Iverson provided a book with some information about poison ivy that I'd like to pass along. According to "Edible, Medicinal, Useful, and Poisonous Wild Plants of the Northern Great Plains-South Dakota Region" by Dilwyn J. Rogers, all parts of the poison ivy plant may cause a severe inflammation of the skin from contact or breathing in the smoke of burning plants.

People become increasingly susceptible with repeated exposure but it is apparently not poisonous for livestock to eat. Children have developed digestive tract irritation from eating the white berries.

Studies indicate that laundry soap, epsom salts, baking soda, boric acid, and many commercial preparations are available to help dry up the rash and soothe the itching.

According to the American Dermatology Association, poison plant rash causes an allergic inflammation caused by contact with the oil, urushiol, which is found in the sap of poisonous plants like poison ivy, oak or sumac. It is a colorless or pale yellow oozing from the cut or crushed part of the plant.

Contact can take place in one of three ways: direct contact by touching the sap of the plant; indirect contact by touching something else that had come in contact with the poisonous sap such as a dog, an article of clothing, gardening tools; and airborne contact by breathing in the fumes of burning plants.

Iverson knew about a compound called poison ivy tincture available through a pharmacy in Iowa. I spoke to Susan Ellsworth, who makes the compound at Sun Pharmacy in Johnston, Iowa. She said the liquid tincture is taken orally by mixing about 15 drops in a glass of water.

"It takes about three weeks to build up an immunity in the body," Ellsworth said. "It seems to work; people come back year after year. People that used to get it often get just a light case of the rash. The mixture used to be available on the market, but the FDA (Federal Drug Administration) required extensive testing and instead of going through the process, they (the company manufacturing the product) pulled it off the market. I think we're probably the only pharmacy in the area that sells it."

Ellsworth is checking with her employer to see if they will provide the ingredients, or even the recipe, for the compound.

Updates

An update: Bonnie from Sunshine Garden asked me to clarify an item from my column of June 2: hardy roses have no graft. The sentence should have read: "Hiniker recommends that Minnesota hardy roses be planted 3-inches deeper than they are in the pot as they will form more of their own roots.

In response to my mum article last week, she indicated that the Clara Curtis lavender mum is very hardy in our area and attracts bees. Hiniker also mentioned that her tree peonies are now in bloom.