Phytophthora alni

(Phytophthora disease of alder)

This disease, first described in southern Britain in 1993, is specific to alders (Alnus spp.) including the native A. glutinosa. By 2003, in a survey of riparian alders, 15% had been killed. The disease may be a new hybrid of native Phytophthora spp. or be native to Alaska. Symptoms include a black bark exudate near the base of the tree, and in the vicinity of the exudate a reddish discoloration between the bark and the wood.



This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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