Insects battle knapweed vegetation in Garfield County

July 12, 2011

In an effort to find another tool in the box on Garfield County’s most invasive noxious weed, Russian knapweed, the county vegetation management team, in cooperation with the Colorado Department of Agriculture’s Insectary in Palisade, released 100 gall midges to work on the knapweed. The release site was on County Airport property along Mamm Creek and took place in late May.

This new agent is Jaapiella ivannikovi. It was first released in North America in 2009 in Fremont County, Wyoming. Last year the Insectary successfully reared and raised the Fremont offspring in their facility in Palisade. Jaapiella is a gall midge that lays its eggs on the growing tip of the plants causing the plant to form a gall around that growing point. This reduces seed production and plant height.

The Mamm Creek release site was one of the first sites in Colorado chosen by the Insectary to be a new home for the Russian knapweed gall midge.

In 2010, the same property was the ste of a release of 10,000 tamarisk leaf beetles, Diorhabda elongata.

Russian knapweed close-up with gall midges at the tip
Russian knapweed close-up with gall midges at the tip (inside stem)
Noxious weeds