University of Vermont Extension
Department of Plant and Soil Science
Spring/Summer/Fall News
Article
POISON IVY
Dr. Leonard Perry, Extension
Professor
University of Vermont
Whether you garden, or just go
hiking along country roads and in natural areas, you should be
familiar with
poison ivy. Pets, and in particular
dogs, that run in natural and overgrown areas also can bring the oil
of this
toxic plant back on their fur to share with you. While animals
aren’t sensitive to poison ivy,
you may be one of the 85 percent of people that are allergic to this
groundcover and vining plant, which you already may have discovered
by
accident.
“Leaflets three, let it be” is a
phrase you may have heard, referring to the three leaflets of this
common plant
in eastern states (as well as the poison oak which is more common in
the
northwest and southeast states). The
leaflets of poison ivy which are up to several inches long, rather
oblong and
with pointed tips, shouldn’t be confused with the weedy box elder
small maple
tree (its leaflets have more pronounced indentations). Nor should
you confuse it with another common
vine, the Virginia creeper, with five leaflets.
Poison ivy can be an attractive
vine, growing on the ground or up trees.
Early spring growth is reddish, fall growth can be various shades of
yellow to orange. Rather inconspicuous greenish flowers in early
summer lead to
white, waxy berries in late summer. It’s
these berries that birds eat, spreading their seeds and so the
plants. Plants also spread by underground roots.
You should notice the woody stems
as well, having aerial rootlets giving the overall appearance of a
fuzzy
rope. Some gardeners, clearing out vines
in the fall after leaves have fallen,
end up tangling with this and its sap by mistake.
When the plant surfaces are brushed
against by person, animal or object, the toxic oil (urushiol,
pronounced you-ROO-she-all) is released. This causes the usual
skin rash that develops
in a few hours to several days. The rash
may have streaks, the skin itches (but resist scratching), and
rashes often
swell creating watery blisters. Although
painful at first, rashes will go away in a few weeks with the pain
and itching going
away sooner. Rashes spread only by the
active oil from the plant, not from touching the rash or blisters
and fluid
they create.
Some don’t get this rash the
first time they’re exposed to poison ivy; others need a high
concentration for
symptoms to develop; a few are lucky and are immune. Sensitivity
varies with several
factors—thicker skin (palms of hands) is less sensitive than thinner
skin
(faces); hairy or dark skin is less susceptible; a person sweating
is more
susceptible. Children become susceptible
by age 3, and are quite susceptible by age 12.
Obviously the best control is to avoid this
plant. But if you do find you’ve brushed against it, wash the oil
off with soap
and water as soon as possible—ideally under 10 minutes after
exposure. Make sure to clean under fingernails. Cold
water is best (it doesn’t open up skin pores as does hot water), and
alkaline
soap is said to break down the oil more effectively.
If just a small amount of oil is
on the skin, and you’re not near a sink, use one of the several
creams available
from drugstores containing hydrocortisone.
(I like to carry a tube in my gardening tool kit for exposure to
this
and other plants such as stinging nettle.)
Other treatments for mild rashes include antihistamine pills,
placing
cool wet cloths on the infected skin, taking a cool shower, or
taking a
lukewarm bath with baking soda. Once you’ve washed up or treated the
rash, wash
all clothing (separately from others) and tools or objects that also
may have
touched the poison ivy. The oil can
remain on objects, and so cause problems, for many years.
If you’ve contacted much poison
ivy without knowing, or are one of the few to develop severe
symptoms, contact
a doctor or poison control center immediately ( www.aapcc.org or
800-222-1222—a
good number to have handy on the fridge or by your phone). Severe
symptoms include extensive rashes,
rashes on the face or tender areas, fever, or signs the rash is
becoming
infected. Prescription medicines are
available for severe cases. If you have
problems breathing and swallowing, go to an emergency room at once.
To get rid of this plant in
landscapes, make sure to wear long sleeves and pants, gloves (heavy
duty vinyl
or nitrile, not cloth or rubber which the oil can penetrate), and
even face
protection. If your dog has played among the ivy, use such
gear too when giving the bath. Pull
roots from the soil or they’ll resprout.
Herbicides can be used, just make sure to get the correct ones and
follow all label directions. Above all,
make sure not to burn poison ivy, or even wood and firewood that may
have the
vines attached. The oil can be carried
by the smoke, causing major eye and respiratory problems.
Photos to recognize poison ivy, as well as more
tips, are available from the University of Connecticut IPM program
(www.hort.uconn.edu/ipm). Photos of this plant, its rashes, as well
as photos
of poison oak and poison sumac, can be found easily with a search at
the
American Academy of Dermatology website
(www.aad.org/skin-conditions).
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