Careful scouting of a cornfield recently after application of a combination mix of post herbicides at the V2 to V3 corn leaf stage turned up scattered marestail and trumpet creeper plants. Fortunately, they are few and far between. The leaves were burnt back, especially on the trumpet creeper, and on the top of the marestail. Green growth was sneaking in under the marestail from the lower leaves.

Down but not out- This trumpet creeper is burnt back, but likely will recover. A shot of Clarity would probably knock it out for good, Tom Jordan says.

If it's very spotty and a plant here and there, it's not likely to affect yield. However, Tom Jordan, a Purdue University weed control specialist, says that if your goal is to get the weed s out of the field, there are herbicides that will do iti. The only catch is that if it's only spotty weeds, you may want to go out with a backpack sprayer and apply the herbicide directly. Rather than spray herbicide over the entire field.

"It's a lot of work but if you're just trying to clean up a field and the weeds are spotty, you can cover quite a few acres in half a day with a backpack sprayer," he says.

First, consider trumpet creeper. The best product for this perennial is dicamba. A brand name that contains dicamba is Clarity. "If you can give them a shot with Clarity, it will help take care of them," Jordan says.

Part of how effective it is depends upon the age of the trumpet creeper and the underground root system it has established. If it's a young vine, it's more likely to be wiped out permanently than if it's an established vine with a large underground root mass.

For marestail, you could knock them all the way out with 2,4-D, Jordan says. However, 2,4-D won't do much for trumpet creeper. An application of Clarity will get both.

If the weeds are spotty, it likely won't affect yield. Part of the reason for controlling the weeds, especially trumpet creeper, a tough perennial, would be to prevent future problems with the weed.