Moldy core

Moldy core is a fungal disease primarily affecting apple trees, caused by various pathogens including Coniothyrium species. Unlike surface rots, this disease develops inside the fruit, making it a significant quality issue for fresh market producers and storage facilities.

The infection process typically begins during the bloom period. The fungus enters the apple through the calyx end, particularly in varieties with open or semi-open calyx tubes. The spores settle on the floral parts and remain latent until the fruit develops, eventually colonizing the core.

Key symptoms include the growth of fungal mycelium within the seed cavities, which can appear as grey, green, or brown mold. In later stages, the rot can spread into the flesh, causing it to darken and soften. Because the fruit skin often appears intact, the internal damage is typically discovered only by the consumer.

Favorable conditions for the development of moldy core include cool, wet weather during the bloom phase. These conditions promote spore germination and establishment within the calyx. High humidity throughout the growing season further increases the potential for the pathogen to penetrate deep into the core tissues.

Integrated management is essential to control this disease. Effective strategies include:

• Selection of apple cultivars with closed calyx structures.
• Thorough orchard sanitation to remove debris and mummified fruit.
• Application of targeted fungicides during the blossom period.
• Optimizing orchard density and pruning to improve airflow and drying.
• Monitoring storage conditions to slow down fungal growth.