Bull's Eye Rot
Bullís eye rot occurs on both apples and pears in the U.S. Pacific Northwest. In Washington State, Bullís eye rot is more commonly seen on Golden Delicious, particularly on apples from orchards with perennial canker problems on trees. Bullís eye rot also occurs in Europe and some other fruit-growing regions.
Bullís 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). Bullís eye rot commonly originates from infection at lenticels on the fruit skin, but stem-end Bullís 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 Bullís eye rot has also been observed on Golden Delicious fruit.
Four species of Neofabraea are known to cause Bullís eye rot on apples. Three species, N. alba, N. perennans, and a Neofabraea sp., have been reported to cause Bullís eye rot on pears in the Pacific Northwest.
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 Bullís eye rot fungus may infect fruit anytime between petal fall and harvest but remains latent. Symptoms of Bullís 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.
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 Bullís eye rot in the Pacific Northwest.
Photo Plate: Bull's Eye Rot
Fig. 6. Symptoms and signs of Bullís eye rot (Neofabraea spp.) on apples and pears.
|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
||B: Multiple Bull's eye rot lesions on a Golden delicious fruit
||C: Bull's eye rot originating from infection at the stem-bowl area of a Golden delicious fruit
|D: Bull's eye rot originating from infection at the calyx end of a Golden Delicious fruit
||E: Bull's eye rot on a d'Anjou pear fruit
||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
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 bullís 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 bullís eye rot of pear caused by Neofabraea spp. in Oregon, Washington, and California. Plant Disease 88:1134-1138.