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Northwest Florida Equine Management School Identifying Poisonous Weeds in the Pasture October 12, 2009 Dan Mullins, IFAS Extension Agent Santa Rosa County 1 Poisonous Plants Include over sixty plant species with the potential to poison horses. Only a few species cause most of the problems. Both native and exotic Most are broadleaved plants 2 Some Plant Poisoning Effects (A wide range depending upon the plant and conditions) Diarrhea, weakness, labored breathing, vomiting, gastroenteritis, tremors, sweating, weak or accelerated pulse, high temperature, low temperature, coma, convulsions, dizziness, paralysis, cardiac/circulatory failure, hemorrhaging, liver or kidney damage, skin rash or blisters, fainting, bloating, depression, loss of appetite, dilated pupils, stupor, increased blood pressure, death. 3 Conditions Under Which Poisonous Plants are Eaten Starvation Deficient Rations Overgrazing and Drought Fed Inadvertently as Fodder Incidental and Curiosity Some Taste Good! Ex. Maple Unknown 4 Poisonous Plants Most Often Found Under These Conditions New Pastures Neglected, overgrazed pastures Old burn Piles and decomposing trash piles Areas with recent soil disturbance Dry or partially dry water holes Fence Rows Creek/ditch edges “Rich areas” – feeding sites, manure piles 5 Florida’s Climate is Ideal for Dozens of Species of Poisonous Plants Prevent Plant Poisoning by Identification and Control I.D. as to Genus and species Not just the local common name! Walk the pasture frequently and observe Collect and submit samples of any unfamiliar or suspicious plant Take a knowledgeable person along for another set of eyes and an objective view. 7 Bracken Fern – Pteridium aquilinum All parts (fresh or dry) are toxic with thiaminaseA The enzyme inactivates thiamine in the horse. The toxic principle has an accumulative action. Affected horses stand with legs apart, arch their back and have neck spasms. 8 Showy Crotalaria – Crotalaria spectabilis Toxic Parts All parts, with highest concentration in the seed. Alkaloids cause congestion of the liver. Acute poisoning: gastroenteritis, depression, bloody feces Chronic Poisoning: may have no symptoms Toxic Constituents All parts with pyrrolizidine alkaloids- Toxic to all 9 livestock and fowl. Lantana – Lantana camara L. Acute Symptoms: Sluggishness, weakness, bloody stools, paralysis, death within 3 to 4 days. Chronic Symptoms: Skin and mucous membrane becomes yellow. Skin cracks and peels and sometimes becomes detached. Toxic Parts & Constituents All parts esp. the leaves and green berries w/ lantadene A (lantanin)& 10 unknowns. The Nightshades Solanaceae Includes: • Tomatoes • Irish Potatoes Solanine Poisoning • Eggplant Paralysis of the motor and respiratory centers • Black Night- of the brain shade Weakness, stupor, • Horsenettle staggers, nervousness. Symptoms develop • Jimsonweed Toxicity: All parts rapidly. except ripe fruit 11 Spotted Water Hemlock – Cicuta maculata (Spotted Cowbane, Spotted Parsley) Most toxic plant in U.S. Causes violent and painful convulsions. Death from ingestion in as little as 15 minutes. A member of the carrot family. Has flat topped white flower clusters like wild carrot. Grows near the shoreline of lakes,rivers and swamps. 12 Red Maple – Acer rubrum Toxin is concentrated in leaves when in a wilted condition. Leaves on a fallen branch in pasture are most toxic. High in sugars and tasty to horses. Toxin causes hemolysis – breaks down red blood cells. 1 to 3 pounds of wilted leaves can kill a 1,000 lb. horse. 13 Prunus-All Species Leaves, Bark and Seeds Laurel Cherry Includes: Laurel Cherry; Black Cherry; Plum; Peach; Apricot; 14 Nectarine Prunus-All Species Peach Tree Chickasaw Plum Toxic Constituents Cherry Dried Parts also Very Toxic •Cyanogenic glyosides Respiratory failure •amygdalin & mandelonitrile glucoside within 1 hour which form toxic HCN 15 The Daturas Devils Trumpet Angels Trumpet Yellow Angel’s Trumpet Symptoms Toxicity Jimsonweed Delirium, convulsions, All parts-Especially rapid and feeble the Seeds pulse, dilated pupils, •atropine rarely vomiting •scopolamine (hyoscine) •hyosyamine and other tropane 16 alkaloids The Cassias Fourteen Cassia species listed as being poisonous, including several popular ornamentals All parts toxic, especially the seed. Sicklepod Anthraquinone causes diarrhea, tremors in hind legs, coffee-colored urine. Animal unable to rise after going down. No fever. Candle Bush 17 Oleander All parts of the plant are poisonous to humans and livestock. 15- 20 grams of leaves are sufficient to induce death in mature cattle and horses. Dry leaves are also toxic. Toxic Constituents: Two toxic glucosides have been isolated. 18 Perilla Mint Contains ketones that cause acute respiratory distress syndrome. All parts are toxic, especially the flowering structures. A problem in late summer and early fall 19 Carolina Jessamine Toxic Parts All parts including the flower nectar. Poisons are cumulative. They chiefly depress and paralyze the motor nerve endings. Toxic Constituents: Cystalline alkaloid gelsemine and the amorphous alkaloids gelseminine and gelsemoidine. 20 Heath Family Rhodendrons Azaleas Wild Honey Suckle Mountain Laurel Toxic Parts & Constituents All parts including the pollen with andromedotoxin (a resinoid) 21 Heath Family ctd… Lyonia lucida - Staggerbush Symptoms: Watering of mouth and eyes. Convulsions, progressive paralysis, respiratory F failure. e t All parts including the t pollen with e andromedotoxin ( a r resinoid).l b u s h 22 Pokeberry Phytolacca americana First plant to appear in recently disturbed soil. All parts contain oxalic acid and saponin. Causes cramping, severe gastroenteritis, diarrhea and convulsions Poisoning can occur in spring, summer or fall. 23 Tung Tree Small deciduous tree Large, heart shaped leaves with long stems. Two reddish glands at the base of leaf blade (see photo) All known poisonings from discarded broken branches or prunings. Saponin and another unidentified substance causes gastro-enteritis, dizziness, diarrhea, dehydration. 24 Sorghum Including Johnson Grass, Sudan Under conditions of stress (drought, trampling, frost or second growth) plants may contain cyanide. Heavy fertilization with N can result in nitrate poisoning. 25 Mushrooms ? 26 Other Poisonous Plants Non-native Honeysuckle Hydrangea ■ Boxwood Chinaberry Sweet Potato Hypericum (St John’s Wort) Delphinium (Larkspur) Croton Milkweed Rosary Pea Bulbs: Black Locust Narcissus Castor Bean Amaryllis Red Buckeye Iris Rattlebox Crinum Bladderpod 27 Conclusions: Most poisonous pasture weeds are broadleaved plants (dicots), both native and exotics. The Sorghums (monocots) are an exception as they can cause nitrate or cyanide poisoning when grown under stressful conditons (drought, trampling,frost or overfertilization). Know your hay source as poisonings can result from feeding infested hay. Any cultural practice that results in species diversity in the pasture increases the chances of plant poisoning. Don’t allow your horse to graze in the yard. Many exotic landscape plants are toxic and unfamiliar to the animals. 28 Questions? 29
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