and watersoaked. However, to date (July 30, 1950) this condition has
not proven serious; as long as the cambium cells were not injured no
real trouble has developed. In some cases under observation, even where
some injury to the cambium cells was known to have existed, enough live
ones have been left to effect recovery. Compared to peach, holly, and
even apple trees the Persian walnut has put up a marvelous fight to
recover from the injury sustained.

Factors Accentuating Winter Injury in Walnuts

After the several months of observation, certain factors appear
invariably to account for excessive damage to walnut orchards. Elevation
seems to be a principal factor. The hillside orchards or those on upland
sites (soils) were far less injured than the river-bottom or
valley-floor orchards, even though the latter may be on a better soil as
far as fertility is concerned. My early prediction of 50 percent of a
crop in the hillside orchards seems now to have been about 10 percent
short, unless other factors become involved. On the other hand, my early
prediction of 25 percent of a crop in the valley-floor orchards has been
close to correct. Of course, certain valley-floor orchards with a
combination of adverse factors won't have even a 5 percent crop.

Older orchards were more severely hurt than younger orchards with
otherwise similar conditions. This is possibly due to the lack of vigor
and of reserve material, resulting from crowding and competition for
elements of nutrition.

The size of the crop the preceeding year seems invariably to have had an
effect upon amount of damage done. The matter of reserves is again
involved. Two orchards that bore a reduced crop last year because of
spring frost injury have come through much better than some other
similar orchards, at practically the same elevation and age, that bore a
crop last year.

Two adjacent hillside orchards show considerable difference in degree of
winter injury and crop prospects for this year. It is believed that this
difference was due to the fact that in one orchard 35 percent of the
crop was destroyed by blight last year, in comparison with a 1 percent
loss in the other. The owners and I estimate that there is at least 20
percent larger crop this year in the orchard which had the heavy loss
from blight last year.

In several orchards where different levels of fertilization have been
used by the grower, it appears that the more liberal the application of