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Lily-of-the-valley (Convallaria)

Plant Health Problems
Diseases caused by Fungi:

Botrytis flower and stem rot, Botrytis spp.
Symptoms often appear in early summer when conditions are warm and very humid. All plant parts can be infected including leaves, flowers, and stems. Infected tissues are often covered with the characteristic gray, fuzzy growth of the fungus.

Good sanitation practices including grooming the plants and removing spent or senescing flowers can minimize the potential for infection. These affected tissues should be carefully removed and discarded when they are dry. It is also important to avoid wetting the flowers when watering and crowding plants. Adequate spacing between the plants can promote good air circulation. Control can also be achieved with the use of fungicide sprays during the growing season. These can be applied as soon as symptoms are visible. Among the compounds registered for use in Connecticut is thiophanate-methyl. Consult the label for dosage rates and safety precautions.

Anthracnose, Gloeosporium sp.
Symptoms appear as brown spots or lesions with purplish borders on leaves, petioles, and flower stalks. Diseased tissues often drop out and infected foliage dies prematurely.

Efforts to maximize plant vigor by fertilizing and watering are helpful. However, watering should be done early in the day to give the foliage a chance to dry before nighttime. It is also helpful to pick and remove symptomatic leaves as soon as they develop. Although not usually necessary, applications of fungicides can be made when new growth emerges in the spring. Among the compounds registered for use in Connecticut is thiophanate-methyl. Consult the label for dosage rates and safety precautions.

Insect Problems

Lily of the valley weevil, Hormorus undulatus.
The leaves of lily of the valley are often curiously notched by this weevil, which eats into the leaf margins. Control is seldom needed, but malathion, which is among the compounds registered for use against this pest in Connecticut, sprayed where weevils are feeding will control them. Consult the labels for dosage rates and safety precautions.