At-Plant Insecticide For Thrips Helps Prevent Yield Loss

Thrips Damage on Cotton Plant
Thrips Damage on Cotton Plant

By Clint Thompson

To combat the threat of thrips infestations in cotton, University of Georgia Cooperative Extension cotton entomologist Phillip Roberts encourages Georgia farmers to be proactive with at-plant insecticide applications.

Doing so will provide vital protection to cotton plants during the first two weeks of growth, the most critical stage for thrips protection and seedling development. Failure to apply an insecticide treatment at planting leaves cotton plants vulnerable to increased thrips pressure, which could impact growth. A lack of action during planting also forces farmers to apply multiple foliar sprays later.

“The early stages of seedling development are more sensitive to yield loss compared with later growth stages,” Roberts says. “Once seedlings reach the four-leaf stage and are growing rapidly, economic damage rarely occurs. For every true leaf a plant has, it becomes more tolerant to feeding.” The results of thrips feeding include plant stunting, delays in maturity and even plant death.

Foliar Spray May Be Needed
Although at-plant insecticides provide protection against thrips, additional treatments could be required based on the growth of the plant and the number of thrips, Roberts says.

“The threshold for a supplemental spray is two to three thrips per plant and presence of immatures. When the threshold is met, failure to apply a foliar insecticide likely will result in lost yield potential. It also is important to scout fields where seedlings are not developing rapidly.”

Later-planted cotton can influence thrips pressure, too. Over years of research, Roberts has observed that cotton planted before May 10 generally has higher thrips infestations compared to plantings after May 10. This number may move forward or backward several days.

Roberts believes that using cover crops to reduce populations can also be an effective strategy. “Thrips can be reduced by as much as 50 percent in reduced tillage systems. The greater the cover on the soil surface, the greater the reduction,” he says.

Clint Thompson is a news editor with the UG College of Agricultural & Environmental Sciences in Tifton.

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