Pacific Northwest 1998 An Online Guide to Plant Disease Control

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Raspberry -- Cane Blight
 
Cause: Leptosphaeria coniothyrium, a fungus. Cane blight may weaken fruiting canes of red raspberry. It may attack black raspberry at points where canes have been snapped off or pruned to force lateral growth. 'Boysenberry', 'Loganberry', and 'Youngberry' canes are seldom infected with cane blight unless canes are first frozen, pruned, or mechanically damaged. This pathogen invades wounds; those from fruit-catching plates of mechanical harvesters have resulted in primocane infections. Rain or overhead irrigation at harvest has increased disease incidence because spores are disseminated in splashing water.
Symptoms: The fungus invades through wounds such as from a mechanical harvester or, on some red cultivars, yellow rust lesions near the ground. The infected area flattens and may crack open. On trailing berries, blighted canes turn gray and often show black specks containing the fungal fruiting bodies (pycnidia).

Diagnostic lesions are internal. Scrape the affected cane with a knife to expose vascular tissue. Healthy tissue should be moist and light green; the canker will be orangish red. Vascular discoloration generally extends above and below the external wound.

Cultural control:

  1. Remove infected canes.
  2. Prune black raspberry in dry weather to force lateral growth so wounds will dry.
  3. Prune near the ground; the fungus overwinters on cane stubs.
  4. Minimize or adjust irrigation so plants are not wet long. Switch to drip/trickle irrigation.
  5. Irrigate in the early morning to minimize the period that plants remain wet.
  6. Practice early-season primocane control.
  7. Use the alternate-year fruiting system for blackberry.
Chemical control: Direct spray to the cane's base during or immediately after harvest or during pruning.

  1. Captan is registered for raspberry but has not effectively controlled this disease.
References:
Punithalingam, E. 1980. Leptosphaeria coniothyrium. CMI Descriptions of Pathogenic Fungi and Bacteria, No. 663. Surrey, England: Commonwealth Mycological Institute.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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