Mold in grass

Asked December 18, 2013, 12:00 PM EST

I have spots of mold in my yard. How can I treat this?

Washington County Oregon

9 Responses

There is something commonly called "snow mold" in lawns, and a correct diagnosis is important before treatments are recommended. Please describe your issue more, perhaps including a photo or two (closer and further, showing the pattern of damage). Include description of the area and care of the lawn (were leaves remaining on the grass when the temperatures were unusually low, was it walked on while frozen). There is a general article from Oregon State Extension which you may find helpful, "How to minimize winter cold damage"

I'm not sure if I downloaded the pictures right?
let me know.

Yes, the photos came through fine. Tell me a bit about the lawn, how you care for it, when you noticed this problem, how widespread it is in your turf. Did anyone walk on it when it was frozen? Do you have animals on this area?

Normal fertilization each year.
No animals except neighborhood dogs and cats.
Yes, I probably walk on it.
Noticed it about a week ago.
Mold is not all over the yard, just about a third or so.

The pictures were not as clear as I would have liked. The mold pattern is consistent with snow mold. The good news is the treatment for snow mold is nothing. It will go away in the spring all on its own. This was a great question because we don't notmally get snow mold in the Willamette Valley.

Would you like me to try to get clearer pictures? I appreciate your quick and thorough responses.

No thank you i'm sure it is snow mold I just would like to have a good picture to save.

Are the attached photos better quality? It continues to spread and is covering most of my lawn now. Is there anything I should be doing? Thank you. Mick

Thank you for your question to Ask the Expert.

It does appear that you have a mold on your lawn and there are several "snow molds" fungal diseases that are favored with repeated freeze, thaw, frost events like we have had this winter so far. How much light does this sight get? A shady lawn will be more susceptible to fungal diseases. If this is a shady site, then you will face on-going challenges with moss and potentially with diseases and changing the conditions (removing trees or obstructions) will be your best course of action to grow healthy turf. How much fertilizer did you apply in the late summer/fall? A heavy dose at this time can favor fungal diseases? Also, what type of turf grass is planted?

There are not any available treatments for fungal diseases at this time of year because with winter fungal diseases in cool season turf grass species, the lawn will normally recover once active growth begins in the spring. Once the grass starts to grow, you might re-seed the area with turf grass seeds to fill in any gaps created by the fungus and and other problems incurred this winter. A grass seed mix with perennial rye grass and fescues will be more resistant to fungal diseases. You will also want to apply fertilizer and water next season to encourage vigorous growth of the turf, but be sparing with the fertilizer late in the season.

Please let me know if you have any further questions.