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We have same thing going on the garden paths. We just found the stuff this spring . I want to kill it now !

Thank you  

We had been fighting the green slime of nostoc on our gravel driveway for a number of years with no success.  We tried every kind of weed killer and moss killer.  We tried copper sulfate, lime, and straight bleach.  We tried burning it off.  We even resorted to spray paint to try to sufficate it.  Nothing worked until.......  baking soda.  We just got bags of baking soda (bicarbonate of soda) from the local feed store and spread it on the driveway using a drop spreader.  We put a heavy coat on because we have no idea of the concentration level needed.   Within a week the nostoc turned brown - which from experience we know is the "dead" color.  The cripsy black color is just a "waiting to be rehydrated" color.  We are going to play with the concentration and see if dissolving the baking soda in water and spraying will have the same effect - but for now we are happy with the results.

Hope this helps someone else.  We felt we were fighting a losing battle to the slime!



what about bleach or toilet cleaner if patches are not on gardens..

I havent been anywhere near your gravel 


I want to make a suggestion and I believe I am right, Have any of you use round-up on your drive to get rid of weeds? I believe that there is a direct correlation between the Round-Up and the Blue Green Algae.

I am very sure where this stuff started from and I would like for you to just think about it. Have you ever used Round-Up or a product that is similar to kill weeds on your driveway? I believe that is what started our Blue Green Algae problem. Something to think about!

Have you tried using Jeyes fluid neat? That is quite good at killing algae.

What about vinegar??  Just a thought.....

Wondering if jchventures has an update? I would love to know if the baking soda remedy is still holding as effective?

Hi rlkatz, I used RoundUp only a month ago and now I have this Blue Green Algae, you may have a point here as I never had this before using Round Up.

Hi all, I have this in my gravel!  I used a BHS path cleaning product twice last year and again in june this year (August now) and I'm very confident that the problem has come from that.  I have been recomended white vinegar by some local chaps, also diluted chloride (bleach).  The stuff sold for keeping swimming pool water clean!  That'll be my next move.  Will let you know how it goes.


If you read this whole thread, the only reported success is baking soda which is also the least noxious and damaging chemical mentioned, so why not try that first?

Hi all, just to let you know this problem isn't only in England we have the algae on our driveway here in NZ. Comes up after spraying weeds with glyphosphate (Round Up).

Hoping the bicarb. of soda treatment will deal to it as it's awful stuff.


I tried bicarb with no joy...I just had to manually remove it all and it's not returned so far, we are in autumn now though.


Steve 309

Nostoc is a member of the Cyanophyta (actually they probably have some trendy modern name now*) which used to be called blue-green algae because some of them were blue-green and some of them looked like algae.  However, they'e a much simpler (prokaryotic) form of life, much more akin to bacteria.

Why am I telling you all this?  Because, not being an alga, it's possible that stuff designed to kill algae won't kill Nostoc.  Looks like sodium bicarbonate's the stuff,  but it might be worth doing some dosage investigation.

*Just looked it up.  Cyanobacteria.

yep north auckland  newzealand . I have the same problem . I also have used roundup on the drive. I see it along the gravel road also . I think the council may use roundup ont he edge of the road. 

Also from Nth Auckland, New Zealand. I believe that alkaline soil also plays a part. We do not have any problems in our lawn or garden. The soil is quite acidic here, with clay and a thin layer of top soil. However, the gravel drive where the problem of Nostoc Commune is quite severe, has a lime base. We also use glyphosate to control the weeds.

So . soda bicarb may controll it ? Yep may drive has a lime base also. 

Mid Devon, UK: gravel driveway. Same green algae, Nostoc. Its been on and off for 3 years now; disappears in dry summers and recently came back after spraying the driveway with Roundup (to kill the weeds) and we had lots of rain... will try baking soda....