How strange! Does it have any ties with any of the "browns"?

Hmm never thought of that...ohh thats interesting; one of its parents is Chateau de Clos Vougeot, bred by Joseph Pernet-Ducher .HMF doesnt have anything about parentage of CdCV, (seedling x seedling), but he used to breed a lot of coppery toned roses, didn't he?
When I first saw this weird colouring, it almost reminded me of Hot Cocoa, but more orange...

Could be something in the soil affecting it too. That is really orange though. What does it look like the rest of the year?

It looks just like all the other Prosperos I have seen. This ones just a new one, grown from grafted bare root in a pot, new this spring. Its produced a couple of other flowers that were the proper colour, then had an extreme case of mildew ( I started disbudding, cos the buds were pretty manky looking). Then after getting over the mildew, it got spider mites, which after dutiful hosing I think have now gone... I checked it today, and theres another orangey bud coming in..

I have another one, a year older potted in exactly the same mix ( but now kept in another section of the yard with slightly less sun - I used to keep it in the exact same spot as the other one) that went this orange colour last year. Come to think of it, it got spider mites last year too - not this year though... Its been sulking ever since its spring flush, but has finally decided to produce a couple of buds- they're not fully open yet, but the colour on this one seems to be the usual dark crimsony red !

This is really interesting! I'm a lapsed biologist (taking a break raising my kids - and I'm an animal biologist, not plant), but I've lately become obsessed with gardening in general and roses in particular. In any case, I've been bouncing around Google scholar trying to find probable explanations for this phenomenon.

I didn't find anything definitive in my short search but lots of papers indicating that stress can affect the biochemistry of a plant and that in turn will affect the genetic expression of pigments. Soil composition and pH, of course, also affects the biochemistry and hence the colour. Since these guys have been in the same soil over time, and since the flowers have not been consistently orange, soil alone can't account for the change. But, given the history you describe, it seems likely that the acute stress inflicted by disease(s) may have acted in concert with the soil composition in this case to temporarily affect the biochemistry of the plant such that it expresses this orange colour, with less of the 'blue'. Because the disease stress is temporary, subsequent flushes revert to the more 'normal' plummy tones. Just a guess. The effect could also be intensified given the youth of these particular plants - younger roses tend to be more susceptible to disease. It will be interesting to note your observations in the future!

I have to thank you - I get lost in being 'Mommy' sometimes - it's nice to have a brain puzzle!

Karen

PS, my DH actually prefers the orange!

hehe thanks redwolf. Prospero no.2 (the older one) has now opened up, and it is a lighter colour than normal - ( dark raspberry pink as opposed to the really dark purply red).

That I can understand, as its been really really hot here, but orange is definitely odd. I was kind of puzzled because thought it was a rather radical change..I mean, you hear about colours intensifying or bleaching out, but loosing the blue tone altogether struck me as a bit odd.

I find the orange interesting, but I wouldn't want it to stay that way....the gold stamens contrast much better with the original colour .