Diseases

Apple Phytophthora Rot

Malus domestica (Suckow) Borkh.

A disease of the apple tree root system and lower trunk caused by the oomycetes Phytophthora cactorum and Phytophthora syringae. It manifests as collar rot, crown rot, root rot, and fruit infection.

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

The disease affects the vegetative parts of the tree, causing destruction of the root system or necrosis of the scion and rootstock bark. In the affected area, the cambium and bark acquire a reddish-brown or orange hue with a distinct border between diseased and healthy tissue. Unlike stone fruit crops, gummosis is usually not observed when apple bark is affected.

At initial stages, symptoms manifest as general decline and chlorosis, mimicking iron deficiency. Severely affected trees may suddenly wilt and die at the beginning of the growing season. In rainy weather, the pathogen can infect low-hanging fruit, causing rapid decay.

Specific resistance genes to Phytophthora rot in apple trees have not yet been described, and resistance is determined primarily by the choice of rootstock. The pathogen is a widely specialized wound parasite that does not have highly specialized races adapted exclusively to apple trees.

General information about the subject — on the page Late blight.

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.