Life cycle and pathological importance
of the genus Phytophthora
life cycle of phytophthora
(to enlarge)
Fungi of the genus Phytophthora (Greek: plant destroyer) are worldwide known as primary parasites of fine roots and causal agents of root and collar rots and bark cankers on young and mature specimens of hundreds of tree and shrub species. Many Phytophthora species belong to the most aggressive and most important plant pathogens of the world.
As a consequence of the root and bark damages the crowns of affected trees develop typical symptoms, eg. increased transparency, sparse ramification and stunted growth of lateral twigs leading to whip-like branch structures and clustering of leaves at the end of branches, and finally small-sized and often chlorotic foliage, dieback of branches and crown-dieback. Despite of lack of any scientific proof these symptoms are still erroneously assigned to air pollutants in the annual reports on forest condition of most European and German countries.
From a global perspective, more than 66 % of all fine root diseases and more than 90 % of all collar rots of woody plants are caused by Phytophthora species.