Apple scab

Apple scab is a severe fungal disease caused by Venturia inaequalis. It is considered one of the most economically significant diseases affecting apple trees worldwide, impacting both foliage health and the quality of the fruit produced in the orchard.

The disease manifests as olive-green to black velvety spots on the leaves, which later turn brown and can cause leaves to drop prematurely. On fruit, the lesions appear as dark, scabby areas that often lead to deformation and cracking of the fruit surface as it continues to grow.

The fungus thrives in cool, wet conditions, especially during the spring when susceptible young leaves and flower parts are present. Spores are released from overwintering infected leaves on the ground during rainfall, leading to primary infections that can spread rapidly throughout the season.

The impact of apple scab is substantial as it drastically reduces the market value of the harvest. Severe infections not only spoil the aesthetic appearance of the fruit but also weaken the tree's vigor, making it more susceptible to environmental stress and other opportunistic pests.

To effectively manage and prevent the spread of apple scab, growers should implement the following practices:

• Sanitize the orchard by raking and removing or shredding fallen leaves in late autumn.
• Promote good air circulation through proper pruning to help the canopy dry quickly after rain.
• Choose disease-resistant apple cultivars whenever possible.
• Apply fungicide sprays at critical timing points, particularly during the primary infection period in spring.