Melting Out

Disease

Dreschlera poae

Photos

melting out 2.jpg

Symptoms of melting-out resemble leaf spot symptoms and these two diseases are often grouped together. Melting out however is a cool-weather disease where leaf spot is a warm-weather disease. Symptoms first appear as black to purple spots on the leaf blades. Spots eventually move to the leaf sheaths, and the fungus invades the crowns and roots of the grass plant. The turf stand will appear yellow or blackish brown from a distance depending on the nitrogen level of the turf during infection.

Melting-out has two stages of disease development; one being in the early spring in cool, wet weather, which brings about spotting on the leaves of the turf. As cool, wet conditions persist, the crown and root rot stage of the disease follows, and infected turfgrass begins to thin and die. Fall infection should also be noted, but is rarely seen unless extended cool, wet weather occurs.

  • Crops Affected: turf

    Damage

    The location of this disease is home lawns and golf courses. General symptoms are spots or wilted grass. Foliar symptoms are browning and spotting. This can occur during the months of April, May, June, and July. Hosts of the disease are Kentucky Bluegrass.

    Management

    Raising the height of cut during the cool, wet weather of spring and fall will help turf to survive an attack of melting-out. Adequate nitrogen fertilization during the cool weather of the spring and fall will help to reduce disease severity. Daily, midday irrigation will reduce the severity of melting out. The turf should receive between 0.10 and 0.20 in. (0.25 and 0.5 cm) of irrigation every day. Proper nitrogen fertility and irrigation practices should allow for sufficient management of melting-out, avoiding the need for fungicides.

    Many improved cultivars of Kentucky bluegrass have resistance to melting-out.

    Fungicides for the control of melting-out include iprodione, vinclozolin, and chlorothalonil. These can be applied to golf course turf, but no longer be used on home lawns due to EPA regulations. Fungicide application should take place between 50° F and 60° F (10° C and 15.5° C) for effective control of melting-out.

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