controlling spotted knapweed

Asked December 31, 2018, 2:24 PM EST

Is it possible to purchase/release insects for control of spotted knapweed in Michigan? I have approx. 5 acres in Emmet Co. that is highly infested with knapweed and it is killing off all the grasses and other plants in our field. I am not interested in using insecticides. I have read about various insects that are used for knapweed control but the only websites I find that have these insects are in Montana. Related to this, does MSU have any field restoration programs/research projects that I might participate in for control of knapweed and restoration of native plants?

Emmet County Michigan

1 Response

At this time it is not possible to purchase and release insects for the control of spotted knapweed in Michigan per Michigan Department of Agriculture and Rural Development (MDARD) regulation. In consultation with Dr. Doug Landis in the Department of Entomology, he indicated that the regulations have to deal with spotted knapweeds positive impacts on the beekeeping industry.

Dr. Landis also indicated that there have previously (2010 and before) been releases made in different locations throughout the state of the seedhead-feeding weevils (Larinus spp.) and the root-boring weevil (Cyphocleonus achates). All three species have been reported as successfully established. It is likely that the two seedhead-feeding weevils would be present in your area already as they can fly. The root-boring weevil, which is most effective in combination with the others, however, does not fly and therefore dispersal is much more limited. It may not be in your area yet.

We do have a newer faculty member in the Department of Entomology, Dr. Marianna Szucs, who is focusing on the biological control of invasive weeds and insects, but she is not doing research on spotted knapweed. More information about Dr. Szucs program can be found here