UA Weed Scientist Tackles Weed Control On Rice Levees

FAYETTEVILLE, ARK.   
   Floodwater suppresses weeds in a rice field, but the levees are a different matter. “The levees provide a moist environment without flood,” said University of Arkansas Division of Agriculture weed scientist Jason Norsworthy. “Weeds emerge continuously on the levees.”
   In response to a weed management survey of Arkansas producers, and with support from the Arkansas Rice Research and Promotion Board, Norsworthy has conducted about a dozen trials over the last three years in search of the best management program to tackle grass and broadleaf weeds on rice levees.
   The most problematic grasses rice growers face are barnyardgrass, broadleaf signalgrass, sprangletops and large crabgrass, Norsworthy said. The top broadleaf weed problems are coffeebean, northern jointvetch, teaweed and Palmer amaranth, or pigweed. Palmer amaranth has become even more problematic because of spreading glyphosate resistance, he said.
   Norsworthy’s research focused on two herbicides that provided the most consistent weed control, Propanil and Facet. He examined each of them alone and in combination with other herbicides. Facet, he said, has superior control when used in tank mixes with other herbicides.
   “Facet at full rate combined with 24 ounces of RiceStar HT appears to offer the most consistent levee grass control,” Norsworthy said.
   Facet alone gives good control of grasses as well as broadleaf weeds, Norsworthy said. Adding RiceStar HT will take down the grasses that Facet misses.
   Norsworthy noted that 2,4-D offered weed control “head and shoulders above the rest.” But the State Plant Board doesn’t permit use of 2,4-D between April 15 and Oct. 15 because of the risk it poses to cotton because of drift. Δ 

Photo on left: Weed scientist Jason Norsworthy conducts research on weeds that infest rice fields.

This test plot was not treated with herbicides for use as a control in comparison with plots treated with various combinations of commercial herbicides.

This test plot was treated with a mix of Facet and Ricestar HT herbicides in a study of weed management on rice levees.