Need help identifying disease affecting my Viburnums

There is some disease affecting some of my Viburnum carlesii - about 6 years old, and my hedge of Viburnum awabukii 'chindo', same age. I have no idea what it is - but it causes red splotches on the leaves and then they fall off. The plants that are affected are otherwise looking fine, that is to say, new growth is occuring, no cankers, no tip dieback. I do not know if this is something happening locally (in the greater Seattle area) or if this is common. I have lived on my property for 20 years & have never seen this before. I have other Viburnums that show no signs of this. All are planted in different areas of my property, so I don't think it could be attributed to location. Is anyone familiar with this? And if so, what might be the best remedy. The local Master Gardeners had no clue. Help, and thanks!

I guess this has to go by elimination for now. The Viburnum Beetle would leave actual holes in the leaves not red splotches. The Viburnum Borer would leave noticeable damage to the stems and you'd lose a good portion of your leaves. Leaf Blight sort of looks yellow but then the spots turn brown so maybe you have some sort of a fungal pathogen that is attracted to Korean Viburnums? Try raking up all the leaves that fall on the ground and bagging or burning them until ViburnumValley spots this thread.

Katye:

Note that I am from the Ohio River valley region, and my knowledge and experience base lies in the eastern half of the US. I have had the good fortune to have visited and traveled in the great state of Washington, and I hope to do so again this fall. This (in no way) replaces good local knowledge, which there is an awful lot of on DG from your area. Have you posted on the Pacific Northwest Gardening forum?

Viburnum awabukii 'Chindo' is outside my experience (meaning I haven't tried killing it here, yet). Viburnum carlesii is rather commonly grown, and it has a host of leaf diseases in the heat, humidity, and high soil temps around here. I suspect it can have a few foliar foul-ups with the high moisture levels available in your part of the world. Bacterial leaf spot, or some local fungus is probably the culprit, but I would not be kidding anyone that this is a concrete confirmation when there is no evidence to examine.

I'd submit a decent sized sample of your plant with the affected leaves still attached (maybe 12-24" of branching) to your cooperative extension service office and have a diagnostic test for pathogens performed so that you have a positive answer. Master Gardeners are great people supporting a great service, but they cannot know everything.

With the positive ID, then you can proactively prevent the spread of whatever it is, since sometimes diseases like this can be virulent under the right conditions.

BTW, what other host of viburnums have you around your property? Intrigued minds want to know...

Here's a shot of my Viburnum carlesii 'Aurora', in full leaf spot glory this morning.

Equilibrium: thanks for the quick response. Hey - the elimination method works for me!
Branches look great - with budding on all affected branches. New foliage is still good, old foliage that is affected has no holes. I thought I read somewhere that something was affecting Viburnums this year, but it was in passing, so I did not pay attention to where or
what the problem was. When I did my walk around this a.m., I noticed that some leaves on the Amelanchier have the same red blotches. Next time I'll listen up!

V. Valley: appreciate the info - Chindo is borderline here for me, but I am somewhat adventurous, and usually push the zone specs. My property has a few areas that I would consider Banana belts, and the Chindo hedge is in one of them. I also have V.bodnantense - she's 7' and a stunning example of a very gorgeous shrub (sort of hits me like my Ceanothus 'Julia Phelps' - I must look at them every day!); V. tinus - which I am not real crazy about - she's a bit fussy with a cold snap (like 30 degrees!); V. plicatum 'Mariesii' - still in the juvenile stage - but I know what's coming down the road, and I'm patient!; several carlesiis - I don't know the cultivars off the top of my head, all nice, dependable shrubs; let's see - what else? V. burkwoodii, and hoping to get my hands on a sargentii 'Onondaga', 2 more bodnantense & 2 more plicatums this autumn.
I am so thankful that I have the room to grow shrubs & trees - so many wonderful things that most people miss out on. I only wish that when we moved here that I had logged the property of the western red cedars & doug firs (I consider them as weeds), and had planted some of the more grand deciduous trees. We have a great climate here - except for the wet. We are able to grow such a wide variety of things, and what do people plant? More of the same. amazing.....
Thanks again, both of you!