Biscogniauxia nummularia decline of European beech ("Fagus sylvatica") in Sicily and Calabria (Italy) has been linked to "B. nummularia" and experiments have suggested that this ascomycete plays a primary pathogenic role under certain environmental conditions. It typically causes strip‐cankering and general wood decay. Biscogniauxia nummularia Biscogniauxia nummularia is a plant pathogen in the family Xylariaceae, known as the beech tarcrust. The specific epithet is derived from the Latin "nummus" meaning a coin, referring to the often rounded and coin-like encrustations. The fruit body forms a thick and shiny black crust, on beech ("Fagus") bark and is found at all times of the
Fagus sylvatica in the buds. In autumn, the tree builds the reserves that will sustain it into spring. Given good conditions, a bud can produce a shoot with up to ten or more leaves. The terminal bud emits a hormonal substance in the spring that halts the development of additional buds. This tendency, though very strong at the beginning of their existence, becomes weaker in older trees. It is only after the budding that root growth of the year begins. The first roots to appear are very thin (with a diameter of less than 0.5 mm). Later, after a wave of above