The Hood River glacier. (Hood River, Or.) 1889-1933, 1916-01-06
NOTES ON CONTROL
OF LEAF-ROLLER
lBy Leroy Childs)

Ter. this paper and the work that 1t
represents might appear to some as
superfiuous. In citing the literature.
however, find little or no published
experimental work dealing with the
control of this serious and numerically
increasing apple pest on the Pacihe
coast. A still more important point
which made experimentation, at least
with oils, imperative. was to determine
il possible what influence spring appli-
cation of oils have on the adhesive
properties of fall applications of Bor-
deaux mixture. In the northwest we
have very serious apple disease known
as apple tree anthIacnose, for control
of which Bordeaux is applied before the
early rains in the fall. 1t has been sug-
gested, and seems, indeed, quite possi-
Bile, that there may exist some such
condition, information relative to which
is desired before the general use Of oil
can be recommended. The anthracnose
spray has not been applied with the re-
suit that report on this point is i'm
possible at this time. The leaf-roller,
however, has passed through its period
of activity for this season and the data
gathered relative to its control is COM
plete.
In the Hood River valley the pres
ence of the apple leaf-roller is not gen.
eral. The limits of the present infest.
alton are we'll defined, comprising at
the present time some 500 or 600 acres.
A yearly expansion of these limits oc-
ours and the losses are increasing, with
the result that the orchardists are plan
ming a vigorous campaign against the
pest next year.
At no time in Hood River has the in
festation occurred to such an extent as
to cause noticeable defoliation: occa-
sionally the tender foliage of growing
terminals is severely injured, but in no
place has there occurred the complete
defoliation that has been reported in
different sections of the east. The in
jury to the fruit, however, in several
orchards where extensive countings
were made produced surprising infor-
nation. The losses incurred by the
feeding worms often approached 40 per
cent Of the entire crop. 1t was found
that the injury was even more severe
on trees in light bearing, where the
percentage of injury amounted to more
than so per cent. This loss, together
with the other losses that must be con.
sidered in the form of scab, codling
moth, bruises, etc., make 1t imperative
that some means of be employed in re-
ducing this waste.
In order to determine the most ad-
vantageous method that could be EN-.
loyed under Hood River conditions. a
series of experiments embracing lead
arsenate in various strengths, crude
oil emulsion, kerosene emulsion, distil-
late emulsion and miscible oil were
used during the past spring.
Owing to the fact that it is neces.
sary to make four or five spring and
early summer applications of fungicide
for apple scab control in Hood River
lead arsenate, if efficient, seemed to
offer the least expensive plan lat least
from the standpoint of labor) in bring
ing about leaf.roller control for this
material is usable in combination. Six
different plans of procedure we're out
lined. Lime sulphur was the fungicide
employed throughout the season.
Spraying in the spring began in what
is termed at Hood River the delayed
dormant spray, or an application ap-
piled at time when the more advanced
foliage has reached the size of squirrel
ears. At this season it was very diff
cult to find any hatched leaf.roller
eggs.
The orchard in which the experiments
were conducted was planted to Spitzen
burg apples. which are now about IL
years old. Two rows across the orch.
ard were used in each experiment.
Between each was left one as a check.
The degree of infestation, based on the
presence of egg masses, indicated that
it was at least typical of the conditions
as existing in the valley. A power
sprayer fitted out with New Way"
engine and two leads of hose was en-
ployed throughout the season in ap-
plying the materials. Frembo nozzles
with medium sized hole in the disc
were used.
Two essentials were considered in
the scheme of the arsenate expert
ments: First, to determine, If possible,
the least amount of poison that must
be used in bringing about control, and
second, to determine if possible the in
sect's most susceptible period to poi
son.
With these thoughts in mind, six ex.
periments were outlined. In the de-
layed dormant spray lime-sulphur was
used at the rate of to lS throughout.
10 this fungicide was added in expert
ment and 3, arsenate of lead (paste in
all cases) at the rate of two pounds to
each SO gallons; in experiments 2 and
4. four pounds to each SO gallons and
in experiments and 6. six pounds to
each so gallons of water. A large
number of egg masses we're examined
at this time: none of the eggs we're
found to be Matching, the embryonic
development was far advanced The
date of this application was April 8.
A second or ''pink application" Il.
e.. at the time the flower clusters were
beginning to show pink was made in
April IA. The fungicide employed was
as in the first, lime-sulphur, used how
ever in more dilute ratio to q. The
arsenate of lead was omitted in expert
ments 8, 4 and 6. The poison applied
at this time in experiments ], 2 and 5
was in the same strengths as used in
the delayed dormant spray, two, four
and six pounds respectively. To de-
termine the condition of the eggs a
large series of egg masses were exam
ined and it was found that Matching
was actively taking place, 5S per cent
of the worms having emerged. On the
Goth of April, or four days later, no
unmatched eggs could be found. At
this time large portion of the foliage
was still we'll covered with the poison.
From these observations it is clear that
material placed upon the trees during
the time that the blossom buds are
showing Is most advantageous with
reference to the emergence of the
worms.
Unfortunately, a series was not run
in which pink" spray only was
used; a series of this sort would un-
doubtedly show more clearly the rela-
tive values of this application than can
be shown with the data at hand.
At the time of the calyx application.
May /. large majority of the worms
Al ~