Season can start early for herbicides Row crop weed fighters can get a head start on some acres this year with early preplant herbicides, says Leon Wrage, extension weed specialist at South Dakota State University.
Spring weather that gives an opportunity to get into fields early also is an opportunity to apply early preplant (EPP) herbicides as at least part of a row crop weed program, Wrage said.
Many soil-applied herbicides can be applied at planting (pre-emergence) or before planting, either on the surface or incorporated.
Early preplant options make it possible to spread the application work load and allow some time for precipitation before weed emergence, said the specialist.
Early preplant treatments work very well in no-till systems. A burndown can be used later if weed escapes are up at that time. For conventional till systems, a shallow tillage at planting is an option for most treatments, Wrage said.
Herbicides vary in how far ahead of planting they can be used, Wrage said. Specifications vary from about two weeks to 30 to 45 days before planting. Some require split applications for long intervals.
"Getting too far ahead of emergence can reduce activity on late weed flushes, especially if the crop canopy is inadequate," Wrage cautioned.
Using the EPP approach is one way to develop a weed control plan that provides residual weed control, at least on some acres.