Pest, disease, too dry or just one of those things

mjm3346

3 years ago I brought some Gaillardia Arizona as tray plants - Used in various beds they have been excellent, flowering March to October ( when I cut them back ) they seem to be pest free, the bees love them and there is usually over a bucket a week in deadheads - But every year, usually from July onward, bits of some plants, could be in any of the beds,  wilt and die - there doesn't appear to be any sign of pest damage or animal breakage (cat or fox) that I can see  - cutting the dead bits out the plants just to continue to grow but anyone any idea what might cause it or know what could be done to prevent it. (plants are fed with M-gro and watered if it gets really dry (there is not a great depth of soil before there is a concrete/rock base)

This is a section from 05/06/2020 




and this is a wilted bit from today (I am a slightly behind with the deadheading at the moment)

trellohell0

Based on my experience with similar plants its normal. As the plants begin to age, bits will start to die off. I just trim these bits out to encourage newer growth, and then when they go dormant before winter i do a full dead head where needed.