Learn About Whitehall Bio Control: 7/19/2023

Our summer is quickly moving along. The toadflax insects are finished. All the adults have laid eggs, and most have died of old age. We are in the middle of collecting leafy spurge flea beetles (Aphthona spp.) and are doing well with numbers. Next week we hope to start collecting spotted knapweed root boring weevils for the many requests we are receiving.

We tried going to a former good flea beetle site in Missoula that we have collected from before however, it also is crashing so we only collected 6 releases. Then we found a site near Whitehall where because of irrigating, the spurge has come back after mostly being killed by the flea beetles (the larvae that do the major damage to the roots drown if the site floods or is heavily irrigated). This site has attracted many, many flea beetles, and Oberea (the red-headed spurge root boring beetle) which is allowing us to collect a good number. We have now collected 97 releases of 1000 insects each and should soon be able to reach the number requested by all you good landowners.

Many of the landowners who have received insects from us in the past are reporting a good decrease in their weed problem. It is gratifying to see and hear that biocontrol insects are a large part of this! Remember, biocontrol will not completely eradicate the weed (they didn't in Eurasia where they and the weed came from and evolved together), just knock it back enough so the weed is no longer a major environmental and/or economic problem. The goal is to control the noxious weed so well that it becomes just another pretty little flower scattered throughout the environment.

Feel free to contact us for a release of leafy spurge or spotted knapweed insects. Call Todd at 406-498-5236 or Brynna at 406-202-2393, during normal business hours, please. Most of the releases we provide would be worth about $100.00 on the open market. Because we receive most of our project money from a Montana State Noxious Weed Trust Fund grant, we do not charge for releases. We do, however, accept donations.

Another noxious weed that we do not have a good biocontrol agent in Montana is field bindweed (Convolvulus arvensis). This plant has white or pink morning glory-like flowers, alternate leaves that are arrowhead-shaped, and is viny with a deep root. It climbs on other plants and can form dense tangled mats. It reproduces from root fragments or seeds which can lie dormant in the soil seed bank for 50+ years. There is a biocontrol gall mite that forms galls (swellings) on the leaves and stems. However, the mite does not do well in Montana where it is probably too dry and cold. We have tried working with this gall mite in the past but did not have any success. This gall mite (Aceria malherbae) does do well further south in states like Utah.

There is a scattered but increasing amount of field bindweed in Jefferson County. If you have it try using an appropriate herbicide. You can cut, mow, and dig it out but the deep roots and long-lasting seeds will keep coming back over time. Therefore, you need to keep monitoring the site and re-apply your treatment and/or control measures when it reappears. Do not move soil that might have bindweed seeds or root fragments.

Keep to your weed management plan and be patient!