Tar over my Bonsai soil !


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Leamington Spa
I don't know if anyone else has had tar form on the top of the Bonsai soil.
A couple of months ago I re- potted a few of my trees. I make my own soil/mixture. I use Akadama, crushed lava, Pumice, fine gravel , composted bark, and chicken granite. Now a few of my trees have developed watery tar over the top of the soil.
Could this come from the crushed lava ? I have been through the bag and found no trace. I have asked around and nobody seems to have a clue. I have scraped off most of the tar, but other than potting up again, which I am loathe to do at this time, I can leave it to spring. However will tar hurt my Bonsai trees ? And would anyone go ahead and repot without the crushed lava and use Kyodama and more granite chippings instead ?
I have been into Bonsai since 1971, but it has taken ages to build up ,. especially as I paid a so called friend to water them about 4 years ago, but he didn`t water them and I lost most of my trees .. I had shown him how easy it was and provided a lance > Paying £100 was the last straw : he insisted and the wives were great mates. !!!!!
So I started again a couple of years ago....difficult when I cannot walk ( MS )


Bonsai Nut alumnus... we miss you
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South East PA
I don't know if anyone else has had tar form on the top of the Bonsai soil.

Random quote from the net -

"Black algae isn't actually algae but is in the phylum Cyanobacteria (http://en.wikipedia.org/wiki/Cyanobacteria[/url) in the domain of bacteria so do not have nuclei. It is more commonly called blue-green algae, but the type found in pools usually looks black until swiped on white paper at which point it looks dark green. They usually contain phycocyanin instead of chlorophyll for photosynthesis. A typical black algae found in pools is in the family Phormidiaceae (http://eol.org/pages/3261/overview)."

It randomly occurs here in very shaded areas during hot humid weather and dies off. Might be a bit more sunlight will kill it off faster if it is a bother but a light spray of copper fungicide will do nicely. A VERY light spray ;)


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