Anthracnose caused by Colletotrichum queenslandicum

The disease is caused by the fungus Colletotrichum queenslandicum, a significant pathogen in the Colletotrichum genus responsible for various forms of anthracnose. This fungus is a hemibiotroph, initially colonizing living tissue before killing it, which allows it to thrive in diverse environmental conditions and remain persistent in the soil or crop debris.

This pathogen primarily infects various horticultural crops, fruits, and tropical plants. It is highly aggressive during the reproductive stage of the host plant, often causing decay of ripening fruits and lesions on stems or leaves. Its ability to spread via water splashes makes it particularly dangerous in greenhouses and humid field conditions.

Clinical signs include sunken necrotic lesions on fruits, stems, and leaves. These spots are often surrounded by a dark margin, and under humid conditions, salmon-colored or greyish conidial masses can be observed on the lesion surfaces. Eventually, the affected areas become brittle, leading to fruit drop or premature foliage loss.

Environmental conditions favor development when temperatures remain between 22°C and 28°C accompanied by high humidity or leaf wetness periods exceeding 12 hours. Rain splashes and irrigation water serve as the primary dissemination methods for fungal spores, facilitating rapid infection spread within a crop canopy during the growing season.

Economic damage caused by Colletotrichum queenslandicum is substantial due to yield loss and severe post-harvest spoilage. Infected crops often become unsellable, and the fungus's ability to survive in various forms makes complete eradication from a field difficult, requiring a systematic management strategy.

• Application of targeted fungicides during the flowering and fruit development stages.
• Implementation of strict sanitation practices to remove inoculum sources.
• Ensuring proper spacing between plants to maximize airflow and reduce humidity.
• Selection of resistant plant varieties where available.
• Regular monitoring of fields for early signs of lesions to prevent widespread outbreaks.