To prevent this disease, thin plants to improve air circulation within the bed and use straw mulch. Fungicides may also be applied. Leather rot is caused by a fungus that infects the berries when ripening fruit clusters are in contact with the soil or standing in water after a period of warm, rainy weather. Infected immature fruit turns brown. On ripening fruit, the color becomes bleached out and infected areas are tough and dry.
Berries taste bitter and smell rotten.
A single infected berry can ruin the flavor of a whole jar of jam. To prevent this disease, use a mulch to minimize rain splash onto the fruit, or fungicides may be applied. Viruses may stunt plant growth or cause mottling or curling of leaves. They are introduced by insects such as aphids or leafhoppers. To prevent viruses, use certified plants and control these insects.