Fungus on Centipede Grass

Native to China and southeastern Asia, centipede grass (Eremochloa ophiuroides) has become a popular lawn turf since its introduction into the United States in 1916. A relatively low-maintenance lawn, it requires very little fertilizing to flourish. A warm-season grass, centipede grass spreads rapidly through stolons. The grass is moderately shade tolerant but prefers full sunlight. Centipede grass is susceptible to fungal infections.

Types of Fungus

The fungal infections brown patch (Rhizoctonia species) and dollar spot (Sclerotinia homoeocarpa or Lanzia and Moellerodiscus) commonly afflict centipede grass. Brown patch develops rapidly when the temperature hovers between 70 to 90 degrees Fahrenheit. Centipede grass normally suffers from brown spot in the spring or fall months. Dollar spot occurs from late spring into the early fall months. It prefers warm days and cool nights to flourish.

Appearance

Brown spot appears as circular areas of brown lawn. The brown patches may thin out over time. The brown spots normally have a darker brown ring around the perimeter. The spots' diameter can range from only a few inches up to several feet. Dollar spot begins as small yellow spots in the grass that quickly progress to a pure white color. The grass begins to die from the tip and death works its way downward. Rarely the grass begins to show white lesions in the middle of the blade with the tip remaining green. When the grass is damp from morning dew a fine spiderweb appearance can be seen which is the fungus growing on the blades and spreading.

Factors

Centipede grass that is suffering stress from inadequate watering or over-watering can develop fungal infections. The grass is also more susceptible if it is receiving too much fertilizer. The fungus can also be spread through poor mowing practices. Grass cultivation tools can harbor the fungus and spread it to newly clipped lawns. Centipede grass does not tolerate areas that suffer severe frosts in the winter. Rapid cooling and warming will deplete the grass over time, according to Texas A&M University. The grass requires a warm, year-round temperature to flourish and fight off fungal diseases.

Prevention

Avoid applying nitrogen fertilizers in the fall or spring because this will only help the fungus that causes brown patch to flourish. Mow centipede grass closely to limit dollar spot fungus from taking hold of the grass. A lower mowing height helps air to circulate through the grass blades. Centipede grass that is allowed to exceed 5 inches in height has a higher risk of developing fungal infections. Irrigate only during the early morning hours so the grass has a chance to dry out before nightfall, which can help prevent fungal infections.

Solution

Using fungicide to control both brown patch and dollar spot fungal infections should be a last resort, according to Colorado State University. Apply fungicides that contain propiconazole or mancozeb to help control dollar spot fungus. Fungicides that contain triadimefon or myclobutanil have shown success in helping treat and reduce brown spot fungus. Alternating fungicides between applications can help the fungus not build up a resistance to the fungicide.