Both poison oak and poison ivy are readily identified by their leaves, which are divided into three leaflets. Shiny when young, the leaflets usually range from half an inch to two inches long, although poison oak leaves may be larger. Flowers are greenish white, about a quarter-inch across and are borne in clusters in the leaf axils. The fruits are white, berrylike, glossy and dry when ripe, about a sixth of an inch in diameter in poison ivy and a little larger in poison oak. All parts of poison oak and ivy except the pollen are poisonous, year-round.
Human reactions vary from extreme susceptibility to near immunity.
And people may become allergic later in life after repeated exposure. Pets, especially dogs, are another source of the irritating oil, said Ball. If they wander through an infested area, they can carry poison oak or ivy's urushiol into the home to their unwary owners. To control poison oak or poison ivy on your property, Ball offered three possible strategies - pull or dig out the entire plant, graze goats in infested areas or use chemical control. Burning is not recommended as inhaling dust and ash from the smoke can result in poisoning of the lungs that can require hospitalization.