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My neighbor  has a gravel only drive . and never uses roundup  , NONE of this stuff on his drive to date .  So  round up and its generic derivatives is a common denominator here . .   .

if it is a bacterium  then the pool algacides would be of no use ?

or copper ,? 

I'm in Ohio and have been fighting this stuff for years and had the same conclusion that Round Up plays a roll in this problem but definitely worse if applied to exposed  clay soil.   I did try vinegar on a small area  and it did seem to inhibit the growth but was concerned with how it would effect the plants around so never used it on a larger scale ...I have just been picking it up and putting it in a bag in the garbage  but it just expands to more and more areas.  I'd love an easier SAFE solution , sounds like after reading through all this, that acidifying the soil  and perhaps contacting ROUND-UP might help ? ? 

I have it in my yard and we live in ireland all thats been done so far is scrape it away when sun shines but then it increases when it rains any advice ?

We have the wretched stuff down here in Cornwall as well !!!   Most pronounced after rain and spreading like crazy - also, appeared in strength not long after using Round-up !

It's on a stone chipping yard so not easy to clean up.  Very unsightly and slippery.

Will advise if we come across anything that gets rid of it.



I have been told that appears in places that are sprayed. Also I was told to sprinkle biological washing powder on it and the rain will wash it in.


I've just read through all comments and not on solution does any know how to get rid of this very unsightly stuff ! Help.

Evidently these algae are over 2.8 billion years old and have survived the ice age and volcanic activity but can be banished on hard surfaces with a 20% sodium hypochlorite solution - but will it work - I'll be trying it on a gravel path shortly and will report back . . .  Happy New Year.


I have a driveway 20' X 12' and covered with stone chipping. I have used Dri Pak Fine Soda Crystals 1 kg which I dissolved in hot water in a 10ltr watering can and then filled to the top with cold water. For this area I used 3 X cans and a fine rose to spray the whole area. I repeated this about 2 weeks later and now the whole area is clear.  Cheap, easy and safe.


Would be great to hear from Margaret Ibbs and David White3 and hear how things are going with their solutions. 

I have nostoc on a driveway that is compacted gravel (not sure what kind) on clay soil where roundup has been used quite a it. That is a consistent theme in this thread.

Tried Margaret Ibbs method and - hooray - results! The fungus is affected in a way that no othe treatment has produced, so I am very hopeful. Will update with further results. Meanwhile, a tentative thank you to Margaret.

Unfortunately I have been unable to trial the solution that I proposed as my customer went ahead and had his paths relaid with fresh gravel however I now know that this stuff can be tracked in on the feet of visitors as I now have it on another customer's site and I think I was the unsuspecting carrier. It does disappear in dry weather so inhibiting light and moisture will help to eradicate the problem but this may not be possible over large areas or where there is a mixture of the algae and other plants growing together.

In the instance I originally quoted, no weedkiller of any sort had been applied for several years as we had been harvesting lavender seedlings from the path for at least two seasons.


So the upshot is - no positive news at present . . .

would love to have an update on the Dri pak soda crystals??

plant pauper

I'm going to give it a go parker. Nothing to lose I suppose. I'm imagining any soda crystals would work so I shall be sprinkling liberally as they're tuppence a ton. Here's hoping.

we bought some and are going to give it a shot also.  Will update with our results, applying today.  Believe it or not we are from Southern Illinois, but this appeared on our driveway a couple of years ago that is covered with limestone rock, but we have very heavy clay soil.  Seems to mostly appear and spread to areas where we need to replace the rock.  we just started spraying this area with round up a couple of years ago.  we have had a very rainy spring and it has spread like crazy. 

I see that CobCottb tried the soda crystals and I'm very interested in follow up results to see if it sustained. I decided to try a different solution. I found a research report by the Oregon Department of Agriculture that studied 6 solutions for nostoc over several weeks. (Here is the report: The best results were achieved using Scythe Herbicide. Their test areas had heavy and healthy nostoc growth and in one location (a nursery) there was an overhead watering system in regular use during the test weeks. The active ingredient is NOT glyphosate (Roundup) which is good since I think Roundup was the instigator for me, and Scythe is a broad spectrum herbicide ( that will probably kill all the things I was using Roundup for. So that's a bonus. I will do the first application in a couple of weeks and will follow up this post with results. 

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