Residual soybean weed control pays

Published on: 15:02PM Dec 29, 2009
Gordon Vail
This harvest left a few surprises, especially from “economical” total-post glyphosate herbicide programs, particularly in soybean. Even though the growing season was delayed, many weeds – like waterhemp and giant ragweed – thrived with plenty of rain this summer, creating a seed bank that will need to be managed next season and beyond.
It makes sense to use a strong residual program for your soybean crop. Research by Bryan Young from Southern Illinois University has shown that a pre-emergence herbicide followed by glyphosate will out-yield two properly timed post applications of glyphosate by 3 bu/A, when glyphosate was applied to weeds
So, if soybeans are at $10/bu, you can do the math: Using a soybean residual herbicide could return $30/A more in gross profit than two applications of glyphosate. The yield advantage of the residual followed by glyphosate program increased to 6 bu/A when glyphosate was applied to weeds up to 8” tall, which is certainly not uncommon, especially in a year like 2009.