Allotments 4 All

I plated a Victoria plum two years ago, on a very dwarfing rootstock. By this June, a few thin young branches were trailing in the ground, so I cut them back until they could hold themselves upright.
All seemed fine until this morning, when I noticed that one branch was wilted. No sign of damage, no discoloration, no bugs. All other branches were fine. I removed the wilted branch (about 10 mm diameter)  on the basis that if there was anything wrong, I'd rather it didn't spread. Wood inside is fine; no stain, healthy-looking throughout. It has been very hot here (28-30 degrees) for several days, but that doesn't explain one branch wilting and not the others. It's not in full sun all day as other things shadow it for part of the day.
Is it blossom wilt, in spite of the fact that I haven't had any blossom? It did have two small fruits the year it was bought, so has flowered in the past.

Could it be a leopard moth caterpillar tunnelling inside the branch? My plums are doing nothing this year; I think the temperature when they were flowering was probably too low for pollination. Pity.

It's an interesting possibility, Robert - I didn't see caterpillars, but I have seen the moth.  In which case, getting rid of the branch was presumably the best thing to do anyway?

It's the recommended treatment. If you cut into the branch you may find it, if it's there. My Rosa Mundi is in full bloom, incidentally; do you grow it?

I do - have two, one about five foot tall, the other about three. Both are blooming happily - started about a week ago. The bigger one is going to have to be pruned down a bit, though - it's so tall that it's trying to flop over the other shrubs around it with the weight of the flowers. How hard do you prune yours?

Not much at all. If it gets to the point where it starts flopping over I may have to to go harder. That's a problem with roses; they're probably best (in my view anyway) grown among other shrubs which can give them a bit of support.

I tend to leave them, too - hence the five-footer. It's between a giant pieris and spirea, but now seems to be making a bid for domination ...

Short of tying them into something when they start flopping, or planting them between sturdier shrubs, there's not a lot you can do apart from cutting them back.