Wheat harvest started last week and will be wide open this week of May 21st

Double-crop soybean planting will begin in earnest.

Typically, good stands of wheat shade the soil and reduce emergence of weeds. This can make a wheat/double-crop soybean rotation a good rotation to reduce the Palmer amaranth seed bank.

In thin stands of wheat or in drowned out areas there is often considerable weed pressure to be a concern. The two weeds most common in these situations are horseweed and Palmer amaranth.

Giant ragweed can also be an issue in areas as well.

As you all are aware, we have struggled trying to burndown horseweed and Palmer amaranth this spring. It is typically even more difficult to control them when most of the weed material we want to spray has been cut off with wheat harvest. 

Moreover, in the many very dry areas of Tennessee, growers will often want to be conservative on how much they will invest in herbicide for a soybean crop that may make very little unless the weather turns around.

There are two main management strategies to control these cut-off weeds. 

First is to use a tank-mix that has a good probability of controlling the weeds and second is to apply these tank mixtures in the most effective way possible.

In my mind there are three herbicide mixtures that have the best probability of removing horseweed and Palmer pigweed following wheat harvest.

First is a combination of paraquat and metribuzin. Be sure to utilize the higher rates of the paraquat product which would be 48 ounces of Gramoxone SL or 32 ounces per acre of a generic paraquat. 

The metribuzin rate should be 4 to 6 ounces per acre.