Whiteflies: They're Back...
A step-by-step short guide to successfully & economically managing
Ellsworth, P.C. 2001. Whiteflies: They're Back... A step-by-step short guide to successfully & economically managing whiteflies in 2001. University of Arizona, College of Agriculture and Life Sciences, Cooperative Extension, Tucson, Arizona. 1 pp. URL: http://cals.arizona.edu/crops/cotton/insects/wf/wfback.html; http://cals.arizona.edu/crops/counties/all/papers/pcewfback.pdf
Whiteflies are back once again! In the current (depressed) economic climate, the question often comes up, What's the best strategy? First the objectives:
With these objectives firmly in mind, the strategy is actually quite clear, quite definitive, and very well grounded in practical research. For in-season whitefly populations (i.e., more than 30 days to green-leaf drop), the steps are as follows:
2) Compare findings to action levels for treatment with IGRs (12 of 30 leaves or 40% with 3 or more adults on them; 12 of 30 disks or 40% with 1 or more live, large nymphs).
3) Use an Insect Growth Regulator (IGR) FIRST. Either Applaud or Knack will do, though consider the relative balance (in comparison to the established threshold above) of adults vs. nymphs to help you choose. Ratios that favor adults, select Knack; ratios that favor nymphs, select Applaud.
4) Follow-up sampling to ensure that numbers decline within 10-12 days. If all goes well, it would be rare to consider a follow-up treatment before 30 days and many growers have experienced season-long suppression. If additional sprays are required, follow the 3-stage resistance management program.
5) Do NOT substitute broad-spectrum insecticides in place of the IGRs. The IGR first strategy is one that not only accomplishes the most economical whitefly control, but prevents costly problems with other insect pests. Furthermore, IGRs, under conditions of non-disruption (i.e., use of broad-spectrum sprays), will last even longer because of their bioresidual. That is their insecticidal effects combined with the biological effects of the conserved natural enemies within the system. Our research clearly shows a benefit to forestalling all broad-spectrum sprays as long as practically possible.
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director Cooperative Extension, College of Agriculture and Life Sciences, The University of Arizona.
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This material provided by:
Peter C. Ellsworth, firstname.lastname@example.org Specialist, IPM/Entomology
University of Arizona, Tucson, AZ
Material written July 2001.
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