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STAR Fellow helps Arizona farmers grow cotton more safely
Anyone who has purchased fine cotton clothing or bed linens will recognize Pima as a synonym for quality. Pima cotton, one of the finest cottons grown in the United States, is named for Pima County, AZ, where it was developed in the early 1900s. Dave Crowder, an EPA STAR Fellow at the University of Arizona in Pima County, is working to ensure quality cotton continues to grow in Arizona while helping protect the environment.
Whiteflies are a serious cotton pest in Arizona and throughout the world. They are controllable with pesticides, but pesticide use is of increasing concern. In particular, broad-spectrum pesticides, which have been used in the past, are troublesome because they kill beneficial species as well as pests and can remain active in the environment for a long time.
New types of pesticides, such as insect growth regulators, are more specific to individual pests and avoid the problems of broad-spectrum pesticides. They offer farmers a safer and more effective method of controlling pests but little is known about the effects of long-term use of these new compounds. Since these new pesticides are specific to individual species, pests have the potential to develop resistance to the pesticides, causing them to become less effective.
Dave Crowder is investigating the sustainability of the insect growth regulator pyriproxyfen on whiteflies in Arizona cotton. His research provided fundamental insight into whitefly genetics, which has led to understanding the mechanisms that could allow this pest to become resistant to pyriproxyfen. He has shown how different farm management strategies involving pyriproxyfen could affect the evolution of whitefly resistance.
Through field experiments, theory, and computer modeling, Dave has devised simple rules to prevent whiteflies from developing pyriproxyfen resistance. Planting early, ensuring adequate water and nitrogen, and waiting until 3-5 whiteflies per leaf are seen before spraying pesticides, could delay the onset of resistance by several decades or prevent it completely. Additionally, these strategies will preserve natural enemies that can provide biological control of whitefly populations.
Dave and his colleagues presented this information to the Arizona Cotton Council and Arizona Cross Commodity Management Team, groups that involved in managing whiteflies and other pests in Arizona. They also presented the results to groups of cotton farmers at town-hall meetings. The research has resulted in 6 peer-reviewed publications that are printed or in press and abstracts of the research have been published in the Resistant Pest Management Newsletter which is disseminated to agricultural experts around the world.
For more information about this fellowship: http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/7577/report/0
For more information on this research, contact:
David W. Crowder
(dcrowder@ag.arizona.edu)