Evaluation of genus Rosa germplasm for resistance to black spot, downy mildew and powdery mildew

authored by
Dietmar F. Schulz, Marcus Linde, Oliver Blechert, Thomas Debener

Black spot resistance in the field was visually evaluated for a total of 581 accessions at two locations in central and northern Germany. At Sangerhausen rose garden 289 of 486 accessions have shown a high level of disease resistance. After subsequent resistance tests in the detached leaf assay 33 of these accessions did not show any signs of black spot infections. At Ahrensburg 41 of the 130 wild rose accessions from 65 species were not infected in the field. Leaves of the accessions without apparent black spot infections were sampled and inoculated under laboratory conditions with different single spore isolates and field collected samples of the pathogen. A total of 11 accessions were found to be highly resistant to all black spot isolates. Powdery mildew resistance of 39 accessions at Ahrensburg was identified after field evaluation and artificial inoculation with different samples of Podosphaera pannosa from naturally infected leaves. Downy mildew resistance was estimated in detached leaf assays after inoculation of a subset of 85 accessions from Ahrensburg with single spore isolates and field collected samples of Peronospora sparsa among which 13 wild rose accessions were found to be resistant. Multiple resistances to two of the pathogens were found in 13 of the investigated accessions of which R. majalis 93-09-01 is highly resistant to all three pathogens, except for isolate Diplocarpon rosae 'AHE10'. These accessions, primarily those carrying multiple resistances, are a valuable genetic resource for the introduction of resistance genes to black spot, downy mildew and powdery mildew into cultivated garden roses.

Institute of Plant Genetics
Section Molecular Plant Breeding
External Organisation(s)
National Research Council of Canada
European Journal of Horticultural Science
No. of pages
Publication date
Publication status
Peer reviewed
ASJC Scopus subject areas