Keeping weeds down in a wet year

Add weed control to the list of elements of growing your 2011 crop that is being complicated as cool, wet weather continues to delay planting in the bulk of the Corn Belt.

If you’re too far delayed in your planting and were originally planning on using a quick tillage trip to knock down early-emerging weeds, you may not be able to pull that off this spring. “Preplant tillage operations can effectively control existing vegetation while preparing a seedbed,” says University of Illinois Extension weed specialist Aaron Hager. “However, as weeds become larger, the effectiveness of tillage to control weeds before planting can be reduced.”

Even if you are able to squeeze in a round of tillage as things start to dry out, it may lose some efficacy, Hager says. “Reduced weed control may also occur when fields are slightly wet during the preplant tillage operation,” he says. “Soil disturbance may not be as extensive when soils are retaining moisture, and clods are more likely to be formed. Weeds sometimes take root again after tillage when soil disturbance is inadequate and soil moisture is abundant.”

So, what’s the answer? If tillage is already done, you don’t have enough time before you plant, or you were already thinking of a burndown application anyway, Hager says you can control winter annual weeds with a little stronger rate of burndown herbicide to “account for the large and dense vegetation.”