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Perilla Mint: Dangerous to Livestock

Perilla Mint: Dangerous to Livestock

AUBURN, Ala. – During droughts, livestock are tempted to eat anything green. While grasses dry up, some poisonous plants can survive the dry weather. Perilla mint is one of the most dangerous.

Perilla mint is found throughout the South in pastures, fields and along roadsides. The leaves of perilla mint make the plant look  attractive. Leaves are egg shaped and purple or green tinged with purple. The toxic element in perilla mint is perilla ketone. This toxin causes fluids to collect in and around the lungs in a variety of animals. Most cases are in cattle and horses.

Dr. Joyce Tredaway Ducar, an Alabama Extension weed scientist, said that livestock will only eat perilla mint under certain conditions.

“Normally, animals won’t graze perilla mint unless there is no other available forage,” said Tredaway Ducar. “Producers should remember that perilla mint is found near wooded areas where livestock may stand for shade.”

Cases of perilla mint poisoning are seen sporadically in the late summer or fall. When livestock ingest the plant, the effects are deadly.  It  accounts for birth defects in calves when hay containing perilla mint is fed to cows early in pregnancy.

Signs of Perilla Mint Poisoning

Producers should check their livestock regularly for symptoms of perilla mint poisoning.  Affected animals affected exhibit signs of major respiratory distress. Animals have difficulty breathing, especially when trying to exhale. They may grunt while exhaling or have a nasal discharge and an elevated temperature.

Treatment is usually ineffective once symptoms become severe. Producers may try injecting the animal with antihistamines, steroids and antibiotics. Producers should handle affected livestock gently and quietly. This can reduce further respiratory complication and subsequent death.

Control Perilla Mint

Producers should take every measure possible to control perilla mint, especially in their pastures, barn lots and forage fields. The best time to scout for and control perilla mint is late April to early June. It is more difficult to control it in late summer and early fall when it also becomes the most dangerous to livestock. If control methods are not taken early, producers need to keep an adequate supply of quality feed on hand for cattle and other farm animals. This will ensure that livestock do not eat the toxic weeds. Producers should limit grazing in infested pastures during late summer when perilla mint is flowering. Avoid harvesting forages in areas infested with the weeds.

Robert Spencer, an Alabama Extension animal science and forages specialist, said there are several control options that producers can choose.

“Producers can mow perilla mint plants before it goes to seed to reduce weed population. This will prevent more seed therefore more plants from growing,” said Spencer. “If there are few perilla mint plants, you can manually pull and burn the plants.”

Dr. Steve Li, an Alabama Extension specialist of crop science, said that there are several herbicides that producers can choose to control perilla mint.

“Some control options include several of the broadleaf pasture herbicides, such as Weedmaster, Grazon next HL, Graslan L, 2,4-D, Banvel and Crossbow. All these should provide good to excellent control if applied timely at label recommended rate. You should use the label recommended surfactant and spray settings,” said Li. “Producers should avoid herbicide drift if spraying these auxin herbicides in summer where sensitive crops are growing nearby. Producers should keep livestock away from the sprayed area for the recommended amount of time. You can find the recommendations on the label instructions.”


Featured image by :Ansel Oommen, Bugwood.org

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