Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
The weather patterns lately have resulted in situations where the risk of crop injury from postemergence herbicides is higher. Specifically, prolonged periods of overcast skies, cooler weather, and plenty of rain. If postemergence herbicide applications are made as the days turn hot and sunny, the risk of injury is greater. This is due to the wax layer on the leaves not having developed and the leave surface being “tender”. If spraying during these sensitive periods, switch to “softer” additives if the label allows it; for instance MSO increases the risk of injury over COC; and non-ionic surfactants (NIS or 80-20’s) reduces the risk further. Consider using the lower allowed rate of the surfactant or nitrogen. Be sure to read the label and see what is allowed by the manufacturer.