Eutypella canker

The causative agent of this disease is the ascomycete fungus Eutypella quaternata, which acts as a parasitic pathogen on woody stems. It is primarily known for causing perennial canker formations on the bark and cambium of infected trees.

The primary host plants for this fungus are species of the maple genus (Acer). The infection typically initiates through wounds in the bark, such as frost cracks, pruning wounds, or mechanical injuries caused by maintenance equipment or wildlife.

Symptoms are characterized by the development of sunken, target-shaped cankers on the stems or branches. Over time, the fungus produces visible, small, black perithecia (fruiting bodies) that erupt through the bark surface within the infected area. These cankers can eventually girdle the stem, disrupting nutrient and water transport.

The spread of Eutypella quaternata is driven by environmental moisture and wind. Spores are released during wet weather and travel to susceptible host wounds. The fungus establishes itself in the bark tissue and expands laterally and vertically, slowly encroaching on the tree's vital functions.

The impact of the disease includes reduced tree vigor, structural weakness leading to windthrow, and degradation of timber quality. Management strategies focus on sanitation, which includes the removal and destruction of heavily infected branches or trees, the protection of pruning cuts, and maintaining forest or garden health to ensure trees can mount an effective defense against colonization.