UW Extension Offers New Grass Thrips Management Guide

field of grasses with mountains in the background
A blue grama grass seed field sits in Wyoming’s Big Horn Basin. (Gary White Photo)

For grass seed producers and others concerned about controlling grass thrips populations, University of Wyoming Extension has released a new management guide.

The free digital publication, “Grass thrips in Perennial Grasses Grown for Seed,” provides instructions on how to sample grass seed fields for thrips as well as recommendations for cultural and chemical control. The authors also address the efficacy, application rates and possible advantages and disadvantages of six insecticides labeled for grass thrips control.

These small insects, which feed only on grasses, damage both annual and perennial species. Grass thrips can survive in perennial grass fields year-round and endure temperatures well below freezing.

“A perennial grass seed field will look perfect, and only after harvest will grass thrips damage be revealed,” says Scott Schell, UW Extension entomologist and co-author of the new publication. “Only pest survey and insecticide treatment, if warranted, can prevent crop loss.”

Researchers have determined that grass thrips have an extremely high potential for developing insecticide resistance, which makes informed management even more critical.

Despite the importance of grass thrips control, little research has been conducted on the topic, and Wyoming-specific recommendations are largely absent from scientific literature. The most recent research publication Schell found addressing thrips management in grass species relevant to Wyoming dated back to 1957.

It was time for an updated publication.

“For perennial grass seed producers, preventing the damage the thrips can inflict on the developing seeds can be the difference between profitability or loss,” Schell explains. “Applying insecticide at the correct time in plant development can reduce the grass thrips population and prevent yield losses.”

While perennial grass seed production represents only a small portion of Wyoming’s agricultural economy, specialty crops, such as perennial grasses, may provide supplementary income in years when conventional crops fare poorly, Schell notes. Proper management can help ensure these crops thrive without contributing to potential insecticide resistance.

For more information, call Schell at (307) 766-2508 or email sschell@uwyo.edu.

About University of Wyoming Extension

Since 1914, UW Extension has provided lifelong learning opportunities to Wyoming citizens across the state. With roots in agricultural education, UW Extension supports rural communities facing contemporary challenges and changes. UW Extension brings the university’s resources to each of the state’s 23 counties and the Wind River Indian Reservation. To learn more about UW Extension, visit www.uwyo.edu/uwe or call (307) 766-5124.

Contact Us

Institutional Communications
Bureau of Mines Building, Room 137
Laramie, WY 82071
Phone: (307) 766-2929
Email: cbaldwin@uwyo.edu

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