A little archeological research on my side here, but it's not exactly worth a new thread.
I just received this T. geometricus to attempt a rehab, not much to lose except hopes really. Does it look like the discussed "black rot"? It's not soft by any means, so maybe just a systemic fungicide could be enough? If not, I'm considering chopping the top off and hoping it will offshoot from the bottom, there seem to be plenty of areoles left.
Hi mat
Cut its head off and make sure you do a few extra slices and clean the knife well with alcohol each time.
It's not contagious and just something they can be prone to I wonder if they would grow better with extra heat, maybe a top shelf candidate.
Tina
varied collection of succulents and cacti but I especially like Euphorbia's, Ariocarpus and variegated agaves.
Not much to moan about really, it's far away from other plants (except on the photo when I was unpacking them) and actions will be taken immediately! Will do the chop as advised, and kind of planned, and report in half a year. Maybe the indoor shelves will be more gentle to Tephros than the rather unfavourable UK weather.
I'm not so sure it's not contagious, as a few of my Tephros have this problem. It is possible it is spread by e.g. biting insects moving from plant to plant.
I also have geometricus plants with this growing next to ones which don’t and have seen no evidence it spreads. Some clones seem to get it whilst others don’t and despite that I am still convinced its really an environment problem. In habitat they grow at high altitude where there is always air movement and the temperature is low in winter which is why I think our general damp and dull climate doesn’t always agree with them. I also have some clones of T alexanderi (which some would argue is the same thing anyway) which suffer from it and others in the same greenhouse which never do. In my experience it the ‘rot’ is hard and scaly the plants with damaged segments continue to grow so yours may well put out new growth next year.
Like most Opuntiods. Tephrocactus push out juice/resin from the top areoles if slightly over watered then fungi get to work on the sticky moisture.
I have had this myself on green plants, but never seen it on dry brown looking plants of this species.
This time of year with cooler nights and higher humidity seem to be the starting point.
It seems to do very little harm to a plant, but looks terrible but it does fade away over time to a very pale grey.
Ray
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I have been spraying my Tephro's and small Opuntia's with Rose Clear Ultra for the last three years and not yet had any further losses. This could just be luck and a longer review period may be necessary, but Rose Clear is a systemic insecticide and fungicide which kills aphids and also controls blackspot, powdery mildew and rust so I thought it might be worth a try.
MatDz wrote: ↑Sat Oct 23, 2021 3:19 pm
A little archeological research on my side here, but it's not exactly worth a new thread.
I just received this T. geometricus to attempt a rehab, not much to lose except hopes really. Does it look like the discussed "black rot"? It's not soft by any means, so maybe just a systemic fungicide could be enough? If not, I'm considering chopping the top off and hoping it will offshoot from the bottom, there seem to be plenty of areoles left.
(Photo does open in the correct orientation.)
20211023_135830.jpg
You can also cut an areole and graft it on an Pereskiopsis spathulata. Your plant will regrow in a matter of months.
