Good weed control is necessary for maximum production of crops in Illinois including small grains. When properly established (seeding at the recommended rate, optimal soil fertility, and timely planting), these crops can usually compete effectively with weeds so the need for herbicide application is minimized.

What if broadleaf weed problems develop after planting? The decision to use a postemergence herbicide for broadleaf control in small grains should be based on several factors.

Nature of the weed problem. Identify the weed species, their size, and consider the severity of the infestation. Weeds are usually best controlled while small.

Stage of the crop. Most herbicides are applied after full-tiller until boot stage. Do not apply herbicides from the boot stage to the hard-dough stage.

Herbicide activity. Determine the crop tolerance and weed susceptibility to herbicides. This information can be found in Chapter 3 of the 2008 Illinois Agricultural Pest Management Handbook.

Presence of a legume underseeding. In most cases, 2,4-D ester formulations and certain other herbicides should not be applied because they may damage the legume underseeding.

Economic justification. Consider the treatment cost in terms of potential benefits, such as the value of increased yield, improved quality of the grain, and ease of harvesting the crop.

The 2008 Illinois Agricultural Pest Management Handbook, IAPM-08 can be purchased at this University of Illinois web site: https://pubsplus.uiuc.edu/IAPM-08.html Also, local Extension offices can facilitate people getting a copy.

Always read and follow the pesticide label for specific directions and information.