native butternut, also known as white walnut, is the hardiest member
of the walnut family. It is found throughout Southern Ontario and
is often found growing in association with black walnut. Though
it has similar timber qualities to the black walnut, it is prized
also as a carving wood.
When the green
husk is removed, it reveals an oval dark brown shell with deep longitudinal
ridges. The kernel is often caught in the shell cavities making
the meat difficult to remove. Grafted cultivars have been selected
for cracking quality. Our best selections will usually come out
in 2 pieces when cracked from end to end with a hammer or a suitable
nut cracker. Beckwith, George Elmer, and Kenworthy are among the
best cultivars for Ontario.
is very susceptible to the fungus disease Sirococcus claviginenti-juglandacearum,
that causes cankers and open oozing wounds in the trunk, eventually
killing the tree. It is estimated that over 90% of the trees in
North America are infected. It is believed that the disease was
introduced from offshore. The tree has been placed on the endangered
list. It is believed that some trees are resistant to this disease.
Through breeding it may be possible to save this species.
leafs out and blooms about the same time as heartnut, Persian walnut
and Manchurian walnut. As a result it crosses readily with them.
Along with hybrid vigor, low fertility and disease resistance, the
crosses often exhibit the hardiness of the butternut and unfortunately
the thick shell and poor cracking quality of the parents. Very few
good hybrids have been identified. Only heartnut so far has made
a noteworthy cross. They are termed buartnuts, the "bu"
from butternut and the "eartnut" from heartnut. Mitchell,
from Scotland, Ontario is the best buartnut found to date. It is
a productive tree having a nut shaped like a heartnut with the rough
shell and hardiness of the butternut. This area in breeding has
largely been neglected. It should be possible to extend the range
of the heartnut through breeding with the butternut and existing
buartnuts like the Mitchell.