Diseases

Rose leaf spots

Rosa L.

A complex of fungal diseases of roses, dominated by black spot caused by the pathogen Diplocarpon rosae. The disease manifests as necrotic spots on leaves and stems, causing premature defoliation of plants.

In the reference 789 varieties crop Rose, where this is mentioned in the description.

Black spot is caused by the fungus Diplocarpon rosae and its anamorph Marssonina rosae. Black, brown, or purple-black spots with characteristic radiating margins, surrounded by a zone of chlorosis, develop on the upper side of the leaf blades. Severe infection leads to premature leaf drop and the appearance of raised red-purple or black spots on young stems. Other pathogens causing rose leaf spots include Cercospora rosicola, Sphaceloma rosarium, Phyllosticta rosae, Septoria rosae, Ascochyta rosicola, Monochaetia depazeoides, Ramularia banksiana, Coryneum confusum, and Pestalotia rosae.

The causal agent of black spot is characterized by high genetic variability, with at least 13 identified races. In rose breeding, a key defense tool is the Rdr1 gene, belonging to the TNL class, which provides a broad spectrum of resistance to various pathogen isolates. In addition to monogenic resistance, partial polygenic defense mechanisms are being studied, represented by quantitative trait loci (QTL) located on linkage groups 3 and 5.

General information about the subject — on the page Leaf spot diseases.

Sources8

Varieties of Rose mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.