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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Turf > Discolored leaf blades

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Turf > Discolored leaf blades

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  • Image: Rust 1
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Puccinia sp. or Uromyces sp.

  • Infected lawn area looks thin and tinted orange or brown
  • Powdery orange dust like spores can be seen on light colored shoes after walking through an infected lawn
  • Raised orange or yellow spots or bumps on the grass blade
  • Powdery orange or yellow dust-like spores easily rub off leaf spots and can be seen on a white tissue
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  • Image: powdery mildew 1
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Powdery Mildew
Blumeria graminis

  • Infected grass is powdered white to gray, as if flour had been spilled
  • Grass blades have fluffy to powdery white spots
  • Common in grass grown in shady areas
  • More information on Powdery Mildew...
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  • Image: leaf spot 1
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Leaf Spot and Melting Out
Dreschlera sp. and Bipolaris sp.

  • Infected grass looks thin and weak
  • Irregular small patches of dead grass throughout the infected area
  • Spots on leaves, stems and rhizomes
  • Spots vary in size and color and may be reddish-brown, purplish-black, black and may or may not have a light colored center
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  • Image: slime mold 1
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Slime Mold
Many different myxomycetes

  • Many round pin head sized balls (fungal structures) cover the surface of the grass leaf blade
  • Round fungal structure may be black, white, yellow, purple, orange or many other colors
  • Colorful round fungal structures disappear in 1 to 2 weeks
  • Typically grass in only one small area of the lawn is affected
  • Commonly seen after periods of rain or high humidity
  • More information on Slime Mold...
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  • Image: dollar spot 1
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Dollar Spot
Sclerotinia homeocarpa

  • Randomly scattered tan to gray round dead patches, 2 to 6 inches wide
  • Cobweb like fungal growth on infected grass blades during cool wet periods like early morning
  • Leaf blades have dry, tan sections with a rusty-brown border, early leaf infections may be a dry, tan oval with a rusty brown border
  • Many small patches may grow together to create larger areas of thin, tan grass
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  • Image: red thread 1
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Red Thread
Laetisaria fuciformis

  • Irregular to round patches of tan grass 2 to 24 inches wide
  • Grass blades die and turn tan from the tip down and are often mixed with healthy grass blades
  • In humid weather, clumps of pink cotton candy-like fungal growth can be seen on infected patches of grass
  • Hard pink to red thread shaped fungal structures emerge from the tip of infected grass blades
  • Common in cool, wet weather and N-deficient grass

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