Problems with Lilies
suffer from pests, particularly leather-jackets, cutworms and slugs. Regular use of meta baits, pellets or sprays will take care of the slugs, and dusts such as aldrin or gammexane should discourage the other soil pests. Aphids are a serious pest, because they not only spoil the appearance and cripple the leaves and buds of the lily, but also carry the deadly virus diseases. Use D.D.T. Dusts or sprays such as malathion for these.
Lily diseases are few but serious. Botrytis is a fungus infection not unlike potato blight or black spot in roses. It produces brownish patches which spread and ruin the whole leaf and stem, and even the buds. Burn the affected leaves, and spray the plant with Bordeaux mixture, or use a fungicide dust. Botrytis is spread by airborne spores originating in grey mildewy patches on the plant. These need damp and warmth to germinate, and can survive the winter as sclerotia or little black seed-like objects in the soil.
Virus diseases stunt and cripple the plant, eventually killing it. Pale streaks, spots and mottles appear on the leaves giving them a variegated appearance, and the petals stick together. Sometimes the top of the plant is bent over like a walking-stick handle; or the stem is shortened between the leaf axils as if it had been shut up like a telescope. As there is no known cure, do everything possible to prevent infection. These diseases are carried in the sap. Biting or piercing insects, such as aphids, can carry them, and they can be carried by scratching or bruising infected plants and handling healthy ones afterwards. They can also be carried on shoes and tools.
Diseasedshould, therefore, be burnt, but only after making quite sure that they really have got virus disease. Symptoms similar to those of virus diseases may be caused by underground pests, too much or too little water, or growing the lilies in the wrong kind of soil. Even a touch of frost earlier in the year may have caused the trouble.
Fusarium basal rot is a nuisance. The basal plate starts to rot away into a brown mess and the trouble spreads up the scales until the whole bulb falls to pieces. Burn every scrap, and do not plant lilies in the infected soil for four years, unless it is sterilized with formalin. If in doubt, grow the suspect lily in a pot for a year.
If a choice collection of lilies is desired, grow as many as possible from seed, since lily diseases are not carried by seed. If bulbs are bought, be sure they come from a reputable nurseryman.