Several fungi cause canker diseases of raspberries and blackberries. Early symptoms of these diseases may include unusually colored, spotted or necrotic areas on canes, frequently centered around buds. Individual laterals may wilt when canes are completely girdled by cankers.
The three most commonly encountered canker diseases are anthracnose, spur blight, and cane blight.
Anthracnose cane blight
Anthracnose is most common on black raspberry, red raspberry and occasionally blackberry. Symptoms of this fungal disease (Elsinoe veneta) are most obvious on canes but may also occur on leaves and fruit.
Symptoms of anthracnose on raspberry canes begin as reddish purple round spots (lesions).
These later become sunken buff to ash gray spots with dark margins.
More information:
- Anthracnose of Raspberry and Blackberry– (Ohio State)
- Raspberry Anthracnose – (Purdue)
Cane Blight
Cane blight is a fungal disease which infects canes and girdles them, causing the upper portion of the canes to die.
More information:
- Cane Blight of Raspberries– (Ohio State)
- Cane Blight of Blackberry– (University of Georgia)
Spur blight
Spur blight, caused by (Didymella applanata), is a fungus that infects fruiting laterals of red and black raspberries, and blackberries, especially on the lower portion of canes where conditions are more favorable for disease development.
Individual laterals wilt, and at the base of the lateral is a brown or black lesion.
Infections can occur on primocanes as well, as indicated by lesions that already exist surrounding the dormant buds.
More information:
- Spur Blight of Red Raspberries– (Ohio State)
- Raspberry Spur Blight– (Oregon State)