The plant is a Kramer's Red Winter Heath which has been in my yard for 15 years. It was fine until last summer when it started turning brown with only the edges looking OK. It's been sprayed several times for insects but without success. Would appreciate any thoughts you may have on what might be causing this.

Not sure where you are, but some plants run out of the nutrition they need when they stay in the same spot too long, so I would hazard it thinks the dirt is old and tired.

Thanks for you comments. I'm in Central Washington State, Zone 6A.

Central as in east of Snoqualmie? Beautiful area. All I can say is many plants have died this past year or so for no discernable reasons, sometimes our sun contributes to the demise, othertimes the earth does the same, do try new soil, or layering new parts of the plant, let me see. Needs high acidity, can be expected to live 20 years (it may be older than you think) can not tolerate standing water...

If you're interested in saving the remaining plants, it's possible to trim off the living ends and replant in light airy potting soil by removing the remaining bottom leaves and plant in the damp soil. In a few months the new plants will have rooted well enough to replant .

Yes, east of Snoqualmie in the Lake Chelan area. The part about not being able to withstand standing water got me thinking. We had lots of snow this winter and the plant was covered in it from mid-October thru March. That could be part of the problem.

What was going on last Spring before it started declining? That's when the issue started and this Spring it may actually improve if conditions are better than last year.