North American Fruit Explorers mailing list at ibiblio

[Lucky Pittman <lucky.pittman@murraystate.edu>]

At 10:25 PM 2/25/2004 -0500, Doc L wrote:
> They are pest trees here, kinda like Sweet Gums which Lucky Pittman abhors.
Indeed, I do.  Would much prefer hawthorns, which I could use as rootstocks 
for pears & quinces.

I'm neither a chemist nor a toxicologist, but deal with the cyanide issue 
in livestock on a regular basis.  Cherry leaves are most toxic in the 
wilted state - I've seen cows eat them fresh and green off the tree, and 
they'll vaccuum up the yellow senescent leaves that drop off from time to 
time throughout the season - with no ill effects.  It may be that the fresh 
green leaves are toxic as well as the wilted ones, but that the animals 
aren't usually able to access them in the large amounts that precipitate 
death like when people inadvisedly pitch big piles of prunings over the 
fence to them or a storm comes through and blows trees over or splits big 
limbs off - at which time the cows/goats/sheep mob around 'em and race to 
see who can eat the most leaves.  Japanese yew prunings do a very efficient 
job of killing cattle, as well, due to their high cyanogenic potential.

Prunus spp. leaves contain cyanogenic glucosides and enzymes which alter 
those glucosides, but in normal, undamaged leaves, they're contained in 
separate cells.  When the leaves are damaged - freezing, wilting, chewing, 
etc, this allows the chemical reaction to take place between the enzymes 
and the cyanogenic glucosides, liberating cyanide, which can then be taken 
up into the bloodstream, where it binds to hemoglobin in the erythrocytes, 
interfering with its capability to carry oxygen.

On the subject of cyanide in the seeds or a cherry leaf in my jam or wine, 
personally, I wouldn't have too much concern about it - wouldn't even be 
concerned with crushing seeds in the process of making jelly or 
wine.  HCN(hydrogen cyanide) is volatile, and any that might be liberated 
would probably dissipate harmlessly into the atmosphere during the course 
of canning, fermentation, or storage, for that matter.
I wouldn't want to sit down and eat a big bowl of cracked chokecherry pits, 
though.

For more info on prussic acid poisoning, have a look at the following 
extension bulletin:
http://ianrpubs.unl.edu/range/g775.htm#what



Lucky Pittman
USDA Zone 6
Hopkinsville, KY