Weird marks on gymnocalycium

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makleodss
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Weird marks on gymnocalycium

Post by makleodss »

Hello everybody.
Couple of weeks ago I discovered such marks on my gymnocalycium. Since then nothing has changed but I want to understand what I did wrong. Is it sun burn or chemical damage of insecticide?
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Peter
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Re: Weird marks on gymnocalycium

Post by Peter »

It's sometimes difficult to pin these marks down. It happens and could just be a change of environment and/or compost. If the plant is going to die you should know soon, otherwise it will grow on and the marks will get less significant. Have you sprayed it and with what? Also, Bryan Goodey at Southfields traditionally used a Scandinavian peat based compost for his plants (if I recall correctly) and it is difficult for us to obtain this compost, so have you changed it?
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Tina
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Re: Weird marks on gymnocalycium

Post by Tina »

I have often thoughts it water/cold damage but have no proof.
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Diane
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Re: Weird marks on gymnocalycium

Post by Diane »

Looks like cold damage.
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makleodss
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Re: Weird marks on gymnocalycium

Post by makleodss »

This particular species can withstand up to -12c and in recent weeks lowest temperature on night outside was 7c in my conservatory was about 14c close to this plant was pereskiopsis in completely damp soil and feels pretty happy and growing. There were couple of hot days in time when I did not check my plants and couple of my gymnos got soft due the lack of water. Now they all are hard again even this one. Insecticide I used is "Resolva Bug killer" only chmichal that is listed on package is 0.015g/l lambda-cyhalotrin as a microemulsion.
And yes I have moved to new house about 3 months ago so now my plants gets more sun in conservatory. I changed soil to 1part john innes, 1 part perlite, 1 part sand.
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phil
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Re: Weird marks on gymnocalycium

Post by phil »

It looks like cold damage to me.
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uzbeck
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Re: Weird marks on gymnocalycium

Post by uzbeck »

I don't think that I can add any more then previous posters. However last summer I re-potted 2 plants of G. pflanzii (different ssp or var), one in the next size pot and one in a bowl - probably over-potted. Both planted in the same mix of cat litter/grit/JI.

The plant in the pot has romped away and flowered again and shows some pretty fierce spines, it is unmarked.

The plant in the bowl has sulked for 12 months, not flowered and is only recently showing signs of new spines. It also developed marks similar to yours over the last winter. These have not spread and are now hard to the touch.

I thought this was cold damage also but wasn't positive, both plants were side by side in my greenhouse that I keep frost free.

I don't suppose growing the plants would be such fun if it was easy and we knew all of the answers!
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Re: Weird marks on gymnocalycium

Post by graham »

I would ask whether the 'marks' are actually on or in the skin ? The photos are fine but they don't really show whether this is some damage within the skin or something on and above the skin which would make it more likely to be an infection.

Looking at the third photo I notice a rather round spot quite close the the spines which does look quite like a fungal ring; and where the discolouration is in the indentations it seems to fill them. That would suggest to me that it is some growth in or on the surface of the skin which is causing the top surface to die, hence brown. That's unless the brown colour is caused by something that is separate from and on top of the skin - so have you tried to scrape at the marks - using something generally blunt so as not to damage the plant ?

As it's just a single plant (so far ?) I wonder whether it may have been under a drip from the roof, either carrying some fungal spores or simply dirt.

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makleodss
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Re: Weird marks on gymnocalycium

Post by makleodss »

Hi graham you were right about that small ring. as soon I touched it it fell off leaving little scar on cacti body. Rest of marks seems like skin itself turned brown. It is not soft. By scraping with blunt stick it feels same like skin all way round.
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Re: Weird marks on gymnocalycium

Post by graham »

That does make it likely to be damage within the skin - so definitely something to keep an eye on whatever the original cause especially if the brown areas get any larger, if there is a fungal infection it is likely to grow.

fingers crossed...

graham
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