Apple anthracnose

Pathogen and disease type
Apple anthracnose and the associated bull's-eye rot are fungal diseases caused by the pathogen Pezicula malicorticis (syn. Neofabraea malicorticis). The disease manifests as both bark cankers on woody tissues and as a post-harvest decay on fruit. The fungus overwinters in the bark tissues, producing spores that are disseminated primarily by splashing rain during cool, wet autumn weather.

Affected crops and impact
The primary hosts of this pathogen are pome fruit trees, specifically apple (Malus domestica) and pear (Pyrus communis). The infection can lead to the death of limbs or entire trees if the trunk becomes girdled by large cankers, while the fruit rot phase causes significant economic losses during cold storage, rendering the fruit unsaleable.

Symptoms and identification
On branches and trunks, the infection appears as small, reddish-brown, circular spots that gradually depress and expand into sunken cankers. On harvested fruit, symptoms start as small, light-brown spots that enlarge over time, often exhibiting concentric light and dark rings—a pattern that creates the characteristic appearance of a bull's-eye.

Development and environmental conditions
The development of the disease is highly dependent on humidity and temperature. Periods of prolonged rainfall in autumn facilitate the massive release and spread of spores. Because the infection on fruit is latent, the fungus can penetrate the skin of the apple before harvest without showing obvious symptoms until the fruit has been stored for several weeks or months.

Control and prevention measures

• Regular removal and destruction of infected branches to reduce inoculum sources.
• Application of protective fungicides during late summer and autumn prior to fruit harvest.
• Maintaining proper orchard hygiene to ensure airflow and reduce humidity levels.
• Monitoring storage conditions, as low temperatures and proper ventilation are essential to slow the spread of the pathogen in cold storage facilities.