I have a Viburnum carlesii ‘Compactum’ which I planted 11 years ago. This year, it has brown spots on the leaves. I’ve looked on the shrub and can’t find any bugs or lumps. I live in mid-town Toronto.
Thank you for contacting Toronto Master Gardeners.
It would appear that you have some type of leaf spot disease on your Viburnum. The exact type is difficult to determine.
It is not possible to identify the exact disease from a photo. The following links will take you to websites which discusses leaf spot diseases. By closely examining your shrub and comparing the symptoms to the photos on the site you may be able to narrow down the possibilities. The site also discusses management strategies.
It is imprtant to note that some leaf spot diseases are caused by fungi; some by bacteria. With any disease of this type, the best practice is to remove the affected leaves and destroy the leaf debris, and this includes leaves that fall at the end of the season because often spores or bacteria will overwinter in fallen leaves, or in twigs. Do not put the leaves in your compost but put them either in the City of Toronto’s leaf pick up or the garbage. Your compost will not get hot enough to destroy fungi and spores.
We have a several helpful Q&A posted on our website that might help. The link is noted below: