Tree rusts are fungal diseases causing dusty orange, brown or black spots (pustules) on the leaves of poplar, willow, birch and plum, and cankers on the stems and branches of five-needled pine.
Scientific name Various
Plants affected Mainly Populus spp. (poplar), Salix spp. (willow), Betula spp. (birch), plum and Pinus spp. (five-needled pine)
Main symptoms Orange or brown pustules
Caused by Fungi
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