Diseases

Apple powdery mildew

Malus Mill.

A fungal disease of apple trees caused by the obligate pathogen Podosphaera leucotricha, which overwinters in buds as mycelium. It is characterized by the appearance of a powdery coating on young shoots, leaves, and fruits, causing their deformation and drying.

In the reference 153 varieties crop Apple, where this is mentioned in the description.

The disease is caused by the ascomycete fungus Podosphaera leucotricha Salm., whose conidial stage is known as Oidium farinosum. The pathogen attacks the vegetative and generative organs of the apple tree. The primary symptom appears as a delicate white powdery coating, which eventually densifies and darkens to a gray or reddish hue.

The infection leads to serious developmental disorders: shoots are stunted, leaves curl into a "boat" shape, and flowers become deformed and drop. On fruits, the disease may manifest as a rusty netting. The fungus overwinters primarily in the fruit and growth buds of the plant.

In breeding, resistance genes such as Pl-1 (identified by the AT20-SCAR marker), Pl-2, Pl-w, and Pl-d are used to combat the disease. These loci are utilized in pyramiding programs to develop varieties with complex resistance to the infection.

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

Sources8

Varieties of Apple 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.