o weak. Finally he succeeded
in grafting a branch from an affected tree on to a branch of a normal
individual. The only result was an increased vigor of the healthy
branch. This year he rubbed juices from leaves of such an abnormal
individual on to wounded healthy leaves, without result. Moreover, such
sick individuals, although growing for years close to healthy trees,
have never communicated the malady to their neighbors. Growth is
comparatively slow, and there is much dying back or dying out of the
slender branchlets.

The evidence indicates that this is _not_ a virus trouble, but a
systemic defect, probably caused by chromosome aberration or gene
abnormality. It is significant that this trouble occurs only in hybrids.
Such trees never flower. We have known four such cases, two of which are
now dead. Similar types appear in other species as inherited deviations
from normal.

Insect Injuries

A heavy attack from the spring canker worms developed in 1951, but
spraying with DDT on May 24th prevented serious damage. No outbreak of
canker worms appeared in the spring of 1952. The Japanese beetle has
been very little in evidence. The principal bad actors are the mites,
_Paratetranychus bicolor._ Although barely visible to the naked eye, the
effect they produce of whitening the leaves is conspicuous, especially
on the Chinese chestnut and its hybrids. These insects overwinter in egg
form on the surface of the bark. Last winter they were so numerous on
some of the trees that the bark had taken on a red color--especially on
smooth-barked trunks just below a branch. An application of "Scalecide"
on April 21, while the trees were still dormant, followed by two heavy
applications of "Aramite" (6-7 lbs. per acre) on June 13th and 27th,
gave good control for the rest of the summer. Spraying with DDT for
weevils was done on August 18th and September 3rd in 1952 with good
results.

Cooperative Hybrid Chestnut Plantations

In 1947 the first hybrid chestnut plantation under forest conditions was
made in cooperation with the U.S.D.A. Bureau of Plant Industry, Division
of Forest Pathology. The plantations are made in order to test the
hybrids under normal forest conditions and different climatic
conditions. In general, each plantation consists of about 100 trees, 50
U.S.D.A. hybrids and 50 Connecticut hybrids. The trees are planted at a
10' by 10' spacing, and the overstory is girdled at the time of planting
in order to give