What do marestail and henbit have in common? They’re two species of weeds that can remain dormant all winter and spring back to life before planting, causing serious problems for U.S. soybean farmers. But keep in mind, these are just two of many winter weeds.
“Fields that have heavy infestations of winter annuals in the fall are the ones where weeds could cause problems at planting,” says Bob Hartzler, Iowa State University extension weed specialist.
Henbit is like marestail in that a fall treatment is recommended to avoid fighting large amounts of biomass during spring burndown. Applying a residual herbicide in the fall will control any henbit that emerges. Scout your no-till fields a week or two after harvest for the presence of marestail and other winter annuals to stay ahead of the game.
Henbit and marestail aren’t the only weeds that can survive the winter. Here are eight other examples:
- Annual bluegrass
- Cress leaf groundsel
- Field pennycress
- Italian ryegrass
- Shepherd’s purse
- Purple deadnettle
Research funded by the Louisiana Soybean & Grain Research & Promotion Board has shown that maintaining weed-free soybean fields for the first five weeks after planting maximizes yield. Similar results exist in other states, ranging from four to eight weeks, although the exact time frame varies.
For more weed-management tips, visit www.TakeActionOnWeeds.com.