Taxonomy

Domain	Eukarya
Kingdom	Fungi
Phylum	Ascomycota
Subphylum	Pezizomycotina
Class	Dothideomycetes
Order	Botryosphaeriales
Family	Botryosphaeriaceae
Genus	Phyllosticta

Scientific Name

Phyllosticta vaccinii

Scientific Name Synonyms

Botryosphaeria vaccinii

Guignardia vaccinii

Common Name

Phyllosticta leaf spot

Author: Ke Zhang, University of Florida

Reviewed by: Jeffrey Rollins, University of Florida

Pathogen

Phyllosticta vaccinii is the causal pathogen of cranberry early rot. It has been reported from leaf spots of Vaccinium arboretum, on cankers of V. ashei, V. corymbosum, V. macrocarpon, V. ovatum, and V. vitis-idaea from China and the USA. Pycnidia are globose or subglobose, black, 90-190 mm in diameter on cranberry leaves. Conidiogenous cells are hyaline and cylindrical. Conidia are hyaline, nonseptate, broadly ovoidal, ellipsoidal, or obovoidal, seldom subglobose, 7-11 x 4.5-7 μm, surrounded by a slime sheath, with a 4-10 μm apical appendage (3).

Symptoms and Signs

Vaccinium spp. infected by P. vaccinii show symptoms including blighting of flowers and young fruit, preharvest fruit decay, post harvest storage rot, circular, brown, slightly depressed fruit lesions, and circular brown leaf spots with dark margins. Mature black globose or subglobose pycnidia can be observed in the middle of the fruit lesion or leaf spot (1, 2).

Ecology and Spread

Phyllosticta vaccinii overwinters on leaves and stems but not in fruit. The pathogen is not likely to persist through the winter in the soil or water. Pycnidia may be visible from spring to fall and release conidia by rain splash and wind driven rain. Compared to old tissue, young plant tissue is more susceptible to infection. Phyllosticta vaccinii may also infect related plants in the genus Vaccinium (1). Higher temperature (above 84 F) favors the growth of P. vaccinii, so in warmer conditions, the disease is usually more severe (2). Phyllosticta vaccinii conidia can be spread by rain splash, irrigation water, and wind-driven rain. Wet vines may also help the conidia spread by foot traffic or machinery (1).

Geographic Distribution

The known distribution of P. vaccinii is China and the USA (3).

Management

Do not establish vines from a P. vaccinii infected planting.
Clean vines from beaters and other equipment when working between beds.
Use daytime sprinkling to reduce the temperature.
Apply mancozeb and chlorothalonil at full bloom and during late bloom (1).
Consult your local extension specialist for legal and efficacious fungicide products available in your state. Remember, the label is the law and the product applicator is responsible for reading and following all chemical labeling.

Diagnostic Procedures

Examine fresh material under the microscope. Plant material with lesions that contain mature pycnidia are preferred. Incubation of fresh material in a moist chamber can promote the production of mature pycnidia. Diagnostic features include:

pycnidia that are globose or subglobose, black, 90-190 mm in diameter;
conidiogenous cells that are hyaline, cylindrical; and
conidia that are hyaline, nonseptate, broadly ovoidal, ellipsoidal, or obovoidal, seldom subglobose, 7-11 x 4.5-7 μm, surrounded by a slime sheath, with a 4–10μm apical appendage (3).

ITS sequence of the epitype strain sequence is in GenBank database KC193585.

Resources and References

1. EARLY ROT IN WISCONSIN Special factsheet from the University of Wisconsin-Madison http://longbeach.wsu.edu/cranberries/earlyrotinwisconsin.pdf.pdf

2. Weidemann, G. J., and Boone, D. M. 1983. Incidence and pathogenicity of Phyllosticta vaccine and Botryosphaeria vaccinii on cranberry. Plant disease, 67: 1090-1093. http://www.apsnet.org/publications/PlantDisease/BackIssues/Documents/1983Articles/PlantDisease67n10_1090.pdf

3. Zhang, K., Zhang, N., Cai, L. 2013. Typification and phylogenetic study of Phyllosticta ampelicida and P. vaccinii. Mycologia, 105: 1030-1042. http://www.mycologia.org/content/105/4/1030.full.pdf

Acknowledgements

National Institute of Food and Agriculture, U.S. Department of Agriculture, under Agreement No. 2011-41530-30708 as part of "Diagnostic Image Series Development for Supporting IPM in the Southern Region" (USDA-NIFA-RIPM-003351)