Black/Brown Stem

11 years ago

I FOUND THE PROBLEM
Old soil. It is dirt around the stem at the soil line. The soil mix I am using is washing out and compacting so the bottom of the stem is exposed. With small plants, a loss of a fraction of an inch exposes roots which die. And the plant slowly expires.

I am repotting everything that hasn't be potted up in the last 6-8 months and covering the base of the plants carefully.

Here is what the problem looks like, No, not INSV, thank goodness!

The creeping black rot on the stems. The "rot" starts where stem emerges from the soil.

The black/brown looks like dirt (soil) at the soil line. When I first saw it, I thought soil was washing up around the base of the but looks like brown woody stem further up.

It gradually creeps up the stem until the entire stem is necrotic. The roots look fairly good but the crown/leaves gradually die

The stem turns black/brown and the plant dies slowly.

This post was edited by lucky123 on Tue, Jan 27, 15 at 15:48

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Comments (5)

lucky123
Original Author
11 years ago
Salt
I repotted the two plants with the black stem problems. The pots were crusty. I had the problem on the geraniums one year. It is salt build up, rots the stem at the soil line, then the plant dies further up.
It is a combination of fertilizer, minerals from the water and and other toxic buildup.
Now I know how often I have to repot with this potting mix/hard water combination
Karin
11 years ago
i haven't had any plants die slowly... unless i neglected to water them...
i get salt build up a lot too, even though i use a mix without fertilizers, mixed with MG perlite (supposedly only has a tiny bit of fertilizers). - a week in, i get orange crusts on the perlite / soil.
so far, it hasn't (directly) killed any plants, but none are doing as well as they should.
i refuse to buy a ginormous $30 bag of perlite, and it irks me to drive twice the distance and pay twice as much for non-fertilized small bag... can't win either way.

repotting i do on a priority basis - my favourites first, then the others. or not.

K.
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lucky123
Original Author
11 years ago
Karin
Thanks for answering!

My plants die fast if I don't water.

My crowns start yellowing when this rot begins nibbling the stem. Surprisingly, the roots and leaves stay fairly healthy for a while. It is a slow eating away of the stem at the soil line.

I knew about this black stem rot, probably because of the minerals in this water, when the geraniums started rotting at the soil line a few years ago. I didn't expect it on the African Violets. It wasn't until I actually took a plant apart, scraping away the rot, examining the roots, that I noticed the salt crusts on the pots and on the base of the plants.

Something to watch for with very hard water. I thought I had that problem solved by lowering the Ph but that only made the salts accumulation slower.

INSV has the stem rot also but I believe that is only spread by thrips and I have never had thrips. I haven't brought any new plants in since September so the plants are very clean right now. No sign of pathogen or insects.

Mechanical damage = Salt buildup
Sans2014
11 years ago
what about using distilled water?
lucky123
Original Author
11 years ago
Sans2014 That might work or at least slow down the accumulation. There are still fertilizer salts and mineral/salts in the potting soil which breaks down after a while. It would mean longer times between repots perhaps.

Karin, I see those orange crystals. I fertilize as per directions and use plain water every other watering..so it must be in the potting mix. I will check that out.