Tuesday, May 19, 2020

Russian Knapweed Biocontrol

Noxious Weed and Pest Management Coordinator Montana Cohn releases Gall Wasps as a Russian knapweed biocontrol in Whitewater.

Mesa County Noxious Weed Management, alongside the Palisade Insectary and local landowners, is releasing Russian knapweed biocontrol.

The biocontrol used is a short-lived stem galling wasp, which acts as a nutrient diversion, so the plant is forced to use energy towards the gall instead of the flower, seed, and plant growth.

Russian knapweed is a non-native, deep-rooted perennial that spreads by aggressive, creeping, horizontal roots (rhizomes) and seeds. The roots are brown to black with a scaly appearance. Russian knapweed can grow up to three feet in height. The stems and leaves are covered with short gray hairs. The flowers are urn-shaped, pink to purple in color, and are solitary at the tips of the upper branches. Russian knapweed emerges in early spring after soil temperatures remain above freezing. It produces flowers from June to August and sets seed in late summer to early fall.

Russian knapweed (acroptilon repens).

Gall Wasps help suppress Russian knapweed, but biocontrol will not get rid of this noxious weed. If it is growing in an area that can be treated with herbicides, it's best to use that method instead.

Biocontrol is helpful in remote areas or large areas for long-term management and treatment suppression. For example, a landowner with several acres, may not be able to financially treat large acreage all at once, but doing it in stages may be more affordable and more manageable. Biocontrol can be a successful part of an overall management plan with integrated pest management strategies to help suppress the knapweed in the areas to be treated over a few years.

More information on Russian knapweed biocontrol may be found here.

Contact Mesa County Weed Management if you would like more information on biocontrols, at 970-255-7121 or weed.pest@mesacounty.us.

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