Other postemergence herbicides that can be used for morningglory control with any type of corn hybrid include Aim®, ET®, Clarity, Status, and 2,4-D. Liberty (LL corn hybrids) has always been more effective than glyphosate for morningglory control. However, split applications of glyphosate can be effective if applied when morningglory plants are small and not running into the next county!! Post-directed applications of Evik can be effective for morningglory control as well. For those fields that get out-of-hand, some growers have had success using a harvest-aid such as Aim®. Aim applied at that time will not remove large weeds from a field but will dessicate the plants enough to facilitate harvesting.
Enlist corn hybrids will be available that will permit higher rates and wider application windows of 2,4-D to be used. Enlist Duo will be a combination of glyphosate + 2,4-D choline for use in all Enlist cropping systems. This technology may prove useful in the war on both morningglories and pigweed. Time will tell.
Lastly, growers may want to consider harvesting corn early in fields with a known morningglory problem. In this situation, drying costs will be increased but you may be able to get the corn out of the field before the morningglory makes combining a nightmare.
Morningglory may be the bane of many a corn growers existence. The use of maximum labeled rates of atrazine, timely postemergence applications, harvest-aids, and early-harvesting will be crucial for optimum control programs. Unfortunately, morningglory control in SE field corn will never be easy! As always, good weed hunting!
Prostko is a weed specialist with the University of Georgia Cooperative Extension.