The Indiana Certified Crop Adviser panel includes Danny Greene, Greene Crop Consulting, Franklin; Brian Overstreet, soil conservation coordinator, Rensselaer; and Dan Ritter, Hoegemeyer Hybrids, Rensselaer.

 

I noticed more than a handful of waterhemp plants that went to seed in one of my fields going to soybeans next year — one I planned to seed with cover crops. Will those covers be enough to suppress weeds in the spring? What else can I do to keep waterhemp pressure at bay?

 

Greene: Those waterhemp plants that went to seed will make future weed management more challenging. A single female waterhemp plant can produce a tremendous number of seeds, and once those seeds enter the soil, you’re managing the problem for more than one season.

 

A cover crop can help, but don’t expect it to control waterhemp by itself. If you’re going to soybeans, cereal rye would be my first choice. The goal of the cereal rye is to establish a solid stand and produce enough spring biomass to shade the soil surface and suppress weed emergence. Crimping a mature cereal rye cover will help blanket the ground.

 

Waterhemp is particularly difficult because it can emerge over an extended period, including well after soybean planting. Cereal rye can reduce early pressure, but it should be one layer of the control program.

 

Start with a strong cereal rye stand and make sure the field is clean at soybean planting with an effective burndown. Follow with an effective soil-residual herbicide and scout early for escapes. A timely postemergence application while waterhemp is still small, potentially including another residual, can extend control later into the season.

 

Pay particular attention to areas where waterhemp went to seed this year. The long-term objective isn’t just controlling next year’s weeds; it’s preventing escapes from adding even more seed to the seed bank.

 

Overstreet: Yes, a good, thick stand of a cover crop like cereal rye can help suppress many weeds, including waterhemp. In addition to the cover crop, make sure you use a residual herbicide with waterhemp on the label in your burndown program in the fall. Waterhemp is persistent and can germinate throughout the year, so you will still have to keep an eye out for it later next season, especially if it is a wet spring.

 

Ritter: Waterhemp is a long-term battle that should be fought using various methods. Cover crops can help suppress many weeds. The challenge is that waterhemp is more of a mid- to late-season weed, so plants will be emerging after your fall cover crop is gone.

 

Consider applying a strong preemergence herbicide followed by a planned postemergence program. Don’t forget the pigweed family is very prolific at seed production. One plant can produce 500,000 to 1 million seeds, so you need to be diligent in controlling this weed.