Every summer, poison ivy causes much suffering, yet it can be controlled. The rash is caused by a volatile oil produced by the plant leaves.
It is said that Indians immunized themselves to poison ivy rash by eating the leaves. I have had several cases called to my attention of people who were affected internally by this rash and were very sick from it for 3 to 6 weeks.
I would, therefore, not advise anybody to try to immunize himself in the Indian way. Susceptibility to this poison ranges from complete immunization to extreme susceptibility.
The effects of the poison are so uncomfortable and disastrous that people who do not know whether they are susceptible should avoid poison ivy.
How Poison Ivy Is Transmitted
The old idea that poison ivy is transmitted through the air is erroneous. You can, however, brush off the oil on your clothes while walking through the growth and then pick up the infection when undressing.
The chief method of infection is direct contact with the plant or its roots. Your dog or cat may walk through poison ivy, and you get it from the animal when you pat it.
Poison ivy is a wild plant. It cannot stand cultivation and will disappear as soon as the land is plowed. Our Horticultural farm had three stone walls covered with luxuriant growth.
Upon removing walls and plowing the land, the poison ivy disappeared so completely that even the first year after plowing, only two or three spears were found.
Poison ivy is a plant found only in waste places, along stone walls, in the woods, under trees that are never cultivated, and around rocks and ledges where the land cannot be plowed.
Using Weed Killers
It is sensitive to several weed killers — common salt, potash salts, borax, sodium chlorate, and other weed killers have been recommended in the papers.
All of them will kill poison ivy when used properly.
There are various objections to most of these weed killers. Sodium chlorate is very flammable and may cause fires. Common salt or crankcase oil will likely poison the land for years after its application. Some of the other treatments are expensive.
Ammonium Sulfamate Treatment
Undoubtedly the cheapest and most satisfactory treatment that has been tried in the tests at the Horticultural Farm of the University of New Hampshire is the ammonium sulfamate treatment. And bear in mind that ammonium sulfamate is very different from the fertilizer known as ammonium sulfate.
Ammonium sulfate is a very deliquescent salt — that is, if kept in a moist place, it will take water out of the air and melt away on you.
Ammonium sulfamate should be kept in a metal or wooden container and in a dry, warm place. In a damp cellar, it is likely to turn to water.
The proportions to use run anywhere from 1/2 pound to 1 1/2 pounds of ammonium sulfamate to one gallon of water.
For poison ivy, a pound per gallon of water is enough. The foliage of the poison ivy is sprayed so that it will be wet during the day’s heat.
The spraying can be done anywhere from June 1 to September 15. Thorough spraying, using a gallon of this material to 100 square feet of poison ivy, will eliminate 90% to 97% percent of the plants.
A follow-up in the second year to eliminate stray plants that have escaped the first spraying is advisable.
Ammonium sulfamate is an easy method of eradicating poison ivy. It doesn’t poison the soil; it doesn’t permanently injure the grass underneath the poison ivy; it makes no fire hazard; in fact, it is sprayed on a cloth to make the cloth fire-resistant; and it will not stain or bum your bunds or your clothing.
Its final effect on the soil is fertilizing it since ammonia is an excellent grass fertilizer. It will, however, corrode a cheap spray pump, which must be considered.
Wash out that $5.00 or $10.00 sprayer thoroughly after you are through spraying the poison ivy.
Where a town does spraying on a large scale, it is suggested that a fairly large air-tight tank be used and pressure obtained at filling stations.
A 25-to-50-pound pressure will be high enough to wet the foliage. The old-fashioned barrel pump sprayer also works well for this purpose.
Using Borax
Lately, the use of borax has been advised to kill poison ivy. We have not used this method at the New Hampshire Experiment Station. The recommended amounts are 10 pounds per square space rod or 1000 per acre.
For small areas of poison ivy, ordinary household borax could be used. This is spread over the poison ivy in much the same way that grass seed would be sown.
The borax should prove to be as efficient a killer as ammonium sulfamate. Applying it will lie much easier, but the material cost would be about the same.
Roofing Poison Ivy
I have found nothing better than pieces of roofing for killing patches of poison ivy under trees and shrubs.
I use the cheaper asphalt-based roofing that runs about 60 pounds to the roll. A piece 3’ by 4’ feet is easily handled and can be used over and over for years.
Lay it over the ivy, step on it if necessary to press it flat, and leave it there for several months. Poison ivy does not live long during the growing season without leaf growth.
The leaves can, of course, be kept hoed back as a means of killing the plant, but I prefer smothering with roofing.
For one thing, there is a risk of poisoning when the ivy is hoed out. For another, one often forgets the second and third hoeing necessary for its extermination.
44659 by J. R. Hepler