Is this fungus on the lawn? - Ask Extension
There are a couple spots on the lawn that popped up after the recent rain that we think might be a fungus. Is this large patch, or something else? Do ...
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Is this fungus on the lawn? #867667
Asked May 08, 2024, 8:37 PM EDT
There are a couple spots on the lawn that popped up after the recent rain that we think might be a fungus. Is this large patch, or something else? Do we need to worry about this spreading?
Montgomery County Maryland
Expert Response
We're consulting a couple turf specialists to see if they recognize these symptoms, but more information about the lawn would be useful. Is the lawn comprised mainly of tall fescue, or perhaps Kentucky bluegrass? We ask because their vulnerability to certain diseases differs. Was any fertilizer or pesticide applied to the lawn this spring? Do the brown areas lift up fairly easily, like the turf is disconnected from its roots (or like the roots are mostly missing), or is it still firmly rooted-in to the soil?
Miri
Miri
Hi Miri,
Thank you! I honestly don't know which grasses these are because we seeded it with a grass mix (last fall and again a bit this spring) - I know there is bermuda grass in the yard but I also suspect tall fescue was part of the mix that was seeded.
No fertilizer or pesticide was applied in the spring.
The brown areas don't lift up easily - feels firmly rooted to the soil.
Nadia
Thank you for the additional information. We heard back from one of the turf specialists and they don't think this is a disease like Large Patch or Summer Patch (or even Brown Patch) as it's too early in the season for symptoms to be this advanced (nor would we tend to see them this drastic in such concentrated spots). After a rainy/dewy/foggy morning, do you see any fungal growth on the grass itself? (It will not be visible when it's been dry for a while.) This is called mycelium, and would look like tufts of grayish-white filaments in the close-up photo on our Brown Patch web page. A photo of visible mycelium would help us narrow-down which fungus, if any, is responsible.
Another possibility is a fungus-like root rot organism called Pythium, which takes advantage of poor drainage, compacted soil, and/or warm-wet conditions. It can cause more drastic die-off like we see here, though in that case, we'd expect the dead grass to pull up more easily.
For now, we suggest just waiting until next week in case this is mainly affected by recent rains and unusual early-season heat. You can rake-off all the brown/dead grass foliage, though if you wanted to patch an area, sod would be easier to work with than seed for this late in the season. If you wanted to wait until late summer or early autumn to seed (the ideal time for cool-season turf like fescue), look for a seed blend that includes at least one of the Recommended Turfgrass Cultivars, which are locally tested for heat tolerance and disease resistance (though none are immune). Maryland Certified Sod will already contain recommended varieties.
Dormant Bermudagrass will also be totally brown before regrowing in late spring, and it will be hard to pull up as well. If this was an area where that weed thrived last year, perhaps at least some of this brown growth is the not-yet-regrown Bermudagrass. If so, it will need to be dug out.
Miri
Another possibility is a fungus-like root rot organism called Pythium, which takes advantage of poor drainage, compacted soil, and/or warm-wet conditions. It can cause more drastic die-off like we see here, though in that case, we'd expect the dead grass to pull up more easily.
For now, we suggest just waiting until next week in case this is mainly affected by recent rains and unusual early-season heat. You can rake-off all the brown/dead grass foliage, though if you wanted to patch an area, sod would be easier to work with than seed for this late in the season. If you wanted to wait until late summer or early autumn to seed (the ideal time for cool-season turf like fescue), look for a seed blend that includes at least one of the Recommended Turfgrass Cultivars, which are locally tested for heat tolerance and disease resistance (though none are immune). Maryland Certified Sod will already contain recommended varieties.
Dormant Bermudagrass will also be totally brown before regrowing in late spring, and it will be hard to pull up as well. If this was an area where that weed thrived last year, perhaps at least some of this brown growth is the not-yet-regrown Bermudagrass. If so, it will need to be dug out.
Miri
