Rhacodiella

Rhacodiella is a genus of pathogenic fungi that causes severe diseases in woody and shrub species. The most notable representative is Rhacodiella castaneae, the agent responsible for black rot in chestnut fruits. This fungus belongs to the mitosporic fungi category and presents a significant challenge for the industrial cultivation of nut crops.

The primary hosts of this pathogen are the fruits of the sweet chestnut. The disease manifests as deep necrotic lesions on the tissue, which gradually darken, turning a distinct black color. Inside the affected fruit, the mycelium proliferates, destroying the kernel and rendering the produce completely unsuitable for human consumption or processing.

Infection development is favored by high air humidity, frequent rainfall during the fruit ripening period, and moderate temperatures. The fungus spores are dispersed by wind and rain droplets, entering the fruits through micro-cracks or damage caused by insect pests. Under prolonged humid autumn conditions, the pathogen can affect a substantial portion of the harvest both in the orchard and in storage facilities.

The economic damage caused by Rhacodiella results from direct losses of marketable produce. In cases of severe infection, losses can account for 30-50% of the total yield. Furthermore, the disease reduces the reproductive viability of the seeds, which is critical for nurseries involved in chestnut seedling production, as infected fruits produce weakened sprouts.

Control measures involve a comprehensive approach:

• Gathering and destroying fallen infected fruits to reduce the primary inoculum load.
• Applying preventive fungicide treatments during the vegetative growth phase.
• Ensuring optimal ventilation conditions during the storage of the harvested crop.
• Monitoring orchard health and performing timely pruning of dead or diseased branches.