Hello,

It's a Dublin Bay rose plant. I've been recently getting these weird brownish areas on some of the leaves. I'm not sure what it is and if I should be worried at all.

This looks like downy mildew, not blackspot. Downy mildew is quite different (it's more closely related to an algae), and can do some serious damage and spread very fast. It's named for the tiny downy-like micro-fibers that grow out of the spots underneath the leaves, which are very difficult to see. It's usually not treated by the customary fungicides used for blackspot. Instead, try Mancozeb fungicide.
https://www.amazon.com/dp/B09V77MLBM/

Several of us have had to battle it this year, after not having it in our gardens for many years.

Mike, I was also thinking about Downy Mildew, but was waiting for your opinion. Peter, I am using Previcur Energy. Not very common in US, but can find it on eBay. Works very good for me.
https://www.bayercropscience.i...

Thanks guys - Can I remove the leaves or will that not take care of it? Also with these links you gave, do I feed the plant this stuff or do I spray it on the plant and leaves?

In my case I have sprayed. Initially I have removed very odd looking leave, later just sprayed. Would say carefully that brown spots just disappeared compare to black spots making leaves dead.

Elena999 said: In my case I have sprayed. Initially I have removed very odd looking leave, later just sprayed. Would say carefully that brown spots just disappeared compare to black spots making leaves dead.

Hi Elena,
I'm so sorry, but can you repeat what you said? It was a little hard understanding your post.

In my particular situation, I opted for a different approach. At the outset, I meticulously pruned away the oddly looking leaves, and subsequently, I applied a precise spray treatment. I must admit, it's quite satisfying to report that those troublesome brown spots simply vanished, leaving me rolling my eyes in disbelief. This stands in stark contrast to the black spots that had previously plagued my plants, rendering the leaves lifeless.

Remove all affected leaves, and spray the entire plant. You will need to spray repeatedly several days apart for best results, and you will need to spray the underside of the leaves where the downy fibers grow.