That's what I meant to say. WorryING.

Could be the lack of sewer leak. Could be lack of water. Could be a number of things. I'd dig down and look at and smell the soil, and the roots. Is the soil wet? it should be. Is it sopping wet? that's bad. Does it stink? very bad. Are the roots black? bad. Pale or brown? good. Are there fat white grubs? that's real bad. Rodent burrows? they eat roots.

Many rhodies are blooming now because of the up and down temps. It got cold, then warm again; as far as the rhodies know it could well be spring. Nothing to do with stress.

You are correct that individual dead branches on maples is verticillium. But rhodies do get it too. Lots of things do, it's not very fussy about what it attacks. Overall sparseness is often a lack of water, or an excess rotting the roots, or other root damage that prevents the plant from getting sufficient water. Cool weather such as we've had helps the damaged plant limp along, but they're still damaged.

Yes, that pretty much sums it up...it could be anything, and I just don't know how to figure it out. The soil doesn't appear different, and I haven't found any unusual insects. The big point here is that nothing visible has changed - nothing has been dug up, covered, built around, the watering hasn't changed...etc, etc. I have only dug in the general area - I'll try digging right under the bushes tomorrow.

I'm surprised - I haven't been able to turn up a single reference to v. wilt in rhodies (probably haven't been looking at authoritative sources) - I sure hope that's not it!

Wait a minute here....before we get too carried away with disease issues, I'd look to what changes in cultural conditions may be causing the distress in your plants. Issues with water (too much/not enough) and drainage typically top the list. And these can be factors that encourage disease problems as well. But often just repetitive mulching in the area of rhodies will cause enough of a buildup that the plants will suffer from lack of oxygen. One thing to consider is that perhaps the correction of the sewage leak has resulted in a lower moisture level in the soil than these plants were used to, despite your regular irrigation and you are seeing their reaction to it. Or conversely, the constantly moist conditions the leak provided are only now taking their toll and becoming evident. But you do need to check the roots and the moisture levels in the surrounding soil to be certain what is going on.

As to verticillium wilt, yes it can cause the dieback of single branches or even portions of maples, but it is more often pretty rampant in its spread and will cause complete failure of the vascular system, sometimes with alarming speed. IME, excessive cultivation in the root zone of these trees damages enough feeder roots so the pathogen can take hold, but other environmental stressors are big contributors as well. VW is very particular in its host plants and although that is a fairly wide palette, it does NOT include rhododendrons. Single branch dieback could just as easily be phytophthora as well and this soil borne pathogen can infect rhodies also.

If no cultural conditions exist that would cause these symptoms, taking samples into the cooperative extension office for examination and analysis is your best bet for an accurate diagnosis and recommended treatment, if any.

Thanks, Gardengal. The sewer leak was one of my big questions: do you think the rhodies could have roots that could reach the leach from a sewer leak 40' down hill of them? I'd believe it of the maple. I confess I'm not sure how far the roots of a mature rhodie this size could spread.

We don't cultivate that area at all. We usually spread bark around the base of the tree and lightly around the base of the rhodies, but didn't this past year. That would be my guess for changes in moisture levels, but they went 30+ years without regular mulching. The only other thing near them is the lawn, and we don't do anything to that. I'll do some digging and see if I can find an extension office. It's probably over at UW.

Well, I went out and dug around. Nothing looks out of place in the soil - normal wetness and consistency. On closer inspection, only one of the rhodies is really suffering - it has significant die-back. I think I'll send some samples out for testing. The other one just has slug damage. I'll cut back the lowest branches and get all the leaves out and that should solve the worst of that. My theory is that the virburnum, which we don't particularly care for, is a vampire plant and sucking the life out of everything else.

Japanese maples are prone to dying back in this region (and elsewhere). Earlier this fall I encountered a dead Japanese maple branch being scrutinized and talked over at a Master Gardener Clinic in the Center for Urban Horticulture lobby. Larvae were found under a patch of dead bark close to the bottom of the cut branch. The upper parts had the dead, clinging leaves often seen on these when they blight off here. Nobody was sure if the larvae might be the sole cause of just joining the party.

No streaking characteristic of verticillium was seen. However, maples are liable to be infested by other pathogens, pseudomonas for instance.