Horseweed Response to Rice Herbicides
2009
Bond, Jason A. | Eubank, Thomas W. | Poston, Daniel H.
Rice acreage impacted by horseweed has increased in Mississippi in recent years. Rice producers have few options for managing horseweed that survives a burndown herbicide application or emerges between burndown and planting. Field research was conducted over 2 years to determine the efficacy of postemergence rice herbicides against horseweed. Only penoxsulam or propanil plus quinclorac provided > 60% control 14 days after treatment (DAT). At 21 and 28 DAT, penoxsulam and propanil plus quinclorac controlled more horseweed than all other treatments with control ranging from 80 to 92%. Control following quinclorac (73%) and triclopyr (65%) was equivalent 28 DAT, and both were more effective than bispyribac-sodium, orthosulfamuron, and propanil. By 35 DAT, horseweed control with quinclorac, propanil plus quinclorac, and penoxsulam was equivalent (77 to 87%), and control following these applications was better than that from all other treatments. Due to variability across plots, no differences in horseweed dry weight following herbicide treatments were detected. Horseweed management in rice remains problematic because complete control was not achieved with any herbicides evaluated. Quinclorac, propanil plus quinclorac, and penoxsulam are best options to suppress horseweed until rice is flooded.
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