Colletotrichum proteae

Colletotrichum proteae is a fungal pathogen recognized as the causative agent of anthracnose in various species of the Proteaceae family. As a specialized parasite, it significantly impacts the vitality and commercial value of ornamental plants, particularly those grown in nurseries and specialized greenhouse facilities.

The primary host range includes Protea and Leucadendron species. The fungus targets leaf tissues, stems, and bracts, often causing severe blight symptoms. Its ability to survive on plant debris makes it a persistent challenge for commercial growers aiming to maintain high quality for international markets.

Symptoms initially appear as small, water-soaked lesions that rapidly expand into necrotic spots. These lesions often exhibit distinct dark centers where acervuli—the fruiting bodies of the fungus—are produced. In favorable conditions, these spores become visible as gelatinous masses, which facilitate further spread across the plant canopy.

The development and dissemination of Colletotrichum proteae are heavily influenced by environmental factors, most notably temperature and humidity. The pathogen thrives in warm, humid climates, where persistent leaf wetness allows for the germination of conidia and subsequent infection of healthy tissues. Spores are primarily dispersed through water splashing during irrigation or rainfall.

Management strategies for this pathogen focus on minimizing environmental moisture and implementing strict sanitation practices. Growers are advised to improve airflow within the canopy and remove infected plant debris promptly to reduce the inoculum level. Chemical control involving systemic and protective fungicides is recommended as part of an integrated pest management (IPM) program.

• Improving greenhouse ventilation and air circulation.
• Regular removal of infected plant tissues.
• Avoiding overhead irrigation to reduce leaf wetness.
• Application of approved fungicidal programs.