NATIVE RANGE: Severna Amerika

FIRST FINDING IN SLOVENIA: not yet found in Slovenia

PATHWAYS: transported with wood and bark

POSSIBLE TO FIND: yearround

DESCRIPTION: The first symptom of the disease is wilting and dieback of the canopy. The bark peels off in rectangular pieces and long strips. Underneath the peeling bark, there may be a large quantity of soot-like brown-black spores, which are dispersed by wind. When spores are washed down by the rain, the lower part of the trunk and nearby plants are coloured black. Due to the infection, the heartwood colours greenish-brown. The fungus spreads from the wood towards the bark. It is usually non-pathogenic, but causes damage to maples in periods of drought and heat stress.

HOST PLANTS: All species of maples (Acer spp.) and birch (Betula spp.). Sycamore (A. pseudoplatanus) is the most susceptible.

STATUS: The disease has been found locally in several European countries.

SIMILAR SPECIES: When large amounts of soot-like spores are present, it cannot be mistaken for any other disease. Heartwood may be discoloured due to infections with a variety of wood-rotting fungi.

SOURCE: Field Guide to Invasive Alien Species in European Forests