Dealing with Thrips
Could you please give some information and recommended treatment for silver leaf? I noticed it on a rose Sally Holmen. I dug it out, binned it and watered the area with Trichoderma powder. I also had the disease in Viburnum davidii and Elaeagnus.
From the information provided we suspect that thrips may actually be the cause of the problem you describe, not silver leaf. Silver leaf normally attacks peach trees. Thrips are actually tiny insects and can only be recognised with a magnifying glass; however its symptoms are very obvious with silvering on the uppers side of the leaf and a brown sticky colouration on the underside.
Normally thrips appear during hot dry summer months when plants become stressed. This particularly applies to your Viburnum. The thrips affected leaves will fall off at the end of the growing season. They should be collected and removed from your property to prevent re-infection the following spring.
It is best to try and prevent outbreaks of thrips by keeping your plants well fertilised with Daltons Premium Rose & Flower Fertiliser and adequately watered throughout the summer months.