We have also observed occasionally in the last few years that ALS inhibitors can cause injury to corn when they are applied at the end of a sustained cool period. Our assumption is that, along with some drying of soil, several days of warm weather will be required for corn growth to resume to the point that the detoxifying mechanisms are working adequately. It may work out that corn growth will resume well before soils are dry enough to handle application equipment, which should alleviate injury concerns somewhat. This may require a few warm days in some fields. Look for an improvement in the color of corn and any increase in size that will signify better plant health.
Weed control is also likely to improve when weeds are actively growing under warmer temperatures.
Even where stress on corn has been relatively minor delay herbicide applications until after one morning's low temperature is greater than 50 degrees and the daytime temperature is greater than 70 degrees. Most injury seems to occur in the first day that warm temperatures return. Be sure to check the size and growth stage of corn in each field before applying herbicide. Corn that is growing rapidly may become too big for certain herbicides or herbicide mixtures, or rates of herbicide. A better strategy would be to plan for a second application, possibly post-directed, if needed.