Risk of Greater than Expected Herbicide Carryover
In season rainfall following the application of a residual herbicide is the most important factor in the breakdown of herbicides in the soil.
Less than normal rainfall can result in residual herbicides remaining in the soil at higher levels than expected and increase the potential for herbicide injury to more sensitive crops registered for planting the following year(s). Check the Guide to Crop Protection for a list of residual herbicides and always read the label for specific recropping instructions.
Producers in the normal risk areas should follow label directions to determine what crops they may plant following the application of a residual herbicide, but may still have localized areas that are susceptible to extended carryover due to low in season rainfall. Producers in the extreme, very high risk and high risk areas that applied a residual herbicide in previous years requiring restrictive cropping practices in the present year should contact the manufacturer of that residual herbicide for rotational crops supported by that company. Producers in the moderate risk areas that also have low organic matter or have soil pH less than 6.5 or greater than 7.5 should also contact the manufacturer of the residual herbicide used previously.
It is important to have rainfall records for each field in order to determine localized risk and follow label.