In article 6AJ5d.266224$mD.96644@attbi_s02, "Pam - gardengal"
wrote:

"paghat" wrote in message
news
In article , "Guyz-N-Flyz"
wrote:

You say, however, "I think" it was black walnut -- if no one's sure there
were walnut leaves involved, there could be some other problem. I mulch
with fallen leaves of chokecherry & sweet cherry & plum trees which all
have juglone & this does't bother the plants at all, not even the azaleas
which can be juglone-sensitive, but of course the concentrations are a
fraction that of walnut, & I don't use these leaves for anything as
senstive as tomatoes.

This is pretty interesting............I was not aware that juglone was
present in any plant outside of the Juglandaceae and not even present in
very high concentrations of most members of this family outside of the
Juglans genus itself. Since I can find no references which address this
phenomenon in any Prunus species, I'd be interested in being directed to a
source or link which discussed this.

pam - gardengal

Good catch, & wouldn't that explain why it doesn't bother the azaleas that
get chokecherry leaves as mulch. Just muddy-thinking & quick-writing
relying too much on an aging memory. It is of course cyanide-related
toxins in the roots, leaves, & fruitstones of the trees we have whose
leaves we use for mulching. The cyanide exuded from roots functions as a
growth suppressant to give these trees an edge over competing plants in
the immediate vicinity, the function also of juglone, but I've never seen
any negative effect from using the leaves.

-paggers

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
Visit the Garden of Paghat the Ratgirl: http://www.paghat.com