Raspberry Cane Blight
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Raspberry Cane Blight .jpg) Raspberry Cane blight is caused by 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. Susceptible Plants- Raspberry, blackberry, strawberry, and hybrid berries. 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. Canes become brittle. Prevention and Control:-Remove infected canes. Prune black raspberry in dry weather to force lateral growth so wounds will dry. Prune near the ground; the fungus overwinters on cane stubs. Minimize or adjust irrigation so plants are not wet long. Switch to drip/trickle irrigation. Irrigate in the early morning to minimize the period that plants remain wet. Practice early-season primocane control. Use the alternate-year fruiting system for blackberry. If canes are infected cut back to below soil level. Burn all infected material. Disinfect tools after use. Keep plantings free of insects, since they may cause wounds that serve as entry points for the fungus. Avoid any other pests or cultural practices that result in wounding of the canes. Fungicidal Control- If raspberry cane blight is a serious problem, the use of fungicides such as a Copper 4E Fungicide
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