soon become worthless for nut production, as
few nuts are set and those that mature are usually poorly filled.

Susceptibility of Species

Extended observations show that of the walnut species now grown in
eastern United States, the Japanese walnuts, i.e., the Siebold and
the heartnut, are by far the most subject to attack by this disease.
These walnuts are so susceptible that in localities where this disease
is present the planting of young trees is inadvisable, as they are
almost certain to be short lived. Once infected, will endanger other
walnut trees in the area.

Observations at Beltsville show that the butternut is almost as
susceptible to attack as is the Japanese walnut. Some workers are
inclined to believe that the rather serious decrease in numbers of
butternut trees in some areas is due to the bunch disease. The Persian
(English) walnut is also quite susceptible, although probably not so
much so as the butternut or the Japanese walnut. The eastern black
walnut seems to be the most resistant of all, although some evidence
indicates that at least certain trees of this species may have the
disease but not show symptoms of it. Gravatt and Stout[17] report that
walnut trees may be affected for a considerable length of time without
showing recognizable symptoms. Out of a lot of 300 healthy-appearing
trees, 37 per cent showed bunch disease symptoms following pruning. Only
four percent of the unpruned check trees developed similar symptoms
during the same period of time.

Distribution

At the present time bunch disease is quite widespread in eastern United
States, occurring in Maryland, District of Columbia, Delaware, New
Jersey, New York, Michigan, Ohio, Indiana, Illinois, Pennsylvania, West
Virginia, Virginia, North and South Carolina, Georgia, Tennessee,
Alabama, and probably other States. No special surveys have been made
for bunch disease, and all distribution information has been obtained
from observations of U. S. Department of Agriculture or State workers or
from specimens submitted.

Damage Caused

Trees with bunch disease may live for several years in a stag-horned or
tufted condition. Affected trees generally set few nuts and the nuts
that mature are usually poorly filled and hence low in oil content. It
is likely that a part of the unsatisfactory growth and fruiting
performance of certain eastern black walnut trees may be due to the
disease, even though they do not show the symptoms as th