Phytophthora alni

Phytophthora alni subsp. multiformis was found on alder in many Central European countries. The first symptoms present tarry spots on the stem base, spreading of dead under-bark tissue along the trunk and dieback of trees in groups. Phytophthora is the genus within which almost all of species are parasites. According to taxonomy, they belong to the strain Oomycota which previously belonged to the family Myceteae (fungi), however, at present they belong to the kingdom Chromista (approximately since 1986). Most of the species produces sexual oospores able to survive for a long time (resistant to soil and climatic impacts) and at the same time to provide genetic variability for future generation (difficult fight by fungicides).