A standard set of host differentials and unified nomenclature for an international collection of Diplocarpon rosae races

V. M. Whitaker, T. Debener, A. V. Roberts, S. C. Hokanson

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Black spot of rose is distributed throughout the world and is the most serious disease of roses (Rosa spp.) in the outdoor landscape. Resistance breeding has been frustrated by the occurrence of races of the causal pathogen Diplocarpon rosae. Races from Germany, North America and the UK have been characterized and maintained in a pathogenic state. However, these races were characterized using independent sets of host genotypes and are referenced using different nomenclatures. In the present study, a total of 15 D. rosae isolates from these locations, as well as Belgium and Italy, were inoculated to a common set of 15 rose cultivars in replicated, detached leaf trials. Baby Love™ (cv. Scrivluv) was resistant to all isolates except for one originating from the UK. The rose cultivars Mrs Doreen Pike (Ausdor) and Hansa were resistant to all isolates except for one originating from Minnesota, USA. No rose genotype was universally susceptible. A total of 11 pathogenic races were differentiated based on their unique host ranges and were assigned an international race nomenclature. Nine cultivars are proposed as the first standard set of differential genotypes for characterization of D. rosae races.

Original languageEnglish (US)
Pages (from-to)745-752
Number of pages8
JournalPlant Pathology
Volume59
Issue number4
DOIs
StatePublished - Aug 2010

Keywords

  • Black spot of rose
  • Disease resistance
  • Marssonina rosae
  • Pathogenic phenotypes
  • Rosa spp

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