Biatorella canker

Biatorella canker, caused by the fungus Biatorella difformis, is a destructive bark disease that affects various pome and stone fruit trees. This pathogen attacks the cambium and bark tissues, causing localized necrosis that disrupts the transport of nutrients and water, often resulting in limb dieback.

The disease primarily impacts apple and pear trees, though it can occur in other woody species. The fungus acts as a facultative parasite, often invading trees that are stressed by environmental factors such as severe frost, drought, or physical injury to the bark, which provides an entry point for the fungal spores.

The symptoms are marked by depressed, discolored lesions on the bark that turn brown and necrotic over time. As the infection progresses, the bark cracks and fissures form, often displaying the fruiting bodies of the fungus—small, yellow-to-brown disc-like structures visible to the naked eye under humid conditions.

Environmental conditions play a critical role in the disease cycle, with high humidity and moderate temperatures favoring the development of the fungus. The pathogen spreads via wind-borne or water-splashed spores that land on vulnerable, open wounds in the tree bark, making the management of bark integrity essential.

To effectively prevent and manage Biatorella canker, growers should implement the following strategies:

• aggressive pruning to remove all infected branches, ensuring cuts are made into healthy, clean wood;
• disinfection of all pruning tools to prevent the cross-contamination of healthy trees;
• application of wound dressings and protective copper-based sprays on significant bark injuries;
• maintaining tree vigor through proper irrigation and fertilization programs to ensure rapid wound healing.