It’s nice seeing cattle being turned out into corn stalks! One point that I haven’t mentioned recently is that we all need to be checking the herbicide label for any grazing restrictions of crop residues.
So check the labels from in-season applied herbicides to row crops and fall-applied herbicides to crop residue for any potential grazing restrictions…and any restrictions on grazing cover crops planted into crop residues following application of those chemicals to a row crop. If the label doesn’t specify any restrictions, then it should be ok. If you want to be on the safe side, a rule of thumb many chemical reps use is to use the pre-harvest interval for the amount of time to wait before grazing stalks.
Some labels will say that residue should not be grazed or baled and fed to livestock. Sometimes studies were actually conducted to know there is a safety concern. In other cases, the chemical company may not choose to conduct all the studies the Environmental Protection Agency (EPA) required for labeling due to high costs. If that’s the case, the EPA requires the strongest restrictive language be placed on the label.
Regardless, if it says there’s a grazing restriction on the label, the label needs to be followed as it is a legal document and the law. Your cattle may/may not be affected by grazing stalks or cover crops where a chemical with a grazing restriction is on the label, but there may be other concerns such as problems with the chemical affecting the calf or being retained in the cow’s milk.
For quick references, the 2015 UNL Guide for Weed Management shows Forage, Feed, Grazing Restrictions for Row Crop Herbicides on pages 174-177. A new weed guide will be released January 2016. These pages just provide a reference; it’s truly best to read and follow the label.