I have two massive viburnum. Due to their size spraying is Impractical. Is there a pesticide available which I can use in the ground around the base of the shrubs to help solve the problem?
Unfortunately, with these types of infestations, you really need to treat/spray in the spring stage when they are damaging the leaves. By the time you have seen the beetles, a whole cycle has nearly completed. Eggs have been laid into the branches and they over-winter and then begin their new cycle for next year.
I don't mind waiting till spring. I inherited these plants when we moved here a couple of years ago so I have been sniping out what I can reach. I would like them to be healthy and flourishing happily, I don't like seeing sad plants!
is there anything I can put on the ground in spring To treat them. One is on a raised bed, taking it to approx 14' so I would struggle in the spring with spraying
I can only recommend you grow these shrubs well. Not sure which types of Viburnums you have. Maybe Opulus judging from your measurements? If you have inherited them, I would suggest you dig out the first 3 inches of soil around the shrub and then lightly turn the soil a bit. Shrubs suffering will eventually get weak. Loosen the soil and put in a new layer of compost and then if possible put a layer of mulch like bark chips. Do your shrubs need pruning, thinning, or removal of weak looking stems? The branches are definitely harbouring this infestation, but I don't suggest you chop them all off, but when you spray next spring when they start to feed on your leaves, you will be breaking the cycle then.
Others may have other solutions, but I have not seen anyhing for putting into the soil.
I have just been out doing some nocturnal detective work!
could it be viburnum white fly? At dusk while I was in the garden there were a noticeable number of what looked like fine white thunder/fruit sized fly around the shrub
I have attached two photos. One showing the typical damage and one showing what appear to be larvae on the underside of the leaves
on the second photo there is also what appears to be powdery mildew on the smallest leaf
was my first instinct of beetle correct or could it be fly?
hilary.christie, thanks for taking photos. They do however look like the original diagnosis. Flies of all kinds can be present in the garden. Some are attracted to sticky sweet residue from leaves or even neighbouring plants. Viburnum tend to be quite trouble-free shrubs, it's very unlikely to be any other pest that could strip your leaves this way.
Sounds like the shrubs are very mature, and may have been under attack from the Viburnum Beetle for a while. Action now is needed to stop the cycle. You need to be patient as it will not suddenly disappear next year once you start spraying.
The other option is to prune away 1/3 of your branches. If you look carefully, you may see signs in your branches and leaves. Look for raised round areas, or sunken round areas on leaves and branches. Removed dead looking wood too as prolonged attacks can cause some die-back.