Canadian Havens from Hay Fever Author:none This publication presents up-to-date information on the incidence in Canada of ragweed pollen, the main cause of hay fever, and is intended to help sufferers plan their Canadian vacations accordingly. It describes the biology of pollen, the different kinds of ragweed, distribution of pollen causing hay fever, Ragweed pollen air indexes and contr... more »ol of Ragweed. Illustrated with black and white photos and drawings.« less