|Maxwell, Douglas - UNIV OF ILLINOIS|
Submitted to: Research Report North Central Weed Science Society United States
Publication Type: Other
Publication Acceptance Date: December 15, 1998
Publication Date: N/A
Technical Abstract: The purpose of this study was to evaluate weed competition with delayed postemergence with and without sequential soil applications in glyphosate resistant conventional tillage soybeans. The study was established at the University of Illinois South Farm, Urbana. The soil was a Flanagan silt loam with a pH of 6.3 and 4.8% organic matter. Pioneer 9333 glyphosate resistant soybeans were planted 1.0 inches deep on May 19 in 30 inch rows. Treatments were arranged in randomized complete blocks with four replications of plots 7.5 by 38 feet. Herbicides were applied with a CO2 backpack sprayer delivering 20 gpa and equipped with 8003 flat fan nozzles for preemergence applications and 8002 flat fan nozzles for postemergence applications. Plots were not cultivated after planting. Soybean tolerance was excellent to all treatments. Weed control and yield decreased as weed competition and pressure increased in the later total postemergence treatments. Preemergence only treatments failed to provide season long weed control. A very dry August also contributed to lower yields with the soil applied only and the later total postemergence treatments. Sequential treatments performed consistently well.