Ranchers and other owners of large herds of cattle are likely already aware of the dangers of growing cherry trees near their pastures. However, anyone who keeps animals on their land, regardless of herd size, should be aware of cherry trees’ effects.
Cherry trees—their leaves in particular—are toxic to cows, horses, sheep, donkeys, mules, goats, and any other mammal who grazes. Animals poisoned by cherry leaves often die very quickly after eating small amounts.
It seems strange to think that cherry trees can be harmful when their fruit seems to pose no problems. However, it’s important for anyone who keeps grazing animals to understand cherry trees’ toxicity, how to prevent them from hurting your animals, and how to remove them.
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Cherry Trees’ Toxicity
No part of a cherry tree is truly safe for grazing animals when chewed or eaten in large quantities. Various cherry tree species, including black, rum, wild, and chokecherries, contain toxins in their seeds, bark, and foliage (source).
However, the most poisonous parts of cherry trees are their leaves because this is where they store prunasin.
Prunasin is a non-toxic chemical stored in healthy cherry leaves. One of the tree’s defense mechanisms is to metabolize prunasin into prussic acid when leaves become damaged (source). Prussic acid is a form of cyanide.
Depending on the variety of cherry, younger leaves may present a higher risk of toxicity than older ones (source); however, damaged leaves at any stage of the tree’s life cycle are dangerous to grazing animals (source).
How Cherry Leaves Become Damaged
Leaves may be damaged in a variety of ways:
- Frost, especially later in spring
- Wilting (source)
Tornadoes and thunderstorms can be especially problematic, since they may carry leaves and branches from a considerable distance away and into your animals’ grazing areas. Even if leaves still appear to be green and healthy, they pose a huge risk to cattle because they begin to wilt once they are separated from the tree (source).
However, be mindful of any cherry trees growing wild near your pastures. Even healthy cherry leaves pose a danger to hungry or curious animals, since the act of chewing can damage them enough to release prussic acid (source).
Prussic acid and other forms of cyanide can kill any mammal. However, cows, sheep, horses, donkeys, mules, and other grazing animals are especially susceptible (source). This is mainly due to a couple of factors:
- Lack of food due to overgrazing
- Cherry leaves mixing with grasses and harmless feed during storms
While animals can eat a little bit of cherry bark without effect, it can take very small amounts of cherry leaves to kill them. In fact, depending on the season and moisture levels, as little as two ounces of damaged leaves can be lethal (source).
Cyanide is extremely potent, and the general rule of thumb is that a lethal dose is between 2-2.5 milligrams per kilogram of body weight (source). In other words, for a cow weighing approximately 1,200 pounds, just over one pound of wilted cherry leaves could be deadly. A 180-pound sheep could die after eating less than half a pound (source).
Timing seems to play a part, too. The 1,200-pound cow may eat over a pound of cherry leaves, but if that pound is consumed in small amounts throughout the day, she may not show any poisoning symptoms at all (source). The problem, of course, is that there’s no way to control how quickly an animal might eat a lethal dose of leaves.
Symptoms and Treatment of Cyanide Poisoning
The following are signs that your animal has ingested cyanide:
- Rapid, deep breathing
- Signs of anxiety and stress
- Collapse (source)
Unfortunately, cyanide is a fast-acting poison. Most of the time, animals only live up to an hour after eating from a cherry tree (source).
If you notice an animal with the above symptoms, try not to stress it. Animals exhibiting these symptoms can be difficult and dangerous to handle, so make sure to protect your own safety first and foremost (source).
On rare occasions, you may be able to contact a veterinarian in time for them to treat your animal. However, prevention is a much more surefire way of protecting your livestock from cherry tree poisoning (source).
The most effective way to prevent cyanide poisoning from cherry leaves is to remove cherry trees from the areas surrounding your pasture, but access to feed and adequate space can also be effective.
Access to Feed
The good news is that even if you grow cherries, or they grow wild near your pastures, your livestock are unlikely to eat them on purpose unless they don’t have enough grass or other feed (source). Make sure your animals have access to adequate feed at all times so they won’t be tempted to nibble on any wild cherry trees (source).
It still pays to be vigilant, especially after strong storms, since your cattle could ingest cherry leaves accidentally while grazing.
Livestock owners, especially those who live in windy regions where leaves and limbs tend to travel, should probably not plant cherry trees, unless you have enough land to maintain a good distance between your pastures and your fruit trees.
If you own livestock but still want to plant cherry trees, good site selection is one way to prevent toxicity. Plant your cherry trees well away from grazing areas, keeping in mind that high winds and severe storms may carry leaves and limbs into those areas.
You will also need enough space to keep your livestock sequestered until you can clear your pasture of any rogue cherry leaves or branches after a storm. Remove animals from the paddock until you can clean up cherry tree debris or until the leaves have turned completely brown (source). If you don’t have adequate space to keep your cattle elsewhere, it may be best to avoid planting cherries altogether.
Identification of Volunteer Trees
Even if you don’t intend to plant cherries, it is still worthwhile to know how to identify volunteer cherry trees, since identification is the first step to removal.
Birds will often eat cherry fruits, then drop the pits when they sit on fence posts (source). The trees that sprout from these pits are the most likely to cause problems for your livestock.
Cherry tree leaves are dark green, spoon-shaped, and have serrated edges. Their stems have white spots called lenticels (source). Very few other trees have these white lenticels, making them a good way to tell a cherry tree from something more harmless.
In the spring, they are easy to identify by their blooms, which range from white to bright pink. Cherries also bloom earlier in the spring than many other trees—another effective way to tell them apart from other trees (source).
If you find volunteer cherry trees along your pasture fence lines, remove them as soon as possible.
How to Remove Cherry Trees
Removing cherry trees is not an easy task, but is well worth the investment in your animals’ safety.
One of the most effective ways to remove cherry trees from your fence lines is to cut them down and remove logs, branches, and leaves from the area. If your cherry trees are fairly large or well-established, you should contact a professional, since tree removal can be dangerous for people without proper training (source).
However, that step alone won’t be enough, since cherry tree stumps can resprout. To prevent resprouting, treat the stump surface with an herbicide such as a 25% solution of triclopyr ester (source).
The herbicide imazapyr may also be effective in killing your cherry trees when applied to their leaves. However, it will require more than one application to be effective and is a more complicated process overall than cutting your trees down and treating the stumps (source).
If you own livestock, particularly grazing animals, it is in your best interest to remove cherry trees from the areas surrounding your pastures. Even in very small quantities, cherry leaves are lethal to animals, especially if they have been damaged by wind, frost, drought, or simple wilting. Since the cyanide in cherry leaves works so rapidly, prevention and removal are the surest ways to keep your animals safe.