Montana Governor and First Lady's Math and Science Initiative
Nelson Godbolt showing Nancy Schweitzer the damage the knapweed root boring weevils do the knapweed roots in the Victor, MT knapweed insectary.
Knapweed Insectory
Boxing Knapweed
The Montana Department of Transportation wants to take a new approach to help knock out spotted knapweed with a one-two punch.
Currently, MDT is helping fund six K-12 school systems that are either growing, or are planning to grow insectaries that will cultivate insects used to kill spotted knapweed. Students will hand harvest the insects and release them onto MDT's right-of-ways and neighboring lands that are infected by this noxious weed.
According to Dan Williams, MDT maintenance division, many landowners are jumping at the opportunity for students to release the insects adjacent to their property. The insects are host specific and feed solely on spotted knapweed.
MDT has obligated $35,000 to their biological program to purchase and release the insects within select counties, as well as develop the insectaries located at each school.
The school systems currently involved are Bonner Junior High, Darby Public Schools, Noxon Public Schools, Eureka County Public Schools, Victor High Schools, and Whitehall High School. A seventh school in Seeley Lake is also looking to join the fight. MDT is funding each program with $2,500 each year, for two years. Whitehall's program includes a training program for educators and therefore is receiving $5,000 each year, for two years.
"We are attacking knapweed through air strikes and ground strikes," said Williams.
The schools are using root boring weevils and seed head moths as their
ammunition. The insectaries are about 100-feet by 30-feet rectangular
pieces of land that are enclosed by metal flashing that is inserted four
inches into the ground, and protrude eight inches high. Knapweed is
planted within the metal flashing and purchased insects are then placed
inside the insectaries. Williams estimated the female insects may lay
100 larvas annually and the surviving insects multiply by as much as
90-times their original amount.
After the insects have matured, the students capture and release them along appropriate roadways and fields. Students then monitor progress through the use of a GPS-system, which locates the sights and photographs the area. The GPS-system also allows the students to monitor the progress of the insects and reduction of knapweed plants by counting the insect to knapweed plant ratio.
Root boring weevils kill knapweed by burrowing into the plant's root system and eating the root. The seed head moths land on the plant's blossoms and lay larva on the plant's seeds. The larva, when hatched, feed on the florets and seeds of the spotted knapweed. This inhibits the seeds from dispersing creating more of the noxious weed.
The two insect species being used were the same ones that kept the noxious weed under control in Asia, which is where spotted knapweed is believed to have come from. By reintroducing the two, MDT hopes to help balance the plant ecosystem.
The biological approach is a "slowly but surely" method because as the insects travel, they kill knapweed and inhibit future growth. Chemical herbicides, although immediately effective, kill only the sprayed weeds and the chemicals used do not spread beyond that specific area.
According to Williams, MDT can spray and kill knapweed along highways, but if the adjacent landowner is not able to maintain the knapweed, it will simply re-develop.
Knapweed was introduced to Montana in the early 1900's and now contaminates all 56 Montana counties, it is considered Montana's number one problem weed. Knapweed spreads rapidly by seeds hitching rides on vehicles, humans, animals, and through wind and water. Seeds can remain viable in the soil for seven to ten years.
MDT uses a number of methods to manage every problem weed and is excited about the interest each school is showing for the fight against knapweed.
"It is a great way to educate youth and employ another method of control, instead of depending solely on herbicides," Williams said.
Although this biological weed control method is not immediately effective, Williams does believe it will be incredibly sufficient in the long run.
"This is a Johnny Appleseed story," William said. "We are planting shade trees for our grandchildren."
For more information, please contact Dan Williams at (406) 444-7604.
For the hearing impaired, the TTY number is (406) 444-7696 or
1-800-335-7592 or Montana Relay at 711.
