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Take All & Large Patch Attack Georgia Lawns

Lee Burpee, Plant Pathologist
Alfredo Martinez, Extension Plant Pathologist
Mila Pearce, former IPM Homeowner Specialist
University of Georgia

Take-All Root Rot

Caused by the fungus Gaeumannomyces graminis var. graminis.

 

Susceptible Turfgrass: St. Augustinegrass, Bermudagrass and Centipedegrass. Bluegrass and Fescues are rarely affected in Georgia.

 

Symptoms:

Take-all patch causes wilted, circular patches that are brown or bronze-colored and measure up to several feet in diameter. Infected plants have dark-brown roots.

 

Conditions Favoring Disease:

Take-all root rot typically occurs in wet conditions and in areas with a high soil pH -- most severe at pH 6.5 or above. This disease is more severe on less fertile and sandy soils.

 

Signs:

Strands of darkly pigmented, ectotrophic, runner hyphae can be seen on roots, stolons, and rhizomes both with the dissecting and compound microscope. Infection hyphae originate from lobed hyphopodia.

 

Management Tips:

  • Use acidifying fertilizers.
  • Apply moderate to high levels of phosphorous, potash and minor elements where these nutrients are depleted from the soil.
  • Improve the drainage of the turf.
  • Reduce thatch.
  • Fungicides are available to control the disease. Consult the current Georgia Pest Management Handbook.

Brown Patch/Large Patch

Caused by the fungus Rhizoctonia solani

 Susceptible Turfgrass:

Brown patch: All species of cool-season turfgrass.
Large Patch: All species of warm-season turfgrass.

 These are the most frequently diagnosed diseases on turf samples at University of Georgia Disease Clinics.

 Symptoms:

Brown Patch: The symptoms of brown patch can vary depending on the grass cultivar, climatic and atmospheric conditions, and soil management of the turfgrass. This disease typically causes rings and/or patches of blighted turfgrass that measure 5 inches to more than 10 feet in diameter. It also causes leaf spots and "smoke rings" -- thin, brown borders around the diseased patches that appear most frequently in the early morning. After the leaves die in the blighted area, new leaves can emerge from the surviving crowns. On wide bladed species, leaf lesions develop with tan centers and dark brown to black margins.

 Large Patch: Large patch occurs during the spring and fall, when warm-season turfgrasses are entering or exiting their period of winter dormancy. Circular patches of diseased turf are observed, ranging in diameter from less than 3 ft. up to 25 ft. Leaves of recently infected turf, located at the periphery of the patch, may appear orange in color. Some patches may be perennial, recurring in the same location and expanding in diameter year after year. In contrast to brown patch, R. solani infection of warm-season grasses occurs on the leaf sheaths, where water-soaked, reddish-brown or black lesions are observed. Foliar dieback from the leaf tip toward the base occurs as a direct result of these leaf sheath infections.

 Conditions Favoring Disease:

Brown patch favors high relative humidity as well as temperatures of over 80ºF during the day and over 60ºF at night. This disease can be quite active at cool temperatures on warm season grasses in the spring and fall. It also occurs in areas that experience more than 10 hours a day of foliar wetness for several consecutive days. Brown patch infestation is more severe when the turf is cut to a height less than the optimum for the turf-grass being grown. Large patch is favored by high relative humidity as well as temperatures of over 80ºF during the day and over 55ºF at night.

 

 Signs:

Rhizoctonia produces distinct mycelia with three characteristics for diagnostics. Rhizoctonia always has septate hyphae that branch at 90 degree angles, constrictions at the base of the branching, and is tan to light brown color.

 

 

 

Management Tips:

  • Use low to moderate amounts of nitrogen, moderate amounts of phosphorous and moderate to high amounts of potash.
  • Avoid nitrogen applications when the disease is active.
  • Increase the height of cut.
  • Increase the air circulation.
  • Minimize the amount of shade.
  • Irrigate turf early in the day.
  • Improve the drainage of the turf.
  • Reduce thatch.
  • Apply lime if soil pH is less than 6.5
  • Remove dew from turf early in the day.

Fungicides are available to control the disease. Consult the current Georgia Pest Management Handbook.

 

Please share this information with others in the landscape & turf industry. For more information:

Call your local Extension Agent at (800) ASK-UGA1 or locate your local Extension Office at http://www.caes.uga.edu/extension/statewide.cfm

www.georgiaturf.com

Pest Management Handbook (Follow all label recommendations when using any pesticide) - www.ent.uga.edu/pmh/

 

For more Landscape Alerts please visit the Georgia Center for Urban Agriculture

 

   

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