By TIM THORNBERRY
Kentucky Correspondent

LEXINGTON, Ky. — Forage has been a hot topic so far this year. A dry spring followed by lots of rain left fields full of clover causing problems for cattle producers and now with the first cutting of hay taking place, farmers are being urged to check for poison hemlock.

An invasive weed native to Europe, the plant was introduced as an ornamental in the U.S. in the 1800s and posses a threat as being potentially poisonous if ingested by livestock or humans in both its vegetative growth stages and when dry, according to information from the University of Kentucky (UK) College of Agriculture.

J. D. Green, UK extension weed scientist said the presence of the weed in pastures has been on the rise for the last few years.

“It’s been my observation in the last four or five years, especially, that it is a slowly growing progression of a plant that has been around for years typically in non-crop areas like fencerows that weren’t taken care of or abandoned areas of a field, but in recent years I’m seeing more of an encroachment to hay fields and pastures,” he said.

As that has happened there is more opportunity for the plant being harvested as hay, Green added.

“This is a classic example of one invasive plant problem that has gotten out of hand, but people may not be as alarmed about it as with other invasive plants because they may not know what it is,” he said. “There are no state laws that mandate control of it by landowners or along rights-of-way areas.”

In some ways the poison hemlock is replacing another invasive weed, musk thistle, becoming more commonplace said Green and growing in the same areas at the same time of the year.
Recognizing the plant, which isn’t always easy, is paramount in eradication efforts.

“It’s certainly a lot easier to recognize when it is in full flower,” said Green. “It is a fairly tall plant and produces white, showy-type flowers when it is in full bloom. The difficulty is learning to recognize the plant in its young vegetative growth stages because it will actually start germinating in the fall of the year.”

It then goes dormant in the winter months and starts as vegetative leaves in March and April and then into May it begins to elongate and come off the ground explained Green.

“The time to really control it is back when you can’t see it and it’s on the ground,” he said.

“Unless you know where your problem areas are or what you’re looking for, it’s not a plant you’ll readily see from a distance.”
Green noted that herbicides such as 2, 4-D can be applied during the plant’s vegetative growth stage in the late winter or early spring or with an herbicide treatment in the fall.

At this point in the season, it’s too late for herbicide application so producers can mow the plant before it produces new seeds, which occurs soon after flowering.

“As a whole, we usually don’t do a lot of spraying for weeds in pastures. We’re doing more than we used to, but it’s still not a widespread practice,” said Green.

He pointed out another important fact. In some cases, if a producer sprays a more mature plant in a pasture used by livestock, it might attact animals to the plant.

“Typically in a pasture situation, as long as there is other available forage to consume, animals tend to leave it alone, they don’t graze it,” said Green. “But say the plant is coming off the ground in the spring and it’s sprayed with a herbicide, (livestock) may be more tempted to consume the plant, and create some animal loss.”

And losses it will create since consumption of the plant is lethal. “This plant is one of the few plants that can kill livestock,” Green said.

According to information from the University of Georgia’s Center for Invasive Species and Ecosystem Health, “the seeds contain the highest concentration of poison. It contains highly-poisonous alkaloids toxic to all classes of livestock and humans. Human deaths have occurred from harvesting and consuming the roots as wild carrots or parsnips.”

In the event the plant has been cut during hay harvesting, Green warned that it still can be dangerous to animals even after it has dried.

“It is my understanding that even when the plant is dry, it can still maintain its toxic compound,” he said. “A few plants in a bale with other material to help dilute any potential effect may not be of any consequence, but the potential is there even when the hay is dry.”