Tansy Ragwort

If you've ever lived in a rural area, you've probably heard farmers and ranchers gripe about Tansy Ragwort (Senecio jacobaea). The griping is for good reason: it's a toxic, invasive species, with a cluster of attractive yellow flowers on top. It grows up to 6 feet tall and spreads easily by thousands of wind borne seeds. According to the Oregon Department of Agriculture, Tansy seems to be spreading now in a cycle of increased growth. Even on our small rural property, we have noticed hundreds of them (6/26/2013).

The alkaloid toxins in all parts of the plant are lethal to most livestock and can cause liver damage in humans as well, through milk from animals that have fed on it. Even honey from bees in contact with Tansy pollen can cause problems for us.

Fortunately there are a few natural ways to curtail their growth. One method, shown below, is to let the cinnabar moth (Tyria jacobaeae) have its way with the flowers. The caterpillars of this moth (shown below) have a voracious appetite for Tansy. We've see hundreds of these just in the past two weeks and we are doing everything we can to cheer them on! They eat the leaves and flowers, thus preventing them from going to seed. My heroes! The ragwort flea beetle also helps by feeding on the roots. Not sure if we have any of those in our army yet!

Tansy Ragwort is similar looking to several other yellow, daisy-like plants now blooming. Not the odd configuration of the leaves for full identification. However, I have noticed Tansy Ragwort along roads and open spaces in town. If you see any in your yard, put on some gloves and cut it off at the base before it goes to seed!