We are
going to see most of our cotton emerging from the ground over the next week or
so. I am seeing swarms of thrips coming out of drying wheat and other
vegetation, which will be moving into cotton. It is important growers start
thinking about thrips management if they haven’t already. Insecticide seed
treatments such as imidacloprid still work in our region where thrips species
composition in seedling cotton is mainly comprised of onion thrips and western
flower thrips.
There has been a decent amount of soil moisture to start with this season, which should help the activation and absorption of seed treatments little better. Seed treatments usually run their course by the second true leaf stage, requiring a foliar application under high-pressure scenarios such as in the northern regions of the South Plains and the Northern High Plains. The presence of immatures (wingless) is a good indicator of seed treatment not being sufficient. Rarely do we need two over-the top-applications for thrips, but there have been situations in the past where a second application was needed, especially in the northern counties. Our action threshold for thrips is one thrips per true leaf on an average in non-ThryvOn cotton.
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| Thrips injury to seedling cotton |
ThryvOn cotton does not need additional control measures for thrips. Field trials
conducted throughout Texas have demonstrated that ThryvOn has excellent
activity on all commonly encountered early-season thrips species, including
western flower thrips and onion thrips. Adult thrips may still be found in
ThryvOn cotton, but they do not feed as much or reproduce. The fact that fewer
eggs are laid results in a great reduction in immature thrips in ThryvOn
cotton. Our research indicates that ThryvOn cotton does not economically
benefit from additional thrips control delivered from foliar insecticides.As far as
foliar insecticide choices are concerned for non-ThryvOn cotton, acephate at 3
to 4 oz/a still works well in our region, and so does Bidrin. Bidrin does
provide a bit longer residual activity and is more rainfast than acephate. We
had included Intrepid Edge in last year’s trials. This product offers a
different mode of action, but its performance at the 3 fl oz/a rate was not
necessarily any better than acephate.
Many of
you must have heard of EPA’s interim decision to ban acephate uses in
agriculture. It is one of the most widely used insecticides in cotton for the
management of various insect pests, including thrips, cotton fleahopper, plant
bugs, and stink bugs. The 60-day comment period is open until July 1. I would
encourage folks to submit their thoughts on the EPA’s website.
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