chapter  23
28 Pages

Noxious Weeds That Are Poisonous

WithRussell J. Lorenz, Steven A. Dewey

A noxious weed is one that has been legislated against in some way because it has an undesirable property or trait. A noxious weed may be an annual, biennial, or perennial species, a grass or a broadleaf, woody or herbaceous, thorny or smooth, unsightly or beautiful, nutritious or poisonous. Leafy spurge contains toxic substances that cause skin inflammation in cattle; prolonged exposure causes swelling of the tongue and lips, reducing the ability of the animal to graze. Cattle avoid grazing palatable forage species growing among leafy spurge plants, and the competitive nature of leafy spurge rapidly reduces forage production. Vigilance is especially important in controlling an aggressive, persistent weed like leafy spurge. A biological control program is being developed for leafy spurge, using host-specific insects and diseases from Europe and Asia. The mature plants become brittle and stiff, facilitating lodging of plant parts on vehicle undercarriages and on machinery.