When it was too wet to get back into many soybean fields to spray on time in late June or early July, it was time to make a decision. Should you go in once it was dry enough to spray, rut it up and go now, or just skip the application because there weren't that many weeds out there anyway in some fields? Maybe you had applied a residual herbicide early and there were only scattered weed escapes.
All three options were chosen based upon the situation from what farmers tell us. Those who chose the don't spray post at all option may have not suffered that much in terms of yield from weed competition, but by harvest, weeds that did escape were often tall and nasty.
Fields where marestail escaped were certainly no exception. They're easy to see in soybean fields.
The stand in this picture was not this bad by any means in the whole field. However, this clump shown here is enough to produce considerable weed supply for the weeds seed bank for years to come. It's one of the risks of not wiping out every weed, and one of the reasons researchers in part of the world are looking at some pretty drastic measures for destroying weed seed left behind in a field.
Weed control specialists believe it will be some time before tools specifically designed to destroy weed seed after harvest debut or catch on in the U.S.
If this was your field where this marestail was spotted, what would you do now? It may be easier to control in corn if you rotate next year. But no doubt there is enough weed supply to bring up a new crop where you plant soybeans.
Purdue University Extension weed control specialist Bill Johnson says you need to plan to get on marestail early next spring. If you're not applying fall herbicides, then jump on it early in the spring. It starts out in a rosette stage, growing close to the ground. But once it bolts and puts up a main stem, it is harder to control, he says. The taller it gets, the harder it is to control.
Marestail can be controlled, however, he says. Spend time this winter and develop a plan for control.