2020 Planting Prep: Manage Unruly Weed Seed Banks

08:00AM Feb 04, 2020
Pests and soil conditions fade with out-of-control weeds.
( Darrell Smith )

2019 prevent plant (PP) meant many weed species ran rampant with little to no control. With each growing weed comes hundreds—if not hundreds of thousands—of seeds that can emerge over the next five or more years.

“On our farm [prevent plant] wasn’t a choice; it was muddy and our tractors would have torn up the ground irreparably—we took a lot of prevent plant,” says DuWayne Bosse, Britton, S.D., corn and soybean farmer and broker for Bolt Marketing.It was so wet all year that Bosse only got across PP fields once.

“We just had to get in to spray for weeds, but we never got to till it, so even now it’s pretty saturated,” Bosse says.

“The big concern [in PP fields] is the summer annual population and how high that weed density could be,” says Aaron Hager, University of Illinois Extension weed scientist.

High weed population means farmers need to take a whole-season approach to weed management—don’t just rely solely on a post herbicide application, Hager warns. “It’s a recipe for disaster.”

Here are a few tips from Hager and other experts for managing weeds on PP fields:

  • Consider planting PP fields last. As seedling weeds emerge you can control them before you plant, it kills the weed and the viable seed, a one-two punch.

  • Use a multi-faceted weed control approach. Consider tillage if that fits your management, use pre-emergent residual herbicides and overlap residuals when you do your post application.

  • Don’t skimp on herbicide rates.

  • Remember, you’re fighting more than just waterhemp. Don’t forget about velvetleaf or cocklebur—those populations likely increased last year.

  • Scout for escapes and check for weeds you don’t recognize. Fields near rivers could have had some weed seed from other counties come in with flooding.

The only good weed is a dead one, start clean, stay clean.

Read more about how to prep 2019 prevent plant fields for 2020 planting:

New to Cover Crops? Make Sure You Terminate Them in Time

2019 Prevent Plant Still has Market Implications

Manage Fallow Field Syndrome for 2020 Planting