Diseases

Powdery mildew of zucchini

Cucurbita pepo L.

A fungal disease of zucchini caused by obligate biotrophic fungi Podosphaera xanthii and Golovinomyces cichoracearum. It manifests as a white powdery coating on the upper leaf surface, which eventually spreads to all above-ground plant organs.

In the reference 333 varieties crop Field pumpkin, where this is mentioned in the description.

The pathogens Podosphaera xanthii and Golovinomyces cichoracearum can develop either individually or together, forming a mixed infection. Symptoms of the disease begin to appear on the upper surface of the leaves as localized light spots that gradually enlarge, coalesce, and transform into a dense “felty” coating, spreading to petioles and stems. Under conditions of severe infection, plant tissues become chlorotic, toughen, and die.

The development of the pathogens is favored by moderate temperatures in the range of 18–25°C, high air humidity, and dense planting that limits ventilation. Genetic resistance of the crop to the disease is most often polygenic and classified as intermediate. In zucchini breeding, the PMR label is used to indicate the ability of plants to suppress infection development, although specific alphanumeric gene designations are rarely encountered in general practice.

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

Sources8

Varieties of Field pumpkin 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.