Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2004
Publication Date: 9/1/2004
Citation: Creech, J.E., Monaco, T.A., Evans, J.O. 2004. Photosynthetic responses of corn and four weed species following postemergence treatments with mesotrione and atrazine. Weed Science.
Interpretive Summary: Mesotrione and atrazine are herbicides used to control weeds in corn crops. We studied how plants respond photosynthetically to these herbicides. It appears that broadleaf and annual grasses weeds lose photosynthetic capacity prior to expressing any visual damage. A combination of atrazine and mesotrione provided the greatest photosynthetic damage to weeds.
Technical Abstract: We compared photosynthesis and growth of corn and four weeds (green foxtail, barnyard grass, velvetleaf, and redroot pigweed) following foliar applications with either atrazine, mesotrione, or a combination of atrazine and mesotrione in a greenhouse experiment. Plant responses to the three herbicide treatments were compared to those of untreated controls. Long-term photosynthesis and dry mass of corn were not reduced by any of the herbicide treatments. Photosynthesis and dry mass of barnyard grass, redroot pigweed, and velvetleaf were significantly reduced by mesotrione and atrazine alone and in combination. Long-term photosynthesis and dry mass of large green foxtail plants were not suppressed by either herbicide applied alone. The mesotrione plus atrazine treatment was the most effective treatment for grass weed control because plants did not regain photosynthetic capacity and had significantly lower dry mass. Shoot dry mass of broadleaf weeds was reduced by all three herbicide treatments, except for large redroot pigweed treated with mesotrione alone.