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Title: Species Identification and Variation in the North American Cranberry Fruit Rot Complex

item Polashock, James
item Caruso, Frank
item Oudemans, Peter
item Mcmanus, Patricia
item Constantelos, Chris
item Crouch, Joanne

Submitted to: Acta Horticulturae International Symposium on Vaccinium Culture
Publication Type: Proceedings
Publication Acceptance Date: 2/8/2008
Publication Date: 3/1/2009
Citation: Polashock, J.J., Caruso, F.L., Oudemans, P.V., Mcmanus, P., Constantelos, C., Crouch, J. 2009. Species identification and variation in the North American cranberry fruit rot complex. In: Acta Horticulturae International Symposium on Vaccinium Culture Proceedings, July 13-16, 2008, Corvallis, Oregon. p. 395-399.

Interpretive Summary:

Technical Abstract: Many different species of pathogenic fungi cause cranberry fruit rot. The contribution of any given species can be quite variable depending on a host of cultural and environmental factors. Control of fruit rot can be problematic in the Northeast and in other growing regions losses due to fruit rot can be episodic. One possibility for inadequate control is that pathogenic fungi typically have differential sensitivity to fungicides. Thus, variation in the species or populations of the fungi present can affect the success and quality of control. Our primary objective in this project was to determine the variation within five species of cranberry fruit rot pathogens (Phyllosticta vaccinii, Coleophoma empetri, Colletotrichum acutatum, Colletotrichum gloeosporioides, and Physalospora vaccinii) across geographic regions [NJ, MA, WI and British Columbia (BC)] using both morphologic and molecular characters. Our secondary objective was to reexamine the taxonomy of these pathogens at the molecular level, particularly those that are cranberry or Vaccinium species-specific. Our results suggest that morphologically, within-species variation was low. We did however collect atypical non-pigmented C. acutatum from BC and Physalospora vaccinii isolates varied from dark gray to pure white on V8 juice agar medium. Molecular analysis of ribosomal ITS sequences showed a low level of variability for most pathogen species, with the exception of the morphologically distinct isolates. Phylogenetic analysis showed that the atypical, non-chromogenic C. acutatum formed a distinct, but closely related clade, to the normal pink-pigmented isolates. In contrast, the pure white isolates of Physalospora vaccinii possessed an ITS sequence distinct from those strains that were gray, suggesting they may represent a different species.