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Large Scale Whitefly Management and Trials Using Insecticide Rotations to Develop IPM Strategies for Arizona Upland Cotton

D.H. Akey, T.J. Henneberry, T.J. Dennehy, P.C. Ellsworth


The silverleaf whitefly (SLWF), Bemisia argentifolii often interacts between melons, cotton, and vegetables and is particularly difficult to control. Integrated crop management should be considered necessary for SLWF control, but a first step is to develop integrated pest management (IPM) for specific crops, e.g., cotton. IPM strategies that reduce the likely development of insecticide resistance and help bridge biological with chemical control are desirable. Efficacious insecticides from different chemical classes (including biopesticides) were rotated and compared with pyrethroid (low chemical class diversity) based regimes. The rotational regimes (high diversity) were investigated as a component of insecticide resistance management, (IRM) for use in IPM programs. We conducted 3 field trials by ground application between 1993-1995. The 1st 2 trials used 4 blocks of 5 ac each for a total of 20 acres each; and the 3rd trial, part of a larger trial, used 18 plots of 5 ac each, for a total of 90 acres.

In two of the trials, yields of cotton were similar between the high and low diversity chemical regimes. In the 2nd trial, the low diversity regime had yields of 2.5 compared with 2.3 bales/ac for the high diversity regime which included biopesticides (significant at P < 0.05). The 1st 2 trials used ground applications with 25 or 30 gal./ac., 70 psi, and booms with 18 in. drops; the 3rd trial used ground applications similar to grower usage with, 15 gal./ac, 40 psi, and a broadcast boom without drops. The most significant application difference occurred not between the two types of ground equipment but between the more efficient ground application in the 2nd trial compared with an aerial control of "best agricultural practices" movement in fields surrounding the 20 ac trial site. In this case, the low diversity regime had yields by aerial application of 2.5 compared to 3.4 bales/ac by ground application (significant at P < 0.05).

The tendency toward increased resistance to Danitol in the 2nd trial and the seasonal effect of increased resistance as the season progressed in the 3rd trial, leaves uncertainty regarding resistance which will require further study.

The IRM management programs tested in these three studies tried to use true IPM and present methods of insecticide usage to promote biological control by beneficial arthropods and prevent insecticide resistance from occurring. The use of different action thresholds for different parts of the insecticide season proved useful toward achieving these objectives. Likewise, the absence of sticky cotton in any of the regimes tested in all three studies shows that these management strategies prevented the occurrence of sticky cotton.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 817 - 819
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998