Horticulture : News
DATE: July 20, 2010
HARDIN COUNTY COOPERATIVE EXTENSION SERVICE
201 Peterson Drive
Elizabethtown, Kentucky 42701-9370
BY: Amy Aldenderfer
County Extension Agent for Horticulture
Poison Ivy Spoils the Last Days of Summer
Uh-oh. What's that nasty three-leafed weed hanging out in the hostas and climbing up the hollies? And is it just our imagination, or is poison ivy showing up in more places and growing faster than usual this summer?
"All that rain early in the season probably did help it along a little bit," said Jim Martin, Extension weed scientist for the University of Kentucky College of Agriculture, "but it's a pretty prolific plant in Kentucky anyway. However, the weather has been favorable for a lot of perennials this year, and unfortunately that includes poison ivy."
Some people are so sensitive to poison ivy that the slightest contact causes blisters and swelling, while others can pull it up barehanded with little or no adverse effect. The different reactions arise from varying degrees of allergy to an irritating oil found in poison ivy's leaves, vines, and roots.
It's also possible to come in contact with the oil, or "urushiol," without touching any part of a poison ivy plant.
It can get on your pets' fur and when poison ivy burns, there's oil in the smoke too.
Poison ivy can be identified by careful leaf-counting. Martin says all poison ivy leaves are composed of three leaflets. Some poison ivy plants may also have clusters of whitish-green drupes, a berry-like fruit that serves as a winter food source for birds.
"Hand removal or digging it up with a shovel is good," Martin said, "but wear gloves, and throw them away when you're done." Then scrub up with an alkaline soap like old-fashioned bar soap.
If you're uneasy about handling poison ivy at all, a lawn mower or string trimmer may be your best defense. "You can just keep mowing it down," Martin said, "And you'll eventually kill the plant by starving out the root system."
Poison ivy can be controlled in grassy areas using 2,4- D. Selective spraying with a 2 percent solution of Roundup or other products containing glyphosate will usually kill poison ivy after the second or third application, but Extension weed specialist Martin stressed that herbicides are a method of last resort. "In a home landscape situation," he said, "chemical control is just a risky proposition."
"It's also a little late in the year to use herbicides," Martin said. "Glyphosate is most effective in June and July." He added that late-season treatments can still provide some help in managing the weed, but they must be applied before poison ivy's leaves turn red.
Whether you dig, pull, mow or spray, the roots of poison ivy have to go. "It's a perennial, and it's not easily controlled," Martin warned. "If you don't get rid of the roots, it's probably going to come back."
For more information about caring for your home landscape and gardens, contact your Hardin County Cooperative Extension Service by phone: 270.765.4121, email: Amy.Aldenderfer@uky.edu or via website: www.hardinext.org .
Educational programs of the Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability or national origin.
NOTE: Applications are being accepted for the 2010 Master Gardener Volunteer Program until
August 1, 2010. Contact the Hardin County Extension Office for more information at 270.765.4121.
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