Hi everyone, I'm hoping that someone can give some advice on young willows I started growing this summer.

They've been outside and received far too much water with all the rain we've had in the past few weeks in the UK. I've brought them inside now, but wondering if it may be too late. The leaves went an unhealthy looking dark green with browning edges/tips and have started falling off, but I'm unsure if the tree itself is dead/infected or whether willow's lose their leaves in winter and this is just normal? They are only around three feet tall at the minute, I'd say about 60% of the leaves have fallen off so far.

Really, what I'm asking, is if there are any obvious symptoms of diseases I can look for? or is it just a case of waiting until spring to see if they recover? I've searched online for symptoms to look out for but nothing seems to give a description, only title's of diseases.

Some more images that may help:

How they used to look about a month ago:
http://www.growfruitandveg.co.uk/grapevine/attachments/new-shoots/40682d1384085065-new-willow-tree-dead-just-dropping-leaves-winter-img_2882.jpg

Some of the dropped leaves:
http://www.growfruitandveg.co.uk/grapevine/attachments/new-shoots/40685d1384085075-new-willow-tree-dead-just-dropping-leaves-winter-img_3076.jpg

Thanks!