Agricultural News: Perilla Mint – How to Identify and Control

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   Perilla Mint, also known as Beefsteak plant or Purple Mint, is an herbaceous annual weed that’s spread by seed. Originally from eastern Asia, it is considered an ornamental plant and was cultivated for its purple and green foliage. This plant has escaped ornamental cultivation and has become a noxious weed in Tennessee and is particularly problematic for ruminants and horses. 

   Perilla mint causes more cattle deaths in Tennessee than any other poisonous plant. As previously mentioned, it is highly toxic to ruminants and horses. All parts of the plant are toxic, but the flowers and fruit of the plant are the most toxic. The toxicity remains when the plant material is dry (such as in hay), but fresh plant material poses the greatest risk of poisoning, especially when fruits and flowers are present. 

   So what happens if animals consume the plant? Well, perilla mint contains ketones that cause acute respiratory distress syndrome (ARDS) in cattle (i.e. “panting disease”). Some symptoms include labored breathing, grunting upon exhaling, nasal discharge, and elevated body temperature. Treatment is often ineffective and the result is usually in death, but some do survive. Mild exercise for cattle with ARDS can cause the animal to collapse and die, so it is important to handle animals you suspect with ARDS as low stress as possible to avoid sudden death.  

   The good news is that perilla mint is not a forage of choice for livestock. They typically only consume it when there isn’t adequate forage or nutrition available for them. This is why cases of perilla mint poisoning typically occur late summer to early fall because this is the time when forages might be in short supply and the perilla mint is flowering.  Since treatment is ineffective, it’s crucial to have a steady supply of quality feed available for animals during late summer to early fall.

   It’s very easy to identify this plant right now. Plants should be 1-2 feet tall right now. The leaves are simple, coarsely serrated (toothed), opposite of one another, larger at the base of the leaf, and are purple or green tinged with purple. The stems of perilla mint are square in shape and are usually purple tinged as well. The flowering bodies contain many small white to purple flowers. They give off a distinct minty smell when the plant material is crushed. While perilla mint can grow anywhere, it typically favors semi-shaded areas such as wood-understories, fence rows, and farm structures.  

   A good broadleaf herbicide will help control this plant, but the timing of your applications is crucial to get good control. Right now is NOT the time to spray for this weed because the most we will achieve is wilting the plant, which will only increase the likelihood that our livestock will consume it. The best time to scout and spray for this weed is late April to early June. Most broadleaf herbicides will control perilla mint (Please see our 2020 Weed Control Manual, PB 1580). This is the time to scout your pastures to see if you have this weed growing, mark its location(s), and make plans to come back and spray for it in late April to early June when the plants are young and actively growing. You should avoid making hay from pastures where perilla mint is present. You should also avoid grazing cattle in pastures where perilla mint is present and flowering. You can limit the spread of seed by mowing the plant down before seeds are produced, but keep in mind clippings will still be toxic and could be consumed by livestock. 

   If you have any questions on how to control this weed or any other weed, please call our office at 931-722-3229 or e-mail me at mdharris@utk.edu.

   ***NEW FINANCIAL RELIEF PROGRAM FOR AGRICULTURAL AND FORESTRY BUSINESSES***

   Coronavirus Agricultural and Forestry Business fund (CAFB fund) is a NEW program established to provide financial relief to Agricultural and Forestry businesses that have been or will be impacted from March 1-December 31, 2020 due to Covid-19.

   TDA will begin taking applications through August 31st. There is only an online option to apply. Priority will be given to those who have not received Covid-19 relief funding yet, but you are still able to apply if you’ve received funds from other sources already.

   Some of the eligible industries include: Agritourism, Food Processors (including meat and cheese/dairy processors), Forest Product Manufacturers, Loggers, Sawmills, Wineries, Transportation Providers, Commodity Groups, Agricultural, Food, and Forest product exporters, and Horticultural and Specialty Crop Producers (please visit their website for more details).

   If you have any questions about the CAFB Fund, please call TDA at 615-837-5160. The website for information and to apply is www.tncaresact.tn.gov/TDA.