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Evaluation of Two Seasons of Acaricide Rotation Trials on Spider Mite (Acari: Tetranychidae) Resistance in San Joaquin Valley Cotton

Samuel J. Bruce-Oliver, Beth Grafton-Cardwell


With significantly higher spider mite densities in 1995 compared to 1994, the following results were observed - 1) T. turkestani was the dominant spider mite species during the early season before acaricides were applied, shifting to T. urticae thereafter; 2) T. turkestani continues to respond with almost complete susceptibility to dicofol (Kelthane®;), propargite (Comite®;) and abamectin (Zephyr®;); and 3) T. urticae continues to exhibit high levels of resistance to Kelthane and Comite when exposed to these compounds. Residual leaf bioassays in the laboratory suggest that all rotations helped to reduce T. urticae resistance to Kelthane. Acaricide rotations were less effective in reducing resistance to Comite. The same field studies will be continued in the assigned plots in 1996 to further evaluate the effects of within-season rotations compared to single and multiple consecutive acaricide applications on spider mite resistance.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1128 - 1131
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998