Mosaic Disease, a virus disease of plants. The leaves of diseased plants usually turn a mottled dark green and light green, or yellow and green. In some plants, the leaves become spotted, curled, or dwarfed. Mosaic disease is spread by humans or farm machinery that have come into contact with diseased plants, or by insect carriers, such as aphids. Crops attacked include sugarcane, snap beans, apples, cantaloupes, tobacco, soybeans, peppers, potatoes, celery, and tomatoes. Diseased plants should be destroyed. Mosaic disease is controlled by spraying and dusting plants to destroy aphids, and by planting mosaic-resistant varieties.