Designing a Season-Long Weed Control Program for Rice
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The old proverb that says, “an ounce of prevention being worth a pound of cure” also can be said for weed control in rice, with the prevention being a solid herbicide program, and the cure being improved weed control leading to higher rice quality and yield potential.
From some of the most commonly found weeds like yellow nutsedge, barnyardgrass and alligatorweed, to weeds that are inching a path toward more and more rice fields such as Brook paspalum and Italian ryegrass, the gauntlet of weeds which rice farmers and their consultants must deal with seems endless.
Farmers often hear the following recommendation from researchers and consultants: Start clean, stay clean and always have a backup plan. Putting that advice into practice should start in the fall.
"It's estimated that more than 80 species belonging to more than 40 genera of grasses, broadleaves and sedges can be problematic weeds in U.S. rice production," says Connor Webster, rice Extension weed specialist, LSU AgCenter. "A thorough all-season weed control program should begin with a good fall burndown to help establish a clean seedbed to give young rice the best chance to get off to a good start, establish a good stand and prevent young nutrient-stealing weeds from becoming larger and more difficult to control."
One option many rice farmers in certain areas of the Midsouth are choosing for their fall burndown program is Elevore® herbicide, with Arylex® active. This Group 4 herbicide continues to be a very popular tank-mix solution among rice farmers because it is not antagonistic with other commonly used burndown herbicides, like glyphosate. Elevore herbicide helps control many ALS- and glyphosate-resistant species, plus marestail up to 8 inches tall.
"It has a 14-day plant back to rice and excellent contact activity," says Malori Lansing, crop protection territory manager, Corteva Agriscience. "It's also relevant to rice production regions including most of the Midsouth.
According to the National Agricultural Statistics Service October 11, Crop Production report, more than 2.2 million acres of rice is forecasted to be harvested from Midsouth states in 2024.1
Despite the additional cost of inputs, a solid residual herbicide program is more than just important. As erratic weather patterns continue, many farmers count on residuals for extended weed control in case fields are too wet for an equipment pass.
Resistance
Resistance development continues to haunt rice weed control programs in general across the agricultural landscape. Rice flatsedge has developed resistance to ALS herbicides, but there are alternative options, with Loyant® herbicide featuring Rinskor™ active being one. Loyant herbicide also provides excellent activity on alligatorweed and some weeds resistant to ALS, ACCase, glyphosate, propanil and quinclorac chemistries.
"Loyant herbicide is a good option for postemergence weed control in rice," Lansing says. "It provides grass, sedge and aquatic weed control and is an effective tool in the fight against resistance development."
Development of resistance is more likely when farmers grow crops, like rice, back-to-back. Rotating crops also allows farmers to put more modes of action on those acres, which helps strengthen their fight against resistance development.
More rice farmers have leaned on Novixid® herbicide with Rinskor™ active the last few years because it continues to show good activity on alligatorweed, barnyard grass and flatsedge. Novixid herbicide, a Group 2 and Group 4 herbicide, puts dual modes of action to work against weeds, including broadleaf and aquatic species and sedges, along with control of grasses susceptible to these two herbicide groups.
"We’re starting to deal with another weed that’s only relevant to south Louisiana currently - Brook paspalum," Webster says. "I think it’s worth mentioning to place on the radar of consultants and farmers in other rice production regions because weeds obviously spread."
Webster also notes that another option farmers have found is that Grandstand® R herbicide is a nice fit for fimbristylis. It can be applied at preplant, and pre-flood from the two-leaf stage to 1/2-inch internode stage. It also fits within all tillage practices and is labeled for all Midsouth states where rice is produced.
Good Advice
Despite commodity markets not being where farmers would like to see them and input costs continuing to rise, Webster encourages farmers to remember three things about weed control.
"Start clean and stay clean, rely on residuals and target weeds when they're small. I always recommend that farmers never cut back on their herbicide programs. Always give your rice the best opportunity to reach its yield and quality potential," Webster concludes.
Start off clean and stay clean for better yielding rice.
To learn more about the importance of rice weed control and the Corteva Agriscience rice herbicide portfolio, visit Corteva.us/Rice.
1National Agricultural Statistics Service. 2024.
Elevore®, Grandstand®, Loyant® and Novixid® are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Consult the label before purchase or use for full details. Arylex® is a registered active ingredient. Rinskor® is a registered active ingredient. Always read and follow label directions.
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