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Black Slime in Grass

Over the summer, a black shiny substance has appeared in one corner of our lawn. I am not sure what it is. The grass remains fine and it seems to live at the base, on the thatch/soil. It is really shiny but not wet or slimy.

I have twice used a hose to blast it away, but it always returns. I suspect I am never getting all of it and thus it just grows again.

I am really concerned as the pacth is slowly growing.

Anyone know what this is and whether treatable ? I am thinking of either putting in a small trench to try and save the rest of the lawn or perhaps hammer in some wooden shuttering to form a barrier.

If not treatable, assume my only choice is to remove the affected area and re-turf ? Hopefully this is surface infection only, not in the ground (i.e. would come back through new grass).

Any help or ideas welcome.



  • Alina WAlina W Posts: 1,445

    It may be a form of slime mould. Slime moulds are harmless to grass, and no treatment is necessary - you can blast them away with a jet of water, as you have been doing.

    A possible cause is lack of nutrients in the soil, possibly caused by this year's heavy rain. You may well find that it vanishes next year.

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