Diseases

Downy mildew of zucchini

Cucurbita pepo L.

A fungal disease of zucchini caused by the obligate parasite Pseudoperonospora cubensis. It manifests as oily spots on the leaves and a characteristic gray-violet coating on the underside of the leaf, leading to premature drying of the plant.

In the reference 20 varieties crop Field pumpkin, where this is mentioned in the description.

The pathogen is the oomycete Pseudoperonospora cubensis, whose population is heterogeneous and represented by various pathotypes with differing levels of aggressiveness. The disease develops actively under a combination of high humidity and moderate temperatures. Initial symptoms on the upper side of the leaf appear as vein-limited yellow-green oily spots, which eventually turn brown and resemble burns.

A diagnostic sign is a gray or gray-violet coating on the underside of the leaf, corresponding to the pathogen's sporulation zone. The infection leads to leaf brittleness, accelerated plant senescence, and a significant reduction in yield. Specific resistance genes in zucchini to this pathogen have not been identified in agronomic practice, so breeding focuses on achieving varietal tolerance.

General information about the subject — on the page Downy 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.