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ARS Home » Research » Publications at this Location » Publication #71821
Title: INTERACTIONS OF SETHOXYDIM AND CORN (ZEA MAYS L.) POSTEMERGENCE BROADLEAF HERBICIDES ON THREE ANNUAL GRASSES

Author
item YOUNG, BRYAN - UNIV OF ILLINOIS
item HART, STEPHEN - UNIV OF ILLINOIS
item WAX, LOYD

Submitted to: Weed Technology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The herbicide sethoxydim is very effective for postemergence control of annual grasses in soybean. With the development of corn hybrids that tolerate sethoxydim, this treatment is available for control of grasses in corn. Use of this herbicide in corn can reduce inputs of soil-applied herbicides that have potential for contaminating ground and surface water. Fields often are infested with both grass and broadleaf weeds, and a combination treatment is desired. Mixing sethoxydim with broadleaf weed herbicides sometimes results in reduced grass control with the sethoxydim. We established experiments to determine possible interaction of sethoxydim with a variety of herbicides used for broadleaf weed control in corn. We compared the herbicide mixtures either together or with the broadleaf herbicides applied a few days before applying the sethoxydim. We also compared the effects of different adjuvants to reduce antagonism of grass control. Absorption and translocation was investigated to determine the cause of reduced grass control. Most of the combinations, when applied together, did reduce grass control with sethoxydim, compared to using sethoxydim alone. We found this to be due to reduced absorption of sethoxydim. When the broadleaf herbicide component was applied at least 3 days before the sethoxydim application, there was little if any reduction in grass control. The use of the adjuvant DASH, a proprietary product, rather than the adjuvant COC (crop oil concentrate), also alleviated most of the reduction in grass control. The combination of split application and the use of DASH provided the most effective broad-spectrum control. This information should be very useful to all personnel involved in developing and implementing weed management programs in the Corn Belt.

Technical Abstract: Greenhouse and laboratory studies were conducted to determine the effect of 22 postemergence corn broadleaf herbicide combinations on the efficacy of sethoxydim applied to giant foxtail, large crabgrass, and shattercane. Eighteen combinations caused a reduction in sethoxydim efficacy on at least one grass species. Dicamba, atrazine plus dicamba, atrazine plus bentazon, ,bromoxynil, primisulfuron, CGA-152005 plus primisulfuron, MON 12000, and flumetsulam plus clopyralid plus 2,4-D (NAF-73) were evaluated further on the efficacy and foliar absorption of sethoxydim applied to giant foxtail, large crabgrass, and shattercane. In timing studies, applying all herbicide combinations at 7 or 3 d before sethoxydim application eliminated significant antagonistic interactions. However, applying NAF-73, primisulfuron, or CGA-152005 plus primisulfuron 1 d prior resulted in a reduction in sethoxydim efficacy on at least one grass species. Dicamba, atrazine plus dicamba, and atrazine plus bentazon decreased 14C-sethoxydim absorption 9 to 63% across grass species. Replacing crop oil concentrate (COC) with DASH increased sethoxydim absorption when applied with these herbicides but not to the full extent of sethoxydim applied alone with DASH. Sethoxydim efficacy was retained or improved with DASH when applied with dicamba, atrazine plus dicamba, atrazine plus bentazon, or bromoxynil. When primisulfuron, CGA-152005 plus primisulfuron, MON 12000, and NAF-73 were applied with 14C-sethoxydim, no effect on sethoxydim absorption was observed. DASH was less effective at restoring sethoxydim efficacy when applied with these herbicides.