Blackberries can suffer from virus-like problems that may be caused by cool weather, late spring frost, powdery mildew, mineral deficiencies, or feeding by leafhoppers, aphids, and red spider mites. Identifying which one may require local advice.
Your canes could be suffering from Verticillium wilt, a fungus that will cause leaves to turn yellow, wilt, and fall off. Did you plant the canes where potatoes, tomatoes, eggplant, peppers, squash, melons, strawberries, stone fruit trees were grown in the past? Your problem could stem from the verticillium being in the soil from any of those. Remedies include fumigating the growing area or planting it with a nonhost crop (not one of the vegetables listed) for three or four years.
Blackberries can suffer from virus-like problems that may be caused by cool weather, late spring frost, powdery mildew, mineral deficiencies, or feeding by leafhoppers, aphids, and red spider mites. Identifying which one may require local advice.
Your canes could be suffering from Verticillium wilt, a fungus that will cause leaves to turn yellow, wilt, and fall off. Did you plant the canes where potatoes, tomatoes, eggplant, peppers, squash, melons, strawberries, stone fruit trees were grown in the past? Your problem could stem from the verticillium being in the soil from any of those. Remedies include fumigating the growing area or planting it with a nonhost crop (not one of the vegetables listed) for three or four years.