GARDEN COLUMN FOR THE SALISBURY POST
Darrell Blackwelder
May 17, 2002
Home gardeners and others with outdoor activities
unfortunately
come in contact with poison ivy. The plant contains powerful
compounds which produce a painful rash, in some instances severe
enough to hospitalize those that have extreme allergies.
Identification and control of poison ivy is one step in prevention of
dermatitis.
Poison ivy is usually found as undergrowth in woods, fence rows,
recently cleared lots or growing as a vine on trees. The plant may
also grow as a lowgrowing shrub. The stems of poison ivy are smooth
with a light brown to gray color. Poison ivy is an attractive vine
with dark, green, shiny leaves with broad serrated leaf margins. The
leaves are trifoliate, or in groups of threes producing graywhite
berries 1/4 inch in diameter. The berries are a favorite food of
birds, therefore the plant is found almost everywhere. Underground
stems or rhizomes is another method of reproduction.
The poisonous substance which causes skin rash found in the
leaves and stems is called urushiol. The poisonous substance is also
found in all parts of the plant: roots, bark, berries and stems.
Urushiol is an oily substance that does not dissolve in water and is
not volatile. Physical contact is necessary to obtain the poisonous
oil and cause a skin rash.
Susceptibility of dermatitis depends upon the individual,
however,sensitivity can change. Those that are not affected at one
time may be affected later.
Minute amounts of the oil can cause a rash penetrating skin
tissues in ten minutes after contact. Two weeks may pass before
symptoms to appear.
Contact with the oil may occur indirectly by smoke, pets,
clothing, garden tools, golf clubs, guns or fishing rods. Splashing
sap from stems and twigs when cutting trees is often a source during
the winter months while cutting firewood. Research has proven that
the oil can remain active for months on objects. Dead plants can
still cause allergic reactions for a couple of years!
Shower with warm water and plenty of soap when working or
playing near heavy infestations of poison ivy. It is important to
bathe immediately after contact. Avoid using complexion soaps that
contain oils. These types of soaps may actually spread the poisonous
oil.
Now is an excellent time to control poison ivy. The best
time
to control poison ivy is in early spring and summer before bloom.
Brush killers or herbicides that contain dicamba or trichlopyr should
be sprayed to runoff to effectively control poison ivy. Herbicides
that contain glyphosate (Roundup) also kills the vine, systemically
destroying underground rhizomes. Wear long sleeved shirts, long pants
and protective gloves(plastic disposable gloves are ideal) when
working in patches of poison ivy.
Follow instructions provided by the label before application of
any pesticide. Contact the Cooperative Extension Service at 704-
6330571 if you have questions about application or control using pesticides.
Darrell Blackwelder is an agricultural agent in charge of
horticulture with the North Carolina Cooperative Extension
Service in Rowan County. For archived garden columns or other
information visit the Master Gardener Web site at
www.rowanmastergardener.com or email
darrell_blackwelder@ncsu.edu.