Stigmochora spot

Stigmochora spot is a fungal plant disease caused by the ascomycete Stigmochora controversa. It is primarily identified as a foliar pathogen that targets specific woody plants, most notably the redbud tree (Cercis species). The fungus manifests as necrotic lesions on the leaves, impacting the plant's overall health and photosynthetic capacity.

The biology of the pathogen involves the formation of stroma within the host leaf tissue. As the fungus matures, these structures erupt through the epidermis, creating the characteristic black, spot-like symptoms that give the disease its name. These structures serve as the primary site for spore production, ensuring the survival and transmission of the fungus.

The severity of the disease depends largely on environmental conditions, particularly high humidity and persistent rainfall during the growing season. These conditions favor the germination of spores and their spread to healthy foliage. When favorable weather persists, the infection can spread rapidly across a canopy, leading to significant foliage loss.

Damage caused by Stigmochora controversa is primarily aesthetic and physiological. In cases of high infestation, early defoliation weakens the host plant, making it more susceptible to environmental stressors and other secondary pathogens. While rarely fatal to mature trees, it can significantly hinder the growth of young specimens.

Integrated management is essential for controlling this fungal infection. Cultural practices such as removing and destroying fallen leaves during autumn are crucial to reducing the inoculum density. Additionally, applying copper-based fungicides or other appropriate chemical treatments during the early stages of the growing season can help prevent the disease from establishing a foothold in the garden.