| Cane blight of raspberries is a late season disease
caused by the fungus, Leptosphaeria conithyrium.
Infected canes may blossom normally, but they
usually wilt and die before they can set fruit or
while they are heavy with fruit. Black raspberries are
more susceptible than red or purple raspberries.
Cankers on apples and roses are also caused
by this fungus.
Symptoms and Diagnosis
Brown-purple areas develop around cuts or wounds
in infected canes. The discoloration will slowly
spread down the cane, encircling the stem. Small,
smutty patches of olive-green fungal conidia (spores
or conidiospores) develop on the bark. The spread of
the disease through the canes blocks water
movement through the plant, causing wilting and,
eventually, death. Cane blight reduces yields
because symptoms appear later in the growing
season, when branches may be laden with fruit.
Life Cycle
Spores of the fungus overwinter on dead infected
canes. In the late spring, fungal spores are spread
from plant to plant by the wind and splashing water.
Infection takes place when there is sufficient
moisture allowing the spores to enter the plant
through wounds. Spores may continue to live on
dead, infected canes for 2 or more years.
Integrated Pest Management Strategies
1. Prune and destroy all infected stalks. Blighted
canes cannot be cured.
2. Do any pruning work during dry weather to
allow wounds to dry out and prevent infection by
the fungal spores.
3. Prevent damage and wounds to canes by
controlling cane borers. Vigorous, adequately
fertilized and watered plants are more resistant to
injury and less likely to attract harmful insects. If
borers have infected canes, the tips will begin to
wilt; prune these tips well below any insect
punctures.
4. Plant resistant varieties. Red-fruited or purple
varieties of raspberry are less susceptible to
cane blight.
5. Use fungicides. Pesticides registered for use
include copper and mancozeb. | 
