Plant Health Problems
See Bulbs for a detailed discussion of problems that may occur and are common to most bulbs.
Diseases caused by Fungi:
Botrytis blight, Botrytis spp.
This is one of the most widespread and common diseases of all bulbs. Symptoms are variable and can appear as oval or circular spots which are initially reddish-brown and develop pale centers and purplish margins. These spots may run together and rot the entire leaf. These can progress into the stem and cause the stalk to fall over. If the spots dry out, they turn brown or gray. Buds or flowers may turn brown and rot and are often covered with the diagnostic gray, fuzzy growth of the fungus. This disease shows up and spreads rapidly under cool, humid conditions especially if plants are crowded.
Control involves raking and removing any affected plant parts after the tops are killed in the fall. It is also helpful to avoid overhead irrigation and crowding of the plants. When conditions are favorable, applications of fungicides can be made when new growth emerges in the spring. Among the compounds registered for use in Connecticut are chlorothalonil, thiophanate-methyl, iprodione, and mancozeb. Consult the label for dosage rates and safety precautions.
Diseases caused by Bacteria:
Soft rot, Erwinia carotovora.
Infected plants fail to flower or blossoms fall off before they open. Tops may appear water-soaked and collapse. Infected bulbs have a strong odor and are soft and mushy.
Since this pathogen is highly contagious, all infected bulbs should be discarded. It is helpful to carefully remove any symptomatic foliage and plant debris in the fall after the tops have been killed by frost. Bulbs should be planted in well-drained soil and watered early in the day. This disease can also be minimized by avoiding overcrowding and wounding during cultivation. Sanitation is also very important. All equipment should be disinfested between use with 10% household bleach, 70% alcohol, or one of the commercially available compounds. It is also helpful to control insects and mites since injuries associated with their activity provide sites for infection.