Answer: The technical term for the symptoms you describe is "Orange Rust", caused by Arthuriomyces peckianus, and it affects blackberries and raspberries. It's a fungus that attacks the entire plant, with fruiting spores (the orange rust)appearing on the undersides of leaves. Because it's a systemic disease, your raspberry plant will eventually die. You might be able to nurse the plant along this season by picking off the affected leaves, but all the canes and the roots of this plant should be removed from the garden.
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