Morelet, Scleroderris Canker. In 1964 the first cases where reported from plantations in Quebec. The chief mode of infection for this fungus is by windblown ascospores which takes place under moist conditions. Hosts become infected through wounded buds, shoots and needles. Infection occurs during the active growing period of the tree but the disease can not progress aggressively until winter when the tree is dormant and the environmental conditions are right.
Infected branches are usually dead the following spring.
The North American strain attacks young trees but rarely damages tree over 2 meters. It has been observed that the European strain produces few apothecia and ascospores in the field. In contrast, the North American strain produces numerous ascospores. Infected trees will not show clear symptoms until the following spring. In the spring look for brown or orange coloured needles.