|Maxwell, Douglas - UNIVERSITY OF ILLINOIS|
|Hager, Aaron - UNIVERSITY OF ILLINOIS|
Submitted to: Research Report North Central Weed Science Society United States
Publication Type: Other
Publication Acceptance Date: December 18, 1997
Publication Date: N/A
Technical Abstract: The purpose of this study was to determine the optimal herbicide application rate and timing for control of common waterhemp with glyphosate in glyphosate resistant soybeans. The study was established on a growers field near St. Elmo, Illinois. The soil was a Cisne silt loam with a pH of 6.3 and 2.4% organic matter. Pioneer 9363 glyphosate resistant soybeans were planted 1.0 inches deep on May 14 in 30 inch rows. Treatments were arranged in randomized complete blocks with three replications of plots 10 by 30 feet. Herbicides were applied with a CO2 backpack sprayer delivering 20 gpa and equipped with 8002 flat fan nozzles. Soybean tolerance was excellent. No injury from any herbicide application was noted. Control of common waterhemp at two weeks after application of very early postemergence, early postemergence, and postemergence treatments was 90% or greater. Ratings of very early postemergence treatments decreased over time due to additional waterhemp emergence. A sequential application of glyphosate following the initial very early postemergence application resulted in complete control of common waterhemp.