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Market Diseases of Apples, Pears, and Quinces
Fisheye Rot |
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Corticium centrifugum (Lev.) Bres.
Fisheye rot occurs on apples grown in the Pacific Northwest, including British Columbia, and also on those grown in the eastern United States. In all localities, fisheye rot resembles bull's-eye rot in general appearance. The spots may be only specks or up to 1 inch in diameter, but most of them are less than 1 inch unless several coalesce. The surface of a spot is usually brown and the center pale, but a spot may be cream-colored or uniformly brown. The rot is firm, the skin is tough and leathery, and the larger spots are sunken. The decayed tissues are spongy or stringy and do not separate readily from the healthy tissues. The rot is easiest to identify when accompanied by a surface growth of white cobweb-like mold. Fisheye rot differs from bull's-eye rot in being firmer, with tougher skin over the rot; in not having spore-bearing mold over the rot spot; and in having dry, spongy, or stringy decayed tissues. The occurrence of fisheye rot seems to be associated with an abundance of rainfall before and during harvest. In the East, fisheye rot frequently follows scab (see photo), which is favored by similar weather conditions. Fisheye rot, like bull's-eye rot, can develop at 30° to 32 °F, but only slowly, and is not often found in stored fruits until late in the season. No evidence has been seen that it can spread in transit or storage. The decay is most common on windfalls and perhaps on those apples hanging near the ground. The reason is that the causal fungus is present on decaying weeds or cover crops. Consequently, apples that have dropped to the ground should never be packed with fruits intended for storage, even when they are apparently sound. |
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