Mammillaria problem

[juster]

I cannot work out what has gone wrong with this M. pennispinosa; can't recall seeing anything like it before. Please can anyone help?

[ralphrmartin]

Walked too close to it and got the spines caught in your jumper?

[Cidermanrolls]

I’ve had small birds get caught in hooked spine mamms before now. I cannot see if the spines have been pulled off or if they’re just stunted. If pulled off, birds could be to blame?

[juster]

Thanks for the suggestions and no, I haven't got it caught in my jumper or anything else, although a perfectly possible explanation. I have had birds in the greenhouse once or twice this year, didn't think they had done any damage, but again a possible explanation. I have taken a close up of the damage and to me the spines look stunted

Perhaps I should just be content that it seems to be growing on OK, but it's a bit of a puzzle.

[Kees]

How about a cat or any other animal living in your greenhouse?

[Kees]

How about a cat or any other animal living in your greenhouse? I have had a cat rub itself against a cactus on purpose.

[MikeT]

When the areole and spines have been pulled off, they can occasionally re-grow, but for several areoles to be damaged and all regrow seems very unlikely. I think this occurred when these tubercles were growing. I've seen this happen at times on some of my Mammillarias - maybe it's a random thing, maybe it's damage to the growing centre, maybe it's my cultivation.

[juster]

Thanks for sharing your experience Mike and I'm interested that you have had a similar experience. Something in the growing conditions seems to be indicated and I now wonder if the extreme heat has played a part.
Kees we do have a cat but she is banned from the greenhouse, the door is covered by a grill in the summer.

[jfabiao]

I suspect these fits of spineless growth, in Mammillaria and other genera, may be related to thrips attacks. I'd love to have the time (and means) to verify this.

[Ali Baba]

I'd agree with the thrips idea. Thrips do graze on young spines, usually producing banding on the spines, but if spines are feathery they can reduce the spines to stubs. I have seen this on Mammillaria luethyi.
The other pest that can sometimes do this are earwigs.