University of California

Insecticide choice for alfalfa may protect water quality


Rachael Freeman Long
Mary Nett
Daniel H. Putnam
Guomin Shan
Jerry Schmierer
Barbara Reed

Authors Affiliations

R. Freeman Long is UC Cooperative Extension (UCCE) Farm Advisor, Yolo County; M. Nett is owner, Water Quality Consulting, Colorado Springs, Colo. (formerly Walnut Creek, Calif.);; D.H. Putnam is UCCE Specialist in Alfalfa and Forages, UC Davis; G. Shan is Research Scientist Dow Agroscicnces, Indianapolis (formerly Dept. of Entomology, UC Davis); J. Schmierer is Farm Advisor, Colusa County; B. Reed is Farm Advisor, Glenn County.

Publication Information

Hilgardia 56(5):163-169. DOI:10.3733/ca.v056n05p163. September 2002.

PDF of full article, Cite this article


Some insecticides used for controlling Egyptian alfalfa weevil have been detected in California's surface waters and are of concern, due to their impact on water quality and toxicity to some aquatic life. To assess the impact of insecticide choice on water quality, we collected tail-water samples from on-farm alfalfa sites in the northern Sacramento Valley over a 3-year period. Samples were collected during irrigation after organophosphate and pyrethroid sprays were applied. We found significant differences between insecticide classes in the mortality of Ceriodaphnia dubia (water flea), a test organism used to detect pesticides in water. Nearly all sites where organophosphate insecticides were used resulted in 100% water flea mortality in a 24-hour test of tail-water samples; pyrethroid-treated sections of the same fields exhibited insignificant flea mortality. The pyrethroids we used provided significantly better control of Egyptian alfalfa weevil than the organophosphates, with no significant differences in beneficial insect counts. Although water runoff does not always occur in alfalfa fields, insecticide choice may be an important tool for protecting water quality. In addition, consideration should be given to the fact that pyrethroids, while they proved advantageous in these experiments, can affect beneficial species and do have high toxicity to fish at extremely low concentrations.


Bailey HC, DiGiorgio C, Kroll K, et al. Development of procedures for identifying pesticide toxicity in ambient waters: Carbofuran, diazinon and chlorpyrifos. Environ Toxicol Chem. 1996. 15:837-45. https://doi.org/10.1897/1551-5028(1996)015/0837:DOPFIP/2.3.CO;2

deVlaming V, Connor V, DiGiorgio C, et al. Application of whole effluent toxicity test procedures to ambient water quality assessment. Environ Toxicol Chem. 2000. 19:42-62. https://doi.org/10.1897/1551-5028(2000)019/0042:AOWETT/2.3.CO;2

deVlaming V, Norberg-King TJ. A review of single species toxicity tests: Are the tests reliable predictors of aquatic ecosystem community responses?. Report #US EPA/600/R-97/114. 1999. MN: Duluth.

[DPR] California Department of Pesticide Regulation. Summary of pesticide use report data 1998-2000. 2002. indexed by commodity. Sacramento, CA. http://www.cdpr.ca.gov.

Emanuel M, Cabugao K. Standard Operating Procedures of the UC Davis Aquatic Toxicology Lab. UC Davis 2000. p.448 p.

Foe C, Sheipline R. Pesticides in surface water from applications on orchards and alfalfa during the winter and spring of 1991-92. 1993. Technical report. Central Valley Regional Water Quality Control Board, Sacramento, CA.

[PAN] Pesticide Action Network database. 2002. www.pesticideinfo.org.

Summers CG. Integrated pest management in forage alfalfa. IPM Rev. 1998. 3:127-54.

Summers CG, Godfrey LD. Egyptian alfalfa weevil and aphids. UC IPM Pest Management Guidelines for Alfalfa Hay. UC Davis 2001.

[SWRCB] State Water Resources Control Board. California 303(d) list and priority schedule. Approved by US EPA, May 12, 1999. 2002. Sacramento, CA. www.swrcb.ca.gov.

[USDA] U.S. Department of Agriculture. Preferred values from the USDA pesticide property database. 2002. http://wizard.arsusda.gov/acsl/ppdb.html.

Werner I, Deanovic LA, Hinton DE, et al. Toxicity of stormwater runoff after dormant spray application of diazinon and esfenvalerate (Asana) in a French prune orchard, Glenn County, Calif. Bull Environ Contam Toxicol. 2002. 68:29-36. PubMed PMID: 11731828

Long R, Nett M, Putnam D, Shan G, Schmierer J, Reed B. 2002. Insecticide choice for alfalfa may protect water quality. Hilgardia 56(5):163-169. DOI:10.3733/ca.v056n05p163
Webmaster Email: wsuckow@ucanr.edu