Diseases

Verbena powdery mildew

Verbena L.

A fungal disease of verbena primarily caused by the pathogens Podosphaera xanthii and Erysiphe cichoracearum, manifested as a white coating and deformation of vegetative organs.

In the reference 69 varieties crop Vervain, where this is mentioned in the description.

The causative agents of powdery mildew on verbena are members of the Erysiphaceae family, specifically Podosphaera xanthii and Erysiphe cichoracearum. The disease must be distinguished from downy mildew caused by Peronospora verbenae, which affects the crop in a significantly different way.

Symptoms appear as a characteristic white or grayish mycelial coating on stems, flowers, and leaf blades. Affected areas often acquire a purple hue or become chlorotic, leading to leaf curling, stunted growth, and cessation of flowering. Primary signs usually appear on the lower tier of the plant, gradually covering the entire aerial part.

At present, the genetic basis of verbena resistance to this pathogen has not been studied, and specific resistance genes have not been identified. Breeding work with the crop is based on the phenotypic evaluation of varieties under disease-pressure conditions, as there is high variability in susceptibility among members of the genus.

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

Sources8

Varieties of Vervain 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.