Notes on Raspberry Diseases
Verticillium wilt (bluestem)
Identification
Two related soil-borne fungi cause Verticillium wilt. The fungi infect
plants through roots, which eventually colonize and plug the vascular
system. Leaves develop a dull green colour, dry up and drop. This begins
at the bottom of the plant. Frequently, only canes on one side of infected
plants wilt or show symptoms. A blue or purple streak on the stem is characteristic
of this disease. Black raspberries are much more susceptible to verticillium
than red -raspberries.
Period of Activity
The disease infects in cool weather, especially in poorly drained soils
or after wet springs. The symptoms develop in warmer weather and are associated
with periods of water stress or crop development.
Management notes
- Fungicides are not effective for the control of -verticillium.
- Purchase disease free plants grown according to accredited plant propagation
guidelines.
- Do not plant raspberries after tomatoes, potatoes, eggplants or peppers
because these crops are good hosts for the pathogen. Do not replant
raspberries where verticillium has been a -problem.
- Soil fumigation before planting raspberries provides good control
on soil types suitable for fumigation.
- If the problem occurs on red raspberries, cut out and destroy infected
canes. On black and purple raspberries, dig out and destroy infected
plants.
- Resistant cultivars are not available.
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