WSU Extension

Hortsense

Caption: Raspberry spur blight
Photo by: R.S. Byther
  
print version| pdf version| email url    

Raspberry : Spur blight
(revision date: 2/26/2016)


Biology
In early April, pin-point size black fruiting bodies (perithecia) can be found in the gray affected areas of cane tissue. The fruiting bodies release ascospores, which infect leaves on both fruiting canes and primocanes. Brown necrotic spots with yellow margins form on fruiting-cane leaves when rainy weather lasts through late spring. Infected leaves become chlorotic and drop prematurely in severe cases. However, primocane leaves develop brown "V-shaped" lesions (with a yellow margin between the dead and living portion of leaves). The fungus then grows through the leaf stalk (petiole) and invades stem tissues around buds, turning them brown or purple. Buds on infected canes are more susceptible to winter injury, and fruiting laterals may be stunted. Infected areas become gray in winter. Spur blight is also found on Loganberry and Youngberry. The "Willamette" cultivar of red raspberry, while susceptible, suffers little damage and is considered "tolerant".
Management Options

Non-Chemical Management
  • Remove and destroy old fruiting canes after harvest.
  • Keep plant rows narrow.
  • Practice good weed control.
  • Control early primocane growth.
  • Plant resistant or tolerant cultivars.
Select non-chemical management options as your first choice!

Chemical Management


Spray at bloom or when shoots are 8 to 10 inches long. Repeat applications according to label instructions.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Captan 50% WP Fruit & Ornamental
    Active ingredient: captan  |  EPA reg no: 4-459
  • This list may not include all products registered for this use.
Images
    - hide images

+ Show larger images

 
Caption: Raspberry spur blight
Photo by: R.S. Byther
Caption: Raspberry spur blight
Photo by: R.S. Byther
Caption: Raspberry spur blight
Photo by: R.S. Byther
Caption: Raspberry spur blight spore tendrils
Photo by: L.J. du Toit