The yellow/orange spots on many of the lower leaves of my raspberry plants are from a fungus called Raspberry Yellow Rust (species #924). This is not something I’ve seen before in the garden, but it thrives in wet conditions, as we have had for most of this Spring. The pustules appear on the leaves in the spring and slowly darken over the summer. Apparently it’s harmless and won’t reduce the raspberry crop, so that’s good news.