Begin at the Beginning

The most problematic weed species have an unmatched potential to spread. Left unmanaged, both waterhemp and Palmer amaranth can produce up to 1 million seeds per plant, according to Ohio State University Extension.

- By Chelsea Dinterman Agronomy & Livestock Editor chelsea.dinterman@ agriculture.com

“Thirty years ago, weed control programs would cost $10–15 per acre,” said Josh Putman, a technical marketing manager for BASF. “Today, we are up north of $100 per acre, primarily due to the resistance and competitive nature of a lot of weed species.”

Understanding how weeds spread is the first step in building an effective control program and reducing the risk of herbicide resistance.

How Weeds Spread

Seeds are spread through a variety of methods, including wind, water, and wildlife.

For example, marestail seeds can be picked up by the wind once the plant has reached 3–4 feet, and viable Palmer amaranth seeds have been found in the stomachs of geese and deer.

Farms located near rivers can see weed species from the south moved by the water current.

However, for the average farmer, weed seeds most often spread through everyday operations. Small seeded weeds, such as Palmer amaranth and waterhemp, are especially easy to spread unintentionally. “Their seed is extremely small — about the size of the ballpoint tip in a pen,” Putman said. “That can get caught on the bottom of your boot in some mud. It can get in your truck tires, tractor tires, or sprayer tires. It can be transported in manure. It can be transported in cottonseed meal that gets sent from Texas onto dairy farms in Wisconsin and New York.”

Minimizing Seed Spread

The best ways to prevent weed spread are timely applications and proper use of herbicides. Be sure to follow all directions and restrictions on the label for best results.