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K-State Today

Division of Communications and Marketing
Kansas State University
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Manhattan, KS 66506
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February 2, 2024

K-State graduate student recognized for research on herbicide-resistant kochia

Submitted by Kelsey Stremel

Headshot of Sachin Dhanda.

Sachin Dhanda, a doctoral student researching weed science at Kansas State University, has been honored with the prestigious Outstanding Graduate Student Award from the Weed Science Society of America for his work on herbicide-resistant weeds in dryland production systems of the Central Great Plains.

Under the guidance of Vipan Kumar and Anita Dille, Sachin's research focuses on understanding the geographical spread of herbicide-resistant kochia populations and evaluating integrated management strategies that wheat and grain sorghum farmers in Western Kansas can use to control this yield-robbing weed.

According to a 2022 study by Geddes and Sharpe, herbicide-resistant kochia, if left untreated, can result in a nearly 90% crop loss in corn, sorghum, and sunflowers and significant damage to wheat, spring canola, field pea and spring oat yields.

"Herbicide-resistant kochia is a widespread problem for farmers in western Kansas and much of the High Plains region, so providing farmers with practical solutions to address this problem is critical," said Kumar. "Sachin's research on integrating cover crops in the fallow periods in combination with effective herbicide strategies will generate real-world recommendations that will have an immediate impact on managing herbicide-resistant kochia seedbanks in water-limited environment."

Sachin's research plots south of Hays on the K-State Agricultural Research Center provide a firsthand look at integrated strategies he's testing to control stubborn kochia populations. Kochia emerges early in the spring — as early as end-May through early March — and continues germinating for an extended window during the summer months. This makes it a challenge for Kansas farmers to manage.

"Kochia adapts quickly, and in many fields, it has developed resistance to common herbicides like glyphosate, dicamba, and atrazine," said Sachin. "A single kochia plant can produce more than 100,000 seeds that can be dispersed long distances via the tumble mechanism, contributing to the spread of herbicide resistance."

Understanding how resistant kochia plants survive certain herbicides helps guide Sachin's management recommendations and research. He advocates using a combined approach, including crop rotation, multiple herbicide modes of action and some mechanical cultivation where possible.

"There is no silver bullet, but farmers have more tools today to diversify their defense against this yield-robbing weed," said Sachin. "It takes perseverance, but integrated weed management strategies can significantly improve control."

Sachin's research evaluates cover crops, herbicide tank mixes and other practical solutions farmers can implement to control kochia. Continued innovation and adaptation will be key to staying ahead of the evolving kochia threat in Kansas fields.

Some key findings from Sachin's work include:

  • Documenting the distribution of kochia populations across western Kansas, Oklahoma and Texas that are resistant to multiple herbicide modes of action. 
  • Investigating plant processes causing kochia to develop resistance to several herbicides. 
  • Testing herbicide tank mixes and cover crops to manage resistant kochia in wheat and sorghum fields. 

In addition to the Weed Science Society of America award, Sachin has received more than 30 other scholarships and accolades, recognizing his outstanding achievements in weed science. He actively shares his work with the agricultural community through papers, presentations, and direct outreach.

"As a first-generation student from a family farm in Haryana, India, receiving this level of recognition is extremely humbling," said Sachin. "I want to thank my advisor, Dr. Vipan Kumar, for the nomination and unwavering support, and express my gratitude to Dr. Anita Dille, Dr. Augustine Obour, Dr. John Holman, Dr. Elizabeth Yeager, Dr. Vara Prasad, Dr. Amit Jhala, and Logan Simon and the team at the Western Kansas Research Extension Centers. I'm proud that this research will contribute to more sustainable weed control practices throughout the Central Great Plains."