Skip to main content
ARS Home » Research » Publications at this Location » Publication #81102
Title: RESULTS OF A TWO YEAR REGIONAL PROJECT TO DETERMINE AN ACTION THRESHOLD TO MANAGE WHITEFLIES IN COTTON

Author
item Naranjo, Steven
item Chu, Chang Chi
item ELLSWORTH, P. - UNIV. OF AZ
item Henneberry, Thomas
item NICHOLS, R. - COTTON INCORP.
item RILEY, D. - TX AGRI. EXP. STA.
item TOSCANO, N. - UNIV. OF CA. RIVERSIDE
item WATSON, T. - UNIV. OF AZ. ENTOMO. DEPT

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sweetpotato whitefly has been a key pest of cotton and other crops in the southwestern US since the early 1990's. High populations of this pest can reduce lint yields and contribute to degradation of lint quality through the deposition of honeydew. Action thresholds define a rational level of pest density where the benefit of yield and quality enhancement exceeds the cost of control. Such thresholds are urgently needed in order to optimize whitefly control in cotton. In 1994 a multi-state, multi-institutional experimental study was initiated to develop action thresholds for applying insecticides for whitefly control. Results suggested that there was little difference in either insect population density or plant responses to damage when insecticide treatments were initiated between about 2.5 to 10 adults/leaf. Sticky lint results were more difficult to interpret due to weather factors and inconsistent correlations with pest abundance. A simple economic analysis assuming ca. $24/A for a spray treatment, $0.85/lb for lint and an $0.08/lb discount for sticky lint suggests that the net return was generally highest for action thresholds of 5-10 adults/leaf across all sites and over both years.

Technical Abstract: A regional, two-year project sponsored by Cotton Incorporated and the Arizona State Support Committee was initiated in 1994 to determine action thresholds for management of Bemisia tabaci in cotton using chemical insecticides. This cooperative study involved Cotton Incorporated, the Universities of Arizona and California, Riverside, Texas A&M University and the USDA-ARS, Western Cotton Research Laboratory. Replicated field trials were conducted in 1994 at sites in Maricopa and Yuma, AZ, Bakersfield and Brawley, CA, and Weslaco, TX using a standard set of protocols. Trials were repeated in 1995 at all locations except Bakersfield, CA. Results suggested that there was little difference in either insect population density or plant responses to damage when insecticide treatments were initiated between about 2.5 to 10 adults/leaf. Sticky lint results were more difficult to interpret due to weather factors and inconsistent correlations with pest abundance. A simple economic analysis assuming ca. $24/A for a spray treatment, $0.85/lb for lint and an $0.08/lb discount for thermodetector ratings > 5 rating suggests that the net return was generally highest for action thresholds of 5-10 adults/leaf across all sites and over both years.