May be having the same problem with a Black Lace that grew like a weed (as elders often do), becoming large in a short time only to start presenting numerous drooping side shoots just this past month. One or more other elders in the same group may have been becoming gaunt the past year or so. A 'Vulcan' magnolia dropped upper leaves early this year but kept a good appearance on a basal sprout.

Honey-colored mushrooms seen in that part of the bed may have signaled what was afoot. You are likely to be having the same kind of problem, honey fungus, verticillium or some other pathogenic infestation affecting your plants. You might have to take samples and get them tested by WSU to find out exactly what is going on. Garden plants can get sick from a variety of things, just like pets and children.