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Field and Forage Crops |
Unfortunately, the last four weeks of cotton updates seem like a broken record. This is about as long a period that cotton has remained vulnerable to thrips as I can remember, and that goes back a few years. I suppose we are fortunate that thrips levels are not higher so far this year, as would be the case if wild and cultivated hosts such as wheat had dried down more quickly. Finally, it appears that the hot, humid weather favorable for cotton development will begin this weekend (June 4 and 5) and extend into next week.
Much of our cotton looks extremely beat up due to prolonged cool weather and poor conditions for emergence (crusting soils, etc.). Some of this is due to thrips, some not. Be sure to focus on the newly emerging leaves, and try to see if thrips are the culprit either with a hand lens or beat several seedlings against a flat white object like an index card to check for immature thrips. The emergence of flat shiny new leaves often indicate that thrips are not a present problem. If indicated, a foliar insecticide treatment should be applied immediately to avoid any possible further delays in maturity.
With cotton so late almost across the board, we can expect thrips to remain a potential problem for another week to 10 days, or until cotton reaches about the five true leaf stage.
These late foliar insecticide applications for thrips do have the potential to enhance the survival of other insects such as spider mites, cotton aphids and tobacco budworms. Of course, budworms are no longer a problem on Bollgard, Bollgard II and Widestrike varieties, and really are typically not much of a threat on conventional cotton before bloom. And although mite and cotton aphid problems on seedling cotton are not unheard of, these pests tend to come a little later in the season.
Hopefully, by next week with warmer weather, most cotton producers will be finally putting thrips and this poor-looking cotton crop behind them.
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Last modified on June 6, 2005 by Stephen J. Toth, Jr.