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plant pauper

They're crossed.Let us know the results. 

I found this thread with interest. I have the same problem in SW France where May/June weather has been horrendously wet. As far as I can see, soda crystals are sodium carbonate, which is the same compound as used for increasing pH in swimming pools  - commonly labelled pH Plus In France. Anybody agree?

plant pauper

Yes it's sodium carbonate. What it's called in France I could not tell you. 

It could be nostac. This is a bacteria (Cyanobacteria)that turns slimy after rain or exposure to water but driies is in sunshine.

This problem showed on a tarmac path at an elderly relatives home this year a few days after I had sprayed with a moss killer.  It died away but with the rain this week has come back with a vengeance. It has also spread to a small area which has astroturf.   The astoturf was laid 3 years ago on top of an old carpet in an effort to kill ground elder and has never had a problem before.  The area is alluvial soil in a chalk valley so the ph will be alkaline. 

I will try the suggested treatments one by one starting with acidifying though I don't want to take the colour out of the astroturf.

To all those who think astroturf has no place in a garden I would agree but the relative is 95 & it gives her a safe place to potter and tend raised planters.


Thank you for all the feed back from Bill Hall, Cob Cottb, Parker 0482 and others. Yes it is apparently called Nostoc Commune or Star Jelly and is a bacteria. I last wrote 11th March and YES my driveway is still clear. I have since seen 2 neighbour in the past week with it, one outside her front wall on the pavement, the other in his back garden between brick paving, both had used Round Up, it seems this could be the cause.  I've also had another problem, I had to cut down a rotting apple tree last year so I saved a section about 3ft high and put it in the front garden with plants growing out the holes left by the cut off Branches. About 2 weeks ago, after loads of rain, 100's of tiny toadstools appeared  covering an area 2-3 feet wide around the trunk, after a quick panic I made up my soda mix and in 24hours they had disappeared, so far the plants around the trunk look fine. I hope you are all having the same success with good old soda and can't wait to hear. 

Thank you plant pauper for directing me to this thread. Husband online just now ordering soda crystals. Fingers crossed 😊

My father has the same problem after using roundup on his gravel driveway here in West Kerry, Ireland. Roundup must change the ph level in the soil then, he too said he never had it before spraying roundup and he's lived here for a very long time. We're going to try the washing soda solution.  A very interesting thread with what seems to be a simple and non toxic solution, wonderful! :) 

I cannot believe the great and practically instant results I have had using swimming pool PH Decreaser.

i just scattered over the gunk as the rains started and voila, gunk is dead!

Just noticed this slimey green plant on our gravel. It's been exceptionally wet this winter /spring. Husband has been spraying with round up so Will try the soda carbonate. Hope it works. Thank goodness for this site. 

Thanks for this discussion on the slim.  I too have used Round up and as a result have this terrible slippery slime covering my gravel driveway.  I'm thrilled to see that the Dri-Pak Soda Crystals work but wasn't sure how to apply to resolve the problem.  Could someone elaborate on whether you can just sprinkle on or do I need to make a solution and what would the best recipe for the solution?

Also I see these Soda Crystals are located in England.  Does anyone know if there is an equivalent product here in the US?

Thanks again!

Last edited: 22 October 2016 15:16:21

Thanks Bob for the great link!  Any idea how exactly it should be applied?  Could I just sprinkle it on?

Hi from Australia, hey lucky us; we have it too! I have a clay based soil, covered in crushed rock. We had never had this slimy mess until a few months ago. I always weeded by hand but one day I went out and my husband had sprayed the weeds that were coming up through the gravel. This slimy mess appeared but I did not relate it until now. Two days ago I had relaid new gravel over the top of the old thinking this would save the slime returning. We had 40mm of rain in the 2 hours following and within a day the slime had returned. Wow, amazing (said with a lint of sarcasm)!. Anyway I have read these posts with interest this morning and will go and do what I need to do. Thanks


Re this horrible slime problem, I've noticed that some people have tried sodium carbonate (also known as washing soda, soda ash or soda crystals) while others have tried sodium bicarbonate (baking soda and also an ingredient in baking powder and more commonly sold in powder form).

The two chemicals are similar but not interchangeable as they have different chemical formulas (sodium carbonate is Na2Ca3 while sodium bicarbonate is NaHCO3).

NB The bicarbonate used to be used as an anti-acid indigestion remedy (before a greater variety of tablets were designed for this job) whereas the carbonate form definitely can not be used in this way.

Although I am not a chemist I do know that each will react differently in each given circumstance. This should be considered before buying up a load of either chemical in case you get lumbered with the wrong one for your slime problem.

I would imagine the best way to tell which chemical suits your slime problem would be to do a test in 3 sets of flower pots - one set with sodium carbonate, a 2nd set with sodium bicarbonate and a 3rd set with neither - used as a control.

Keep them all separate, ie not touching, but in the same area as each other to create a 'fair test'. Each set should eventually give different results to enable you to see which chemical is most effective.


An update to Slimy Fungus / Nostoc Commune.

Dissolve 1kg bag of Dry Pak Fine Soda Crystals( Sodium Carbonate ) in hot water in a 10ltr 

watering can then fill with cold water. For an area 20' X 12' I used 3 cans. Repeat 2 weeks later.

Cheap - Easy - Safe and I'm still compleatly clear nearly 2 years later. 

Hi Margaret,

Thanks for the update ..... I get this most years so will try your method.


Hi Margaret,

Having spent the morning scraping and sweeping up this stuff from my patio on the east coast of Ireland , I look forward to spraying it with soda crystals tomorrow. We have had it for a few years now after ,, guess what...using roundup on the weeds between the flagstones. I used the spray bottle you apply to individual weeds rather than spraying the whole patio, and only one area seems to be badly affected. It is probably the shadiest and therefore dampest patch. Heres hoping for good results 

So GLAD to read all the replies through the years. Found this forum when looking for identification of Nostoc and how to ERADICATE it. Most significant, I think ----

I was going through in my mind what in the world could have caused it, because I had never seen it before. I came to the conclusion that it had something to do with glyphosate (main Roundup ingredient) because, like in a horror movie, it is taking over the areas of my new LIMESTONE gravel driveway that I had sprayed to kill weeds.

I also believe that Nostoc came in with the limestone gravel because it had never been at my house before. The original drive was an old, worn, rutted, rocky path that had been formed by digging and grading up to the house. I had it re-graded and graveled. The next year I sprayed Roundup and similar products such as Bayer DuraZone for the weeds growing up into the little rocks, especially in the middle that is not worn down by truck tires. The year after that, the Green Blob That Ate My Driveway began its takeover.

I am dirty and in my work clothes sitting here at the library because I absolutely MUST find some way to eliminate the Nostoc. My driveway is 354 feet long, so that is an awful lot of Nostoc. I had gone over in my mind steps and substances that might kill it and not be toxic to my pets; I have found out here that NONE of them work. Therefore, if I can find washing soda I'm going to try it, and if I can't find it I will use baking soda. I have also bought a piezoelectric fire wand to use with propane canisters to burn weeds; I have seen nothing saying that fire doesn't work, so I might use that in the meantime.

Thanks for being here. I will let everyone know the results of my now educated battle with Nostoc commune.


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