Perilla Frutescens ~ Perilla Mint ~ Shiso

If you’ve been following my blog you know that I recently had a devastating loss of nearly my entire flock of sheep and goat, all due to a toxic plant called Perilla Frutescens. You can read about my story here, but this post is going to be an informational PSA. There will be some graphic images at the end. If you have any experience with Perilla please comment on this post or email me at squarepegfarmfl@gmail.com

flowers

Perilla Mint- also called Shiso, Beefsteak Plant and by other regional names- is a non native invasive that is grown as a culinary herb or by permaculture gardeners. As a member of the mint family it has the characteristic square stem, extensive underground root system and minty smell. The smell is more earthy and less sharp than a peppermint or spearmint, but still distinctly minty. The leaves are more broad than most mints and it can be confused for a member of the basil family (if you aren’t sure, smell it– it smells like mint, not basil!) Perilla comes in green or purple. The variety that is on my property is green, but you can see pictures the purple variety here.

hiding

Most information I’ve found about Perilla says that livestock will not eat it unless they are desperate.. Do not let this make you complacent about the dangers of this plant!!

If your animals have not been exposed to perilla before and are introduced to it either due to a move to a new pasture or to the plant spreading to your property then they may not know to avoid it. In fact, they may actually seek out its minty flavor. My flock actively hunted for it, ignoring the plentiful grass and other forage in favor of perilla.

If you have always had perilla in your pasture you may think that you are safe because your animals have ignored it in the past. Unfortunately that is not true. If we have a particularly hot or dry summer your regular pasture forage may get crispy and unappetizing. Perilla doesn’t require much water so it will remain lush and green, inviting your animals to give it try. Because Perilla kills so quickly and there is no treatment, you may not have any warning or get a second chance. 

plant

Identification

  • minty smell
  • square, bumpy stem
  • small purple flowers (and later seeds) on a stalk
  • leaves: broad, ovate, with serrated edges

plant3

Toxicity

  • deadly to all ruminants (cattle, goats, sheep) and horses
  • all parts of the plant are toxic, both living and dried
  • death can occur within 24 hours of exposure so you may never notice symptoms– I didn’t. if you do notice symptoms you may see heavy panting or difficulty breathing
  • death is due to respiratory distress. lungs may swell and fill with fluid (pulminary edema)
  • necropsy findings include hemorrhaging (bleeding) throughout the respiratory system (mouth/throat/lungs) and heart. Photos below are of one of my 3 month old lambs  during a field necropsy performed by veterinarians from the University of Florida
  • necropsy may also reveal undigested pieces of the plant in the rumen/stomach contents and/or a minty smell

Where to Find It

I know for sure that perilla can be found in pastures throughout the southeast US from Tennessee to Florida. If you have seen it growing wild in other areas please let me know!

When looking around your property pay special attention to fence lines and shady areas. You can practically map the spread of perilla in one of my pastures by looking at the shade cast by the trees running down the fenceline.

Also keep an eye on any newly disturbed areas. A neighbor of mine just discovered several plants growing in an area where she recently lost a tree. Remember that even if you haven’t seen it in the past, any changes to the land could provide an opening for it.

Update: after posting this people have let me know that they have found perilla  growing wild in the following states: FL, AR, NC, KY, CA

Keep in mind that these are observations of individuals who are not professional botanists and Perilla can be confused with other wild mints. However if you live in one of these states and find a plant in your pasture that might be perilla, its certainly worth a closer look!

plant4.jpg

Next Steps

If you find Perilla on your property what do you do next?

  1. If you have livestock in the affected field you may want to move them to a non-affected area while you deal with the perilla. If this isn’t possible, make sure that they have plenty of other options for food- supplementing with additional hay or grain if necessary.
  2. If you have small areas of mint, you can remove by hand making sure that you get the roots. If it has already gone to seed make sure to check the area frequently to remove any new plants. Perilla makes a lot of seeds and new seedlings grow rapidly!
  3. If you have a large areas of perilla (like we do) you may need to spray with a broadleaf pesticide. Our agricultural exenstion agent recommended 2-4D. So far we have had moderate succses spraying with 2-4D. Unfortunately it is difficult in Florida to time your spraying to avoid rain and it only works if it doesn’t get washed off. Once you kill off the current crop of perilla you will need to check back often for new growth, either from seeds or from small plants that the spraying missed. Depending on how bad your situation is it may take several sprayings to get rid of it all. Make sure to check back the following spring for any new growth and re-treat.
dead.jpg

Dead perilla all down the fenceline after spraying

Prevention

I’m still researching this and would appreciate any advice or links to additional resources. From what I’ve learned you can keep it from taking over by mowing before it goes to seed, however it grows so quickly that I wouldn’t risk keeping animals on a pasture that has had perilla mowed down since while this might prevent it from spreading it won’t kill what is already there. I’m also hesitant to recommend keeping it mowed short because it opens your pasture up to creeping indigo, which will only survive in short grass. In order to prevent CI from coming in where the perilla used to be, I’m planning to plant a fast growing cover crop anywhere we clear.

 

If you have any experience with Perilla please comment on this post or email me at squarepegfarmfl@gmail.com. I’d really like to find out more about how common perilla is, whether it has affected your livestock or not so please let me know if you identify it in your pastures! 

 

Additional Resources

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9 thoughts on “Perilla Frutescens ~ Perilla Mint ~ Shiso

  1. I live in southeaster NC and I have SEEN this plant… I have sheep .. I have not known of any losses due to this plant , but it isnt impossible.. I usually really pay attention to plants that may be toxic to my sheep so thank you for this article and your photos.

  2. Dear Laura,
    Super-duper fact sheet! Love the variety of pictures: they help make identification easier.
    Again, we so feel for you about the flock. It makes me cry. It was a blessing Elizabeth and Francine were in NC.
    Hugs,
    Natalie

  3. Thank you for sharing. I noticed this plant on my property in the spring and thought it was pretty and sweet. I do not have livestock at this time, but will definitely try purging when I see it for the safety of my future stock and my neighbors’.

  4. I’ve just fenced in about 15 acres and about 10 of those acres is 2 year old clear cut. I let it grow up and just put goats on it and this stuff is every where. It is growing over all the new cut and it seems to thrive there but It’s not bad anywhere else. They have been on this pasture for about a month and have been eating it. I haven’t lost anything yet but I am worried now. I was told a few months ago to watch for this plant. I’m in central Ms and I’m over run with it.

    • Before you panic there are other wild mints that look very similar and are harmless so if they are eating it without problem it may be a different type of mint. If it were perilla they would be dead within a day or two of eating it.

  5. The image you have is not the plant you are describing. Cindy Campbell had a better pic of it on her FB page for her farm. Here is a link that might help too. I agree it can be bad, but it must have the right photo. What you have pictured is common and not toxic. I have it everywhere and it doesn’t meet the description. Hope this helps with a better image. http://plants.usda.gov/core/profile?symbol=PEFR4

  6. Interesting article! In doing a quick research on this particular plant, it seems to be okay for human consumption. I wonder what makes it lethal for animals? Here is what appears to be a very indepth, informative article on this plant. It says that it is growing wild in southeastern USA and was brought over from migrating Asians during the late 1800s. Seems to have a lot of uses for people. https://altnature.com/gallery/perilla.htm

    So very sorry to hear of your loss!

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