Teratosphaeria leaf spot

The disease is caused by the ascomycete fungus Teratosphaeria proteae-arboreae, a specialized pathogen that specifically targets plants within the Proteaceae family. As a significant concern for commercial nurseries, this fungus disrupts the aesthetic quality of ornamental plants by causing necrotic lesions on the leaves, which can severely compromise the plant's structural integrity and market value.

The primary hosts of this pathogen are species of the genus Protea. The disease is frequently observed in cultivation environments where high plant density and specific microclimates create ideal conditions for the colonization and proliferation of the fungal pathogen on susceptible tissues.

Initial symptoms are characterized by the appearance of distinct spots on the foliage. As the infection advances, these spots may coalesce into larger necrotic areas, leading to significant defoliation. A key diagnostic feature is the emergence of small, dark fruiting bodies known as pycnidia within the lesions, which release spores to continue the infection cycle across the canopy.

Development and spread of the fungus are heavily influenced by humidity and moisture. Periods of prolonged leaf wetness, such as those caused by rainfall, high-humidity fog, or overhead irrigation, provide the necessary environment for fungal sporulation and germination. Once established, the pathogen spreads rapidly via water splash or contaminated tools used during maintenance.

Effective management requires a combination of strict sanitation practices and chemical interventions. Growers should prioritize removing and destroying infected plant tissue to reduce the primary inoculum load. Enhancing air circulation to reduce humidity and switching to drip irrigation can significantly hinder the disease progression. Preventive fungicide applications are also recommended during periods of high disease risk.

• Sanitary pruning of infected tissue
• Optimized ventilation and humidity control
• Switching to drip irrigation
• Routine application of fungicides