Certified GKH Gardening Expert
This is a collection of fungal infections. Though They will need water during hotter periods, they will need to dry out down to 5 inches or so, as well. This will be to avoid root suffocation and infection. After this, I would recommend letting the soil dry down to a few inches between waterings, and add shade during the hottest part of the day, if possible.
A fungicide will be necessary as well. These articles will help: