Cindy Donnell wrote:

Hi, folks,

My v. opulus is in trouble. Nearly half of the shrub began to change
color to chartreuse,then yellow and now to browning leaves. I see no
insects, fungus, there's been no damage. I lost one small section to
last year's drought but have nothing to suggest what's going on with
it now. It bloomed, is covered with gorgeous red berries - even in
the dying section and now . . .

I already lost a V. dentatum. Once section died last fall because of
the drought and most of the shrub was dead this spring. I really
didn't mind losing it because as either Pam or Paghat once said, the
blooms smell like innertubes. I really don't want to loose the
opulus, though. The birds love it and it's beautiful.

Any suggestions?

It wasn't me - either viburnums smell very pleasant to me (ie., carlesii,
etc.) or they have no aroma at all :-)) As to what is happening with your
vibs, it may very well be verticillium, a soil-borne fungus that is nearly
impossible to detect until it manifests itself by killing your plant.
Periods of drought followed by heavy rains seem to set up the stress
factors necessary to allow this pathogen inroads and I seem to recall that
many parts of the mid-Atlantic states have undergone this type of weather
pattern recently. Viburnums are quite susceptible to this problem.

It may be possible to diagnose for yourself. Verticillium will often leave
telltale evidence as a darkened center of the stem wood or
discoloration/streaking just under the surface layer of bark. Prune out a
good size branch that has been affected, one as close to the base/trunk of
the plant as you can manage. Cut the stem at a sharp angle and look for
this discoloration in the the branch interior or peel back the bark and
look for the streaking. It is not always present, but is frequently a good
indicator of this problem.

The bad news is that there is nothing you can do for either your plant or
to remove the disease pathogen from the soil. You just need to replace
with something that is resistant to this problem. Do a google search under
"verticillium wilt" - not only will you get some very good explanations
and diagnostic tips on this disease, but you will also get listings of
plants that are both susceptible and resistant to the problem.
Good luck.

pam - gardengal