Choanephora fruit rot

Systematic position and pathogen type: Choanephora cucurbitarum is a fungus belonging to the kingdom Fungi, phylum Mucoromycota, and order Mucorales. It acts primarily as a soil-borne pathogen that thrives on decaying organic matter but readily infects living plant tissues, specifically targeting flowers and young fruits under high-stress conditions.

Diseases and host range: The pathogen causes a devastating condition known as Choanephora wet rot or blossom blight. It has a broad host range, primarily affecting the Cucurbitaceae family (squash, pumpkins, cucumbers, melons) as well as peppers, eggplants, and beans. The disease manifests as rapid tissue maceration and water-soaked lesions.

Biology and life cycle: The lifecycle of Choanephora cucurbitarum is characterized by the production of distinctive dark, spiky sporangia that resemble a dusting of fine needles on the surface of infected tissue. It survives in soil or plant debris. Under warm and humid conditions, spores are released and dispersed by wind, splashing rain, or insects to susceptible host surfaces.

Environmental conditions and impact: Development is favored by high temperatures (25–30°C) and high relative humidity (above 90%). The pathogen's impact is significant during rainy seasons, where it can cause total loss of the fruit set within 48 to 72 hours. The speed of infection makes it a critical threat to cucurbit production in tropical and temperate regions during summer months.

Protection and control measures: Management requires an integrated approach to reduce environmental pressure and inoculum. Key strategies include enhancing air circulation to keep foliage dry, removing diseased debris immediately, and implementing proper drainage. In severe cases, preventive applications of copper-based fungicides or appropriate systemic fungicides during the early flowering stage are recommended to protect the crop.