Perhaps the title is a bit too rife with homophones. However, the subject of yew trimmings and livestock is a serious matter and one that could be a matter of life and death for animals.
It is common for homeowners to be pruning shrubs this time of year – taming those wild growths back to a manageable and more aesthetically pleasing level. If you have yew shrubs around the home, take great care what you do with the trimmings! A Purdue Extension expert recently cautioned that the consequences could be deadly for grazing livestock.
Dr. Keith Johnson, Purdue forage specialist, said recently that many plants have poisonous compounds that can cause all kinds of concerns, and even death, if consumed. “The interactions that I have had with veterinarians, suggest that the yew is right at or near the top of plants that cause livestock death,” said Johnson. “A disheartening scenario is when yew trimmings are thrown over the fence by the livestock owner or neighbor thinking that the trimmings would make a great snack for the livestock.” Fresh or dry trimmings, it doesn’t matter, he said. “The result will be the same – death.”
Johnson referenced the times of most concern are when yew clippings are placed in pastures, when livestock get out of pastures and find yews in landscapes, or when the older leaves are consumed. These situations are concerns in all seasons of the year.
Johnson explained that the compound that causes concern is perhaps an alkaloid called taxine. He said the amount of green foliage consumed to be fatal at 0.1% of a monogastric animal’s body weight (e.g. 1 lb plant material in a 1,000 lb horse), or 0.5% of a ruminant’s body weight (e.g. 5 lbs of plant material in a 1,000 lb cow. Using this formula and harkening back to our title, 1 lb of yew plant material could be fatal to a mature ewe (a ruminant) weighing 200 lb.
Yews are flexible-needled evergreens, either shrubs or small trees. They are commonly used in home landscapes, and may be planted in a row to form a hedge. They have an alternate needle arrangement, with each needle attached singly to the stem. They have long, slender twigs with a reddish-brown hue. Needles are ½ to 1 inch long, flat, tapering to an abrupt point, and they have faint white bands on the undersides of the needles. The cones are red and fleshy, appear berry-like, and one-fourth to one-third of an inch long. Most yews are what we call dioecious plants, having male and female flowers on separate plants. Only the female plants produce the red, fleshy cones called arils, which contain a single seed.
Find Johnson’s original article, “So Lush, So Green, and Oh So Poisonous,” in the June 7, 2024 issue of Pest and Crop Newsletter, https://extension.entm.purdue.edu/newsletters/pestandcrop/. For additional information, see publication WS-37, “Guide to Toxic Plants in Forages,” at Purdue Extension’s Education Store, www.edustore.purdue.edu.