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Take All Root Rot Damages Centipede and St. Augustine Lawns


Original Source: 
Willie Chance, Outreach Coordinator - Georgia Center for Urban Agriculture

Many lawns in Georgia are infected with Take All root rot. This fungus disease affects centipede, St. Augustine and Bermuda lawns, though we mainly see it on centipede and St. Augustine. Affected lawns may have round or irregular dead or dying patches. The grass may yellow or wilt even though the soil is moist.

The organism that causes Take All rots the lawn’s roots and aboveground runners (stolons). To identify the disease:

  • Look for the black, rotted roots.
  • Affected stolons may be brown or black at the nodes or have dead patches.
  • One of the best ways to identify this disease is to look for the black, thread-like fungal hyphae growing on the undersides of the stolons. You will need a microscope or a good hand lens to see these hyphae. Many Georgia Extension offices have microscopes agents can use to diagnose diseases.

Take all root rot prefers cooler weather and may be confused with the green-up problems that are caused by cool spring temperatures. Take all infects lawns in the fall, grows through the winter and begins to slow growth in late spring. Unfortunately, by the time we see the symptoms of this disease in the spring, much damage is already done.

Since this disease destroys roots, lawns may be slow to recover. Affected lawns are also more susceptible to other stresses – herbicides, drought, etc. Affected lawns may not show evidence of this disease on the leaves until the turf is stressed by herbicides or other stresses. Give special care to affected areas until they recover.

Much of the damage of this disease is probably behind us by mid-spring. The damage is done in the fall and spring, but we notice the effects in late spring as temperatures increase and the weather gets drier. Expect the disease to be less active as temperatures increase.

The best year-round control is to improve cultural practices to prevent the disease and to increase the vigor of the grass so that it will recover quickly. These practices will slow disease progress and help the lawn recover.

  • Make sure the soil pH is not too high.
  • Water deeply and infrequently and do not allow the soil to remain wet.
  • Remove thatch if the thatch layer is thicker than one-half inch.
  • Use slow release fertilizers that contain equal amounts of nitrogen and potassium. Soil sample and fertilize accordingly.
  • Do not apply high nitrogen fertilizers in the fall.

Fungicides are best applied in the fall to prevent this disease. Treat in September and again in October to prevent this problem. In the early spring, (February) a fungicide may be helpful in some cases - especially if sodding or plugging turf into these areas.

Fungicides for take all include: (names in parentheses are active ingredients)

Excellent control - azoxystrobin (Heritage, etc.).

Good control under high disease pressure - triadimefon (Bayleton, etc.) fenarimol (Rubigan) and thiophanate methyl (Cleary's 3336, etc.)

Good control under moderate disease pressure - propiconazole (Banner Maxx, etc.)

For more information see http://tinyurl.com/3sxjy7x

    take-all root rot, Gaeumannomyces graminis var. avenae (Incertae sedis: Magnaporthaceae)

William M. Brown Jr., , Bugwood.org