Fire blight of raspberries in Alberta.
Fire blight (Erwinia amylovora) can cause major fruit loss in raspberry (Rubus idaeus) plantings in central Alberta, Canada. Cane health and flower production may look excellent early in the season and honeybee pollination activity may be high with the promise of a heavy fruit set. Unfortunately, a sparse berry crop in July may indicate that up to 90% of flowers were killed at or soon after fruit set. Blighted canes with "shepherd's crooks", typical of fire blight infection, may be hidden in the crop. Examination of new cane growth under the crop canopy may reveal blighted stems. Diseased canes rarely comprise >10% of the current seasons stand. The cultivar Boyne, which is commonly grown in Alberta, is highly susceptible, whereas cv. Honey Queen, a later maturing, gold-fruited cultivar, appears to be relatively immune to fire blight and rarely suffers fruit loss from this disease.