Bull’s Eye Rot

Bull’s eye rot occurs on both apples and pears in the U.S. Pacific Northwest. In Washington State, Bull’s eye rot is more commonly seen on Golden Delicious, particularly on apples from orchards with perennial canker problems on trees. Bull’s eye rot also occurs in Europe and some other fruit-growing regions.

Symptoms:
Bull’s eye rot lesion is circular, flat to slightly sunken and appears light brown to dark brown with a lighter brown to tan center. Decayed tissue is firm. Cream-colored spore masses in the aged decayed area may appear (Fig. 6). Bull’s eye rot commonly originates from infection at lenticels on the fruit skin, but stem-end Bull’s eye rot is also commonly seen on Golden Delicious and Gala apples, particularly on the fruit from orchards with over-tree evaporative cooling or irrigation. Calyx-end Bull’s eye rot has also been observed on Golden Delicious fruit.

Causal Organism:
Four species of Neofabraea are known to cause Bull’s eye rot on apples. Three species, N. albaN. perennans, and a Neofabraea sp., have been reported to cause Bull’s eye rot on pears in the Pacific Northwest.

Occurrence:
N. perennans causes perennial canker on apple trees. On pear trees, Neofabraea spp. may survive on the dead bark. It has been reported that the Bull’s eye rot fungus may infect fruit anytime between petal fall and harvest but remains latent. Symptoms of Bull’s eye rot may appear after only a few months in storage. Fruit become more susceptible to infection by the fungus as the growing season approaches harvest. This disease is more common on fruit from orchards with over-tree irrigation or evaporative cooling, or in years or areas with frequent rains near or during harvest.

Control:
In apple orchards with perennial canker, removal of branches with cankers helps reduce inoculum of Neofabraea spp. in the orchard. Ziram applied within two weeks before harvest is recommended for control of Bull’s eye rot in the Pacific Northwest.

Photo Plate: Bull’s Eye Rot
Fig. 6. Symptoms and signs of Bull’s eye rot (Neofabraea spp.) on apples and pears.

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A: Bull’s eye rot on a Golden Delicious fruit; lesion flat to slightly sunken, brown to dark brown with lighter brown to tan center

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B: Multiple Bull’s eye rot lesions on a Golden delicious fruit

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C: Bull’s eye rot originating from infection at the stem-bowl area of a Golden delicious fruit

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D: Bull’s eye rot originating from infection at the calyx end of a Golden Delicious fruit

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E: Bull’s eye rot on a d’Anjou pear fruit

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F: Advanced stage of Bull’s eye rot on a d’Anjou pear fruit; white mycelium and cream-colored spore masses present at the center

References:
De Jong, S. N., Levesque, C. A., Verkley, G. J. M., Abeln, E. C. A., Rahe, J. E., and Braun, P. G. 2001. Phylogenetic relationships among Neofabraea species causing tree cankers and bull’s eye rot of apple based on DNA sequencing of ITS nuclear rDNA, mitochondrial rDNA, and the β-tublin gene. Mycological Research 105:658-669.

Henriquez, J. L., Sugar, D., and Spotts, R. A. 2004. Etiology of bull’s eye rot of pear caused by Neofabraea spp. in Oregon, Washington, and California. Plant Disease 88:1134-1138.