Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 4, 2000
Publication Date: N/A
Interpretive Summary: Information on effectiveness of cloransulam (new herbicide) and diclosulam (experimental herbicide) under Mississippi delta soybean production systems is lacking. Field studies were conducted by the Southern Weed Science Research Unit to determine the weed control potential of these herbicides on selected weed species in soybean. Cloransulam applied preplant incorporated (PPI) or preemergence (PRE) provided effective control of hyssop spurge and prickly sida. However, control of entireleaf and pitted morningglory and palmer amaranth was variable. Cloransulam applied postemergence provided excellent control of hyssop spurge and entireleaf and pitted morningglory in 1997, but control was less than satisfactory in 1998. Thus, field infested with these weeds may require additional herbicide treatments. Diclosulam applied PPI or PRE effectively controlled hyssop spurge, palmer amaranth, and prickly sida. However, control of browntop millet and entireleaf and pitted morningglory with diclosulum PPI or PRE was variable and tank-mixtures of these herbicides with others may be required for adequate control. Cloransulam and diclosulam have potential to control important broadleaf weeds in soybeans and may alternative herbicides for weed management in soybeans.
Technical Abstract: Field studies were conducted in 1997 and 1998 to determine the weed control potential of cloransulam and diclosulam on selected weed species in soybean. Cloransulam at 35 g/ha applied PPI and PRE controlled > 90% of hyssop spurge and prickly sida in both years. Cloransulam PPI or PRE provided 76 to 93% control of entireleaf and pitted morningglory and palmer amaranth. Control of these weeds within a species was similar regardless of soil incorporation of cloransulam. Control of prickly sida with cloransulam PPI or PRE was better than cloransulam POST. Cloransulam POST provided control of these weeds similar to chlorimuron at 11 g/ha applied POST except that control of hyssop spurge was better in 1997 with cloransulam POST. Soybean yields were similar when cloransulam was applied PPI or PRE and yields were on par with imazaquin at 140 g/ha applied PRE. Cloransulam POST gave yields similar to that of chlorimuron POST. Diclosulam application method (PPI or PRE) had no effect on control of entireleaf and pitted morningglory, palmer amaranth, and prickly sida in both years. Overall, diclosulam PPI or PRE provided hyssop spurge, morningglory species, prickly sida, and palmer amaranth control similar to that of PRE application of sulfentrazone plus chlorimuron. Soybean yields were similar regardless of incorporation of diclosulam and yields were on par with PRE application of sulfentrazone plus chlorimuron.