HomePoisonous Trees of Pasture

Poisonous Trees of Pasture

Black locust (Robinia pseudoacacia)

Black locust trees contain the toxic proteins robin and phasin. The toxins are highest in bark and seeds but is also present in leaves. New black locust growth is most toxic. Livestock species most often affected include horses, cattle, and poultry. Symptoms of black locust poisoning include depression, lack of appetite, abdominal pain, diarrhea, laminitis (horses), weakness, paralysis, and in some cases, death. For this reason, it is best to avoid planting black locust as a shade tree in or around pastures. Young black locust shoots should be monitored for and removed if found.

For more information on black locust toxicity, please visit Colorado State University’s Guide to Poisonous Plants at https://csuvth.colostate.edu/poisonous_plants/Plants/Details/45.

For information on how to identify black locust trees, please visit Ohio State University’ Ohio Perennial and Biennial Weed Guide: https://www.oardc.ohio-state.edu/weedguide/single_weed.php?id=65.

 

Young black locust saplings in field. Image by Leslie J. Mehrhoff, University of Connecticut, via Bugwood.org

Black locust flowers and leaves. Image by the Leslie J. Mehrhoff, University of Connecticut, via Bugwood.org.

Buckeyes/Horse chestnuts (Aesculus spp.)

Trees within the Aesculus genus contain aesculin and fraxin that cause toxicity in animals. These toxins are present in leaves, seeds, and young growing sprouts. Livestock poisoning generally occurs in spring from consumption of leaves and sprouts of the trees since they leaf out earlier in the year than most trees. Livestock effected by Aesculus spp. poisoning include cattle, sheep, horses, swine and chicken. Symptoms of poisoning include vomiting, abdominal pain, muscle twitching, and weakness. Horses typically suffer from colic if exposed to toxins. In more severe cases, symptoms include hyperglycemia, glucosurea, and proteinurea.

For more information on Aesculus spp. toxicity, visit Colorado State University’s Guide to Poisonous Plants at https://csuvth.colostate.edu/poisonous_plants/Plants/Details/62.

See below for resources by Virginia Tech Dendrology on how to identify the most common Aesculus spp. in New York:

Ohio buckeye (Aesculus glabra). Image by Richard Webb, via Bugwood.org.

Common horse chestnut (Aesculus hippocastanum). Image by Richard Webb, via Bugwood.org.

Cherry spp. (Prunus spp.)

Trees within the Prunus genus (cherries, peaches, plums, apricots, almonds) contain Cyanogenic glycosides (prunasin and amydalin) which when digested by ruminants, become cyanide. All part of Prunus spp. contains these toxins except for fresh berries. Wilted leaves are most toxic therefore plant stressed by drought or frost pose the greatest risk. Additionally, fresh growth can also contain higher levels of toxicity. Cyanide blocks the release of oxygen into the tissues and typically results in death from anoxia. Symptoms leading to eventual death from cyanide poisoning include difficulty breathing and cherry-red intravenous blood and mucous membranes. Animals impacted by these poisonings include cattle, sheep, and goats. Horses may be impacted if eating large amounts though it’s not common. Prunus spp. should be monitored for in and around pastures.

For more information on Prunus spp. toxicity, please visit Colorado State University’s Guide to Poisonous Plants at https://csuvth.colostate.edu/poisonous_plants/Plants/Details/29.

See below for resources by Virginia Tech Dendrology on how to identify the most common Prunus spp. in New York:

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Black cherry (Prunus serotina). Image by Barbara Tokarska-Guzik, University of Silesia, via Bugwood.org.

 

Chokecherry (Prunus virginiana). Image by Dave Powell, USDA Forest Service, via Bugwood.org.

​Elderberry (Sambucus canadensis)

Elderberry contains cyanogenic glycoside sambunigrin which, when digested by ruminants, become cyanide. All parts of the plant are poisonous, especially in new growth or wilted plants. Cyanide blocks the release of oxygen into the tissues. Typically, if poisoned, livestock does not survive dies of anoxia, or a lack of oxygen. Symptoms leading up to death include increased respiratory rate, difficulty breathing, and cherry-red blood venous blood followed rapidly by death. Cattle and sheep are most impacted by elderberry poisoning while horses are rarely affected. Elderberry should be monitored for in and around pastures.

For more information on elderberry toxicity in livestock, please visit Colorado State University’s Guide to Poisonous Plants https://csuvth.colostate.edu/poisonous_plants/Plants/Details/32.

For information on the identification of this plant, please visit North Carolina State University’s Extension page on elderberry at https://plants.ces.ncsu.edu/plants/sambucus-canadensis/.

Young elderberry plant. Image by Gerald J. Lenhard, Louisiana State University, via Bugwood.org.

Flowering elderberry. Image by Charles T. Bryson, USDA Agricultural Research Service, via Bugwood.org.

Maple spp. (Acer spp.)​

Wilted and dried maple leaves are toxic to horses. Horses must eat 1.5 to 3 pounds of leaves per 1,000 lbs. of body weight to be impacted by toxins. Symptoms of maple toxicity in a horse include depressed behavior, lack of appetite, tiredness, and dark red/brown urine. In more serious cases, symptoms can include difficulty breathing, increased heart rate, and death.  Dried/wilted maple leaves can remain toxic for four weeks and are most common in fall but can also appear after summer storms. Maple tree branches should be kept out of reach of horses. Horses should also be fenced out of areas with small maple trees and/or maple trees with wilted leaves.

For more information on maple toxicity and horses, please visit the following post by University of Minnesota Extension https://extension.umn.edu/horse-pastures-and-facilities/are-maple-leaves-toxic-horses#treatment-1160961.

See below for resources by Virginia Tech Dendrology on how to identify the most common maple trees in New York:

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Red maple (Acer rubrum) leaves. Image by Karan A. Rawlins, University of Georgia, via Bugwood.org.

Sugar maple (Acer saccharum) leaves. Paul Wray, Iowa State University, via Bugwood.org.

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Oak spp. (Quercus spp.)

Oaks contain tannins in the leaves, bark, buds and acorns. Toxins are especially high in early in the spring when buds are present, and oak are beginning to leaf out. Cattle and sheep are most impacted by oak poisoning. Goats and swine are more resistant to toxins and poisoning rarely occurs in horses but is possible. Generally, livestock can consume some oak and not suffer any severe symptoms especially if there is other forage available. Typically, poisoning occurs after significant amounts of oak is ingested (~50% or more of diet as oak). Oak toxins attack any proteins they come in contact with and have the most significant impact on kidneys and the gastrointestinal tract of livestock. Symptoms from poisoning include ulcers, bloody urine and stool, lack of appetite, depression, hemorrhages, and death. Additionally, consumption of oak by during pregnancy may lead to “acorn calf” syndrome in beef cows in which calves are born with deformed heads, joint laxity, and dwarfism. To prevent oak toxicity, supplement grazing livestock with hay when there is a lack of forage especially in the spring when early oak buds and leaves are present or in the fall when there is an abundance of acorns. In acorn mast years, acorns should be raked and removed from pastures,

For more information on oak toxicity please see the following publication by UC Davis Veterinary Medicine Extension https://ucanr.edu/sites/UCCE_LR/files/151758.pdf or refer to Colorado State University’s Guide to Poisonous plants at https://csuvth.colostate.edu/poisonous_plants/Plants/Details/5

 

See below for resources by Virginia Tech Dendrology on how to identify the most common oak trees in New York:

 

Red oak (Quercus rubra). Image by Paul Wray, Iowa State University, via Bugwood.org.

Black oak (Quercus velutina). Chris Evans, University of Illinois, via Bugwood.org.

References

Colorado State University’s Guide to Poisonous Plants https://csuvth.colostate.edu/poisonous_plants/Plants/Search
Cornell University Department of Animal Science Poisonous Plants Database https://poisonousplants.ansci.cornell.edu/php/plants.php
Virginia Tech Department of Forest Resources and Environmental Conservation Dendrology Database https://dendro.cnre.vt.edu/dendrology/factsheets.cfm
University of California, Davis Veterinary Medicine Extension: Oak toxicity by John Maas (2001) https://ucanr.edu/sites/UCCE_LR/files/151758.pdf
University of Minnesota Extension, “Are maple leaves toxic to horses?” by Martinson K. et al. https://extension.umn.edu/horse-pastures-and-facilities/are-maple-leaves-toxic-horses#treatment-1160961