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Tansy Ragwort is toxic, and can be lethal to cattle and horses, and to a lesser extent to goats (seldom to sheep). There is also concern that it can contaminate flour, milk, and honey…thus entering the human food chain.

The plants contain six (6) different pyrrolizidine alkaloids. Individually, these alkaloids are not toxic, but in the presence of certain liver enzymes they are converted into pyrroles which can cause the liver to stop functioning normally. Damage to the liver is cumulative with time and dose, and it is irreversible. In other words, symptoms may not appear immediately…but when they do it's too late to do anything about the problem.

After consuming enough Tansy Ragwort to equal 3-7% of their body weight (over time), a horse or cow will DIE. Lighter doses may not be fatal, but can still produce conditions such as swelling, diarrhea, and excessive fluid in the body cavity, which set the animal up for other potentially life-threatening problems.

Livestock will not normally graze Tansy Ragwort IF more desirable forage is available. But small plants growing in close association with grasses and clovers, or plants that may occur in hay, cannot be excluded selectively. In silage, the alkaloids diffuse out of the Tansy and into the surrounding material. And to add insult to injury, Tansy Ragwort becomes more attractive to livestock after cutting, wilting, and/or spraying with herbicides.

Pioneer invasion is by seed. One plant can produce 5,000-200,000 seeds in a single season. These seeds can remain viable in soils for 10-16 years. Once established, a plant can also reproduce vegetatively, with root and crown sprouts forming new rosettes. The point being, if you ignore Tansy Ragwort in your lawns, fields, and pastures this year, you will just have more of it next year. Soon, "more desirable forage" may not be so readily available and nearby livestock will begin tempting fate. Is that what you really want?

Put on your gloves and pull! Hand pulling is very effective on small infestations. Work when the soil is moist so you can get the whole root (Tansy Ragwort will resprout from root fragments). When you're done, cover the site with mulch. Studies have shown this will prevent germination of the seed bank. (Don't forget the gloves. This plant is toxic, and may be absorbed through the skin.)

Let the bugs do their job. Three natural enemies have been introduced to control Tansy Ragwort. The ragwort flea beatle (Longitarsus jacobaeae), the ragwort seed fly (Pegohylemyia seneciella), and the cinnabar moth (Tyria jacobaeae) all feed on Tansy Ragwort. They don't produce instant results, however. Several years are required to establish an insect population large enough to reduce a weed population.

Keep your yards and pastures healthy. Tansy Ragwort requires sunlight and a disturbed site to establish…so don't offer those commodities. If you notice bare ground, re-seed, check the soil fertility, examine your pasture management program…do something to promote the growth of "desirable forage."

Follow the label. If you choose to use herbicides, check to see which ones are most appropriate to your site and your situation. And always, always, follow the directions on the label. They are the law. If you choose to use herbicides, time your applications carefully. Tansy Ragwort becomes more tolerant of selective herbicides as the stems elongate in early June. By the time the plants are flowering, control with herbicides (even at maximum doses) is erratic.

Mark your calendar. Start surveying your property in March. Deal with as many plants as you can before they get any bigger. Check your property again in June, again dealing with as many plants as you can. Anything you miss will start flowering in July and August. Deal with those plants ASAP, being careful to pick the plants up and dispose of them properly (at any of the Island County transfer stations). Do one last survey of your property after a couple of hard frosts have hit…you'll be able to see the tall, dark brown seed heads standing in the field/yard. Make a note to deal with the area the following March.

Don't mow. Cutting or mowing is recommended only where plants will soon be eradicated. Cutting stimulates the growth of side shoots, and cut plants often produce a second crop of short-stemmed flowering heads that are more difficult to cut a second time. Normally acting as a bienniel (a 2-year plant), cut plants may survive into the next year to produce a second seed crop and grow even more vigorously than uncut plants.

Don't leave cut or chemically treated plants lying in the field. Such plant material is even more attractive to livestock for grazing. Also, if the plants are already in the bud or flower stage, they may have sufficient nutrients in the stem to set and disperse seed.

Don't stop too soon. Without follow-up (i.e. better pasture management, better lawn care, repeated weed control efforts) Tansy Ragwort will come back. Remember, the seeds can remain viable for up to 16 years in the soil.

Don't assume that because you don't see your livestock eating Tansy, they are not eating it. If you see a Tansy Ragwort plant on your property, deal with it.

Remember...

If you have any questions or concerns, call the program coordinator for the Island County Noxious Weed Control Board.