I am NOT a chemical expert. However, there are many experts I rely on when I need answers. One of the most asked questions I have received over the past three weeks is:
“What chemical program can I use so that I can plant cover crops?”
When it comes to spraying wheat we know that there are a few chemicals to avoid if you want to plant a cover crop. Huskie and Peak have both shown to cause significant injury to the brassica family (Radishes and turnips) and to soybeans. In multiple cover crop meetings these two herbicides were mentioned as excellent wheat herbicides but very harsh on subsequent cover crops planted after the wheat.
Many more producers are looking to plant cover crops after corn and soybeans. Some of the very best information that I have received came from Kevin Shelley from the UWEX Nutrient and Pest Management Program out of Madison, WI. Kevin sent me some links that I think will be helpful when making herbicide choices. Thanks Kevin! I will list these publications below.
Herbicide Persistence and Carryover, by Jed Colquhoun, provides general information on persistence and the potential for carryover to a subsequent crop associated with herbicide chemical families as well as soils, environmental conditions and management.
Here is a link to the PDF for A3646. In the appendix, Table 2 provides a concise listing of the Planting Intervals for Rotational Crops associated with most of the herbicides used on field crops in Wisconsin. It is based on label information from the products listed. This may be somewhat useful for some of the species used as cover crops.
As Kevin (and many others) said, always read and follow the label.
I hope to have another post soon to get more response from farmers on what they do. Anyone wanting to add comments will be welcomed! We all seem to need help in this area.