By Eric P. Prostko
Over the last few years, the attention of most weed scientists has been devoted to the management of herbicide-resistant Palmer amaranth. We had to or U.S growers could have been in serious trouble.
Since more field corn is projected to be planted this year, it might be a good time to review management options for one of the most problematic weeds that corn growers can have. I am talking about the morningglories.
There are numerous species of morningglory that can be found including bigroot, cypressvine, ivyleaf, palmleaf, pitted, purple, red, sharppod, smallflower, and tall.
Before discussing control strategies, I want to make it very clear that morningglory control will always be a challenge for southeastern field corn growers. Why?
There is no herbicide on the market that will provide season-long control of morningglory.
The region's climate favors late-season emergence of morningglory plants as the crop matures and the canopy dries down. For the extreme SE, that could be as early as June!
No field corn weed control system would be complete without the inclusion of atrazine. If I was King, I would make every corn grower (except those dealing with atrazine resistance or vegetable rotations) use a preemergence application of Atrazine 4L @ 1 qt/A followed by an additional 1.5 qt/A in combination with whatever POST herbicide is needed or preferred. The only downside to atrazine is that is does not last as long in the wet, warm and humid Southern climate and in soils where it has been used repeatedly. Please follow all labeled directions for atrazine use rates in your state.