I've had this Australian willow for about 8 or nine months now. Been outside the whole time and it has grown like a newborn baby. Only problem is now the top of it is turning black and when I scrape some away from it in that black/dead looking area it is dead underneath. Below that spot though it is healthy and green. Forgive me as I am still very new to bonsai and do not know all terms and diseases etc. I got this cutting from a very reputable source as he is one a few in the area that has trees so I don't beleive any fault there but You can obviously see it was cut it the top before being sold and I am unsure if maybe cut paste or something was needed earlier on but Im not quite sure.

Any suggestions on this would be greatly appreciated. Im not very concerned with the tree but I really just want to learn more and better about what to do. Ive noticed the black spots on the other willows I have as well and treat them once every two weeks since spring time with a 3:1 pest, fung and miticide. Do you think I should cut the diseased part off and then replace with paste and move forward.

Sorry pictures are kind of crap. Took them with my computer camera.

Thank you!!

YOu mean the area directly below the chopped part of the trunk?

If there is no growth, the trunk dies off. THat is what is happening. Everything above the top branch is dying. Normal process nothing to be worried about.

In bonsai, the trick is to then make the site look like natural. With willow you have a challenge, as this species does not really grow over these sites.