A Few Weed Control Items

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

The June 30th cutoff for dicamba applications to Xtend soybeans has passed and the applications are no longer allowed. Anyone planning to spray with dicamba products they will need to switch a different herbicide. If the soybeans are Xtendflex, glufosinate is an option.

For Palmer amaranth control, a fomesafen product (Reflex, Flexstar GT etc.) is the other option. Fomesafen will also provide residual control for later emerging Palmer amaranth. If Palmer amaranth is getting taller, using a more aggressive (or “hotter”) adjuvant mix should be considered to improve control, although there is a higher risk of leaf burn. For instance, crop oil rather than a nonionic surfactant; and using AMS with Flexstar GT can enhance control.

Double-cropped soybean fields may have some grassy patches where the wheat stand was poor. If the grasses are barnyardgrass, fall panicum or goosegrass, glyphosate may not have controlled them at burndown. These are two species that glyphosate is not as effective in controlling and if the plants were cut off during wheat harvest, there is less tissue to intercept the herbicide. Including a grass herbicide, such as clethodim, as a postemergence spray will control these escaped grasses.