Nothophoma canker of oak

Nothophoma canker of oak is a serious fungal disease caused by the pathogen Nothophoma quercina. This fungus primarily attacks the bark and cambium of oak trees, resulting in the development of necrotic lesions and cankers on branches and stems, which can severely compromise the structural integrity and health of the tree.

The disease primarily affects various species of the Quercus genus. It poses a significant threat to nursery-grown seedlings and young trees, as the infection can lead to girdling of the stems. If the main trunk is affected, the circulation of nutrients is disrupted, often resulting in the dieback of the entire canopy and eventual death of the specimen.

Common symptoms include sunken, discolored patches on the bark of young shoots and branches. As the infection progresses, the bark may split, exposing the underlying wood and forming distinct cankers. During favorable conditions, small fruiting bodies known as pycnidia emerge on the dead tissue, which serve as the primary source of further spread.

The development and spread of Nothophoma quercina are largely facilitated by high humidity and moderate temperatures. The fungus acts as a wound parasite, readily invading tissues through injuries caused by frost, pruning, or insect activity. Stressed trees, suffering from drought or poor soil conditions, are particularly susceptible to severe outbreaks.

Management strategies focus on strict sanitation, including the removal and destruction of infected branches to reduce the inoculum load. In landscape and nursery settings, it is crucial to avoid wounding the trees and to ensure they receive proper care to minimize stress. Chemical control using registered fungicides can be used preventatively during periods of high disease pressure.