Answer: It is more practical to provide a list of trees that should not be planted and why. Do not plant:
Plants in the cherry family (Prunus species). For example, chokecherry, most parts of the plant contain cyanide which causes death if ingested. Black cherry is a common food source of eastern tent caterpillars which are associated with Mare Reproductive Loss Syndrome.
Ornamental shrubs including rhododendron, Japanese yew, and oleander. These ornamental shrubs will cause death when ingested in small amounts.
Be cautious when planting the following trees:
Oak. New buds and green acorns hulls contain tannins. Ingesting large amounts for more than a few days can lead to diarrhea, colic, swelling, and frequent urination.
Maple. Ingestion of 1 to 3 pound of dried or wilted leave (not fresh leaves) can cause toxicity. Signs include red/brown urine, depression, and possibly death.
Female boxelder trees. Seeds may contain a toxin that is known to cause seasonal pasture myopathy. Male trees do not produce seeds.
Oak, maple and boxelder trees are common in horse pastures. They can be planted, but owners should be aware of the potential issues. The only way to ensure the horse will not ingest parts of the tree is to fence the horse out of the trees. Most horses who are well fed will rarely seek out ‘alternative’ food sources like trees.
By: Krishona Martinson, PhD, University of Minnesota