This section is from the book "A Guide To The Poisonous Plants And Weed Seeds Of Canada And The Northern United States", by Robert Boyd Thomson, H. B. Sifton. Also available from Amazon: A guide to the poisonous plants and weed seeds of Canada and the northern United States.
Other Common Names: British Ragwort, Tansy-ragwort, Staggerwort, Stinking Willie.
Stockmen in eastern Canada formerly lost considerable numbers of cattle through a mysterious ailment called "Pictou Cattle Disease." The liver was the organ especially attacked. Long periods of nervous irritability and gradual emaciation were followed by increasing weakness and death. An investigation of the disease by the Canadian Department of Agriculture proved the correctness of suspicions held by farmers for years, that Ragwort was the cause. Since that time experience in England and New Zealand has corroborated this conclusion.
Both in pasture and in hay, Ragwort has proved poisonous to cattle and, to a lesser extent, to horses. Sheep generally eat it with impunity. The effect of the poison is apparently cumulative, and animals may feed on the plant for months before characteristic symptoms develop. Then the hair loses its lustre, the animal becomes irritable and nervous, with occasional chills, followed later by a paleness of the mucous membranes, emaciation, staggering gait, great weakness and death.
Fig. 17. - Ragwort - Senecio Jacobaea.
Strychnin and iron are of some benefit during the early stages, but a dependable cure for the disease has not been discovered. Therefore preventive measures are most necessary. In eastern Canada cultivation and pasturing with sheep have been made use of with some success for the eradication of the plant, but it is still very plentiful in waste areas.
Ragwort is a European introduction. It grows abundantly in the east and locally as far west as Ontario. It is an erect plant eight inches to two feet or more in height, and may be smooth or more or less covered with woolly hairs. The root leaves are lyrate, while those on the stem are deeply pinnately dissected or divided into small lobes. The bright yellow flower-heads, about one-half inch across, contain both tubular and ray florets as in the daisy, and are arranged in a flat-topped cluster. The plant blooms in July and August and forms a very striking feature of the landscape.