University of California

Almond and stone fruit growers reduce OP, increase pyrethroid use in dormant sprays


Lynn Epstein
Susan Bassein
Frank G. Zalom

Authors Affiliations

L. Epstein is Associate Professor, Department of Plant Pathology, UC Davis; S. Bassein is Statistician, Data Analysis and Presentation, Berkeley; F.G. Zalom is Director, UC Statewide IPM Project, and Entomologist, Department of Entomology, UC Davis. The authors thank Larry Wilhoit and Edward Morgan for providing the California Department of Pesticide Regulation's Pesticide Use Report computer files, and Janet C. Broome of UC SAREP for helpful discussions. Funding was provided by the UC Statewide IPM Project.

Publication Information

Hilgardia 54(6):14-19. DOI:10.3733/ca.v054n06p14. November 2000.

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Growers and pesticide applicators in California are legally required to file pesticide use reports with details about every application to commercial crops. We used the individual applicator records to document a decline in the use of organophosphate pesticides (OP) on almond and stone fruit orchards during the rainy season in California, a time period in which the trees are dormant. The decline is important because dormant applications are a major source of surface water contamination and the Federal Clean Water Act mandates a reduction in movement of OPs into surface water. However, the decline in use of OPs has been accompanied by an increase in use of pyrethroid pesticides, particularly in stone fruit orchards. Additional implementation of “reduced-risk” integrated pest management practices could further reduce use of dormant applications of OPs and pyrethroids on almonds and stone fruit orchards.


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Epstein L, Bassein S, Zalom F. 2000. Almond and stone fruit growers reduce OP, increase pyrethroid use in dormant sprays. Hilgardia 54(6):14-19. DOI:10.3733/ca.v054n06p14
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