Tansy ragwort biocontrol

Asked September 16, 2020, 7:20 PM EDT

How can I get my hands on tansy ragwort flea beetles? I have a massive tansy problem on a cattle field and won't use chemical sprays. There are too many to pull.

Linn County Oregon

1 Response

Greetings,

I am sharing the following answer from Melissa Fery, OSU Extension Faculty:

Thank you for reaching out to OSU Extension Service with your concerns. The population of tansy ragwort has been on the incline and is very noticeable in the late summer, especially in areas where it isn't being managed. We have been responding to many landowner requests for information about how to manage this toxic weed and provide resources on our website, social media, newsletters and other methods to help keep the word out about this weed. If you have ideas for other ways to share the importance of controlling this invasive species, please let me know!

The biological control you mentioned, cinnabar moth larvae are still out defoliating plants, along with the ragwort seed fly and ragwort flea beetle. We are currently in a situation and have been for the last few years where the biological controls are rebuilding populations. For a few decades their food source was minimal and now there is plenty. We also need more land managers to be aware of the need to manage tansy ragwort via other methods as well to reduce populations.

The following link goes to a resource that can be shared electronically, detailing the trouble with tansy ragwort, biological control at work and other management strategies. https://extension.oregonstate.edu/pests-weeds-diseases/weeds/tansy-ragwort