Disease of New Dawn
I'm a beginner of planting rose and I'm having some problems for a while.
This is a New Dawn from David Austin which I planted 1 month ago. At the beginning it grows very well, but after a heavy rain, I found many dark spots on new leaves and buds. Some leaves are even twisted and look weird. (but old leaves are fine)
I searched from books and rose forums, I thought it might be black spot, but I'm not sure. Because it seems that black spot doesn't appear on new leaves? Or it might be pest like thrips? But I didn't find any bugs there.
My other roses like Wollerton old hall, Wisley 2008 also have the same problem. I tried to spray several times but it didn't work.
Now I'm really confused, can anyone tell me what the problem is?
(sorry for my poor English)