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Anthracnose and Perennial Canker of AppleCausal Agents: Cryptosporiopsis curvispora; Cryptosporiopsis perennansBoth of these diseases can affect the limbs and trunks of apple, and to a lesser extent, pear trees. The cankers reduce the vigour of trees or limbs with resultant reduction of fruit quality, and can girdle and kill young trees. They are also a source of spores that can infect fruit and cause bull's eye rot in storage. While these canker diseases are rare in the South Okanagan, they can be a significant problem in the North Okanagan and in the Kootenays. Anthracnose canker is severe in most coastal orchards. Nursery stock is sometimes infected in the nursery, but may not show obvious symptoms until after planting. New anthracnose and perennial cankers are indistinguishable in appearance. Anthracnose canker can sometimes be confused with European canker.
Life CycleSpores from new cankers are spread by rain or overhead irrigation during the late summer and fall months, and initiate new infections that appear as cankers during April through July of the following year. Cankers that are allowed to overwinter produce airborne spores during the following spring and summer that can initiate new infections at a distance from the source. The airborne spores function mainly to initiate new infections, while the water-borne spores serve to intensify the disease in trees that are already infected.Cultural ControlPrune out and remove all cankers during winter pruning. Prune out any new cankers that develop on limbs and trunks as soon as they are discovered, and remove them from the orchard. Developing cankers often girdle 1-year-old wood; remove any shoots that wilt or die suddenly during April through July as soon as they appear. The cultivars Elstar, Empire, Gala and Sinta are very susceptible to anthracnose canker.Chemical ControlThere are no fungicides registered for control of anthracnose and perennial canker in Canada, and fungicides have not proven to be effective.February 2004
Return to Tree Fruit Pests and Diseases
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