About Chondrostereum purpureum (Pers.) Pouzar
Chondrostereum purpureum is a pathogen that infects various, mostly deciduous tree species, including Acer, Aesculus, Alnus, Betula, Crataegus, Fagus, Larix, Malus, Ostrya, Picea, Populus, Prunus, Salix, and Sorbus. Its fruiting structure begins as a simple crust on wood, and later develops undulating, intergrowing brackets that grow up to around 3 cm broad, with a tough rubbery texture. While the fungus is actively growing, the edges and fertile lower surfaces of the brackets display a fairly vivid violet color. The upper surfaces are grey in appearance, sometimes with zonation, usually have a lighter edge, and are covered with whitish hairs. After one to two weeks, the fruiting body dries out, becomes brittle, and changes to a dull brown or beige color. Infected wood can be identified by its darker stained appearance. The spores are shaped like rounded cylinders, measuring approximately 5–8 μm by 3–4 μm. The hyphal structure is monomitic and has clamp connections. This fungus is often found on old stumps and dead wood, but it can also act as a serious parasite of living trees. In addition to plum trees, it attacks many other broad-leafed species including other Prunus, apple, pear, willow, poplar, maple, hornbeam, plane, oak, elm, lilac, and many more. It occasionally infects conifers as well, such as fir, spruce, and Thuja. Geographically, its distribution is roughly as widespread as its host trees, and it is common in woods, orchards, and tree plantations in temperate climates.
