Citrus Ecoinformatics: Using Data from California Citrus Growers to Develop Improved Pest Management Recommendations

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Principal Investigator: Jay Rosenheim, University of California, Davis, Department of Entomology and Nematology

Timespan: November 1, 2011 - June 30, 2014

Amount: $150,000

DPR Contract Manager: Kimberly Steinmann

This contract supported a novel research approach to identifying opportunities for enhancing pest control and decreasing the burden of pesticides associated with commercial citrus production in California's San Joaquin Valley. The project used an 'ecoinformatics' approach which works exclusively with data directly from the commercial setting. All data were obtained from a network of collaborating citrus farmers and independent pest control consultants. Data were obtained describing pest densities for >1,000 commercial citrus harvests (one harvest = one year's harvest from a given citrus grove). Analyses showed that farmers face strong economic incentives to control both indirect pests (which decrease total citrus yield) and direct pests (which create cosmetic damage to citrus fruits that cause downgrading at the packinghouse). In almost all cases, because citrus is a high value crop, pests have the potential to generate economic losses that are far greater than the costs of applying pesticides for their control. For this reason, a primary avenue for decreasing the environmental burden of pesticides will be to encourage the adoption of low-risk, or environmentally benign materials, rather than attempts to eliminate pesticide use entirely.

This analysis suggests two primary conclusions. First, farmers face stiff incentives to use pesticides when faced with strict cosmetic criteria for fruit quality at the packinghouse. Many of the pests studied here (citrus thrips, katydids, citrus cutworm) generate cosmetic damage without changing in any way the quality of the consumed fruit. Thus, to decrease pesticide use, changes in consumer attitudes when purchasing citrus fruits will be necessary to decrease farmer incentives to maintain strict control of fruit-damaging pests. Second, given the intense financial incentives to maintain pest densities at very low levels, it becomes imperative to identify environmentally benign or lower-risk materials for farmers to use as replacements for compounds that pose the worst risks to environmental quality. Citrus is a good example where low-risk and high-risk materials continue to be used, side-by-side, to control the same pests. It should be a high priority to develop data demonstrating the efficacy of low-risk materials to encourage growers to switch to their use. This may be a highly effective means of decreasing the environmental burden of pesticide use, and one that can be adopted by farmers without economic hardship.

For content questions, contact:
Leslie Talpasanu
Environmental Program Manager I
Agricultural Pest Management Program
California Department of Pesticide Regulation
Integrated Pest Management Branch
1001 I Street
Sacramento, CA 95814