Farmer loses six cows to toxic ‘Perilla Mint’

Published 5:00 am Tuesday, July 15, 2003

Growing up on the family dairy farm near Caseyville, Dwain Caseremembers seeing the square-stemmed, minty-odored weeds known asPerilla Mint.

“I never knew they were poisonous,” Case said. “Most dairyfarmers don’t know they’re poisonous.”

Case, unfortunately, found out about four weeks ago after hiscattle grazed on the weeds that had come up among some pasturegrasses.

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“We lost six cattle and then seven more had to be taken out anddried up,” Case said. The cows that were dried up were removingfrom the milking cycle. Case plans to have those slaughtered.

Case said there are strict guidelines regulating antibiotics inmilk and beef production, including a 28-day period before the cowscan be killed for slaughter.

“If they die before that 28 days, I just lost,” Case said.

After the third cow died, Case said he had a post mortem done inJackson by the state veterinarian. The procedure pointed to PerillaMint exposure.

“We started looking for the place and found exactly where theygrazed,” the third-generation dairy farmer said.

Lincoln County Cooperative Extension Service officials areurging farmers to be on the lookout for Perilla Mint, also known asBeef Steak Plant. It is extremely toxic to cattle, sheep and horsesand has been found in several fields in the county, said CountyAgent Perry Brumfield.

Brumfield described the weed as an erect herb with distinctivegreen or purplish-green leaves with toothed margins.

The plants emit a distinctive minty odor when mature. Leaves areoval shaped, two to five inches long and one and a half to fourinches wide. Another distinctive factor is that the stems aresquare.

Brumfield and Case said animals typically avoid the plants.However, Brumfield said chances of consumption increase if theplants are baled or harvested as part of forages.

Case’s cows came in contact with the plants due to dryconditions and while looking for something to graze. He said theyoung weed came up in Bermuda grass.

“The conditions were perfect to hurt them,” Case said.

Brumfield said affected animals show signs of respiratorydistress with grunting often heard during exhaling. Other symptomsinclude nasal discharge and elevated temperatures.

Case said it is often too late once the consumed weeds have beendetected. Brumfield said treatment is usually ineffective.

“It’s a terrible death,” Case said.

Case said two affected cows were caught two in time and wereable to be treated.

At the time of the outbreak, Case said he was milking 94 cattle.Due to the weeds, Case said he lost about 800 pounds of productionat what is typically a slower time in the milk industry.

“The economics of this business can’t take this kind of pressureon it,” Case said.

To prevent problems, Brumfield said farmers should avoidharvesting forages in areas contaminated with Perilla Mint.

Brumfield said the weed should be mowed before seeds areproduced in order to prevent livestock grazing and increased weedpopulation. He said several broadleaf herbicides should provide forweed control if applied timely and at the correct levels.

Case encouraged his fellow farmers to watch for the weeds andkeep their cattle away from it.

“I don’t want to see any of my neighbors fight with it the way Idid,” Case said.