Trees, Shrubs and Conifers: Need help identifying disease affecting my Viburnums, 1 by ViburnumValley

ViburnumValley wrote:
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.