By Dwight Lingenfelter
Now is the time to start thinking about the establishment of a forage crop. However, there are certain aspects that need to be considered including herbicide carryover from previous crop and weed management prior to cover crop establishment.
Herbicide carryover from corn herbicides?
Depending on where you are located in the region, the likelihood of herbicide carryover injury to fall-seeded forage crops due to dry conditions during the growing season might be an issue. If you are in a region that was droughty, the potential for herbicide carryover will be highest when seeding small-seeded broadleaf forage crops (i.e., alfalfa, clover species, etc.) on production fields that received applications containing mesotrione or clopyralid, particularly when applied in POST applications. Misapplications or overlapping spray patterns are often an additional contributing factor that increases the likelihood of herbicide carryover.
Burndown herbicides for establishing fall-seeded forage crops?
In addition to rotation interval restrictions, it is important to understand the potential for burndown products to impact forage crop establishment due to soil residual activity. The simplest and most risk-free approach is to use only glyphosate or paraquat to start clean prior to crop seedings. These broad-spectrum products have no soil residual activity.
Source : psu.edu