Dying Viburnum

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thyme4jb (Zone 8b) Aug 09, 2013

I have four 20+ year old Viburnums. Two have already died, and the others look rather iffy. Is there a general herbicide I can use to spray on them to eliminate any bugs that might be doing the damage? I have pruned them from time to time and put pruning sealer on the larger branches that are removed. I tried spraying neem and it seemed to help for awhile. Not sure what is going on. They are some of my favorite plants and would be a huge loss.

The first picture is of one of them in bloom, March 2011. The second picture is of the same one now, same area of the bush, August 2013. The others are of the full bush/tree. They are struggling.

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Post #9625721
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drobarr Hummelstown, PA(Zone 6b) Aug 15, 2013

Its hard to say whats going on.

First of all you do not want to spray them with any herbicide(weed killer).

But since Neem oil seemed to help some it is likely there is an insect or a disease that you have. Neem has both insecticidal as well as fungicidal properties.

My guess is you have some sort of foliar disease, though the closeup you have looks very healthy...the pictures from far away where you have the defoliation looks like it could be some type of foliar disease.

Cann you take some pictures up close of the less healthy areas of the trees?

Post #9632013
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Diana_K Contra Costa County, CA(Zone 9b) Aug 15, 2013

Can you take a close up picture of the current, unhealthy leaves? Some that are still mostly green, and some that are about half dead.
The healthy ones from several years ago look like Photinia, to me. While many shrubs can get the same diseases, there are some special to each species, too.

When you were pruning did the wood look healthy? Some plant diseases attack the part of the plant that sends water and nutrients up and down. When you are pruning affected branches they will look partially creamy (healthy) and partially tan (sick).

Has something changed in the area?
For example, if some paving was done nearby then the water run off might be carrying some petroleum products, and the run off might be more than what they were used to, or the paving could prevent them getting the water they were used to.

Another example of something that could change: If a large tree was removed recently then they might be getting more light than they were used to.

Another example might be that someone planted a plant nearby and that plant had some disease organisms in the soil.

Another idea: Could these plants have simply reached the end of their life cycle, and be ready to give up?

Post #9632017
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plantfreak78 Rolesville, NC(Zone 7b) Aug 24, 2013

Didn't I tell you on another forum that these were Photinia with Entomorsporium leaf spot?http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin011/odin011.htm

Post #9640085
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