AusBonsai

my points exactly, Jow and craigw.

chris

Very interesting .... Will look at later

I have just read Bonsai with Japanese Maples by Peter Adams, highly recommended if you haven't read it already. In the book (page 18) he talks about both total leaf removal (full defoliation) and partial leaf removal. He states that the partial leaf removal is a kinder technique where only the larger individual leaves are pinched off. The other advantages being by taking only the largest leaves off you enable light AND air to reach and strengthen the inner parts where the growth is often weaker.. Not only that, but by only taking the larger leaves off, it reduces stress on the tree as the process is spread over the whole season.

The advantages of total defoliation are that it forces the tree into producing a second season of leave growth thereby increasing the number of twigs (ramification). The second crop of leaves are smaller and often there are more leaves. These are however weaker, but that does trigger brilliant autumn colour (if you don't lose your leaves to dry wind like here in Adelaide)

I think it ultimately depends on whether you are trying to develop good branch structure and ramification, or just keeping the tree healthy by allowing light and air in. I have been told it is not advised to totally defoliate a tree two years in a row.