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Title: WEED CONTROL FOR GLUFOSINATE RESISTANT CORN (ZEA MAYS) AND SOYBEAN (GLYCINE MAX)

Author
item STECKEL, GREGORY - UNIV OF ILLINOIS
item WAX, LOYD
item HART, STEPHEN - UNIV OF ILLINOIS

Submitted to: Weed Technology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: We conducted field experiments to determine the role and limitations of corn and soybean lines that have been developed by others to withstand applications of the herbicide glufosinate. If this technology is successful in the Corn Belt, it would provide another tool for growers to use in resistant weed management strategies, would provide an environmentally friendly herbicide application that does not persist in the soil, and likely would reduce the inputs of persistent soil-applied herbicides in row-crop production. In both years of our research, corn and soybean showed good tolerance to a range of rates of glufosinate. Weed control with glufosinate on the tolerant corn and soybean was better in 1995 than in 1994. We believe that the improved control in 1995 was due to dry weather following application that prevented additional emergence of weeds. The most consistent weed control in both corn and soybean occurred when glufosinate was applied sequentially following another herbicide applied to the soil earlier, with a tank-mix partner at the time of application, or when followed by cultivation. This technology would appear to fit well in an integrated weed management system in corn and soybean. These findings provide important information about the best ways to optimize use of this technology in future cropping systems, and offer alternatives to soil-applied herbicides in many instances. These results should be helpful to public and private sector weed science personnel who are involved in developing improved sustainable weed management systems in corn and soybean.

Technical Abstract: Weed control and crop tolerance were evaluated in glufosinate tolerant corn and soybean in 1994 and 1995 at Urbana, Illinois. Glufosinate tolerant corn displayed excellent tolerance to all of the rates of glufosinate applied during both years of the research. No visual injury, reduction in corn height, or reduction in biomass were caused by flufosinate applications at rates of up to 800 g ai/ha. Glufosinate applications of 400, 600, and 800 g/ha caused some minimal soybean injury that was evident 21 days after treatment (DAT), but soybean yield was not reduced. Yield reductions that did occur in either corn or soybean were caused by weed interference rather than by growth reduction caused by glufosinate. Weed control with glufosinate in genetically transformed corn and soybean was better in 1995 than in 1994. This better control in 1995 was likely due to dry weather after herbicide application that limited regrowth and emergence of additional weeds. The most consistent weed control in both corn and soybean was observed when glufosinate was applied sequentially with a tank-mix partner, or when followed by a cultivation. Tank-mixing 400 g/ha of glufosinate with 1680 g/ha of atrazine for corn or 70 g/ha of imazethapyr for soybean were two of the more effective treatments for season long weed control.