About three weeks later spines have started to grow on the previously bare tubercles of two of the plants. Maybe light intensity was a factor.

Thank you. If it is another mite, I presume spraying with a miticide will deal with it just the same. Terry S., I like your hypothesis, a genetic switch off, what is striking is that the plants became like "inermis or nuda" versions at least temporarily. Maybe the mechanism was something i...

Thank you for all these thoughts. I am doubtful about the over feeding theory because I followed the instructions carefully, I used cactus fertilisers, first "focus", then changed to Chempak cactus fertiliser, fertiliser only on alternate waterings. If there was something wrong in this reg...

1) Red spider mite arrived for the first time in my life this summer. I used to think all creatures had a place in this world, and we just respected that and worked around them. Right now if all RSM were to be exterminated from this world I would be happy. Not sure what good they do, I suppose they ...

Thank you for your suggestion. Five Mamms now have been affected out of about 80 Mammillarias in my collection. The other 75 are fine, as are the other genera, no sign of etiolation, or forced growing. Two of the Mamms have shown signs of some grow back of spines, although I think a disfiguring band...

An update is that two more Mammillarias have also now succumbed, this would be after spraying several weeks ago. I don't think it is nutrient deficiency, I have watered fortnightly with a fertiliser.

Thank you. Yes I see similarities, but still not sure.

I am not sure of the ID of this Gymno:

Topsy, I grow the plants in 50% grit, 50% John Innes2 (changing now to 3). The plants are grown indoors on a south window with many days outside in direct sun when the weather permits. There is some virus around the garden which has affected lilac trees, clematis, snapdragons (last year) and blackbe...

Thank you. Last week I sprayed all my collection with the local garden centre Bug Clear Ultra, which states it includes red spider mite control. Spraying again next weekend. Tempted to use language here which I shouldn't use. Hoping no more plants succomb.