BOSSIER CITY, La. (KTAL/KMSS) – The highly toxic perilla mint (Perilla Frutescens) is in full bloom across Louisiana, and researchers warn ranchers to protect their livestock from the plant, which could kill them if ingested.

Perilla mint is native to east Asia, where its seeds are used in cooking, oil, and fuel. However, compounds within the plant also cause toxicity and lead to the death of livestock and other domestic animals when ingested. Cattle, sheep, and horses are particularly susceptible to the weed.

Also known as the beefsteak plant or Chinese basil, the plant is relatively easy to identify.

Several stands of perilla mint, the highly toxic square-stemmed broadleaf weed easily adapted to southeast climates and were identified in Natchitoches Parish in late September.

All parts of the plant are poisonous, particularly the flowers. However, biological analysis of the seeds revealed anticancer, anti-diabetic, antiasthma, antimicrobial, anti-inflammatory, antioxidant, and cardioprotective effects. 

Perilla mint is also toxic when bailed into hay.

After consuming the plant, livestock may experience labored breathing, open mouth breathing, and death caused by atypical interstitial pneumonia.

Perilla mint is found in shady areas, but the plant can tolerate full sun. It is typically found along damp and wooded edges of pasture lands or meadows, making it easy for grazing cattle to find. Experts recommend restricting animals from locations infested with the weed.

The Red River Research Station recommends inspecting pastures and hay meadows for infestations and spraying infested areas with herbicides.

The best time of year to control perilla mint is late April to early June because the plant is difficult to control in late summer and early fall. This is the time of year when it becomes the most dangerous to livestock.