Rust. Powdery Mildew. Black Spot. We can only be talking about roses. I'm not one to become alarmed at a couple of spots or holes in leaves, but some of my older roses look like twigs by the middle of summer, dropping every last leaf, as the humidity intensifies. I was reading the Toronto Garden blog this morning and Helen Battersby was lamenting seeing rust on her David Austin rose and what she might have done to contribute to it, so even those roses bred for resistance aren't immune.

The problem with these fungal diseases is that they spread rapidly, especially in wet, damp or humid weather. You can't control the weather, but you can take some steps to avoid the problems in the first place and gain control if they appear, despite your best efforts.