BENTON COUNTY — The tall plants with lacy white flowers that fill many ditch banks and fields around Decatur and Gentry may look innocent, but they have a sinister side.
Poison Hemlock, or Conium Maculatum, is the plant associated with Socrates death, according to Benton County Extension Agent Robert Seay. Poison Hemlock has been in Benton County for at least three decades and is becoming more widespread by the year. In fact, hemlock may replace thistle as the “number one poster weed” if it continues to spread as fast as it has within the last 10 years, Seay said.
Poison Hemlock starts growing in the early spring and usually grows for two years but can be a perennial in favorable conditions, according to the United States Department of Agriculture Web site. The plant grows along fence lines, in ditches or other moist places. It can reach 6 to 9 feet tall and has a hollow stem marked with small purple spots. The leaves are delicate like parsley, and the plant has white flowers that develop into a green, deeply ridged fruit, according the Web site.
All parts of the plant are poisonous, and leaves are especially poisonous in the early spring, according to the USDA. Children have died from using thehollow stems as whistles, the Web site states.
Pin-pointing the level of associated toxicity problems has been difficult, Seay said, but the few reports he has received have been associated with horses, rather than cattle.
“It’s increasing presence in pastures and hay fields raises the question, ‘Why aren’t we seeing more animal health issues?’ One thought is that they may be occurring, but the blame is passed off on other possible causes,” Seay said.
“I’m satisfied that, like a few other plants, taste is a primary factor since animals apparently do not readily graze hemlock. That doesn’t mean they won’t, especially when other forage becomes in short supply, due to overgrazing, etc. That may be one reason that horses are the primary animal of concern since horse pastures are often the ‘perfect picture’ of overgrazed conditions. All animals have a daily dry matter requirement and will try to fill it regardless of the source,” he said.
When livestock do eat Poison Hemlock, the results are often fatal, according to the USDA. Sheep can be poisoned by eating as little as 100 to 500 grams of green leaves, and cattle can be poisoned by as little as 300 to 500 grams - or roughly a pound - of leaves. Signs of poisoning usually appear within an hour, and the animal usually dies of respiratory paralysiswithin two to three hours after ingestion, according to the USDA.
Seay said that he has spoke with several area veterinarians and has observed that Benton County has yet to see any major health problems caused by hemlock but notes that he hasn’t spoken with any veterinarians about the issue in over a year.
Herbicides can be used to control hemlock on farms and rural acreages, according to Seay. The extension office has conducted local herbicide treatment studies for poison hemlock studies in previous years and have one out this year, he said.
“Bottom line: Hemlock is not difficult to control with herbicides, but like most weeds, control is better and less expensive if plants are treated early in the spring,” he said.
News, Pages 11 on 06/30/2010