Phytophthora strikes again

摘要

The genus Phytophthora has caused much death and destruction of plants and, indirectly, of humans, through the ages. The deadly potato blight that destroyed potato crops in Ireland in the 18th century and caused the death by starvation of perhaps a million people and the migration of many, was a Phytophthora. P. cinnamoini, known as Jarrah dieback, kills many plant species as well as jarrahs. Now there is a new bully on the block - P. ramorum - that is devastating oak trees and more than 30 other species in North America and Europe. The pictures below show typical wilting, bleeding and bark cankers of infected trees. Leaves also show characteristic spots.