Site character and infection hazard for the sweetfern rust disease in northern Ontario.

The vegetative and physiographic site characters of jack pine Pinus banksiana stands, and their relation to the hazard of infection by sweetfern rust disease Cronartium comptoniae were investigated. Cankers caused by the disease were prevalent only when the alternate host, sweetfern Comptonia peregrina was present, and the percentage of pine with cankers was principally a function of the abundance of sweetfern. Models for predicting sweetfern abundance indicated an affinity for dry sites that are low in certain soil nutrients. -Authors