Articles
EVALUATION OF ROSE SPECIES AND CULTIVARS FOR RESISTANCE TO MARSSONINA ROSAE (Diplocarpon rosae)
Article number
547_53
Pages
413 – 417
Language
English
Abstract
Blackspot, caused by the fungus Marssonina rosae (Lib.) Lind., is generally considered as the most serious disease on roses.
Evaluation of the susceptibility to the disease in different species and cultivars can be performed in different ways, for example assessments of natural infection in field trials or evaluation of artificial inoculations of different types.
Many authers have used detached leaves or leaf discs in their studies instead of whole living plants.
In this investigation thirty one accessions (species and cultivars) were evaluated in a field trial as well as in an greenhouse inoculation trial with whole living cuttings.
Species and cultivars free from infection was found with both methods.
It was shown that there was a correlation between the two methods.
Nevertheless, there were clear differences in the degree of infection for some of the accessions when the two methods were compared. Rosa rugosa was for example completely free from infection in the field trial but got infected in the inoculation trial.
Three different scales were used for measuring the rate of infection in the inoculation trial.
It was concluded that percentage of leaves infected, regardless of the size of the spots, was the one that separated the accessions most clearly.
Significant differences in the degree of blackspot infection were found between the accessions with all three scales used respectively.
The results from the three scales were significantly correlated to each other.
Evaluation of the susceptibility to the disease in different species and cultivars can be performed in different ways, for example assessments of natural infection in field trials or evaluation of artificial inoculations of different types.
Many authers have used detached leaves or leaf discs in their studies instead of whole living plants.
In this investigation thirty one accessions (species and cultivars) were evaluated in a field trial as well as in an greenhouse inoculation trial with whole living cuttings.
Species and cultivars free from infection was found with both methods.
It was shown that there was a correlation between the two methods.
Nevertheless, there were clear differences in the degree of infection for some of the accessions when the two methods were compared. Rosa rugosa was for example completely free from infection in the field trial but got infected in the inoculation trial.
Three different scales were used for measuring the rate of infection in the inoculation trial.
It was concluded that percentage of leaves infected, regardless of the size of the spots, was the one that separated the accessions most clearly.
Significant differences in the degree of blackspot infection were found between the accessions with all three scales used respectively.
The results from the three scales were significantly correlated to each other.
Authors
B.U. Carlson-Nilsson
Keywords
blackspot infection, natural infection, artificial inoculation, Rosa
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