Poisonous Weed Branches Out

April 14, 2010 05:04 PM
This spring the hillside beyond my house is covered with fern-like leaves that would make a florist green with envy. Unfortunately, this attractive foliage is also lethal.
Poison hemlock is a member of the parsnip or carrot family, but that's where the friendly family resemblance ends. The entire plant is toxic to humans and animals because it contains poisonous alkaloid coniine and other alkaloids. Purdue University weed specialists say in the spring, it's the young leaves that are most toxic—so it's important not to let animals graze on it and you should wear gloves it pulling it by hand.
J.S. Green, University of Kentucky weed specialist, says he's been watching poison hemlock gain ground over the past few years. "It's ordinarily seen along roadways, abandoned lots, fencerows and other non-cropland sites,” says Green.
"However, in more recent years, it's begun to expand beyond the roadsides and into pasture lands and hay fields.”
Mechanical control helps if you can prevent seed production, but I can tell you from experience that mowing didn't slow my patch down much.  Purdue University recommendations indicate control in grass pastures is more effective in the first year of the plant's life cycle. Typically, the weed is considered a biennial, producing leaves during its first year and flowering the second year.
Chemical controls generally involve products containing 2,4-D, glyphosate or dicamba. The challenge this time of year is protecting the surrounding vegetation when using nonselective products.

For More Information
Check with your local extension specialists for recommended controls for specific areas.

Read more about control measures:


You can email Pam Smith at psmith@farmjournal.com.

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