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Updated: Tuesday, November 18, 2003 11:02
(causal agent: Plum pox polyvirus)
Synonym: Sharka.
Severe symptoms have been observed on apricot, plum, and peach trees. The disease tends to be latent in cherry trees, rarely showing symptoms.
Symptoms first appear on new leaves as random vein clearings or oak-leaf patterns bordering the main and secondary veins. Oily patches or green spots develop into characteristic spots, ringspots, and bands of different sizes. Symptoms become less visible during summer, but may remain until autumn. The woody parts of some cultivars may flatten, crack, and become cankerous as the bark , phloem and xylem tissues turn brown.
Fruit symptoms include blue-colored, shallow depressions, which intensify as the fruit ripens, and lead to deformations. Deep rings or irregular lines form on surface. Epidermal tissue and underlying cells turn necrotic, the flesh darkens and is saturated by gum, which penetrates the stone.
Summary: Nemeth 1986
