The rose I bought last year was diseased, it turned out.

[Grasswire2]

The leaves look worse this year, although the blossoms are okay. It appears to be what's known as black spot.

But now I think it has spread to another more expensive rose, a tea rose. It is supposed to be disease resistant.

Do I dump the first rose? Or is there something I should use on it?

Thank you in advance. I don't really know rose diseases.

[Grasswire2]

1. P.S. I have two other roses that don't seem to be involved.

Each plant in its own pot, a couple of feet apart.

[mgardener]

2. Bayer makes a product

Bio advance
3 in one product.

I don't know where you live, I'm in upstate NY, and our growing season is short.
If you search "black spot on roses.site.edu" you should get research based info. Just look for your state.
In NY, counties have Cooperative extensions that have a wealth of info for individual growing areas tied in with Cornell University


https://www.gardendesign.com/how-to/black-spot.html#:~:text=A%20Cornell%20University%20researcher%20demonstrated,the%20spread%20of%20black%20spot.

[spooky3]

3. Hybrid tea and most other roses require frequent spraying

To remain healthy. If you prefer an organic product, neem oil is a good alternative to protect roses from pests and diseases.

Also, the more sunlight they can get (with sufficient watering at the roots), the more able they are to withstand their natural enemies.

If you decide to replace it, certain roses are much better than others at fending off the enemies. One is Pinkerbelle. Knockout roses also have been bred to be resilient, but I don’t think they are very pretty (YMMV).

[CentralMass]

4. I wonder if the Rose Garden could give you some tips ?