The Arizona Veterinary Medical Association islerting equine veterinarians, horse and cattle owners about a toxic weed that is highly prevalent this spring. It is commonly called Fiddleneck or tarweed.
Animals affected by ingesting the weedre horses and cattle. The toxic principle is pyrrolizidine alkaloids which primarily affect the liver. As little as 15 milligrams of dried plant per kilogram of body weight over two weeks can produce liver disease. All parts of the plants are toxic, even when it is dried.
The botanical name is Arnsinckia intermedia. It is a weed of dry cultivated soils/waste areas. Fiddleneck is an erect, sparsely branching annual weed which is approximately 2 to 3 feet tall. The entire plant is very hairy; flowers are orange to yellow in color and are produced terminally on a distinctive fiddleneck-shaped stem. They only bloom on one side of the axis.
Horse and cattle owners are advised to deny access by their animals to this plant. Fence lines should be cleared up to a distance of at least three feet.
For further information, contact the state veterinary association at (602) 242-7936.