By Jamie Martin
Weedy rice, a major agricultural pest, has developed herbicide resistance in the southeastern United States. This close relative of cultivated rice mimics crops, making it difficult for farmers to detect and control.
Scientists at Washington University in St. Louis found that over 57% of sampled weedy rice in Missouri, Arkansas, and Louisiana had resistance to the imidazolinone (IMI) herbicide family. A smaller percentage (3.5%) showed resistance to newer herbicides introduced since 2018.
Herbicide-resistant rice, like Clearfield, transforms rice farming when introduced in the early 2000s. “Clearfield has done wonders for rice farmers... It’s less that Clearfield failed and more that its lifespan ran its course,” said Marshall Wedger, a researcher documenting this trend.
Weedy rice resistance emerged as hybrid rice became popular. While hybrids yield more, they often shatter seeds that survive into future seasons as volunteer rice. These “volunteers” flower over extended periods, increasing the chances of crossbreeding with weedy rice. The result is a more resilient pest that thrives despite control efforts.
The impact is substantial, causing $45 million in annual losses for US rice farmers. “These findings are yet another indicator of the incredible adaptability of weedy rice,” said Kenneth Olsen, senior author of the study.
Managing weedy rice is increasingly challenging as herbicide resistance spreads. Farmers now rely on new solutions like Provisia and Max-Ace rice, resistant to different herbicides. However, experts caution that resistance could develop again, requiring further innovation.
This research highlights the adaptability of agricultural weeds and the ongoing challenges for farmers striving to protect their yields.
Photo Credit: istock-digitalsoul
Categories: National