Anthracnose of cucurbits

Pathogen and disease type: Anthracnose of cucurbits is a destructive plant disease caused by the fungus Colletotrichum orbiculare. It is a common fungal infection that poses a serious threat to cucurbitaceous crops globally, causing significant damage under both protected and open-field production conditions.

Host crops: This pathogen primarily infects members of the Cucurbitaceae family, including cucumbers, melons, watermelons, squash, and pumpkins. It affects all above-ground parts of the plant, including leaves, stems, flowers, and developing fruits throughout the entire growing season.

Symptoms and signs: The disease manifests as circular to irregular, yellowish-brown spots on leaves, which often dry out and crack. Elongated, sunken lesions appear on petioles and stems, which can lead to vine blight. On fruit, the characteristic symptom is deep, circular, sunken lesions that may develop a pinkish mass of spores in humid conditions.

Conditions for development and severity: Colletotrichum orbiculare thrives in high humidity (above 90%), warm temperatures (22–27°C), and frequent rainfall. Splash irrigation or heavy rain facilitates the spread of fungal spores from the soil to the foliage. Its severity lies in the rapid destruction of the photosynthetic leaf area, leading to plant death and total loss of commercial value for the produce.

Protection and prevention measures: Effective disease management involves a multi-faceted strategy:

• Sowing high-quality, disease-free, or fungicide-treated seeds.
• Implementing a strict crop rotation schedule to break the pathogen's life cycle.
• Removing and destroying infected plant debris immediately after harvest.
• Applying systemic and contact fungicides as part of a preventive spray program.
• Ensuring good ventilation and proper spacing in greenhouses to reduce canopy humidity.