The leaves become yellow or reddish-brown in color, sometimes the leaf blade grows, but does not thicken. Often all are affected on the infected shoot.
Mycelium develops under the cuticle, winters in the branches.
The marsupial layer (“ hymenia ”) is waxy, mealy, develops more often on the upper side of the leaf.
The sizes 33–80 × 14–20 µm, wide-elliptical, with a rounded or blunt tip and an extended base, are often deformed due to compression from the sides in a dense layer. Basal cells ( see article Tafrin ) are absent.
Ascospores quickly bud and are not usually detected, blastospores are narrow cylindrical or rod-shaped, measuring 3.5 × 1–2 µm or 1–1.8 × 0.5 µm.
The typical host is dwarf birch ( Betula nana ); in Scandinavia and on the Kola Peninsula, the downy birch ( Betula pubescens ) also becomes infected.
Taphrina bacteriosperma is found in Europe - in Fennoscandia , as well as in Iceland , Greenland and North America .
