; this fungus has also been reported on Persian walnuts.

We are interested in receiving reports of the dying of Persian or black
walnuts in orchards or rows of trees in the Eastern half of the United
States. Persian walnuts suffer from winter injury in many areas and
sometimes this injury is confused with the root disease. However, where
there are indications of continuing dying of walnuts year after year
with a progression from one part to another of the planting, we would
like to receive a report.

Some root diseases are difficult to diagnose, especially when the small
roots are the parts affected.

The symptoms of the root disease of the Persian walnut in Europe are in
many ways very similar to those of the Phytophthora root disease of
chestnut and chinkapin in this country as described in the report by
Gravatt and Crandall in the Northern Nut Growers Association Proceedings
for 1944. In some cases Persian walnuts die slowly and in others death
is rapid, with the entire tree browning in summer. Some trees will show
less green color than normal during the summer and gradually die over a
year or two. Trees in different stages of dying can be seen in the same
planting.

Persian walnuts in the Western States in recent years have been dying
from a disease of undetermined cause. Dr. Paul W. Miller and others have
reported on the black line graft union failure, _Armillaria mellea_ and
dying of roots from undetermined causes. As _Phytophthora cinnamomi_, an
imported fungus, is a comparative recent invader of many parts of the
west, Dr. Miller is giving the fungus some attention as a possible
parasite. On some hosts, this fungus attacks primarily the very smallest
roots at certain favorable times of the year, which makes determination
of its role as a parasite rather difficult.

Factors That Influence Nut Production

W. B. WARD, _Extension Horticulturist, Purdue University, Lafayette,
Ind._

The profitable production of fruit on nut trees under cultivation has no
doubt been influenced by several factors. Assuming that the present-day
seedlings and propagated varieties are winter hardy and the tree of
bearing age, 10 to 15 years old, one may expect a reasonable harvest. It
is somewhat disappointing to the owner of a single nut tree or for the
grower on a semi or commercial basis to find that the tree or several
trees have failed to set fruit.

The commercial fruit grower of apples learned, many years ago, tha