Fungal diseases that cause fruit, leaves, and tubers to develop areas of hardened and sometimes cracked tissue. Fruit scab can be a major problem on apples and peaches. It is recommended to dispose of fallen leaves, pruning to increase air movement, and spraying during the growing season with sulfur. Regular sprays of garlic and seaweed will also help. Compost tea is also beneficial and horticultural cornmeal should be applied to the soil.