What is this growth on my rose?

Question

A fruit tumor growing on my rose bush flower stem. Can you please tell me what this is?

Thanks
Peter

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Answer 1

Hello Peter. Your rosebushes have been visited by what is called a Cynipid Wasp. Inside the gall is a tiny larvae that will hatch out into another Cynipid Wasp. Here is a link to an article I wrote about them, the galls can take on different forms but in roses the gall you have a photo of is the most common. Article Link: https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-cane-galls.htm

Stan The Rose Man
Consulting Rosarian
Gardening Know How