E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Taphrina populina causes golden yellow leaf spots on cottonwood and aspen in BC (Callan 1998). Taphrina populi-salicis Mix causes golden yellow leaf spots on cottonwood and willow in British Columbia (Allen) and is found in Oregon and California as well (collections at NYBG). "Taphrina may live saprophytically in a yeast-like phase, overwintering on dormant bark and buds. Spores from the yeast phase are spread by wind and rain during the spring after bud break, when they infect young leaves before the cuticles has hardened." (Callan from Mix 1949). The first signs of infection are swollen, cupped, round to oval blisters, 0.5-several centimeters across on leaves in spring. The blisters turn golden yellow as asci mature on the undersurface of the leaf. Infected areas may be colonized by secondary molds and yeasts, becoming reddish or blackened late in the growing season.

includes BC

Fruiting body:
There are no fruiting bodies as asci occur naked and form a single tightly packed layer on the yellow blister surface. (Callan)

Microscopic:
spores 4-6.5 x 4-5 microns, round, colorless; asci 30-122 x 13-30 microns, (Callan), no paraphyses (Funk)