Stemming The Spread Of Rice Cutgrass

FAYETTEVILLE, ARK.
   Rice cutgrass is slowly crawling out of the ditches and into rice fields throughout the Delta, said Jason Norsworthy, weed scientist for the University of Arkansas System’s Division of Agriculture.
   “This is a plant that is most common in ditch banks in the Delta,” Norsworthy said. “I see it essentially everywhere I go.”
   Named for its hard, sharp leaves, cutgrass is a slow-growing, slow-moving plant, Norsworthy said. It thrives in ditches because there’s plenty of water and the ditches aren’t tilled.
   Rice cutgrass is a perennial weed, but not a major seed producer, Norsworthy said. “Most often, by the time rice is mature and harvested, cutgrass has not yet produced seed.”
   Instead, rice cutgrass most often spreads through rhizomes, horizontal stems that spread out underground and send out roots and new shoots. Norsworthy said this is why it tends to spread into fields from the edges.
   “Tillage is the major means of control,” Norsworthy said. “But over the last five to 10 years, the intensity of tillage in rice fields has been reduced, and that probably contributes to it moving into those fields.”
   Norsworthy said most herbicides used in rice do not control cutgrass very well. “So, you’re taking out every other weed in the field except rice cutgrass,” he said.
   In fields planted with Clearfield rice, Newpath herbicide does control rice cutgrass well with two applications, Norsworthy said. In fields with other rice varieties, the herbicide Regiment will provide about 60 percent control.
   “Fields where crops are not rotated are especially vulnerable,” Norsworthy said. “If rice is rotated with other crops, especially soybeans, many grass herbicides can control it. This is especially true for glyphosate herbicides, which provide excellent control.”
   He added that cultural practices, especially tillage, are effective at controlling rice cutgrass. Tilling breaks up the soil and the plant’s rhizomes, cutting them up and bringing them to the surface, where they dry out and die in short order.
   “They’re not very hardy,” Norsworthy said. Δ

Weed Scientist Jason Norsworthy conducts research on weeds, like rice cutgrass, that infest rice fields.