma, the Subgroup felt it necessary to include a separate discussion of alternatives which address technology and techniques to reduce methyl bromide emissions.
The overall efficiency and effectiveness of methyl bromide requires a listing of the ideal attributes for alternatives. The following characteristics and attributes were identified:
Rapid mortality (2-24 hours) for most organisms Broad spectrum of activity No known resistance among pests Cost effective Good penetration of commodities Effective at low temperatures [down to 45 degrees Fahrenheit (7 degrees Celsius)] Non-flammable and non-explosive Recognized world-wide as an effective treatment Does not damage the product Acceptance by the public, regulatory, and legal communities Does not create additional or new risks from use Environmental impacts--minimal or none Readily available Adaptable to many scales of use
1. Phosphine - This fumigant has wide use within the industry to control stored product insect pests. Some research has been done which demonstrates that its efficacy can be increased if used in combination with heat and carbon dioxide.
Advantages: Is registered, efficacious for relevant pests, relatively cost effective, internationally accepted, and low product residues.
Disadvantages: Resistance demonstrated in some pests, longer fumigation period of 3-5 days, creates off-flavor in some commodities, particularly walnuts, not effective at temperatures less than 50 degrees Fahrenheit (10 degrees Celsius), less than adequate commodity penetration, corrosive to copper and alloys found in electrical boxes and conduit, long term availability questionable, and not accepted for quarantine.
1. Irradiation - Ionizing radiation is now available to control insects. Further research to implement would be minimal.
Advantages: Has demonstrated efficacy, absence of residues, is not temperature dependent, and can treat sealed containers.
Disadvantages: Potential consumer resistance to irradiated products, high capital costs for facility construction, logistics of construction, use, and scale, not a stand alone treatment, insects not killed immediately, commodity immediately susceptible to reinfestation, and not accepted for quarantine.
2. Controlled Atmospheres - Air space is modified to "suffocate" insects in either low oxygen or high carbon dioxide concentrations by purging or displacement. Some further research on improved sealing of chambers and efficiency may be needed.
Advantages: An absence of residues, proven efficacy, and decreasing costs for nitrogen technology.
Disadvantages: Chamber must be well sealed, higher capital outlay costs, higher operating costs, slow acting, dependent upon optimum temperatures, no residual activity, procedural training needed for the process and variables, commodity immediately susceptible to reinfestation if environment not maintained, and not approved for quarantine.
1. Hydrogen Cyanide
Advantages: Has proven to be efficacious when used to control stored product insect pests.
Disadvantages: Has a "bad" public image, is explosive and flammable, would only be practical as a last resort treatment, and is not currently registered.
2. Ethyl Formate
Advantages: Is proven to be efficacious against stored product insect pests and can penetrate wrapped packages.
Disadvantages: Is flammable and explosive, 72 hour minimum exposure period for efficacy, corrosive to unpainted metals, not currently registered by U.S. EPA, Cal/EPA.
3. Ethylene Oxide
Advantages: Would probably prove to be effective against stored product insect pests.
Disadvantages: Is flammable and explosive and currently only registered for use on spices as a sterilant.
Advantages: Has short term residues and historical use for insect control by the grain industry.
Disadvantages: Imparts a strong odor, surface protectant only, and no penetration capability.
5. Propylene Oxide
Advantages: Currently registered for use on processed nutmeats as a sterilant.
Disadvantages: Is flammable and explosive.
Non-Chemical Methods - These methods can provide opportunities for sustained reduction of methyl bromide use. Several methods probably will be integrated. This requires higher technological inputs and increased knowledge of users.
1. Basic Biology and Physiology - Develop additional data on insect commodity preferences and effect of commodity and environmental conditions on insect growth and development, survival, and reproductive capacity. Determine efficacy of proposed treatments listed below as related to these factors and develop data base for modeling and subsequent integrated management systems.
Advantages: Assists identifying the proper timing of treatment, identification of new alternatives, provide methods to enhance efficacy, and reduce number of treatments required.
Disadvantages: As a single source, does little to control or eliminate pests and infestations.
2. Integrated Pest Management Systems - From databases obtained for potential alternatives listed below, develop optimal strategies for their use and integration into pest control systems.
Advantages: Is predictable and reduces the need for specific control strategies.
Disadvantages: Depends upon control strategies used, assumes that increased emphasis is placed upon improving sanitation and source reduction, higher costs, need for additional training, and difficult for regulatory agencies to monitor.
3. Detection, Sorting, and Certification - Methods which reduce or determine infestation levels in order to reduce or eliminate the need for specific treatments.
Advantages: Is environmentally benign, reduces the need for treatments, and improves safety of the work environment.
Disadvantages: Requires application of high technology, costs unknown, and unknown acceptance by regulatory agencies.
4. Optimized Hot and Cold Treatments - In conjunction with controlled atmospheres or as a modified environment, identify optimum temperature as a procedure for controlling insects.
Advantages: Leaves no residues, public acceptance, limited current use within the food processing industry, environmentally safe, and worker safe.
Disadvantages: Slow acting, potentially harmful to some equipment, no residual activity, procedural training needed for process and variables, higher energy costs, commodity subject to reinfestation if environment not maintained, and not approved for quarantine.
5. Microbial Control - Use of insect specific pathogens for control. This method can be used primarily for long-term protection after an initial disinfestation treatment.
Advantages: No chemical residues, specificity, environmentally safe, worker safe, provides long-term protection, number of chemical treatments reduced, currently approved for food products.
Disadvantages: May be too specific to be practical, slow acting, and not approved for quarantine.
6. Classical Biological Control - Use of predators and parasitoids for insect control, primarily as a space treatment when commodity is not present.
Advantages: Demonstrated effective as a protectant of peanuts, rice and wheat; host specificity; no mammalian toxicity; and long-term protection.
Disadvantages: Host specificity, limited availability, may impact quality control efforts, not compatible with chemicals, not approved for quarantine.
7. Mating Disruption Materials - Use of behavior modifying chemicals to control insect mating and reproduction.
Advantages: Host specificity, compatible with other methods, worker safe, and environmentally safe.
Disadvantages: Used only as a protectant, is species specific, expect control of low insect populations only, and not approved for quarantine uses.
8. Genetic Engineering - Insertion of specific genetic material into plant genome (transgenic plant strains) to provide insect control.
Advantages: Specific, leaves no residues, provides long-term protection, safe for worker and environment, no increased energy costs.
Disadvantages: Reluctant consumer and regulatory acceptance, high research and development costs, and specificity.
9. Packaging and Containerization - Use of insect-resistant packaging of bulk and consumer packages as a post-handling treatment to prevent reinfestation.
Advantages: Unitized packaging could limit losses and infestations, compatible with other alternatives as a post-processing method.
Disadvantages: Logistic problems as to scale and not a stand-alone treatment.
10. Engineering - New engineering research to ensure that alternatives will be effective and efficient, including new methods of application, sealing methods, and redesign technology to allow for multiple application of technology.
Advantages: Will contribute in maximizing the efficiency of newly developed control procedures.
Disadvantages: Unknown costs relating to research and development of new engineering techniques.
Advantages: Precision monitoring of concentration levels could reduce the use of methyl bromide by 15 percent or more and optimum temperatures or use with other compounds could reduce usage requirements up to 50 percent.
Disadvantages: Procedures require high precision with limited margin of error, chambers must be tightly sealed, limited data available regarding efficacy of reduced concentration and exposure periods, and not applicable to all commodities.
2. Improved Fumigation Facilities - Improving the integrity of the chamber by ensuring it is tightly sealed and structurally sound.
Advantages: Improved containment will increase efficiency, address worker safety issues, and reduce concentrations necessary for satisfactory mortality.
Disadvantages: Without the addition of capture/recovery methodology, emission reduction would be minimal; additional cost is necessary to improve structural integrity and/or rebuild poorly constructed facilities.
3. Increased Product Load in Chamber - Reduce methyl bromide usage by using chambers only when they are fully loaded.
Advantages: The amount of methyl bromide used could be reduced substantially if chambers were fully loaded before a fumigation was initiated, and smaller chambers, if constructed, would be less costly to the operator.
Disadvantages: The fumigator may not have control over load size or time constraints for shipping, making this alternative impractical.
4. Improved Non-Sorb Packaging - Use of packaging such as EPS foam packages which absorb less methyl bromide than wood or paper packaging materials.
Advantages: Aeration time after fumigation could be reduced somewhat since less methyl bromide would be absorbed to packing materials. Some reduction in the amount of methyl bromide used per fumigation would also be expected.
Disadvantages: Is dependent upon a precise system to provide control of fumigation concentrations; containers would be more costly than wood or paper packaging materials.
5. Reducing the Number of Applications - Analyze procedures to eliminate unnecessary fumigation of product, such as procedures which require that all incoming product, regardless of final destination, is fumigated, or by improving storage facilities and incorporating other exclusion techniques.
Advantages: Reducing unnecessary applications could significantly reduce the amount of methyl bromide used within facilities. Fewer fumigations would also increase the level of safety in the work area.
Disadvantages: Would be dependent upon incorporation of additional procedures and technology, increased monitoring of facilities and storage conditions, improved storage facilities, and would probably not be acceptable to most importing countries who require mandatory fumigation of all commodities.
6. Technology to Capture Vented Methyl Bromide - Installing additional technologies which capture vented methyl bromide for subsequent destruction or recycling.
Advantages: Successful methods for separating methyl bromide from air during aeration have been developed. These include absorption onto solid material such as activated carbon and various resins, absorption into liquids (scrubbing), refrigeration and condensation, and direct combustion. Currently, technology suggests that up to 95 percent of the methyl bromide remaining at the end of a fumigation can be recovered.
Disadvantages: The costs of "capturing or destroying" methyl bromide prior to venting could be very high, disposal of by-products from processes may be prohibitive, and inability to capture 100 percent of the methyl bromide prior to emitting would be a violation of the Clean Air Act.
The researchable areas for alternatives to methyl bromide were categorized as short term (0-6 years) and long term (more than 10 years). The researchable areas for emissions reduction and/or elimination were short term (0-3 years) and long term (more than 7 years).
A. Research Needs, Alternatives to Methyl Bromide
High Priority, Short Term, and Long Term
2. Develop methods to reduce application times of controlled atmosphere treatment for quarantine use in combination with optimum hot or cold temperatures.
3. Develop methods to verify insects are irradiated for regulatory purposes.
4. Identify available technologies which would be useful for detection, sorting, and certification; determine feasibility and limits of selected systems.
5. Develop commercially available microbial control agents as protectants.
6. Optimize controlled atmospheres by developing accurate time/concentration relationships at elevated temperatures [greater than 80 degrees Fahrenheit (27 degrees Celsius)] and improved application technology.
7. Determine modes of action of insect growth and develop regulators and develop formulations which would provide long-term control.
8. Develop improved packaging and containerization technologies with special emphasis on research on practical volumes for storage, influence of environmental factors on integrity of materials, and possibilities for re-use in combination with specific insecticidal treatments.
9. Develop the engineering components that support priority research, with special emphasis on problems associated with scale of use, integration of alternatives, and specific design of facilities to implement alternatives.
2. Develop formulation and delivery system of microbial control agents, increase efforts to isolate useful pathogenic microorganisms for coleopterans (beetles), and develop efficacy data.
3. Determine applicability of optimized hot and cold treatment methods in combination with controlled atmospheres to reduce treatment time.
2. Establish control levels for mating disruption chemicals, concentrations, persistence, and consideration of formulation.
3. Isolate useful genes with high expression levels for insect control by genetic engineering.
High Priority, Short Term, and Long Term
2. Develop larger scale systems which trap and/or recycle methyl bromide. Larger scale systems are necessary to determine efficiencies and economics of systems.
3. Determine type and extent of potential hazardous wastes which could be generated within systems designed to trap and/or recycle methyl bromide and identify potential regulatory implications pertaining to disposal of wastes.
4. Determine influence of contaminants emanating from commodities that may influence efficiency/product quality.
Methyl bromide is used extensively for quarantine fumigation of fresh fruits and vegetables moving into and out of the United States. California exports significant amounts of fresh fruit and vegetables to foreign countries. Additionally, shipments to Florida, Arizona, and Texas would be subject to quarantine treatment if Medfly became established. This use of methyl bromide ensures that various quarantine pests are not transported from areas where they currently exist to areas where they do not occur.
Methyl bromide is also used to fumigate imported produce infested with quarantine pests at the port of entry. The numbers and types of pests that may be found in such shipments are extensive. APHIS-PPQ has compiled lists which involve nearly all imported fresh produce and hundreds of arthropod pest species. Often, a shipment arrives with hitchhiking pests in the load. A hitchhiking pest is one that is not a known, quarantined pest of the commodity but that is present in the load. As a safeguard, these loads are routinely fumigated with methyl bromide to ensure no live insects are introduced into the U.S. Introduction of these pests into California could have an adverse impact on agriculture. The loss of methyl bromide creates the need to find suitable alternatives for each of these pests and commodities, a task further complicated by the possibility of hitchhiking pests.
Methyl bromide has become the primary means of quarantine treatment because of its general biocidal properties, its ease of application, low cost, and the general tolerance of most fresh products to treatment. Unless another general biocide is developed, new quarantine treatments will likely need to be pest and commodity specific. A given treatment may be feasible for one pest/commodity combination but not another. Given the large volume of potential pests and commodities, an enormous amount of research is needed to develop these treatments. Because considerable time is needed to negotiate acceptance of new treatments with importing countries, time is extremely short. California has much to lose in export marketing of its agricultural products. Research assistance is greatly needed.
California produces a large percentage of the fresh fruits and vegetables marketed nationwide. With the ongoing threat of a Medfly quarantine, continued marketing of these products within the U.S. requires the availability of a rapid and cost effective quarantine treatment. An alternative for methyl bromide is critical.
Several California commodities which are exported to Japan require methyl bromide treatment preshipment, including cherries and nectarines. Approximately 30 percent of the sweet cherries produced in California are shipped to Japan, making this a very important market for the industry. California apples are not currently shipped to Japan but may gain access in the future. A quarantine treatment for codling moth would likely be required. Alternative treatments will be needed for these commodities in the absence of methyl bromide. Many crops are currently shipped to Taiwan without methyl bromide treatment.
For some commodities, alternatives are currently approved and in the Treatment
Cold Treatment: Temperate commodities are more suited to this type of treatment than tropical commodities; however, recent research indicates short term heat treatments may increase tolerance of tropical commodities to cold treatment. For temperate commodities, the main limitation is storage life of the commodity. For example, cherry has only a few weeks of storage-life under optimum conditions. However, codling moth, a quarantine pest of sweet cherry, requires over 3 months of cold storage for mortality. Even the 10 days required for Medfly quarantine may be too long for sweet cherryies In a state such as California where tremendous volumes of fruit are produced, a 10-day treatment could quickly tie up all available cold storage space.
Research Needs: Additional research is needed to study the increase in cold tolerance of tropical commodities to allow cold treatment. Many of the tropical insect pests are more sensitive to cold treatment.
Heat Treatments: Heat treatments are currently used for several tropical and subtropical commodities such as mango, papaya, and citrus. Heat treatments are generally less than 8 hours in length providing the advantage of speed. The main limitation is in commodity tolerance. Tolerance of temperate commodities to heat treatment is generally less than for tropical products. Heat treatments have been shown to be effective against some temperate insect pests, such as codling moth, indicating the potential to develop a rapid alternative for cherry and nectarine if product tolerance is acceptable.
Research Needs: More information about commodity tolerance is needed including determination of the best heating method, and maximum temperature and time combinations tolerated. Further work is needed on conditioning treatments to increase tolerance to heat treatments.
Controlled Atmospheres: Elevated carbon dioxide and reduced oxygen concentrations (CA) have been used for many years to extend product life during storage and transportation. High carbon dioxide (30 to 60 percent) and low oxygen (0.25 to 0.5 percent) have been demonstrated to be effective against a range of insect pests. Most studies have focused on CA treatments at low temperatures or ambient temperatures. Recently it has been shown that high temperature CA treatments can provide short, effective treatments against several insect pests including internal feeders such as codling moth. The limitations to this type of treatment include product tolerance, length of treatment (especially at low temperatures), and cost. Tolerance of commodities to extreme CA atmospheres at low temperatures is often good. At elevated temperatures, product tolerance is more questionable.
Research Needs: Additional research on atmosphere and temperature combinations effective against each insect pest is needed along with product tolerance studies to determine pest/commodity combinations for which CA treatment may be feasible.
Irradiation: Gamma irradiation has been demonstrated to be effective for sterilization of a wide range of insect species. There are indications that product tolerance would be acceptable for several commodities; however, few commercial scale tests have been conducted and dosimetry is a concern. Irradiation would provide a rapid treatment. Disadvantages include potentially poor public acceptance, cost, and presence of live, sterile insects in shipments.
Research Needs: Additional research on product tolerance, particularly in large-scale tests is needed. Electron-beam (non-source) irradiation requires further study for effectiveness against insect pests and product tolerance. A rapid method for assessing if an insect has been irradiated would reduce trade disruptions from live insect detection.
Biocides: There are numerous products that require treatment at the port of entry only when hitchhiking pests or pests that require treatment are detected. It is estimated that up to 40 percent of some commodity shipments require treatment for hitchhikers. It may be impossible to develop specific treatments for over 200 species of potential hitchhikers along with product tolerance information. A general biocide would be the best solution for these issues.
Research Needs: Compile a list of potential chemicals and initiate testing for effectiveness against insect pests and product tolerance.
Pest-Free Zones: Geographic areas where products may be produced and exported due to the absence of quarantined pests. Zones must be isolated and monitoring is very important. The advantage is that a quarantine treatment is not required. The disadvantage is the time and money required to maintain the pest-free zone.
Research Needs: Extensive knowledge of the pest biology is needed including attractant and trap development, host range, and mobility. Sterile insect release programs are often key to such programs. Research to improve methodology in such programs is essential to reduce costs.
Host Suitability: Identifying characteristics of fruit varieties that reduce or preclude their suitability as hosts by certain pests would be useful in a systems approach where the risk of pest introduction is considered when treatment needs are decided. Fruit characteristics have also been modified by growth regulator application to reduce the ability of the insect to oviposit. Genetic engineering may also be useful for this approach although results would be long-term.
Research Needs: Increase research to understand suitability of hosts and determine means of reducing host suitability to reduce risk.
Systems Approach: The systems approach depends on improved knowledge of the pest population levels in the field as well as how various pre-and postharvest practices can affect the numbers of pests in the commodity. With practices that incrementally reduce pest levels, a more realistic assessment of risk and the need for subsequent treatments can be determined.
Research Needs: To effectively use the systems approach, additional knowledge of insect biology and populations is needed. In addition, the effectiveness of various pre- and postharvest practices needs to be determined.
The priority for research funding should be based on which treatment method has the most potential for success for each pest/commodity combination. A successful treatment results in satisfactory insect control (whether reduced risk or Probit 9 mortality) and acceptable product quality while remaining economically and physically feasible. Most importantly, the successful treatment will be accepted by the importing country. A good approach would be to solicit proposals statewide related to postharvest quarantine treatments. A panel of reviewers could select the proposals with the most potential for success for funding.
Commodity: Miscellaneous food items in commercial food processing facilities
Pest Problem: Miscellaneous stored products pests: beetles, moths, cockroaches, etc.
Scope of Problem: Statewide, national, and international impact
Asphyxiant Gases - entire fumigation of structures using a relatively benign gas (e.g., nitrogen, carbon dioxide)
Advantages: Asphyxiant gases are relatively innocuous and ubiquitous in the environment; some consumers perceive the use of these gases as safe to humans, commodities, and the environment; proven efficacy for some commodity pests.
Disadvantages: Gas concentration of more than 99 needed to control insects may not be attainable in certain structures; duration of treatment may take days or weeks; may be cost prohibitive with existing technology.
Issues, Barriers, Research Needs: More research is needed on the types of asphyxiant gases, concentrations, and synergists needed to control different stored product pests especially egg stage; more research is needed on acute and chronic adverse effects of high concentrations of asphyxiant gases on humans, commodities, and building materials.
Heat Treatment - raising the temperature of all infested food to at least 120 degrees Fahrenheit (48 degrees Celsius) for one hour to control insects.
Advantages: A non-chemical method for controlling insects; laboratory data shows this method to be very efficacious for a wide array of structural, household, and stored products insect pests; entire structure and partial treatment options available.
Disadvantages: Some areas of structures are difficult to heat to lethal temperatures (i.e., areas adjacent to heat sinks like concrete); penetrability of heat through foodstuffs may be impaired; many food items may be heat sensitive (e.g., fruits and vegetables); some warping of building materials may occur; technology to treat very large structures needs research.
Issues, Barriers, Research Needs: More large-scale field testing of this method is needed for many stored product pests; more testing of heat effects on common materials in commercial facilities is needed.
Phosphine Gas - entire fumigation using phosphine gas.
Advantages: Not a reported carcinogen or teratogen; not a reported ozone depletor; relatively easy to administer.
Disadvantages: A Category One material which must be handled with care by professionally trained personnel to avoid serious injury or death; cool temperatures may affect efficacy; long treatment times needed; explosive and reactive with metals; some reports of resistance by stored product insect pests.
Issues, Barriers, Research Needs: A sometimes problematic material to use; more research is needed on lower dosages; additional testing of acute and chronic effects on humans, commodities, and structures.
Radiation - use of ionizing radiation to control insect pests.
Advantages: Demonstrated efficacy for a number of pests; radiation treatments affect a broad spectrum of insect pests; treatment is not temperature dependent; theoretically, dosages can be customized for each particular pest life stage; no residuals.
Disadvantages: Pests are not killed immediately; implementation on large-scale may be cost-prohibitive; inaccessible areas of food processing areas may be untreatable with this method. Some consumers perceive radiation as dangerous at any dose; limited data are available on the toxic effects of long-term exposure to commodities, workers, and consumers.
Issues, Barriers, Research Needs: More data needed on effective dosage for many pest (insects, microbes, nematodes, and weeds) systems; the stigma of wartime uses of radiation is a major barrier to public acceptance of this technology; studies exploring the consequences of long-term exposures to commodities, building materials, and environment are needed.
Refrigeration - reduced ambient temperature to at least -25 degrees Fahrenheit (-31 degrees Celsius) for approximately one hour in infested areas to control stored product insect pests.
Advantages: Some consumers perceive non-chemical methods of control as cheaper and safer to humans, commodities, and the environment; no residuals.
Disadvantages: Penetrability of cold through foodstuff could be impaired; for extensive treatments this method can be time consuming and laborious; limited data is available on the efficacy of this technique for many stored products pests.
Issues, Barriers, Research Needs: Large-scale studies will be needed to determine the commercial feasibility of this control method; efficacy studies for a broad spectrum of stored product pests are needed before this treatment technique is accepted; worker health and safety, and safety information on facility materials from repeated exposure to excessive cold are needed.
Spot Treatments with Chemicals - desiccant dust is now topically applied to some bulk foods for stored product insect control.
Advantages: Consumers perceive localized or spot treatment as cheaper, less disruptive, and safer to humans and the environment.
Disadvantages: Efficacy varies depending on chemical, target pest, and method of application; for extensive treatments this method can be time consuming and laborious; long residual life of chemical used may be problem for chemically sensitive individuals.
Issues, Barriers, Research Needs: Research is needed on field efficacy rates for dust formulations; acute and chronic effects to humans, commodities, and building materials also need additional research.
Synergized Methyl Bromide - gaseous fumigation of entire structure to control stored product insects using a reduced dosage of methyl bromide synergized with carbon dioxide.
Advantages: Entire structure is treated in both accessible and inaccessible areas; using carbon dioxide as synergist reduces methyl bromide dosage needed for treatments by 75 percent; proven efficacious in laboratory for some stored product insect pests; gas cost is relatively inexpensive; residues in foods allowed.
Disadvantages: A Category One material which must be handled with care by professionally trained personnel to avoid serious injury or death; cool temperatures may affect efficacy; the active ingredient methyl bromide has been implicated as being a teratogen and ozone depletor; odor problems may occur with certain materials; desorption may occur with certain materials.
Issues, Barriers, Research Needs: More research needed on reducing dosage, adding different synergists, or displaced fumigation techniques (for public safety and cost savings) while maintaining high levels of efficacy; research needed on the efficacy of synergized methyl bromide for additional pests at different field temperature conditions; this treatment technique could be phased out by the year 2001 due to existing federal statutes and international agreements calling for the phasing out of methyl bromide products.
Potential (no order or ranking of control methods implied; listing alphabetical)
Microwaves - uses microwave energy to raise the internal water temperature of insects to lethal levels.
Advantages: A non-chemical method for controlling insects; some consumers perceive localized or spot treatment are cheaper, less disruptive, and safer to humans and the environment.
Disadvantages: For extensive treatments this method can be time consuming and laborious; overdosing of microwaves may result in burning commodities or the structure; efficacy of this method for many commodity pests is not known.
Issues, Barriers, Research Needs: Research is needed to more accurately determine proper dosage of microwave energy for varying pests and field conditions; more testing on acute and chronic effects of microwave energy to humans, commodities, and building materials is needed.
Spot Treatments with Biologicals or Genetically Altered Organisms - topical or subsurface applications of biologicals or genetically altered organisms to stored product pests.
Advantages: Specific, provides long-term protection; safe for workers and environment; minimal energy costs.
Disadvantages: Slow pest killing action; unknown consumer and regulatory acceptance; high research and development costs; high degree of specificity needed; inaccessible areas of structures may be untreatable with this method; for extensive treatments this method can be time consuming and laborious.
Issues, Barriers, Research Needs: Presently there are no known labels allowing application of altered organisms to food or fibers; much of this technology has yet to be developed.
Sulfuryl Fluoride - gaseous fumigation of entire structure to control stored product insects.
Advantages: Entire structure is treated (both accessible and inaccessible areas); proven efficacious in laboratory and field tests for a broad spectrum of insect pests; dosage can be customized to fit treatment situation; no carcinogenic or teratogenic effects; not an ozone depletor.
Disadvantages: A Category One material which must be handled with care by professionally trained personnel to avoid serious injury or death; can be costly especially at dosages needed to kill eggs for some insects; no residuals allowed in food; food in treated areas must be double-bagged in nylon bags or removed; desorption may occur with certain plastics.
Issues, Barriers, Research Needs: Growing regulatory requirements and public negative perception toward fumigants may jeopardize this treatment method in the future; more research needed on reducing dosage (for public safety and cost savings) while maintaining high levels of efficacy; allowable residuals in food studies are needed.
Radiation - use of radiation energy to control stored product pests.
Advantages: Radiation has a broad action spectrum for insects, pathogens, nematodes, and weeds; quick mode of action; treatment down time shortened; theoretically, dosages can be customized for each particular pest; no residues.
Disadvantages: Implementation on large scale may be cost-prohibitive; inaccessible areas of food processing areas may be untreatable with this method; some consumers perceive radiation as dangerous at any dose; limited data are available on the toxic effects of long term exposure to commodities, workers, and consumers.
Issues, Barriers, Research Needs: The stigma of wartime uses of radiation is a major barrier to public acceptance of this technology; studies exploring the consequences of long term radiation exposure on commodities, building materials, and environment are needed.
Refrigeration - reduced ambient temperature to at least -25 degrees Fahrenheit (-31 degrees Celsius) for approximately one hour in treated areas to control stored product pests.
Advantages: Some consumers perceive non-chemical methods of control as cheaper and safer to humans, commodities, and the environment; no or minimal residuals.
Disadvantages: Penetrability of cold through foodstuffs could be impaired; for extensive treatments this method can be time consuming and laborious; limited data are available on the efficacy of this technique for many stored product pests.
Issues, Barriers, Research Needs: Large-scale studies will be needed to determine the commercial feasibility of this control method; efficacy studies for a broad spectrum of stored pests are needed before this treatment technique is accepted; worker health and safety, and safety information on facility materials from repeated exposure to excessive cold are needed.
Spot Treatments with Chemicals, Biologicals, or Genetically Altered Organisms - topical or subsurface applications of chemical liquids, dusts, or biologicals to control stored product pests.
Advantages: Control materials which are benign to humans and the environment can be localized and added to commodities for controlling pests.
Disadvantages: Toxic side-effects may occur in chemically sensitive individuals from treatments; some consumers perceive there are no safe levels of chemicals or biologicals which can be added to food or clothing.
Issues, Barriers, Research Needs: Few chemicals exist which can be safely added to food; the stigma of wartime uses of biologicals and altered organisms may be a barrier to broad public acceptance of this technology; much of this technology, especially altered organisms, has yet to be developed.
Pest Problem: Stored product insect and rodent pests; other general pests
Scope of Problem: Statewide, national, and international impact
Advantages: Not a reported carcinogen or teratogen, nor an ozone depletor. Easy fumigant to apply and can treat railcars and sea-going vehicles in-transit (but no transport vehicles over public highways).
Disadvantages: Generally not as efficacious as methyl bromide. Some insects are showing resistance to phosphine. Fumigation periods are extended and temperature dependent. Exposure periods may be 10x that of methyl bromide. Highly explosive and corrosive to certain metals. Extensive training required for safe handling. Many transport vehicles lack gas-retention qualities. Dust residue from aluminum phosphide reaction may be classified as a hazardous waste.
Issues, Barriers, Research Needs: Phosphine task force will be spending $3 million to maintain federal registrations.
Phosphine Combination Treatments (Phosphine + Carbon Dioxide; Phosphine + Heat + Carbon Dioxide)
Advantages: May be able to shorten the exposure (to 24 hours) of phosphine fumigations by using combination treatments. Not an ozone depletor, carcinogen, or teratogen. May also reduce incidence of corrosion by using low concentrations of phosphine. Phosphine + carbon dioxide combination increases penetration and aeration rates.
Disadvantages: Application equipment is expensive. Application time is extensive. Heat may affect commodities.
Issues, Barriers, Research Needs: More efficacy data is needed for 24-hour treatments.
Methyl Bromide Combination Treatments (Methyl Bromide + Carbon Dioxide; Methyl Bromide + Carbon Dioxide + Heat; Methyl Bromide + Nitrogen, etc.)
Advantages: Up to 75 percent reduction in the methyl bromide dosage. Less worker exposure and off-site release.
Disadvantages: Efficacy data for all major stored product pests not complete. Application equipment is expensive. Carbon dioxide source may be unreliable. Transport vehicles other than ships cannot be fumigated with methyl bromide in-transit.
Issues, Barriers, Research Needs: Still utilizing methyl bromide. This would only be a temporary alternative. May be easier/cheaper to scrub with lower methyl bromide doses.
Controlled/Modified Atmospheres (Nitrogen, Carbon Dioxide)
Advantages: Non-toxic approach using low oxygen content. No pesticide residues on commodities, decreased regulatory requirements, decreased worker exposure, maintenance of product quality.
Disadvantages: Long-term treatments required. Storage facilities will have substantial expenditures in upgrading retention capacity. Application and equipment costs are high. In-transit treatments of transport vehicles may not meet required exposure periods. Can be highly temperature dependent.
Issues, Barriers, Research Needs: Lengthy exposure periods are inhibiting factor.
Advantages: High toxicity to all life states of insects with no chemical residue. Ozone is a strong oxidizer which is reduced to oxygen as a by-product of the reaction.
Disadvantages: Will not penetrate into commodities. Can create worker safety concerns.
Issues, Barriers, Research Needs: Need to experiment with methods to enhance penetration into commodities. May need to be registered with U.S. EPA as a pesticide, and not a process.
Advantages: High toxicity to adult insects and rodents. Easy application process with high volatility and penetrating capacity.
Disadvantages: No food tolerances. Ovicidal activity is poor, but may be enhanced with double applications or high doses. Cost is extremely high.
Issues, Barriers, Research Needs: The manufacturer has no intention of pursuing food uses. Application cost is so high that it would not be considered as a good alternative. If manufacturing costs could be reduced, this fumigant could be used on durables and as a space treatment where no food commodities are involved.
Juvenile Hormones (Insect Growth Regulators)
Advantages: Natural compounds which affect metamorphosis resulting in insect control. No toxic residues on commodities, low mammalian toxicity, and long-term protection.
Disadvantages: Must be directly applied onto commodities or surfaces where control is desired. Control is slow-acting and host-specific. Not an adulticide. Not practical for transport vehicle treatments.
Issues, Barriers, Research Needs: More research required on different commodities and insects.
Advantages: Complete, rapid control of all life stages of insects and other commodity pests. No chemical or toxic residues on commodities.
Disadvantages: Extremely expensive process. Limited consumer acceptance. International agreements will be necessary for movement of irradiated products.
Issues, Barriers, Research Needs: Largest barrier to overcome would be consumer acceptance. Costs to manufacture and use treatment facilities need to be reduced.
Mating Disruption Pheromones
Advantages: Effective, species-specific pest suppression using non-toxic biological compounds. Commodities have no chemical residues.
Disadvantages: Only used as a protectant for pest suppression. Treatment of short-term storage such as transport vehicles will be ineffective.
Issues, Barriers, Research Needs: More efficacy data needed on different stored product pests on many different commodities.
Advantages: Quick knockdown of adult insects. Insecticides such as pyrethrin (natural) have a very short half-life. Also have grain protectants such as chlorpyrifos-methyl, which acts as a protectant for long-term storage.
Disadvantages: Creates pesticide residues. Certain contact insecticides offer short-term adult control. Requires treatment directly onto commodities.
Issues, Barriers, Research Needs: More research required for residual contact insecticides on commodities.
Integrated Pest Management
Advantages: Utilizes a combination of resources to reduce pesticide usage. Sanitation, pest monitoring, exclusion, pesticide usage, and evaluation are all important parameters. By reducing pesticide usage, residues will be reduced, as well as a reduction in worker exposures.
Disadvantages: Still utilizes pesticides, and doesn't allow for margins of error. IPM program must be very intensive in order to compensate for the absence of methyl bromide. IPM techniques for treatment of transport vehicles may not be a viable alternative due to the multiple sources for infestation and control over commodities while in transport. Long-term storage areas can easily incorporate IPM for pest suppression.
Issues, Barriers, Research Needs: IPM is a concept that has been around for many years. More research is needed in the area of stored products. Each individual storage structure is unique and requires individual programs.
Pest Problem: Drywood termites, powderpost beetles, miscellaneous re-infesting wood-boring beetles, carpenter ants
Scope of Problem: Including pests listed above, the scope has statewide, national, and international impact
Electric Shock - the use of high voltage (90,000 v) and low amperage (<1 amp) electrical shock to control insects.
Advantages: A non-chemical method for controlling insects; some consumers perceive localized or spot treatments are cheaper, less disruptive, and safer to humans and the environment.
Disadvantages: Availability of detection equipment to find the right spot to treat is very limited; some inaccessible areas of structures may be untreatable with this method; simulated field tests suggest that this method is not as efficacious as other drywood termite control methods; for extensive treatments this method can be time consuming and laborious; use of the drill and pin technique to treat infested wood behind walls is damaging to wall covering; effectiveness for other wood-destroying insects is not known.
Issues, Barriers, Research Needs: Research needed to explore the feasibility and accuracy of nondestructive and portable pest detection devices; preliminary results on the efficacy of electric shock are being challenged and more testing is planned; research exploring the mode of action of electric shock on insects is needed; research on the acute and chronic effects of electrical shock on humans and building materials is needed.
Heat Treatment - raising the temperature of all infested wood to at least 120 degrees Fahrenheit (48 degrees Celsius) for one hour to control insects.
Advantages: A non-chemical method for controlling insects; laboratory data shows this method to be very efficacious for a wide array of structural and household pests; entire structure and partial treatment options available; treatment time can be less than 24 hours.
Disadvantages: Some areas of structures are difficult to heat to lethal temperatures (i.e., subareas); many materials in homes may be heat sensitive (e.g., plastics); some warping of building materials may occur; technology to treat very large structures is still in development.
Issues, Barriers, Research Needs: More field-collected efficacy data is needed for drywood termite, powderpost beetle, and other wood-destroying insect control; more testing of heat effects on common materials in the home are needed.
Liquid Nitrogen - using liquid nitrogen to reduce temperature to at least -25 degrees Fahrenheit (-31 degrees Celsius) for approximately 30 minutes in treated wall voids to control drywood termites.
Advantages: Nitrogen gas, a byproduct of the liquid form, is a relatively innocuous and ubiquitous gas in the environment; some consumers perceive localized or spot treatments are cheaper and safer to humans and the environment.
Disadvantages: A Category One material which must be handled with care by professionally trained personnel to avoid serious injury or death; availability of detection equipment to find the right spot to treat is very limited; some areas of structures, attics, subareas, and other inaccessible areas cannot be treated with this method; for extensive treatments this method can be time consuming and laborious; no data is available on the efficacy of this technique for other wood-destroying insects.
Issues, Barriers, Research Needs: Research needed to explore the feasibility and accuracy of nondestructive and portable pest detection devices; efficacy data on this method is very limited and suggest about 100 pounds of liquid nitrogen are needed to treat a single average stud bay; lower dosage rate information is needed; more research is needed on the acute and chronic effects of high concentrations of nitrogen atmospheres on humans, materials in the home, and the structure itself; efficacy testing of this method for other wood-destroying insects is needed.
Live with the Problem - do nothing when insect infested wood is found.
Advantages: Some research studies claim drywood termites have small colonies and consume less than one pound of wood per year; no toxic chemicals or methods are needed which may harm humans or environment; no costs incurred from inspections or control attempts.
Disadvantages: Long standing infestations, if left untreated, can cause significant damage to structures; damaged structures may be more susceptible to failure during earthquakes; some consumers perceive that the nondisclosure of any damage during the escrow process is fraudulent.
Issues, Barriers, Research Needs: More research is needed on field survival rates of drywood termites; colony fate after an incomplete or failed treatment needs further investigation; additional studies needed include minimal numbers of drywood termites needed for colony survival and time needed for colonies to rebound.
Microwaves - uses microwave energy to raise the internal water temperature of insects to lethal levels.
Advantages: A non-chemical method for controlling insects; simulated-field tests suggest this method is relatively efficacious against drywood termites; some consumers perceive localized or spot treatments are cheaper, less disruptive, and safer to humans and the environment.
Disadvantages: Availability of detection equipment to find the right spot to treat is very limited; some inaccessible areas cannot be treated with this method; for extensive treatments this method can be time consuming and laborious; overdosing of microwaves may result in burning of structure; efficacy of this method for other wood-destroying insects is not known.
Issues, Barriers, Research Needs: Research needed to explore the feasibility and accuracy of nondestructive and portable pest detection devices; research is needed to more accurately determine proper dosage of microwave energy for varying insect pests and field conditions; more testing on acute and chronic effects of microwave energy to humans and building materials is needed.
Spot Treatments with Chemicals - topical or subsurface wood applications of chemical liquids, foams, or dusts to control insects.
Advantages: A recent university survey study revealed this to be the most popular drywood termite control method used by the industry (>70 percent of treatments); consumers perceive localized or spot treatments are cheaper, less disruptive, and safer to humans and the environment.
Disadvantages: Availability of detection equipment to find the right spot to treat is very limited; inaccessible areas of structures may be untreatable with this method; efficacy varies depending on chemical, target pest, and method of application; dusts applied subsurface appear more efficacious than liquids topically applied; for extensive treatments this method can be time consuming and laborious; long residual life of chemical used may be problem for chemically sensitive individuals.
Issues, Barriers, Research Needs: Research needed to explore the feasibility and accuracy of nondestructive and portable pest detection devices; research is also needed on field efficacy rates for liquid, foam, and dust products; acute and chronic effects to humans and building materials (especially insulation and wiring) needs additional research.
Sulfuryl Fluoride - gaseous fumigation of entire structure to control insects.
Advantages: Entire structure is treated in both accessible and inaccessible areas; proven efficacious in laboratory and field tests for a broad spectrum of insect pests; dosage can be customized to fit treatment situation; no carcinogenic or teratogenic effects; not an ozone depletor.
Disadvantages: A Category One material which must be handled with care by professionally trained personnel to avoid serious injury or death; can be costly especially at dosages needed to kill powderpost beetle eggs; food must be double-bagged in nylon bags or removed; desorption may occur with certain plastics.
Issues, Barriers, Research Needs: Growing regulatory requirements and public negative perception toward fumigants may jeopardize this treatment method in the future; more research needed on reducing dosage or displaced fumigation techniques (for public safety and cost savings) while maintaining high levels of efficacy.
Synergized Methyl Bromide - gaseous fumigation of entire structure to control insects using a reduced dosage of methyl bromide synergized with carbon dioxide.
Advantages: Entire structure is treated in both accessible and inaccessible areas; using carbon dioxide as synergist reduces methyl bromide dosage needed for treatments by 75 percent; proven efficacious in laboratory and field for drywood termites and powderpost beetles; gas cost is relatively inexpensive; residuals ppm in foods allowed.
Disadvantages: A Category One material which must be handled with care by professionally trained personnel to avoid serious injury or death; cool temperatures may affect efficacy; the active ingredient methyl bromide has been shown to be a teratogen and ozone depletor; odor problems may occur from certain materials; desorption may occur with certain materials.
Issues, Barriers, Research Needs: More research needed on reducing dosage, adding different synergists, or displaced fumigation techniques (for public safety and cost savings) while maintaining high levels of efficacy; research needed on the efficacy of synergized methyl bromide for more insect pests at different field temperature conditions; this treatment technique could cease by the year 2001 due to existing federal statutes and international agreements calling for the phasing out of methyl bromide products.
Wood Replacement - replacement of all insect infested wood.
Advantages: No toxic chemicals or methods are needed.
Disadvantages: Availability of detection equipment to find the right spot to treat is very limited; inaccessible areas of structures may be untreatable with this method; may be cost prohibitive to replace all damaged wood.
Issues, Barriers, Research Needs: Research needed to explore the feasibility and accuracy of nondestructive and portable pest detection devices; for extensive treatments, this method can be time consuming and laborious; with wood shortages and pest re-invasions, it may be cost prohibitive to rely solely on wood replacement as an insect control method.
Asphyxiant Gases - entire fumigation of structures using a relatively benign gas (e.g., nitrogen, carbon dioxide)
Advantages: Asphyxiant gases are relatively innocuous and ubiquitous in the environment; some consumers may perceive the use of these gases as safe to humans and the environment; proven efficacy for some commodity pests.
Disadvantages: Gas concentration of more 99 percent needed to control insects may not be attainable in certain structures; duration of treatment may take days or weeks; may be cost prohibitive with existing technology.
Issues, Barriers, Research Needs: More research is needed on the types of asphyxiant gases, concentrations, and synergists needed to control different wood-destroying pests; more research is needed on acute and chronic adverse effects of high concentrations of asphyxiant gases on humans and building materials.
Toxic Baits - the installation of attractive baits to control in situ populations of insects.
Advantages: Some consumers perceive localized or spot treatments are cheaper, less disruptive, and safer to humans and the environment; attractive baits offer long term control for insect pests.
Disadvantages: Availability of detection equipment to find the right spot to treat are very limited; some inaccessible areas of structures may be untreatable by this method; bait resistance by queens may result from using this method; delivery system for baits may employ damaging the building or building materials; for extensive treatments this method can be time consuming and laborious; long-lived chemicals may pose a problem for chemically sensitive individuals; commercialization of baiting technology may be cost prohibitive and perceived as unattractive to industry users and public.
Issues, Barriers, Research Needs: Research needed to explore the feasibility and accuracy of nondestructive and portable pest detection devices; basic and applied research is needed on colony size and foraging behavior of wood-destroying pests; efficacy testing of candidate toxicants for baits (chemical, biological, or molecular) are needed; acute and chronic effects of bait consumption by humans (especially infants) and effects on building materials (drilling of holes for installation) are also needed.
The Department of Pesticide Regulation and the California Department of Food and Agriculture, who co-chaired the Task Force, wish to thank the members of the Methyl Bromide Research Task Force for their participation on the Task Force and in the development of this report.
Dr. Frank Westerlund California Strawberrry Commission
Ms. Patricia Clary Californians for Alternatives to Toxics
Dr. Dennis E. Rolston University of California, Davis
Dr. Tom Duafala Tri-Cal
Mr. Jack Pandol, Sr. Pandol Brothers
Mr. Will Allen California Institute for Rural Studies
Dr. Pat Vail USDA-ARS, Fresno
Mr. Mike Meuter California Rural Legal Assistance
Dr. Frank Zalom University of California UC Pest Management Center University California, Davis
Mr. Louie Ruud Association of Applied Insect Ecologists
Ms. Kim Crum California Agricultural Product Consultants Association
Ms. Denise Delmatier The Gualco Group representing the Cut Flower Industry Mr. John Sansone Pest Control Operators of California Mr. Jasper Hempel Western Growers Association Dr. John Holmes Air Resources Board Mr. Rick Bruno Agricultural Council of California Mr. Jack Wick California Nursery Association Mr. Bill Thomas California Grape and Tree Fruit League Mr. Richard Matteis California Grain and Feed Association Mr. Frank Mosebar Dried Fruit Association Dr. Vernard Lewis University of California Cooperative Extension Mr. Merlin Fagan California Farm Bureau Federation Mr. John Burch Cal Cot, Ltd. Mr. Bob Schramm California Fresh Carrot Advisory Board Mr. Richard Nutter County Agricultural Commissioners Mr. Dave Howekamp U.S. Environmental Protection Agency Region IX Ms. Jennifer Curtis Natural Resources Defense Council Ms. Sheila Daar Bio Integral Resource Center Dr. Ann Schonfield Pesticide Action Network Ms. Ruth Troetschier Sierra Club Dr. Jennifer Ryder-Fox formerly of Western Agricultural Chemicals Association