Realize that yield loss has already occurred from weed competition and weed seed production will add to next year's weed problem. Herbicide drift from preharvest treatments can cause major problems this time of year. The following is a list of herbicides labeled for preharvest treatments in small grains and precautions on their use. There are no herbicides labeled as a harvest aid for use on oats. They are illegal.
Labels vary in crop use.
Follow the label. Not all 2,4-D formulations are labeled for preharvest applications. Some 2,4-D labels only allow use on wheat, others allow use on wheat and barley and others allow use on wheat, barley and rye. Choose a brand that is labeled for use on the intended small grain crop. An ester formulation will give better control and quicker burndown than an amine formulation.