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Joined: Mon Apr 28, 2008 12:22 am
Location: San Jose, CA

Soil mold?

Hi all,

I just Googled "soil mold" and found this forum. Which was great, since my question concerns one of my bonsai trees!

I've just been going through the process of repotting my trees. I'm WAY late, as these trees should have been repotted at least a year ago. Most of them seemed like they were okay, but there were several that seemed like they were "failing to thrive." It turned out that when I pulled those trees out of their pots, the soil practically "disintegrated" (for lack of a better term) when I pulled the tree out. When I examined the soil, it appeared that there was a lot of white fuzzy stuff throughout; there were also some small dark patches, and the soil in all of those areas seemed like a lighter brown than the nearby soil and had more of a sawdust-like texture.

I've posted a picture of what was left in the bottom of one of the containers at [url][/url]. Unfortunately, I couldn't get a decent focus, but hopefully you can tell that the longish bit in the middle is covered with a white substance.

I was just wondering if anyone could shed some light on this. I've had mold grow on the soil surface of houseplants before, but I've never seen what looked like mold inside the soil of a plant before. Is it actually mold? Some other root disease?

I ended up completely combing out the roots and rinsing them under a hard stream, then repotting. Hopefully they'll all survive. I'm a novice at this and none of my trees are show quality, but I like them. :)

I'm very happy that I found this forum! I've already learned lots about bonsai soil, and I suspect that the problem is too much organic material retaining too much water during the winter months. I live in San Jose, CA, and all of my trees are outdoor trees, so I don't think I have the option of going completely inorganic with the soil, as I doubt I'd remember to water five times a day during the summer months. But I'll certainly look at changing my soil mix to more inorganic the next time I go through this process.

Thanks very much,
Always keep an open mind, but not so open that your brains fall out.

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Posts: 5122
Joined: Wed Jul 05, 2006 4:17 am
Location: Western PA USDA Zone 6A


Hello and welcome to the forum. Unfortunately I can't tell anything from the picture but I suspect that what you noted in your pots was mychorrizae, a symbiotic fungus that is associated with the roots of certain species.
This is actually beneficial, in fact some growers inoculate their trees with it deliberately. It serves as a sort of extension of the root system. For future reference if you see it next time reserve a portion of the old soil and mix it in with the new soil.


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