Target control of grassland weeds

By Lauren Peterson

Most producers think in terms of their bottom line. While many shy away at the thought of wasteful application rates, the true waste involved for some practices is sometimes overlooked. Such is often the case when controlling grassland weeds using a broadcast application.

“When broadcast spraying a grassland, beneficial plants such as forbs are killed or injured, decreasing the overall diversity and health of grasslands,” says Gared Shaffer, South Dakota State University (SDSU) extension weeds field specialist.

Balance is key when it comes to managing grasslands. While noxious and invasive weeds should be eliminated, broadcast weed control tends to purge more species than necessary.

“Grasslands typically have about 80 percent of their biomass as grass, 15 percent as forbs (broadleaf plants), and 5 percent as shrubs,” Shaffer notes.

Because of this, Shaffer recommends spot or zone spraying only the affected areas to prevent the loss of beneficial forbs that contribute to a healthy environment. This is key not only to the ecosystem but also to livestock health, as they frequently seek out these additional forage sources.

“It is critical to understand that livestock, including cattle, will utilize a variety of native and non-native broadleaf plants in their diets to meet their nutritional and mineral requirements,” Shaffer adds in SDSU extension’s iGrow newsletter.

This often goes unseen as both wildlife and livestock graze throughout the night. Shaffer notes that what can be undesirable throughout the day may be appealing later, contingent on the plant’s active compounds.

Plant diversity pays dividends

Aside from added livestock performance, plant diversity creates a more desirable environment for useful insects and wildlife. Shaffer points out that conserving additional broadleaf plants attracts not only natural enemies for pests, but also birds and other pollinators. This added pollination through bees, butterflies, and beetles improves both the grassland and the surrounding crops.

Shaffer suggests that producers ask themselves several questions before control options are implemented: Why do I have this weed? What is the source? Is this a result of current or previous management? Can I manage this problem effectively? Is it noxious or problematic? Can I take advantage of this problem?

“Remember, a grassland with only grass is not a healthy grassland,” Shaffer concludes.

Lauren Peterson

Lauren Peterson is serving as the 2017 Hay & Forage Grower summer editorial intern. She is from Wyanet, Ill., and currently attends Kansas State University where she is pursuing a degree in agricultural communications and journalism. While at school, Lauren works at the KSU dairy farm and is an active member of the Horseman’s Association.