On 9/8/2014 10:54 AM, Grub wrote:

I have friend that has a young walnut sapling in his garden but has
found the outer leaves are going brown. Does anyone know what could
cause this?

I assume from your address that this is an English walnut (Juglans
regia). These are often attacked by various insect pests including
aphids, scale, codling moths, and spider mites. While a mature tree
will likely survive such attacks, they can kill a young tree.

Also, walnuts require deep soil and do not thrive if other plants grow
within their drip lines (the extent of their feeder roots).

Walnuts can be quite messy (sooty mildew and a sticky drip from insects)
and not very attractive (leafless for a long time each year). If your
friend nevertheless wants to keep his tree, he should consult a good
local plant nursery or a professional arborist.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary