Mother Nature has a way of balancing the scales, and for farmers looking to manage persistent weed pressure, biological control—or biocontrol—is one testament to that.
Unlike making a traditional herbicide pass with your sprayer, biocontrol isn’t about fast or even total eradication. Instead, it’s usually a long-term strategy designed to tip the scales in your favor, using living organisms to keep weed populations at a “manageable level,” according to William Curran, Penn State emeritus weed scientist.
While biocontrol methods are common in rangelands and perennial systems, Curran notes they can require more effort to adopt in row-crop settings where tillage and rotations can disrupt the very organisms farmers are trying to put to work.
Curran says if you’re interested in using biocontrol measures as part of a comprehensive weed-control program, there are four primary categories to consider, including:
- The Classical Approach: This involves introducing a specific natural enemy into a weed-infested area. The goal is for that organism to establish a permanent home, feeding on the target weeds year after year to naturally suppress their growth and seed development. An example of this would be the use of a Canada thistle rust pathogen.
- The Augmentative or Inundative Method: Bio-herbicides are one example of inundative methods. The intent is to overwhelm the weed population quickly. This practice often requires multiple applications to be effective.
- Conservation Management: Sometimes, the best helpers are already in your fields. By adjusting your cropping system to be more “predator-friendly,” you can boost the populations of native organisms, like ground beetles, that naturally snack on weed seeds.
- Grazing: One of the oldest tools in the shed is still one of the most effective. Utilizing cattle, sheep, or goats to graze down weed-heavy areas can significantly reduce seed banks and keep invasive species in check.
For more information on biocontrol weed control practices, check out a newly updated webpage, authored by Curran and released by the GROW network.
