Sclerotiniose

any one of several plant diseases caused by pathogenic fungi having sclerotia in their growth cycle. The most harmful sclerotinioses are white rot of sunflowers, carrots, and cabbage (especially during storage); sclerotinia crown rot of clover; and sclerotiniosis of winter grains (causative agent Sclerotinia graminearum).

The pathogenic organism that causes sclerotiniosis of winter grains lives in the soil. It damages winter wheat, rye, and a number of perennial grasses (timothy, foxtail, meadow grass, fescue, ryegrass, orchard grass, brome, and many weeds of the family Gramineae). In the spring, the leaves of diseased plants turn yellow and become covered with a gray cottony bloom. Black sclerotia develop under the epidermis of the leaves. Severely diseased plants die or produce a small harvest. In the fall the sclerotia sprout into apothecia, and the ascospores growing inside the latter damage the plants.

Southern blight (causative agent Sclerotinia roefsii), which attacks peanuts, tobacco, and potatoes, and charcoal rot (causative agent S. bataticola), which damages alfalfa, cotton, and corn, are caused by fungi whose growth cycle has only sclerotia and mycelia (there is no sporebearing).

Methods of controlling sclerotinioses involve the creation of conditions that foster healthy plant growth. Measures include deep autumn plowing, adding lime to acidic soil, sowing winter crops at the optimal time, removing melted snow and stagnant water from the fields, and clearing away and burning dead plants and sclerotia.