Walnut problems

I have a walnut tree, bought from a nursery 5 years ago, which is growing well, but suffers from small black spots on the leaves, leading to brown edges, then the whole leaf and stem can turn black and drop off. This does not affect the whole tree, but quite a few leaves have dropped before the Autumn. The nursery have suggested lack of water, lack of nutrients or a fungus infection, and I have tried spraying with Systhane, Dithane and Bordeaux, without success. I have heard mention of walnut blight, but haven't been able to find any pictures matching what I am experiencing. Anybody know anything about this, or can offer other suggestions? Should I remove the affected leaves, or prune back the branches? Also, the branch leader at the top of the tree has stopped growing and branched into three. At this point, there is a growing fissure in the bark and I am concerned that, if I let it grow naturally, the branches may spilt from the trunk when they get bigger. Should I cut off the main stem below this point and let it branch out from lower down? Is the bark fissure likely to be connected to the leaf problem?

 

I dont know much about this meles, but what I can say is I've noticed black spots on the leaves of the walnut trees around here.
I dont have a pic but I could get one maybe if it helps. I've also noticed the spots or rings of black are on the fruits and presumably they wont be any good.
The trees are well established and although its been dry I wouldn't have thought that was the problem, after all, the walnut is native of much hotter places than here.

 

If you can point me in the direction of any pictures that would be good. Or if anyone can tell me how to put a photo into my post I will post a shot of the leaves and the top of the tree.

 

I took these pics at the weekend just in case they were of any use, they are in our local park.
Is it the same problem as you have?

 

http://www.ipm.ucdavis.edu/PMG/r881100111.html
Have a look here Meles, its a big problem in Califiornia, could be due to that wet May we had this year.

 

The pictures you supplied look more like walnut blister mite, and unfortunately the website did not have many pictures on it. Is there somewhere that tells me how to get pictures into my posts? If so, I will post some.

 

http://www.gardenerscorner.co.uk/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=32;t=000001
This 'll tell you how to post pics.

 

Finally managed to get some pics, but I apologise for the size and quality. I haven't worked out how to do this properly yet, but you can see the problems - damaged leaves, blackened stems, split at top of tree...