What a difference a month makes. We went from getting some but not enough rain to what? Just a rotten mess. We had measurable precipitation more than half the days in June with many more cloudy days and that pattern continues here into early July. We are in the midst of an explosion of fungus and rot in our gardens. Tomatoes, petunias and geraniums are particularly hard hit as they just thrive on sunny, dry days. I just replaced an entire planting of Superbells (Calibrachoa) that was lost to rot. Perennials such as Catmint (Nepeta), Yarrow and many others are just looking terrible. Established stands of perennials are more likely of surviving with their crowns intact than newly planted plants. The crowns of new plants just rot along with the foliage. I even saw a 45 year old Yew that died over the course of just a few weeks in June as the drainage conditions in the bed that it was in became saturated.
Now is a good time to thin plants so as to allow for better air circulation and light into the interior of plants. This type of pruning is always good practice as it both encourages interior growth and suppresses conditions that promote fungal growth. Also cut back any perennials that show signs of rot and remove the clippings and dispose of them (but not in the compost pile). If the crown has survived the plant will push new growth out and possibly even bloom again if the weather turns favorable.
Many plants are doing well despite the weather. Established plants always stand a better chance of making it through weather anomalies but some, such as Hydrangea, Hosta and my Daylilies are thriving.