Ask-a-Dave's-Gardener: Fungus on many but not all, 3 by EdInNY

EdInNY wrote:
Fungus is affecting a number of plants in my garden this summer. Yes, it’s been wet. Yes, we live on the edge of a wetlands. I have periodically been applying some antifungal, but I am looking for confirmation that I should have been much more aggressive. Fungi have hit my hibiscus (multiple varieties), lilies, pear tree, forsythia and more. Yet other plants are completely unaffected like amaranth, clematis, nicotiana, foxglove, redbud tree and chrysanthemum. Is that the answer? More anti-fungal? Pictures are attached.