Graft-transmission of Blister Bark and Internal Bark Necrosis in Delicious Apples1

in HortScience
C. L. ParishU. S. Department of Agriculture, Science and Education Administration, Agricultural Research, Fruit Research Laboratory, Wenatchee, WA 98801

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Blister bark, a scaly bark-type disorder of ‘Delicious’ apples (Malus domestica Borkh.) is shown to consist of 3 similar disorders. Two of these, blister bark 1 (the one most commonly encountered in the Northwestern United States) and blister bark 2, are graft transmissible. The 3rd disorder, blister bark 3, was not transmitted. The symptoms are described and the differences discussed. Another bark disorder, a form of internal bark necrosis, is shown to be graft-transmissible. A key to differentiate the blister bark complex is presented.

Contributor Notes

Received for publication May 27, 1980.

The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.

Plant Pathologist. I wish to acknowledge the photographic assistance of Peggy Burts (now deceased).

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