I have newly planted garden phlox, supposed to be mildew resistant. Two plants have yellow lower leaves with dark spots. Some of these have now died. Should I take these plants back to the garden center, or can I treat them? Prefer to keep! We are having a wet summer but I'm not seeing any mildew yet. Thank you!
A wet summer can bring out all sorts of diseases that might not appear at all in a normal summer. My advice in these cases is to simply wait it out -- when the weather dries out, the disease will probably disappear too. A jug of fungicide could cost you as much as replacing a plant! But there is that option, if you wish.