Problem: Viruses (Lily)
Several viral diseases of lilies cause mottling or flecking of the foliage. Mosaic viruses produce leaf mottling and discoloration. Depending on the species or variety, the symptoms of infection can be mild or severe. Fleck is produced if a plant is simultaneously infected by the symptomless lily virus and the cucumber mosaic virus (which may or may not produce mottling by itself). Leaf flecking is usually accompanied by stunting and poor-quality flowers and foliage. The plant is generally disfigured. Viruses remain in infected bulbs year after year, so successive plantings of diseased bulbs will produce only poor-quality flowers and foliage. All of these viruses are spread by aphids, which pick up the virus while feeding on diseased plants and then, at later feedings, transmit it to healthy plants.
Remove and destroy infected plants. Control aphids by applying an insecticide labeled for aphids. Plant lilies that are resistant to viral diseases.