Answer: Sounds suspiciously like Raspberry Streak. This problem, caused by tobacco streak virus, is generally a minor, but widespread disease. The most obvious symptom of the disease is numerous purplish streaks that appear on the lower parts of infected canes. Usually, the streaks are less than an inch long. Terminal leaves on infected canes are often hooked or recurved, twisted or rolled, and darker green than normal. Leaves on the lower positions of the cane may show yellowing along veins and mottling. Fruits on infected canes are smaller than normal, dull, seedy, and crumbly and lack flavor. The individual drupelets often ripen unevenly, giving the fruit a blotched appearance.
If the above symptoms describe your raspberry plants, you'll want to remove and destroy in affected plants so the problem doesn't spread to your entire raspberry patch.
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