Dothiorella canker

Taxonomic classification and pathogen nature
Dothiorella gregaria is a fungal pathogen classified within the order Botryosphaeriales. It is recognized as a facultative parasite that causes necrotic diseases in woody plants. The fungus acts as both an active pathogen invading living plant tissues and a saprotroph that survives on dead organic matter, making it a persistent threat in orchards and forest nurseries.

Host plants and associated diseases
The pathogen is primarily responsible for Dothiorella canker, a disease affecting various fruit and nut trees, including apple, pear, peach, apricot, almond, and walnut. Infection typically leads to bark necrosis, stem cankers, and the gradual dieback of scaffold branches. The presence of the fungus is often signaled by the localized sinking of the bark and subsequent development of pycnidia.

Biology and life cycle
Dothiorella gregaria reproduces through conidia released from pycnidia, which are small, dark fruiting bodies formed within the host's bark. The infection cycle is initiated by the dissemination of spores through water splashes, wind, and insects. The fungus infects the host tree through wounds, such as pruning cuts, frost cracks, or sunscald, where it begins to colonize the vascular tissues.

Conditions and pathogenicity
Environmental conditions characterized by high humidity and fluctuating temperatures significantly facilitate the spread and virulence of the disease. The pathogen causes severe economic losses by weakening tree structures, reducing fruit yields, and eventually causing tree mortality. Weakened trees, particularly those stressed by drought or poor soil nutrition, are highly susceptible to infection.

Control and management strategies
Managing Dothiorella canker requires a strict integrated pest management (IPM) approach:

• Rigorous sanitation: pruning and burning of all infected branches and dead wood.
• Wound protection: applying protective pastes or copper-based agents to pruning cuts.
• Chemical control: preventive spraying programs during the dormancy period and growing season.
• Orchard hygiene: maintaining tree vigor through proper fertilization and protection against sunscald and winter damage.