Ask-a-Dave's-Gardener: Dying Lilies, 3 by Deb18

Deb18 wrote:
Hi All - Hoping for some help. Spring of 2014 I planted several lilies. I used fencing to protect them from the rabbits. This year, they came up beautifully and went into full bloom. They had been healthy until recently.
We have an irrigation system under the wood chips that is set on a timer for 5am and 1pm daily. We feed the flowers as directed. This process / system is what we've done for a few years without a problem.
As you can see from the pictures, they are burning up from the bottom. Is that rot from over watering or is there a bug that would do this? I have sprayed for bugs but that didn't seem to improve the condition.

any help is very appreciated.

Thank you
Deb18