| Apple -- Green Crinkle Disease |
| Cause: This disease is caused by a unknown, graft-transmissible agent. All trees exhibiting this serious disease are infected with Apple stem grooving virus, Apple stem pitting virus and Apple chlorotic leafspot virus. It is not known if the disease is elicited by a combination of one or more of these viruses, a particular isolate of one of these viruses, or a separate, unidentified pathogen. The disease appears not to spread in the orchard. If it does spread, it does so very slowly, and possibly by root grafting. |
| Symptoms: On sensitive cultivars, the fruit will develop deep depressions and distortions that increase in severity as the fruit matures. Cracks may develop in the pits and crevices. Severe fruit symptoms may appear on one or two limbs of an infected tree. There are no leaf symptoms associated with this disease. Fruit symptoms may be distinguished from insect stings by the appearance of discolored vascular tissue extending from beneath the pits to the vascular bundles of the fruit. These strands are not associated with insect stings. |
| Cultural control: Use only virus-tested (and found to be free of all known viruses) planting and propagation material. |
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References: Thomsen, A. 1989. In: Virus and Viruslike Diseases of Pome Fruits and Simulating Noninfectious Disorders. P. R. Fridlund, ed. Washington State Cooperative Extension, Pullman, WA. Publication SP0003. |
| Content edited by: Ken Eastwell on January 1, 2009 |
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