Russian Knapweed
Biological Control Agents
This noxious weed dominates many acres in Fremont County.
The Russian knapweed gall nematode, Subanguina picridis, has been the only bio-agent available for Russian knapweed. This agent is well established and is galling the knapweed plants where it was released, but is does not move on its own.
Fremont County Weed & Pest is helping fund research taking place in Europe to find and test highly selective insect agents of Russian knapweed for introduction into North America. We hope to have two new bio-agents, a gall wasp and a seed head fly, approved for introduction within the year.
For more specific information on Subanguina picridis, visit the Journal of Nematology website.(PDF)
In 2009, after many years of research and testing, a new agent, Jaapiella ivannikovi, was released in Fremont County. Because of prerelease data collection along with cooperation and coordination with both Aphis and the BIA, Fremont County was the site of the first release of this agent in North America. Jaapiella is a gall midge that that lays its eggs on the growing tip of the plants galling that growing point.. greatly reducing seed production and plant height. New galls were found at the release sight within a few weeks of release. Over one hundred (100) galled plants were counted and mapped across the sight by the end of the growing season. In May 2010 we will begin to check for galling at the release site. We are anxious to see how well this new agent over winters.
Another Bio-agent of Russian Knapweed has been approved for release in Wyoming. Aulacidea acroptilonicais is a gall wasp that stunts the growth of Russian Knapweed. We are hoping that there will be enough adult wasps produced for distribution in Fremont County.
For more specific information on Aulacidea acroptilonicais, or Jaapiella ivannikovi, see the USDA Project Evaluation.
For more information on Bio-control of Russian Knapweed visit:
APHIS- Releases of New Bio-control Agents for Russian Knapweed
CABI- Report on New Bio-control Agents for Russian Knapweed
IPMAccess.com- Knapweed Guide (good info for all knapweeds)