osier willow problem

We planted some osier willow about 2 years ago and have been well pleased with their growth and looks, however this year when the leaves came back in first a few and then a lot turned black and are dying, some of the stem is also black on the top. We noticed some rusty brown spots on the stems and branches and believe they have a fungal infection. When looking for something we can do with them we do not find a fungal treatment which we seem to be able to use, the only ones we find are for flowering plants and roses. Does anyone know of a fungal treatment for osier willow? And if you think we have a different type of problem what do you think it is and what can we do to help them.

 

@freeflow
This link may be of help Willow anthracnose, scab and canker/RHS Gardening