Answer: Fungal problems tend to appear during hot damp weather (or on plants that are watered often from above and so the foliage is frequently wet) especially on plants that have been overfertilized. Sometimes it is sufficient to do a thorough clean up of all the fallen foliage and to deadhead the affected blooms, and then do a thorough clean up around the plant again in the fall, so that it does not reappear the following year.
Based on your description it may be infected with anthracnose, which can cause spotting on both the flowers and foliage, or it may have a combination of problems such as cercospora on the leaves and botrytis on the flowers. I would strongly suggest you consult with your local county extension to obtain a specific diagnosis and based on knowing that, determine if you need to treat it with a fungicide either now or preventively next season, or if sanitation should be sufficient.
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