Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Hazelnut (Corylus avellana) -- Bacterial Blight
 
Cause: Xanthomonas campestris pv. corylina, a bacterium that attacks buds, leaves, branches, and trunks. Occasionally it attacks nuts but seldom invades roots. Tree mortality due to this disease is commonly found in orchards the first few years after planting. The most serious phase of the disease is trunk girdling and killing of trees up to 8 or 10 years old; 1- and 2-year-old twigs are attacked and killed. The bacteria are spread by rain splash or the movement of infected nursery stock. Seed borne transmission has been reported but no data is presented to support the claim. Infections are indirect, through wounds or by bacterial invasion of blighted buds and shoots of current-season growth. The disease has been associated with high stress sites.
Symptoms: Small, angular or round, yellowish green, water-soaked spots develop on leaves, later turning reddish brown. Buds may turn brown and fail to leaf out. Shoots may develop but are infected.

The first infections on current-season stems consist of dark green water-soaked areas on bark, which turn reddish brown. Lesions may girdle stems and kill them. Dead leaves often cling to girdled stems a long time. Lesions or cankers may extend into the main scaffold or trunk. Use a pocket knife to determine the extent of canker development. Lesions may be wet and ooze in spring.

Exposed, discolored cambium originating from the top of the tree.

Notice the discolored cambium exposed in this picture of bacterial blight on an older tree. The canker does not go below soil line.

 
Cultural control:

  1. Plant disease-free nursery stock in early winter. Do not let roots dry out.
  2. Prune out infected twigs and branches. Make cuts 2 to 3 ft below affected branches. Sterilize pruning tools between cuts with shellac thinner (70% ethyl alcohol).
  3. Control sun scald during summer using a shield or white paint on trunks.
  4. Irrigate newly planted orchards, if possible, the first 3 years.
Chemical control: Apply sprays in late August or early September before the first heavy rains. If fall rains are heavy, apply another spray when 75% of the leaves have dropped. Note that most copper products do not allow use until after harvest.

  1. Bordeaux 6-3-100.
  2. Champion WP at 16 to 24 lb/A with 1 pint superior-type oil/100 gal water. Can be used only after harvest. 24-hr reentry.
  3. C-O-C-S WDG at 12 to 16 lb/A plus 1 pint superior-type oil/100 gal water. Can be used only after harvest. 24-hr reentry.
  4. Copper-Count-N at 10 to 12 quarts/A. Can be used only after harvest. 12-hr reentry.
  5. Cuprofix Ultra 40 Disperss at 10 to 15 lb/A. 12-hr reentry.
  6. Kocide 3000 at 7 to 10.5 lb/A plus 1 pint superior-type oil/100 gal water. Can be used only after harvest. 24-hr reentry.
  7. Lilly Miller Microcop at 2.3 Tbsp/1 gal water.
  8. Nordox 75 at 8 to 13 lb/A. Can be used only after harvest. 12-hr reentry.
  9. Nu-Cop 50 DF at 16 to 24 lb/A with 1 pint superior-type oil/100 gal water. Can be used only after harvest. Nu-Cop 50 WP can be used for organic production. 24-hr reentry.
References:
Moore, L.W., H.B. Lagerstedt, and N. Hartmann. 1974. Stress predisposes young filbert trees to bacterial blight. Phytopathology 64:1537-1540.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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