Rhytidiella

Rhytidiella is a genus of ascomycetous fungi responsible for causing necrotic bark diseases in various tree species, most notably poplars. The pathogen targets the vascular tissues and periderm, causing significant disruption to the nutrient transport system and weakening the tree's overall structure.

The disease is caused by species of the genus Rhytidiella, such as Rhytidiella moriformis, which act as opportunistic pathogens. They primarily invade trees through mechanical wounds, pruning cuts, or frost cracks, colonizing the inner bark and eventually disrupting the functionality of the cambium layer.

Key symptoms of infection include the development of swelling, cracking, and sunken lesions on the bark surface. As the infection progresses, the bark often becomes dark, brittle, and may detach from the wood, leading to crown dieback, reduced vigor, and in severe cases, the eventual death of the affected tree.

The spread of the fungus is heavily influenced by environmental conditions, particularly high humidity and prolonged moisture on the bark surface. Spores are primarily disseminated by wind, rain splashes, and insect vectors, making the disease difficult to contain once established in dense stands or nurseries.

Management strategies focus on a combination of cultural and chemical controls. Essential practices include the surgical excision of infected bark and branches, followed by the application of fungicidal treatments to protected wounds. Furthermore, maintaining tree vigor through appropriate site selection and thinning helps reduce the susceptibility of plantations to the infection.