Pest Photo

Doug Doohan, Ohio State University/ OARDC,

Tansy ragwort

Senecio jacobaea

Tansy ragwort (Senecio jacobaea) is an invasive plant. It is a native of Europe and was first detected in Montana in 1979.

When prevalent, tansy ragwort is one of the most common causes of poisoning in cattle and horses, caused by consumption of the weed found in pasture, hay or silage. Milk produced by affected cows and goats can contain toxins. Stock does not reject or avoid it in hay or silage. Its poisonous alkaloids are unaffected by drying. Honey from tansy ragwort also contains the alkaloids.