Your photos show small, irregular brown-to-olive lesions on the fruit surface that have a corky, slightly raised appearance. This pattern is characteristic of apple scab, caused by the fungus Venturia inaequalis (often called “black spot” in Australasia).

Why It’s Apple Scab and Not Just Russeting

• Color and Texture: Apple scab lesions begin olive-green and mature to dark brown or black, with a velvety to corky texture. Russeting, by contrast, is a uniform brown roughness caused by cuticle cracking and cork cell formation, usually covering broad patches and without the distinct, often angular margins seen here.
• Lesion Shape: Scab lesions are irregularly shaped and sometimes coalesce; russet tends to form net-like patterns or diffuse patches.
• Distribution on Fruit: Scab often appears where moisture lingers—along the shaded side of the fruit or near stem areas—matching your images.

Life Cycle and Why It Shows Up on Fruit

Impact on Fruit and Yield

• Aesthetics and Marketability: Scabby fruit are unappealing for fresh markets and may crack around lesions as the fruit grows.
• Tree Health: Repeated defoliation from severe leaf scab weakens trees, reducing yield in subsequent seasons.

Management Strategies

Effective control combines cultural and chemical tactics:

The brown, corky spots on your apples are classic apple scab lesions, not simple russeting. Removing fallen leaves, improving air circulation, selecting resistant cultivars, and timely fungicide applications are key to reducing scab pressure and protecting both fruit quality and tree health.

The small, irregular brown-to-olive lesions on your apples—with their corky, slightly raised texture—are classic symptoms of apple scab, a disease caused by the fungus Venturia equalis. Unlike russeting, which produces uniform brownish patches from cuticle cracking, scab lesions start olive-green, darken to brown or black, and often have angular or coalescing shapes where moisture lingers. You can see that in your photos: the spots cluster on the shaded and stem-end areas of the fruit, exactly where rain splash and prolonged wetness promote fungal infection.

Apple scab overwinters in fallen, infected leaves beneath the trees. As spring rains arrive, the fungus releases ascospores that infect new leaves and young fruit. Those primary lesions then produce conidia throughout the season, causing repeated infection cycles whenever conditions remain wet. Over time, the fungus weakens the tree by defoliating leaves, reducing overall vigor and yield. On the fruit itself, scab lesions may crack as the apple expands, rendering the fruit unmarketable for fresh sale.

Managing apple scab effectively requires an integrated approach. In late autumn and winter, clear and destroy fallen leaves to cut down the overwintering inoculum. In spring, begin a fungicide spray program at green tip and continue through petal fall, targeting forecast wetting events; rotating products with different modes of action helps prevent the fungus from developing resistance. Pruning the canopy to improve air circulation and sunlight penetration accelerates drying of leaves and fruit, further discouraging infection. When establishing new blocks, choosing scab-resistant cultivars (such as ‘Prima,’ ‘Redfree,’ or ‘Florina-Querina’) can dramatically reduce disease pressure. Finally, avoid overhead irrigation that prolongs leaf wetness, and instead use drip or microsprinkler systems to keep foliage drier.

By combining sanitation, proper cultivar selection, targeted fungicide applications, canopy management, and careful irrigation practices, you can greatly reduce apple scab incidence, protect fruit quality, and maintain healthy, productive trees.

Apple scab