Answer: This sounds very much like fuchsia rust, which often appears in wet years or towards the end of the season, when there is more humidity in the air and temperatures drop. Pick off the affected leaves as soon as you see them and make sure that all fallen leaves are also disposed of. It's likely that the disease lives inside the plant, so spraying when there are no leaves will not help. Keep a close eye on the foliage next summer, and if you see any hint of reinfection, spray with a product such as Scotts Fungus Clear Ultra. Just be aware that fuchsias are rather sensitive to chemicals, so after spraying, do not repeat for at least three weeks to see if there is any damage.
Send your questions for the RHS to: firstname.lastname@example.org.
Only a few questions per month can be answered. For further advice on handling problems in your garden, visit www.rhs.org.uk/advice.