Fusicoccum canker of almond

The disease is caused by the fungal pathogen Diaporthe amygdali, with Fusicoccum amygdali as its asexual state. This fungus is a significant threat to almond orchards worldwide, known for causing severe cankers that eventually lead to the dieback of entire branches and the decline of the tree canopy.

While almonds are the primary host, the pathogen also affects other stone fruit trees, including peaches and nectarines. The disease targets the woody parts of the tree, focusing on buds, twigs, and larger branches, effectively cutting off nutrient and water supply to the distal parts of the plant.

Early symptoms include dark, sunken lesions surrounding leaf scars or dormant buds. As the infection progresses, these lesions expand into elongated cankers, often accompanied by gum exudation (gummosis). Eventually, the leaves distal to the canker wilt, turn brown, and remain attached to the affected twig.

The development of Diaporthe amygdali is strongly linked to humidity and rainfall patterns. Spores are dispersed by splashing water and wind, entering the tree through natural openings, wounds caused by insects, or mechanical damage from pruning and frost cracks, which serve as primary entry points.

Integrated management is essential for control, starting with the prompt removal and burning of all infected wood to reduce the inoculum level in the orchard. Implementing strict hygiene practices during pruning, followed by the application of copper-based bactericides or site-specific fungicides, helps protect sensitive tissue from new infections.