Diseases

Apple root rot

Malus Mill.

A complex of diseases affecting the root system and root collar of apple trees, caused by pathogenic oomycetes, as well as fungi of the genera Fusarium and Armillaria. Manifestations include bark necrosis, vascular wilting, and decay of root wood.

In the reference 16 varieties crop Apple, where this is mentioned in the description.

The primary pathogens causing apple root rot are Phytophthora cactorum, Phytophthora syringae, Phytophthora cambivora, Phytophthora citricola, a complex of Fusarium species (including F. sporotrichioides, F. proliferatum, F. oxysporum), as well as Armillaria mellea and Desarmillaria tabescens.

Symptoms of phytophthora rot are characterized by the formation of dark necrotic spots on the root collar and a reddish-brown discoloration of the cambium. Fusarium rot manifests as chlorosis and stunted tree growth, often associated with "replant disease." Armillaria root rot is characterized by the presence of white mycelial mats under the bark and the development of rhizomorphs.

Intraspecific race differentiation of these pathogens is weakly expressed. Resistance genes to these diseases have not been identified in apple breeding; the level of plant resistance depends primarily on the genetic characteristics of the clonal rootstocks used.

General information about the subject — on the page Root rots.

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.