Diseases

Powdery Mildew of Watermelon

Citrullus lanatus (Thunb.) Matsum. & Nakai

A fungal disease of watermelon caused by the pathogens Podosphaera xanthii and Golovinomyces cichoracearum. It manifests as a white powdery coating on plant organs, leading to chlorosis, premature tissue drying, and reduced fruit quality.

In the reference 40 varieties crop Watermelon, where this is mentioned in the description.

The disease is caused by fungi from the Erysiphaceae family. Depending on growing conditions, the infection may be caused by either one of the species, Podosphaera xanthii or Golovinomyces cichoracearum, or a combination of both. Resistance of cultivars to the pathogen is predominantly polygenic in nature.

Initial symptoms include the appearance of pale yellow spots on stems, petioles, and leaves, which quickly become covered with a characteristic white coating consisting of mycelium and spores. As the disease progresses, leaf tissues become brittle and dry out. The infection leads to fruit deformation and a reduction in sugar content.

When performing diagnosis, it is important to distinguish powdery mildew from downy mildew caused by oomycetes. Unlike powdery mildew, in downy mildew, the coating has a gray-violet hue and is usually localized strictly on the underside of the leaf, and necrotic spots are confined by the veins of the leaf blade.

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

Sources8

Varieties of Watermelon 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.