University of Minnesota Extension
www.extension.umn.edu
612-624-1222
Menu Menu

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

Turf > Discolored leaf blades

1 of 6
  • Image: Rust 1
    Credit: M. Grabowski
  • Image: Rust 2

    Credit: Bob Mugaas

  • Image: Rust 3

    Credit: Unknown

  • - CLICK PHOTOS TO ENLARGE -

green arrowRust
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
2 of 6
  • Image: powdery mildew 1
    Credit: M. Grabowski
  • Image: powdery mildew 2

    Credit: M. Grabowski

  • Image: powdery mildew 3

    Credit: M. Grabowski

  • - CLICK PHOTOS TO ENLARGE -

green arrowPowdery 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...
3 of 6
  • Image: leaf spot 1
    Credit: K. Snover-Clift PDIS copyright
  • Image: leaf spot 2

    Credit: Bob Mugaas

  • - CLICK PHOTOS TO ENLARGE -

green arrowLeaf 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
4 of 6
  • Image: slime mold 1
    Credit: Lynn Vernon
  • Image: slime mold 2

    Credit: Lynn Vernon

  • Image: slime mold 3

    Credit: Lynn Vernon

  • - CLICK PHOTOS TO ENLARGE -

green arrowSlime 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...
5 of 6
  • Image: dollar spot 1
    Credit: M. Grabowski
  • Image: dollar spot 2

    Credit: M. Grabowski

  • Image: dollar spot 3

    Credit: M. Grabowski

  • - CLICK PHOTOS TO ENLARGE -

green arrowDollar 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
6 of 6
  • Image: red thread 1
    Credit: W. Stienstra
  • Image: red thread 2

    Credit: W. Stienstra

  • Image: red thread 3

    Credit: E. Nelson, PDIS copyright

  • - CLICK PHOTOS TO ENLARGE -

green arrowRed 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

Don't see what you're looking for?

  • © 2014 Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy