Texas Tech grad student gauges cotton response to herbicides

texas tech hppd cotton
Photo courtesy Texas Tech University
The cotton industry is vital to Texas, with the state producing approximately 35% of the United States’ cotton crop, according to a 10-year average from the National Cotton Council of America.

Lubbock and the South Plains has an even loftier claim to cotton: it is the largest cotton-producing area in the world. There’s no doubt cotton is the cash crop that sustains West Texas communities.

But with generations of successful planting and harvesting, there’s one persistent threat to cotton and crop production in general: weeds, which compete with desirable plants, such as cotton.

“Weeds decrease yield and harvest efficiency,” said Delaney Foster, a master’s student in Texas Tech’s Department of Plant and Soil Science. “They compete with our crops for light, nutrients and water, and water is our most precious and limited resource needed to grow crops. Weeds are prolific seed producers, which means we will be fighting them for years to come if not effectively controlled. They’ve adapted the ability to survive, and they are resilient plants.”

Chemicals known as herbicides were developed in the late 1800s to help combat weeds, with newer forms, dubbed “miracle” weed-killers, hitting their stride in the late 1940s. Herbicides today are applied at lower use rates and are less toxic to mammals. But too much of a good thing turned bad and, eventually, weeds became resistant to some of the most effective herbicides.

To fight herbicide resistance, Foster is working on research led by Peter Dotray, the Rockwell Chair of Weed Science in the Department of Plant and Soil Science with a joint appointment with the Texas A&M Agrilife Research & Extension Service in Lubbock.

HPPD-tolerant cotton

Foster is looking at the herbicide isoxaflutole in HPPD-tolerant cotton. HPPD, which stands for P-hydroxyphenylpyruvate dioxygenase, is an enzyme inhibited by isoxaflutole. Foster is testing how HPPD-tolerant cotton responds to isoxaflutole applied pre- and post-emergence and looking at the efficacy of this herbicide to control weeds.

“Isoxaflutole is an effective herbicide used in corn that prevents weeds from coming up through the soil, and may be another tool cotton growers will be able to use in the near future,” Foster said.

She established several cotton studies in 2019 in replicated small-plot research trials and is carefully documenting the results.

“When we go out to a research field, we mark off 4-row-by-30-foot plots and make precision applications using a small plot tractor-mounted sprayer or use a CO2-pressurized backpack sprayer,” Foster said. “Then, we’ll come back and evaluate weed control and crop response visually or quantitatively.”

The hope is that the herbicide she is working with will help increase crop resilience, sustain the longevity of herbicide effectiveness and help grower profitability.

“This research matters to farmers because, for one, they don’t want their cotton injured by herbicides; they want herbicides to be safe,” Foster said. “They also want them to be efficacious; they want them to work really, really well. So our research is basically looking at how well this herbicide will work and how we can best recommend it to farmers once it is available.”

One thing that drew her to Dotray’s research project was the focus on practical long-term solutions that help growers manage weeds.

“I had the option to choose between a lot of different research topics at Texas Tech with Dr. Dotray, and this one was just the most interesting because it involves a systems approach that uses a new cotton herbicide to control troublesome herbicide-resistant weeds,” Foster said. “This herbicide and this new cotton technology actually isn’t on the market yet. It’s not set to be released until about 2023, so it’s still in the early experimental stages.

“I worked on experimental products in my undergraduate research at the University of Georgia and with Syngenta, so it really interested me to keep that focus. Our goal is to better understand how this new technology can best be used when it is released.”

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