Orange rust—Gymnoconia nitens and Arthuriomyces peckianus
Plants infected with the orange rust fungus have orange, blisterlike pustules covering the undersides
of leaves in the spring. Diseased shoots may recover by midsummer, but developing canes are smaller than
normal and bear no fruit the following year. Red raspberries are not affected.
The fungus that causes orange rust is systemic and remains in the host plant. Remove and destroy infected
plants, including the roots. Fungicides are of little value.
rust pustules on blackberry leaves