Garfield County Achieves Biocontrol Milestone
Garfield County is the first county in the state to have its own Russian knapweed biocontrol nursery and distribution program. Since 2000, Garfield County Vegetation Management has worked with the Colorado Department of Agriculture’s Palisade Insectary to release various biocontrol agents on noxious weeds throughout the county. Biological control, or biocontrol, is the use of natural enemies – such as insects or pathogens – to help control weeds or other pest organisms.
Russian knapweed, a deep-rooted perennial plant that is abundant in Garfield County, is the sole host for two different species of biocontrol: the gall midge (Jaapiella ivannikovi) and the gall wasp (Aulacidea acroptilonica). Both insects help to decrease shoot length, plant biomass, and reduce or prevent flowering and seed production.
For the past several years, Garfield County has been receiving biocontrol agent releases from the Palisade Insectary. These agents are then distributed to interested parties throughout the county and released on appropriate sites. One landowner in particular, Brit McLin of New Castle, happened to have a knack for helping the bugs thrive on his property – and a whole lot of Russian knapweed to play host.
A member of the Garfield County Weed Advisory Board, McLin invited the Board to his property this April to learn more about biocontrol from the experts at the Palisade Insectary, Sonya Daly and Teresa Rodriguez. Daly and Rodriguez taught members how to identify stem galls, which look like large, irregular bumps in the plant stems. These are the trademark characteristic of Aulacidea acroptilonica infection. Board members then spent several hours collecting the galls, which will be distributed throughout the county to be released on other Russian knapweed infestations. McLin plans to continue hosting the bugs and allowing Garfield County and the Insectary to harvest biocontrol agents for future releases.
Garfield County Vegetation Management hopes to be able to establish more nursery sites over the next few years, allowing for an increased availability of releases for landowners as well as having agents that are predisposed to the specific conditions of the county.
This is a big victory in the fight against Russian knapweed. While the biocontrol agents do not kill the plants outright, they help to prevent the competitive abilities and further spreading of infestations. Especially when combined with other management methods, such as herbicide, biocontrol can be an effective component of knapweed control.