Notes on Raspberry Diseases
Cane blight
Identification
Cane blight is a serious raspberry cane disease in Ontario. Diseased
canes may die during the winter or they may leaf out erratically in the
spring. Infected canes, initially healthy in appearance, may die-back
above the point of infection just as harvest begins.
Period of Activity
The pathogen enters primocanes or first-year growth, through wounds and
spreads up and down the vascular tissue, which causes the cane to become
brittle and weak. Symptoms are most evident the next spring. Severely
infected canes do not leaf out in the spring because they are unusually
brittle and snap or break easily. Infected canes may leaf out and then
die back before harvest.
Monitoring
Symptoms of cane blight look similar to those caused by cane and crown
borers. However, cane blight can be diagnosed when you scrape back the
bark of infected canes to expose the vascular tissue. The diseased vascular
tissue beneath the bark is distinctly brown instead of green. Check the
crown and roots for borers, nematodes and diseases, which compound the
problem.
Management notes
- Prevent injury to primocanes from rubbing against trellis wires, by
machine harvesters or by summer pruning. These injuries are susceptible
to cane blight infection. Primocanes can also be wounded when they rub
against old canes pruned too high above the ground.
- Carefully prune out old fruiting canes close to ground level when
canes are dormant.
- Avoid pruning or tipping when plants are wet or just before a rain.
Learn more...
