Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
Dicamba Cutoff
Today, Friday June 30th, is the cutoff for dicamba applications to Xtend soybeans and the applications are no longer allowed. Anyone planning to spray with dicamba products will need to switch a different herbicide. If the soybeans are Xtendflex, glufosinate is an option.
Fall Panicum
Fall panicum continues to show up at higher densities this year. S-metolachlor (Dual products) and acetochlor (Harness products) are not very effective on this species. Glyphosate is good on fall panicum assuming the weeds are small (~4 inches). Glyphosate can struggle killing fall panicum that has been cut off during wheat harvest and regrowth can be expected. Including one of the postemergence grass herbicides after the soybeans have emerged and fall panicum has recovered (about 10 to 14 days after harvest) is one option.
Cocklebur
Common cocklebur is another species I have been asked about by a few folks recently. It seems to be showing up with more regularity in some soybean fields. It’s a species with a long germination period and many of our soil applied herbicides do not control it very well. We have gotten away from using a lot of the group 2 herbicides (Classic and Pursuit) but these herbicides are very effective at providing residual control. If you are in a situation with common cocklebur you should consider using Classic, Pursuit, FirstRate in your tank mixture.