Diseases

Powdery mildew of rose

Rosa L.

A fungal disease of roses caused by the obligate parasite Podosphaera pannosa. It manifests as a white coating on leaves and shoots, causing plant organ deformation and underdeveloped buds.

In the reference 785 varieties crop Rose, where this is mentioned in the description.

The causative agent of rose powdery mildew is the fungus Podosphaera pannosa, characterized by the presence of physiological races and pathotypes, which determines the specificity of interaction with host plant genotypes. The infection actively develops at temperatures of 16–27 °C under high humidity conditions, not requiring the presence of liquid water for spore germination.

The disease affects all above-ground organs of the rose: a characteristic coating forms on the leaves, causing deformation and discoloration, while mycelium on shoots and buds leads to stem curvature and premature abscission of ovaries. Field trials, such as the ADR system, are used to evaluate cultivar resistance.

Genetic control of resistance includes dominant genes, in particular Rpp1, as well as the use of NBS-LRR resistance gene analogs. A promising direction in breeding is work with the MLO gene family, specifically RhMLO1 and RhMLO2, which the pathogen requires for infection; their deactivation allows for the development of plants with a broad spectrum of resistance.

General information about the subject — on the page Powdery mildew.

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.