Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Botrytis Blight

Problem
Light to dark-colored spots appear on the leaves and flowers. The spots enlarge to form extensive gray blotches, which may cover the entire leaf and flower. During periods of cool, moist weather, a fuzzy brown or grayish mold forms on the infected tissue. Many of the leaves and stems are distorted, and often rot off at the base. There are dark, circular, sunken lesions on infected bulbs. Dark brown pinhead-sized pellets form on the bulb husks.

Analysis
This common disease of tulips is caused by a fungus (Botrytis tulipae). The fungus persists through the winter and hot, dry periods as tiny fungal pellets in the soil, plant debris, and bulbs. In the spring, these pellets produce spores that attack foliage and flowers, causing spotting, decay, and mold. Wounded, weak, and dead plant tissues are especially susceptible to infection. The fungus is spread by splashing water. Botrytis blight is most serious during periods of cool, moist weather. Tulip bulbs that are injured when they are dug up to be stored are especially vulnerable to infection.

Solution
Remove and destroy diseased plants, leaves, flowers, and debris. Before planting tulip bulbs, check them for signs of infection, and discard diseased bulbs. Start spraying emerging plants when they are 4 inches tall with a fungicide containing mancozeb. Use a spreader-sticker when spraying (see Applying Pesticides). Spray plants every 5 to 7 days until the flowers bloom. Remove tulip flowers just as they start to fade, and cut off the foliage at ground level when it turns yellow. Rotate plants to a new location next year.

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