Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Raspberry -- Pseudomonas Blight
 
Cause: A bacterium, Pseudomonas syringae pv. syringae. Strains are found on many plants, including blueberry, cherry, apple, and pear. Outbreaks are usually associated with cold (31 to 33oF) moist weather. Succulent growth from high nitrogen is more susceptible when conditions favor infection. The disease on raspberry occurs occasionally in the Pacific Northwest.
Symptoms: Brown water-soaked spots on leaves and petioles of developing laterals or young shoots. In wet weather, spots enlarge rapidly, killing leaves and shoots. Brown streaks extend from these dead tissues down under the bark. If the infection does not fully girdle the stem, affected laterals show a characteristic downward bend. If infected laterals are not killed they are often stunted. Other diseases and problems on raspberry can have similar symptoms, which makes positive identification difficult.

Affected laterals show a characteristic downward bend.

The canker on this primocane is due to Pseudomonas.
 
Cultural control:

  1. Avoid overfertilization.
  2. Plant resistant cultivars such as 'Chilcotin', 'Newburgh', or 'Nova'.
Chemical control: Before fall rains and as a delayed dormant application.

  1. Bordeaux 12-12-100.
  2. Champ Formula 2 at 2.66 pints/A. Champion WP can be used for organic production. 24-hr reentry.
  3. Cuprofix Ultra 40 Disperss at 2.5 to 3 lb/A. 12-hr reentry.
  4. Kocide 3000 at 1.75 lb/A plus 1 quart/A crop oil.
  5. Nu-Cop 50 DF at 4 lb/A with 1 quart/A crop oil. Nu-Cop 50 WP can be used for organic production. 24-hr reentry.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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