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Title: GLUFOSINATE EFFICACY ON FOUR ANNUAL WEED SPECIES IS INFLUENCED BY HERBICIDE RATE AND APPLICATION TIMING

Author
item STECKEL, GREGORY - UNIV OF ILLINOIS
item WAX, LOYD
item SIMMONS, FREDERICK - UNIV OF ILLINOIS

Submitted to: Weed Technology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Most of the corn and soybean acres in the Corn Belt are treated with one or more herbicides for weed management. Many of these are soil-applied and some have potential for contamination of surface and ground water. We are devising systems to use more postemergence herbicides that have short persistence and little chance of contaminating water supplies. As a part of this plan, we set out to fully evaluate a new herbicide, glufosinate, for its ability to control annual weeds commonly found in corn and soybean. This herbicide normally kills corn and soybean, but will be safe on some new corn and soybean lines being developed by seed companies. This herbicide is environmentally safe and if effective on weeds, should provide an important tool in our pool of weed management methods, and could replace some of the herbicides now being applied to the soil. We conducted experiments on four species of troublesome annual weeds, using several times and rates of application. The experiments were conducted for three years under field conditions. The results of these experiments indicated which rates of application would be needed for each of the various weeds, and also indicated the best size of weeds to treat for optimum results. These findings provide important information about the way to make the best use of this new herbicide in future cropping systems, and offer atlernatives 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 weed management systems in corn and soybean.

Technical Abstract: Field experiments were conducted in 1993, 1994, and 1995 to determine the effects of glufosinate rate and application timing on giant foxtail, common lambsquarters, common cocklebur, and Pennsylvania smartweed control. Glufosinate at 140 g/ha did not provide good control (greater than 80%) of any of the weed species evaluated. When glufosinate rate was increased to 280 g/ha and applied to 10-cm giant foxtail, control was greater than 80% two out of the three years of the study. Further rate increases to 420 g/ha were required for common cocklebur and Pennsylvania smartweed control; and common lambsquarters was the most tolerant species evaluated and was not acceptably controlled ( greater than 80%) even with glufosinate at rates of 560 g/ha. Control with glufosinate at rates of 420 or 560 g/ha was generally the most effective when applied at the 10-cm weed height compared to either to the 5 or 15-cm height.