Weed scientist looking at combinations to eliminate undesired rice plant

Frances Gould  |  3/3/2014 8:43:08 PM

Research associate Ben McKnight drives a spray rig over a field to apply glyphosate on volunteer hybrid rice plants and outcrossed red rice as part of a study by LSU AgCenter weed scientist Dr. Eric Webster.

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LSU AgCenter weed scientist Dr. Eric Webster is continuing his work on dormant hybrids and red rice outcrossing by starting a new project using several different combinations to eliminate undesired plants from a rice field.

"Undesired rice plants that emerge the next year, during the production of a rice crop, may be due to hybrid dormancy issues or red rice outcrosses," Webster said. "These weedy rice plants are more efficient at competing for nutrients, light and space with production rice than normal red rice."

The test includes planting an infested field in soybeans, allowing part of it to remain in Clearfield rice and allowing the rest to go fallow. The sections of the field were treated with various herbicides, including glyphosate, Zidua, Outlook and Newpath.

"We’ll make our final counts and see how well we did in Year 4," Webster said.

The LSU AgCenter researcher said work started on a new aquatic-weed herbicide, benzobicyclon from Gowan, that shows good activity on ducksalad and cattail. "It looks like it’s going to have activity on sprangletop," he added.

Webster said Nealy sprangletop is becoming more of a problem, and he started a project in the greenhouse to study what can be done to control the weed.

His work also has been expanded to include north Louisiana. Webster said much of his research in that area of the state duplicates what he is doing in south Louisiana, but he’s also been examining 16 broadleaf herbicides in four different tests to determine the optimum time to apply herbicides that control broadleaf and sedge weeds.

The use of Permit for late-season or salvage control of sesbania, jointvetch and nutsedge is working well, he said, but he advises avoiding Permit Plus for those plants because it appears the herbicide tends to delay rice maturity.

Webster said the use of Command, post-emergence, plus a crop oil concentrate, is showing good results on small grasses and jointvetch.

The herbicide Sharpen also is being evaluated for control of small grasses, broadleaf weeds and rice flatsedge. It has shown excellent activity on sesbania and jointvetch, he said, adding Sharpen works well at the 1-ounce rate, but 2 ounces per acre can be very injurious to rice and in some cases reduce stands if it is applied during cool, wet conditions.

Webster said he has been working on burn-down weed control chemicals, including Yukon, a mixture of Permit and dicamba.

Research also continues at the Rice Research Station’s South Farm to determine the distance that jointvetch and hemp sesbania compete with neighboring rice plants.

(This article was published in the 2014 Louisiana Rice Research Board Annual Report.)

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