My ruby rose bush has a bunch of white roses growing in the middle. This has never happened in 7 years. Please can someone tell me why this has happened

It's probably coming directly from the stem, the graft that was used to create the standard. You can snap it off at the base.

From https://www.rhs.org.uk/plants/...

"The rounded canopy of foliage and flowers on a Standard rose is grafted onto the stem of a species rose such as Rosa canina or Rosa multiflora. Any shoots, (also called suckers) that sprout further down the stem should be removed as these will be from the stem species. "

That seems very unusual to me. It's not at all unusual for red blooms to appear in an otherwise white rose, when the grafted root stock 'Dr. Huey' takes over the grafted top, but that's not what's happening here. So then I thought, well, maybe it's a sport... but you have a cluster flower form (i.e., multilple blooms per stems like those on a floribunda or grandiflora) growing in what appears to be a Hybrid Tea with single flowers per stem. So I'm stumped.

I posted at the same time as Sue, and her explanation makes sense to me, since tree roses (aka standards) have a different root stock than Dr. Huey. I hadn't thought of that.

sue os from England where they rarely use Dr. Huey. I suspect that R. Canina or one of the other rootstocks used there as mentioned by Suzanne. :))

Not so fast gang. Take a good look at the foliage on the stem of the white roses. It sure looks the same as the rest of the bush. Now look very close at the stem of the white rose. Follow it from the top all the way down to where it originates. It looks like it is coming from the scion that was grafted. She might have a color sport.

But as mentioned above, I don't see how you could get a sport that has a cluster bloom form on what appears to be an HT.

Thanks everyone. I know absolutely
Nothing about roses but I'm listening with intrigue

What types of roses are used for the middle segment of standard roses?

If you mean the long stem, it's the same as the root. The stems are often kept straight by being taped parallel to a wooden standard (rod) inserted into the pot.

Sue_1958 said: Thanks everyone... I'm listening with intrigue

Then here is the rose for you, from our database...

There can be another rose used for the mid section.

You're right, VV. They can be three-part roses: a vigorous rootstock (such as Dr. Huey); an inner stock with a cane that's straighter and more sturdy than Dr. Huey's (such as De la Grifferaie); and the grafted rose on top.

One of the local nurseries here always used De la Grifferaie for the inner stock of tree roses. They were the strongest and sturdiest tree roses I've ever had.

De la Grifferaie is also worth growing as a rose bush rather than rootstock. It has pretty blooms in addition to its strong canes. I grew one for many years.

Oh, now I've learned something new today!

Does anyone know an inner stock that blooms as the invading rose in question does?

R. multiflora and some others produce clusters of white blooms.

I'm pretty sure I've read that R. Laxa is often used for standard trunks in the UK. The OP is in the UK.

In a few cases in my garden I have seen a standard rose which produces blooms that are typically one to a stem atop tall canes with long stems for cutting. At times I have seen blooms in clusters pop up, and most of the time it is because the side buds produced were not disbudded (removed) before they gain much of any size. It will continue growing and cluster blooms at the top as a result.
Sometimes there is no logical answer. I have had blooms that resemble something from a horror movie. Insects are usually the issue in that case.

Thank you everyone for your comments I am learning a lot. I should say that the red rose has 5 leaflets and the white one has 3 leaflets. Don't know if this makes any difference but thought I should mention it!

I'd be very interested in seeing good detailed photos of the white rose flowers and foliage before you destroy it. From your photo, that doesn't look like any stock with which I am familiar. It's entirely possible they used a commercial rose for the standard stock. I've seen commercially budded roses budded to Bride's Dream from a well known Canadian nursery way back in the 1990s, so anything is possible. But, that white rose doesn't look like multiflora, laxa or any others traditionally used.