Mark VanGessel, Extension Weed Specialist; firstname.lastname@example.org
Herbicide rotational restrictions or guidelines are based on two criteria; regulatory and biological. Both of these criteria are equally important to the end user of the commodity and can be justification for rejecting the harvested product. Maximum residue levels are determined based on a range of tests and studies. Residue levels are determined to ensure that they are below a level that could cause an effect. Biological criteria are established to ensure the succeeding crops aren’t adversely impacted. It is critical that the pesticide label is read and understood before application. It does not matter whether the rotational restrictions were determined based on regulatory or biological criteria, the label needs to be followed. Rotational restrictions are often changed on the labels with little to no publicity, so review pesticide labels every year to be sure you are in compliance with the label.
Where we seem to have the biggest issue with rotational crops is with double cropped vegetables. Products used in sweet corn, peas, or other early-season crops can limit what can be planted after harvest.