My lawn was replanted from seed last fall, and has been looking generally good this year, though the overall color seemed a bit lacking recently. Upon closer inspection, I found that throughout the lawn (no specific localized areas) there are grass blades with orange/yellow/brown bands of discoloration on them (see photo), intermixed with normal/healthy-looking grass.

The discoloration doesn't seem to be strictly the top or bottom of the blades, but can be present only in the middle of the blade as well (with green above and below). In some blades, there are mixtures of multiple green/yellow/orange/brown bands throughout the extent of the blade.

Yellow/orange/red seem to be the main colors, with occasional small bits of brown/black.

The only thing I keep coming across for orange grass is lawn rust, but this does not seem to fit the bill (no spore-emitting orange/red spots visible, no "rust" coming off on fingers/shoes).

Some notes about the lawn:

  • mix of KBG, perennial ryegrass, creeping red fescue
  • irrigated twice weekly (should be about ~1 inch/week, though I haven't accurately measured this)
  • located in Ontario, Canada
  • little to no weeds
  • mowed regularly ~3-3.5 inches (mulched back onto lawn)
  • full sun for a majority of the day
  • fertilized in April and June

Interestingly, the few areas of the lawn that get more shade (near house and around base of large spruce) seem to have this issue less, being noticeably greener and also growing longer/faster.

Any ideas what this could be?

Discolored grass blades

  • Is it only the fescue? It's "red" fescue, right? j/k To me, it looks like it's simply getting roasted/dried in the sun, and fescue is always the bad-stuff canary in my lawn. The shade doing better supports that more than a fungus theory. Do the bands separating the green appear about a half-week of growth apart? I would try hand-watering a small patch twice a week, between timers, and see if that section starts picking up after a week or 2.
    – dandavis
    Jul 30, 2021 at 9:09


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