Gnibersity of Maine.

Maine Agricultural Experiment Station

ORONO

BULLETIN 251 APRIL, 1916

CONTROL OF APPLE MAGGOT BY POISONED
BAIT SPRAY.

CONTENTS.

PAGE

Peiconeds ath OLudies (ins America i.e koe Sok ce et Ueels 149
Hegesiedbionss ere Reported ose k er cbs Sek ce cc wee ee dake see 153
Wares atsmcnreence Of Plies ho 2) Koon. oe ies a eee oe ees 153
Experiments with Kinds and Amounts of Poisons ............. 154
_ Orchard Experiments with Poisoned Bait ..................05- 156
Hs IN PSHM ONE CITE CRG A ee he wee bin 162
esiales thie teenIGetiilalewBHStriCk <=> os ssicc eden sce bcs cde cele eeee 164
WON TRCN eh ee age Se Greg Ske pe wh i Came RUami sede eee. 166
De areIOH OD REAPS eee PCa. cay kas ge cd ence et 167

NES he Sa eye atin Pig gees Te Aa ae A a oS 168

MAINE
AGRICULTURAL EXPERIMENT STATION
ORONO, MAINE.

THE STATION COUNCIL.

PRESIDENT ROBERT J. ALEY, President
DIRECTOR CHARLES D. WOODS, Secretary
CHARLES L. JONES, Corinna, Committee of

FREELAND JONES, Bangor, Board of Trustees
WILLIAM T. GUPTILL, Topsham, Commissioner of Agriculture
EUGENE H. LIBBY, Auburn, State Grange
WILSON H. CONANT, Buckfield, State Pomological Society

FRANK S. ADAMS, Bowdoinham, State Dairymen’s Association
LEONARD C. HOLSTON, Cornish,

Maine Livestock Breeders’ Association
WILLIAM G. HUNTON, Readfield,

Maine Seed Improvement Association
AND THE HEADS AND ASSOCIATES OF STATION DEPARTMENTS, AND THE

DEAN OF THE COLLEGE OF AGRICULTURE.
THE STATION STAFF.

CHARLES D. WOODS, Sc. D., Director

ADMINIS- BLANCHE F. POOLER, Clerk
TRATION GEM M. COOMBS, Stenographer

t ACNE eV) ae Stenographer

RAYMOND PEARL, Pu. D., Biologist

ae M. SURFACE, Pu. D., Biologist

BIOLOGY {4 MAYNIE R. CURTIS, Px. D., Assistant
JOHN RICE MINER, B. A,, Computer

Levees F. MARINER, B. A,, Clerk

JAMES) Mo cBARA Eni Nien Chemist

[ HERMAN He HANSON. Me Se Associate

| EDWARD E. SAWYER, B. S., Assistant

CHEMISTRY 4 pIMER R. TOBEY, B. S, es
ae H. ROGERS, B. S, Assistant

HARRY C. ALEXANDER, Laboratory Assistant

ENTOMOL- EDITH (MO PATCH, (Pave Entomologist
OGY | ALICE) WitAVERTMEs: Laboratory Assistant
WARNER J. MORSE, Pu. D., Pathologist

PLANT *MICHAEL SHAPOVALOV, M. S., Assistant
PATHOLOGY *GLEN B. RAMSEY, A. M., Assistant
DONALD SAG W AR ke Laboratory Assistant

JACOB ZINN, Acr. D., Assistant Biologist

oe C. HARRY WHITE, Scientific Aid
GUY A. BAKER, Superintendent

HIGHMOOR WELLINGTON SINCLAIR, Superintendent
FARM WALTER E. CURTIS, Scientific Aid
ROYDEN L. HAMMOND, Seed Analyst and Photographer
CHARLES C. INMAN, Assistant

*In collaboration with U. S. Department of Agriculture.

BULLETIN 251

SOLUBLE POISONS IN THE POISONED BAIT SPRAY
LO CONTROL LHe ADULT OF ) THE
APPLE MAGGOT (RHAGOLETIS

- POMONELLA WALSH) *

Henry H. P. SEvERIN.+

For a period of ten years a number of Italian entomologists
have been experimenting with various methods of baiting and
a large number of different formulas of poisoned baits to
control the olive fruit fly (Dacus oleae Rossi) and at present
a cheap and practical remedy is used to combat this insect.
After the Italian naturalists demonstrated the effectiveness of
the poisoned bait, French entomologists also tested the different
methods declared a success in Italy to control the olive fruit
fly. After a period of five years, French scientists gave a
striking demonstration of the remarkable success of the poi-
soned bait spray. South African entomologists, apparently
unaware of the work of the Italian naturalists started in 1903,
began to spray with poisoned diluted molasses to control the
Mediterranean fruit fly (Ceratitis capitata Wied.) in the season
of 1904-5. This work was carried on for a period of five years
and during this time a decisive demonstration of the success of
this insecticide was given under South African conditions.
The same remedial measures have been adopted in other parts
of the world to control the Mediterranean fruit fly.

PorsoneD Bart StupIFs IN AMERICA.

Within recent years similar control measures have been
started in the United States and Canada against the adult of

*Papers from the Maine Agricultural Experiment Station: Ento-

mology No. 86.
tMember of the Station Summer Staff in 1914 and trots.

I50 MAINE AGRICULTURAL EXPERIMENT STATION. IQIO.

the apple maggot (Rhagoletis pomonella Walsh), the cherry
fruit flies (Rhagoletis cingulata Loew. and Rhagoletis fausta
O. S.), the currant fruit fly (Epochra canadensis Loew.) and
the imported onion fly (Phorbia cepetorum Meade), The
methods adopted and the results obtained by the different in-
vestigators in the control of the apple maggot are given in the
following paragraphs.

O’Kane* used a “mixture of arsenic, molasses and water
distributed over the leaves of the tree,” to control the apple fly
in New Hampshire. “Through the cooperation of growers this
plan of spraying was tried at several different points. In most
the results were negative. It seems probable that in these in-
stances the possible value of the treatment was obscured by the
proximity of other infested trees not so treated. Also owing
to the pressure of other work the grower was unable to apply
the spray as often as would be needed in order to keep the
poisoned sweet ready for the flies throughout their egg-laying
season. In one instance, however, the treated tree stood alone,
and this tree was given repeated sprayings as primarily planned.
The variety was August Sweet and the fruit had been worth-
less for years. This tree yielded this season practically perfect
fruit.”

An experiment to combat the apple fruit fly with the poisoned
bait spray, was conducted at the Maine Agricultural Experiment
Station. Johannsen and Patch} write, “Our own experiments
made this season upon two Tolman Sweet apple trees, using a
spray of arsenate of lead and brown sugar in solution gave
discouraging results.”

During two seasons, Illingwortht experimented with the
poisoned bait spray to control the adult of the apple maggot in
New York. In the season of 1911, the larve were already at
work in the Primate apples when he began to spray. “Sweet-
ened arsenate of lead proved effective but was rather slow.”
Quick results were desired, and potassium arsenate, a soluble
poison, was used together with syrup diluted with water. TIll-
ingworth (1912, p. 165) observed that the trypetids fed on the
sprayed fruit shortly after the application of the spray. These

*New Hampshire Station Bul. 151, pp. 42-44.
tMaine Station Bul. 195, p. 238.
tNew York (Cornell) Station Bul. 324, pp. 126-187.

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. I51

flies were collected in jelly-glasses, where they became para-
lyzed in about fifteen minutes and in half an hour they were
dead.

_ An application of the bait containing the soluble poison was
made on July 22 and 26, a pint being sprayed upon the lower
branches of a 20-years-old Maiden Blush tree. In a table the
author gives a daily record of the drops from this treated tree
and the number of larve which bored out of the fallen fruit.
All the windfalls picked up under the baited tree after August
15, were absolutely free from larve. From an untreated tree
of the same variety in another field, 180 drops were gathered
on August 23, and from these, larvae emerged during Septeni-
ber. On the other hand, 115 drops collected on the same date
from the treated tree failed to show a trace of a single maggot.
“Hence it is quite evident that the flies deposited no eggs in the
fruit of the sprayed tree after the application of July 26.”

In the season of 1912, Illingworth used arsenate of lead and
molasses diluted with water. On July 3, Red Astrachan trees
received the first treatment. Five applications of the spray
were made during the season, “On August 5, the Red Astra-
chan apples were ripening and showed no trace of the maggots.”

“Slight difficulty was experienced in controlling the flies on a
seedling variety of sweet apples,’ due to showers which came
up nearly every afternoon during the period that the fruit dy
remedy was being applied to the tree. “Even in this case, how-
ever, the fruit was vastly improved over former years.” No
mention is made of the number of trees treated and no check
or control trees were used in 1912.

(Ross* “tested two spray mixtures, one composed of arsenate
of lead, glycerine and molasses and the other of Paris green,
glycerine and molasses, but neither yielded satisfactory re-
sults,’ in the control of the apple fruit fly in Ontario.

For a period of three years, O’Kanej tested the poisoned bait
to control the apple trypetid in New Hampshire. His records
are taken for the most part from typical lots of sprayed trees,
of which surrounding conditions were accurately known. Such
field tests as are recorded consisted of two trees treated wita
the poisoned sweet in the season of Igto, three trees in I9QII

*Ent. Soc. of Ontario. Report 1912, pp. 67-72.
tNew Hampshire Station Bul. 171, pp. 1-120.
2

I52 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

and ten trees in 1913. In the above spraying experiments, dif-
ferent proportions of arsenate of lead and molasses diluted
with water were employed. The results are given in the table
which follows.

Table showing the number of applications of the spray, the
variety of apple trees, and the per cent of apples free froiw
egg punctures on the sprayed trees and on such check or
control trees as were used.

Apples free from egg | Apples free from egg
punctures on sprayed punctures on check
Applica- tree. tree.
tions of VARIETIES OF APPLES. pa ee ES ce :
spray. ‘ :
Drops. Picked. | Drops. Picked.
1910 % % % %
3 Winter Sweet............. 14 (drjops or pickled?) .5
4 IPresidentsasc nian cack ool 0 8.1
1911
10 Granite Beauty........... 55.8 52.7
7 Sops-of-Wine.............. 55.8 46.1
9 IPOrteniacs: satus hee eae 46.4 59.
1913
5 Porters socimcccnie ee eee 39.3 74.7 22.6 32.8
ai (IROTEER Heche Oi ciagans Seem ee nie ees eg 0 ¥8 5 *.8
4 Walliams) Havoriten ae soci ener 3.7
4 August SWeetimas ciecer. it eee nD Lesh 7 (igetntaeae | iss ie ci eae 3.5
7 IBAMMCUSE 25 eric etemierns 0 15.6
7 POL COTS hag aes caucus so ys je sas nel has stare epee 11.9 0
7 IPOTGer sas eee nitions oe 4 9. 0
10 GrimesiGoldenssivine ees leone one BAS Ce Pasl uae cy alls 68.
10 Grimes!Goldenz. 2302 2a | eae eee PAC pent Naina este eres oan 68.9
10 GrimesiGoldentf5ae co elena Fey (Oso tah (eiohy GasaaeR aA 68.9

* Indicates that an ‘‘unknown sweet’’ was used as a check for the Porter.

The author summarized the above results as follows:
“Poison bait sprays, as so far devised, have entirely failed to
insure protection of the fruit of the sprayed trees from attack
by the maggot. In part of the experiments there was appar-
ently some improvement of the fruit, especially in isolated
trees. This may have resulted from the death of flies because
of the spray; or it may have been due to various other factors.
The important point is that no such protection was forthcom-
ing as would be essential if the treatment were to be ranked as
an effective means of control.”

“The above conclusions should not be taken as asserting that
no flies are poisoned by such sprays. Some flies may be. In-

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 153

deed it may be, as will be noted later, that with ordinary spray-
ing of apple trees with a simple solution of arsenate of lead and
water for some other insects, such adults of the apple maggot
as chance to feed or drink at spots where poison has persisted
may be killed. The conclusion offered is that the adults are
not materially attracted to the bait, and that such sprays, or
any others so far devised, are without any adequate avail as
definite and sufficient protection of the fruit, in the absence of
other treatment.”

INVESTIGATIONS HERE REPORTED.

In our work in Maine not only were the entire orchards
sprayed but also apple trees in surrounding fields and dooryards.
An attempt was also made to control the apple maggot under
town conditions. In the season of 1914, different kinds and
amounts of poisons were employed in the bait in spraying the
various orchards and the apple trees in the residential section ;
whereas, in the season of 1915, but one formula was used in
treating the same trees. Before giving the details of the work
in each season, the results of a number of preliminary experi-
ments will follow.

DATES OF EMERGENCE OF FLIES.

The dates of the first and last emergence of the pest have an
important bearing on when to make the first and possibly the
last applications of the poisoned bait spray. In the season of
1914, the dates of emergence of the apple fruit flies were deter-
mined under orchard conditions; whereas, in the season of
1915, similar records were obtained in the residential section of
Orono. Ground cages were placed on the sod or soil below
apple trees. Soil was banked and tamped around the bottom of
each cage to prevent the escape of any of the flies. During
the season the vegetation which sprouted beneath the cages
was cut with a sickle from time to time, Spiders and preda-
cious insects were removed from the cages as soon as they
were noticed. The records of the emergence of the adults, the
maximum and minimum temperature and precipitation in the
season of 1915 are given in the following table:

154 MAINE AGRICULTURAL EXPERIMENT STATION. IQI16.

Dates of Emergence of Flies, Temperature and Precipitation

m IOLT 5 0
Number of Maximum Minimum ; f
Date. flies. temperature. temperature. Precipitation.
July 15 1 80 56 |
16 | 0 83 58
17 | 0 78 57 eal
18 9 76 60 .24
19 0 89 ol
20 1 81 59
21 2 84 55
22 14 83 49
23 9 82 56
24 11 81 49
25 | 5 79 51
26 1 5 79 57
27 0 82 62 35
28 6 85 56
29 0 83 58 47
30 0 73 58
31 | 6 76 60
August 1 2 83 62
2 0 79 62 64
3 3 75 48 05
4 0 78 50
5 2 72 46 04
6 0 80 67
7 0 78 55 10
8 0 | 73 58
9 1 77 58
10 1 69 60 -17
11 0 85 52
12 0 89 58
13 0 87 62 .40
14 1 82 63

In the season of 1914, the first fly issued on July 20, and the
last on August 15, under orchard conditions and on July 17, one
specimen was found dead below a baited plum tree in the resi-
dential section. In the season of 1915, the first trypetid .
emerged on July 15, and the last on August 14, under town
conditions. From these records it is evident that the first
application of the poisoned bait spray should be made on July
15, and the last treatment on August 15, providing that the
adults, which probably live until the apples are harvested, do
not invade the sprayed area from neglected trees.

EXPERIMENTS WITH KINDS AND AMOUNTS OF POISONS.

In view of the fact that a number of entomologists advocate
the use of soluble poisons in the bait to control various species
of Trypetidae, we conducted a series of experiments with dif-
ferent kinds and amounts of poisons to control the apple fruit
fly. In Italy and France soluble poisons, such as potassium or
sodium arsenite and sodium arsenate, were used in a large num-

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 155

ber of different formulas of the poisoned bait to control the
Olive fly (Dacus oleae Rossi). In igrt1, Illingworth used the
following “fly destroyer” as given by Merck to control the
adult of the apple maggot in New York:

SUAPIOGDN Pa i Santen Rai ge Ay Dass, OF 4. pts:
Potassium arsenate ... EDAabe 2Ofi. Fk Ap:
NM Cie mene NaC ACA igte cy 45 parts or 45 pts.
In 1912, Illingworth used the following formula:
IMiplacsesyn ates SS oe ralbon 25) Ip:
mNrsenate Ot dead:. ip .ci.ie 5 20zZ. 00 0751p:
Nvlatbet pens tee. Sok 4 gal.or 100 gal.

The author states that, “If the conditions are such that the
flies do not succumb readily to this treatment, the use of the
soluble potassium arsenate is advisable as previously described.”

To determine the effectiveness of different amounts of vari-
ous kinds of soluble poisons used in the bait, and the extent
of injury to the leaves and fruit, a number of preliminary ex-
periments were performed. With each formula that was used,
cheese cloth was fastened to the ground with spikes below 4
sprayed tree, so that the insects which succumbed to the effects
of the poisoned sweet and dropped from the tree, could be
detected more easily on a white background, By gathering the
dead specimens daily, we endeavored to determine how long
the spray was effective after different amounts of rainfall, and
thus secure a clue as to the minimum number of applications
necessary to insure good results.

Experiment I. In the first experiment one each of the fol-
lowing apple trees, Duchess, Fameuse, McIntosh Red, Tolman
Sweet and three plum trees were treated with the fruit fly
remedy, which was prepared according to the same formula
Illingworth used in r911. One pint to two quarts of the insec-
ticide, depending upon the size of the tree, was applied to the
foliage and fruit on July 11. The sprayed leaves on all of
these trees were scorched and on July 16, some of these leaves
began to drop. The fruit was examined from time to time
and occasionally traces of burning was found but this was es-
pecially marked with the Duchess. A large number of dead

156 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

moths, flies, ants, occasionally hymenopterous parasites, beetles,
etc., were picked up daily on the cheese cloth, and then the
leaves, bits of bark, twigs and wind-falls were swept off with
a broom. Rain fell on July 11, 12 and 19, amounting to a total
of 1.12 inches. On July 16 and 17, the fogs were so heavy that
droplets of water dripped from the wet leaves and probably
washed off some of the bait. On July 109, eight days after the
application of the spray, no dead insects were found on the
cheese cloth and the bait was now considered ineffective.

Experiment II. In the second experiment instead of one
pound of potassium arsenate, one-half pound was used, the
proportions of the other ingredients being the same as in Illing-
worth’s formula of 1911. On July 11, one pint of the poisoned
bait was sprayed on the foliage of the lower branches of a large
Tolman Sweet. The results of the first experiment were prac-
tically the same as in this second experiment,

ORCHARD EXPERIMENTS WITH POISONED BAIT.

In order to give the various soluble poisons such as potassium
arsenate, sodium arsenate and sodium arsenite a most thorough
test under orchard and residential conditions, it was decided to
use 3-4, I-2 or 1-4 of an ounce of these insecticides to every
three gallons of water and One pint of molasses. The different
kinds and amounts of soluble poisons burned the leaves, some
of which finally turned yellow and dropped from the trees.
Some of the owners were considerably alarmed on account of
the scorching of the leaves of their apple trees and we were
compelled to discontinue the use of soluble poisons and substi-
tute insoluble arsenicals. A remarkable peculiarity was the
fact that rarely was a dead specimen collected from the cheese
cloth with the use of Paris green or arsenite of lime in the
bait, and we are inclined ‘to believe that the explanation rests
in the ability of some insects to strain out particles of insoluble
poisons from the diluted molasses. During the two seasons
cheese cloth was fastened to the ground below 29 apple trees
sprayed with different quantities of soluble or insoluble poisons
in diluted molasses, but not a single honey bee was found
among the dead insects. As no conclusion can be drawn on
the effectiveness of the poisoned bait, due to the fact that a

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 157

soluble poison was used in one or more applications of the spray
and an insoluble arsenical in the other treatments, only such
details of the work of 1914, worthy of mention will be taken
up in the following discussion of the season’s work of I915.

Experimental area. As the poisoned bait has been found
to be more effective in the control of other species of Trype-
tidae in a well isolated orchard or in a large isolated area com-
posed of many non-isolated orchards, a description of the loca-
tion of our experimental area is necessary, A glance at the map
shows that all of the apple ‘trees indicated by dots were isolated
on one side by the Penobscot river, and a bay of this river, but
on the other sides apple trees were sometimes found at short
distances from the margin of the experimental area. A more
careful examination of the map shows that there are six or-
chards indicated by the following figures which represent the
number of trees in each orchard: 84, 31, 40, 57, 47 and 38.
The principal part of each orchard is situated above the figures.
A series of dashes indicates the boundary between two orchards
or separates an orchard from trees present in adjacent door-
yards. The residential district contained 274 apple trees scat-
tered in the different yards. The entire area covered about
ene square mile and contained a total of 571 apple trees.

Since we bred the apple fruit fly from haws gathered near
Orono, Maine it was decided to spray all of the hawthorns
near the orchards, and also those located on a hillside along the
bay of the Penobscot river. Seedlings and crabapple trees near
the orchards were also baited.

Care of orchards. The orchard which contained 84 trees
was sprayed on May 4, 1914, with Scalecide to control the
cyster-shell scale. Seventy-five gallons of spray containing
4 1-2 gallons of scalecide were used. On May 23-25, a com-
bination spray consisting of dry powdered arsenate ot lead and
lime-sulphur was applied to control the tent-caterpillar, codling
moth and fungous diseases. On July 8, the combination spray
was again applied. Seventy-five gallons of the following for-
mula were used with each application of the spray:

Dry powdered arsenate of lead.. 1 1-2 Ib.
iave-stilplit Wee hee os a Yon gal.
DN Gice tem NY er cn also eens «x 50 gal.

158 MAINE AGRICULTURAL EXPERIMENT STATION. I916.

In 1915, two applications of the combination spray were made
as in the previous year. The orchard was plowed once during
June and received no further cultivation during the entire
season. The drops were allowed to remain on the ground, and
an examination of this orchard in April, 1914, showed numer-
ous rotted apples below the trees.

A general infestation of the apple maggot had occurred
throughout this orchard during 1913, and all of the differert
varieties of apples had been attacked by the pest. The most
seriously infested variety, however, was the Tolman Sweet.

None of the other orchards had been sprayed for the control
of insect pests and fungous diseases. The owners stated that
they had been troubled for a number of years with the railroad
worm and that the drops had been allowed to decay on the
grass in previous years.

Poisoned bait formula. In 1915, the following formula of
the poisoned bait was used in spraying the six orchards and the
apple trees in the residential section:

Potassium arsenate 3-4 oz. (dissolved in boiling water )
Molasses 7. 422. 1s oh
WEEOR 0 wa vsteen ore 3 gal.

The solution was prepared by stirring the molasses in three
gallons of water until all of the molasses on the bottom of the
pail was dissolved. The potassium arsenate was first dissolved
in about a quart of boiling water and was then added to the
diluted molasses. The poisoned bait was thoroughly agitated
by pumping the liquid back upon itself with a spray pump.

Application of Poisoned Bait. The poisoned bait was applied
with a common, garden, brass spray-pump provided with a rose
sprinkler nozzle, which throws a mist-like spray. A different
method was employed in applying the insecticide in each sea-
son. In 1914, the man applying the spray walked rapidly
around the tree, a yard or more away from the ends of the
lower outermost branches, and at the same time the poisoned
liquid was forced from the pump, into the air toward the top
of the tree. The minute drops fell over and into the tree
resulting in an even distribution of the droplets, for the mo-t
part on the upper surface of the leaves. The dose per tree
varied from a half pint to a quart depending upon the size of

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 159

the tree. In 1915, the fruit fly remedy was applied to the trunk,
large limbs and foliage of the lower branches. The man faced
the trunk of the tree and applied the bait, then he turned his
back toward the trunk, walked around in a circle and at the
same time forced the poisoned sweet from the pump over the
large limbs and foliage of the lower branches. Those droplets
which strike the foliage adhere for the most part to the lower
surface of the leaves, where rains are not so apt to wash off
the spray.

The following table shows the dates of the applications of
the poisoned bait and the number of gallons of spray material
used in the various orchards and the residential district in
IQI5.

Dates of Applications of Spray and Number of Gallons Used

in IQT5,
s Residential
DatT=Es OF Number of trees in orchards. district.
APPLICATIONS Total
OF SPRAY. | gallons.
84 31 49 57 47 | 38 274.
wl |
SFL DPN Fs apes 08 ua ak ee Ue es OS ae 12 12
TLE EP itd | taal eel 4 ide 7 Hoel wall eee sacl eeCHeE RR tC eee oe Peete
20 ee No cla es bees achat al 20 ate Ne at ga) GR ee eae Uae ee er
SATAN eapon OR eT Bee Scan SIME oa ce eed ae 4 26 67
Aupust siento ak 3 3 6 6 Sill | hate aresatwed vies exe RAE aa ae
4 THER Ore esta bea we ent Den ae ar VASES dan [eae 27 60
TG Pee ere 3 3 C3) eSapsee etl eI a PA eee an Mes | ae Rae
One eyes UPS te bore dd ates ra tel nase eepe Mia ne 4 2G y SN eres velaiaes
20 TPA] |e ta Te Sieg | SE eae || Ree RA eons) ret Peat ot mn eae 59
38 10 13 19 16 11 91 198
|

Spray injury from Poisoned Bait. The orchards containing
31 and 40 trees were sprayed with eleven gallons of the bait iu
the first application, but in the second and third treatments the
amount of spray material was reduced to six gallons. Tent-
caterpillars had practically stripped the leaves from some trees,
while others were partially defoliated, and as the partly de-
voured leaves dropped very readily due to the scalding of the
soluble poison in the diluted molasses, it was deemed advisable
to reduce the amount of spray material in the second and
third baitings.

In 1914, a number of complaints were made on account of
the scorching of some of the leaves, which later turned yellow
and finally dropped from the trees. In some of the dooryards

160 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

we were forced to stop spraying before the end of the season
due to the scalding of the leaves, while in other yards and in
the orchards it was decided to discontinue the use of soluble
poisons and substitute insoluble arsenicals, In visiting the
owners during the next season, however, they were so delighted
with the crop of sound apples obtained in the previous year,
that they promptly forgot all about the alarm created by the
partial defoliation, and without exception, permission was
granted to spray the apple trees again. Nevertheless, during
the second season the fear of some injurious effect of spray
injury to the trees was voiced repeatedly. Many people, how-
ever, preferred sound fruit even if burned foliage was the
necessary price. Raking the leaves from well kept lawns where
apple trees were growing proved to be a troublesome task.

Effectiveness of poisoned bait. An attempt was made te
determine how long the poisoned bait would remain effective
after different amounts of rainfall. After each treatmert,
cheese cloth was fastened to the ground with spikes below a
sprayed tree. The insects which succumbed to the effects of
the soluble poison in the sweet were collected daily from the
cheese cloth and it was reasonable to suppose that the insecti-
cide became ineffective due to rains when no dead specimens
were found. As the records on precipitation at the University
of Maine were taken at a distance of about two miles from our
experimental area, no accurate statement can be made as to the
amount of rainfall required to wash off all the bait. It is evi-
dent, however, that an “all day rain” with heavy intermittent
showers will destroy the effectiveness of the fruit fly remedy.
In view of the abundance of rain in the season of I915, the
effectiveness of the poisoned diluted molasses was put to a
most thorough test.

An experiment was performed in the field to determine the
length of time required for the amount of poison used in the
formula in 1915, to kill the adults. A tall Benoni apple tree
(Map, L) received the fourth treatment on August 19, at 3.30
P. M. and on August 20, at 7.30 A. M. six female and four
male apple fruit flies were collected on the cheese cloth sixteen
hours after the application of the bait. Four specimens feed-
ing on the insecticide on the upper surface of the leaves were
captured, but all died in captivity within two days. On Augu*t

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 161

21, two days after spraying, one dead fly was picked up on the
cheese cloth and on August 24, the last trypetid was found, but
due to heavy rains during the preceding day we were unable
to visit the tree. A light shower of rain fell on August 22, but
heavy rains fell during the night and continued throughout the
next day. The precipitation amounted to 1.58 inches on August
23, and the last baiting in the entire experimental area became
ineffective after this date.

We have already called attention to two different methods of
applying the spray. After the above Benoni tree received three
applications of the bait, by spraying the trunk, larger limbs and
foliage of the lower branches, 88 per cent* of the apples were
found to be infested on August 19. On this same date, the
fourth treatment was given by forcing the poisoned sweet from
the spray pump into the air toward the top of the tree, so that
the minute drops fell over and in the tree. On September 2,
49 per cent* of the apples were maggoty and on September 22,
I5 per cent* were infested. In all probability, a general dis-
tribution of the fruit fly remedy over the foliage is more effec-
tive than spraying the trunk and large limbs due to the fact
that the bark seems to absorb the poisoned diluted molasses.
After the water has evaporated, a glossy layer of molasses ad-
heres to the upper surface of the leaves, while the hairy coating
of the lower epidermis prevents the formation of this film of
sweet and seemingly absorbs a considerable amount of the
poisoned liquid.

Attraction to poisoned bait. One observation tends to show
that the apple fruit fly is attracted to the poisoned bait under
field conditions. A specimen was observed at rest on an apple
just at the time that the spray was about to be applied to the
tree. Suddenly the fly took wing and came to rest on my hand
which was spattered with the bait and here it began to feed, The
distance from the apple to my hand was about a yard.

Checking up results. In checking up the effectiveness of the
poisoned bait spray, the apples were picked at random from a
treated tree in the various orchards or residential district and
_on the same day apples of a similar variety were gathered from

*This sequence of per cents is of course only possible where the
infested fruit is dropping and the counts taken each time from fruit
remaining upon the tree.

162 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

an untreated tree in other orchards or another section of the
residential district, at a distance varying from about 1,000 feet
to two miles. Some varieties of apples were kept in the insect-
house for a month or more so as to give any eggs that were
deposited shortly before picking an opportunity to hatch and
also to bring out more conspicuously the tiny tunnel» of the re-
cently hatched larve in the pulp. Each apple was cut in half and
if there was no evidence of an infestation, the halves were thinly
sliced to determine whether there was any trace of the con-
spicuous brown tunnels of the larve in the pulp. In this way
a record was taken of the infested and non-infested apples.
No attention was paid to egg punctures as the apple fruit fly
will sometimes make an egg puncture and not deposit an egg.

RESULTS IN ORCHARDS.

The following table shows the per cent of apples infested on
the sprayed and check trees in 1914 and 1915, the dates on
‘which the apples were picked, the location of the treated trees
on the map in the orchards and the varieties of apples:

Results of Two Seasons’ Spraying in Orchards,

Apples infested Apples infested

on sprayed tree. on check tree.
VARIETIES OF AppLES.|Map.| Picked, | Picked, |-

1914. 1915
1914. 1915. 1914. 1915.
|
% % %

Tolman Sweet*....... Tl |Sept. 19/Sept. 27 4 5 96 100
Tolman Sweeber ic sel weanl eee ee SOUL rates aear Cea leliane caren 100
McIntosh Red........ Di |Sept. 19/Sept. 24 0 0 28) 7 | ears oe
McIntosh Red........ DD yet ase Septig24i oer NURS eae Pha Saleen bese Manteno ore
Pameuse 2% 22/285. 225 Fl |Sept. 29/Sept. 27 0 6 38 52
WAMEUSE hse eee B27) |) ere ashe DED eee ail i eeoeune pet ayaa wae 52
Milder: -Je.ios eee M1 |Sept. 12/Sept. 29 0 2 92 25
NY BUCCLTO AMAA yee im bie IY relics ieee Sept 29h viene Ce Paleo aay Sih i 25
Pyrus prunifolia....... EPA MRSS eats Septal 7-2 eeere RN IES ee eker | ect ae
(Hybrid crab)
ROME sai oe anlortors cekee R_ |Sept. 14/Sept. 8 14 nies | eared any tatceab yb Bs)
Hyslop crab.......... 15 Bie ani na ener y Septltise ease OH i tell Ree rn 1
Large Red Siberian....} S |........ Deptonels vow ssee OVS ai ERE Bae hee aenear
Bells Marly*.......... B Sept. 26/Sept. 12 55 7} Oe ee aE Te hz re c aees
Tolman Sweet*....... T3 |Sept. 26/Sept. 27 40 3 100 100
‘Alexander then tet iene aie Septno14| ate aes APES hai wareteas OFF Uae es
Tolman Sweet........ PE ANS oes Septane al tetrtser Yas | ees veo 100
WaAME USES A spstonysyentaeell haya ots Sept: 219 |e aes ALE). iai| ah ies Sea petra ae | ee aerate
Wealthyeuan aca cesnees RW iil eee Sept 24) 2c ae Ey Gan ane eet a teal tL
Tolman Sweet........ ELT iis oss ae ran ears Septei2m| ean cee SQ Tia ea aa ae 100

* Indicates that the apples were picked from the same sprayed tree during 1914 and
1915, while the varieties not so marked were picked from different trees during the two
seasons.

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 163

It is evident from this table that in the orchard which con-
tained 84 trees (Map, 84) the résults show practically no infes-
tation in the season of 1914, From time to time during this
season, the drops of different varieties of apples were gathered,
but among the windfalls, only one infested Tolman Sweet
apple was found. The Tolman Sweets in this orchard had
‘been badly infested for a number of years. In 1913 no Tol-
man Sweets escaped infestation. In 1914 and in 1915 the
apples were practically free from the railroad worm. In view
lof the flact that the pest was almost completely controlled in
the season of 1914, we are hardly justified in drawing conclu-
sions from similar results obtained in I915; because since
maggots were not present the fall of 1914 we should not ex-
pect to have flies the next summer.

No definite conclusions can be drawn from the results ob-
tained in the two orchards containing 31 and 4o apple trees
(Map, 31 and 40), due to the fact that no check or control
trees of the same variety as the treated trees could be obtained.
In 1914, 14 per cent of the Rolfe (Map, R) were infested ;
whereas, in the season of 1915, the infestation on this same tree
was reduced to 1 per cent. In the season of 1914, there was a
heavy crop of apples, while in the following season there was au
exceedingly short crop and one would naturally expect a heavier
infestation.

Definite conclusions, however, can be drawn from the results
obtained in the orchard containing 57 trees (Map, 57). A
Tolman Sweet tree (Map, T3) showed an infestation of 40 per
cent after the first season’s baiting and 3 per cent after the
second season's treatment, while the check tree showed 100 per
cent maggoty fruit. A Bells Early (Map, B) showed an infes-
tation of 55 per cent and 20 per cent during the two seasons.
The Tolman Sweet and Bells Early trees were by no means
stripped of their fruit in the season of I914, since only 100
apples were picked of each variety for examination in each
year. It must be noted, however, that the Tolman Sweet tree
was sprayed by forcing the poisoned bait into the air so that
the minute drops fell over and into the tree, while in the case

164 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

of the Bells Early tree the insecticide was applied to the trunk,
large limbs and foliage of the lower branches.

The orchards containing 47 and 38 trees were within 100
feet of other untreated orchards and apple trees in dooryards,
and the higher infestation is seemingly due to the invasion of
the apple fruit flies. A Tolman Sweet tree in each orchard
(Map, T4 and T5) showed that 32 per cent and 34 per cent
of the apples were infested compared with 100 per cent mag-
goty fruit on the control or check trees. A Wealthy (Map, W)
showed that 57 per cent of the apples were infested and this
represents the highest infestation under orchard conditions in
the season of 1915.

RESULTS IN RESIDENTIAL DISTRICT.

Lounsbury* of South Africa, demonstrated that the Mediter-
ranean fruit fly can be controlled with the poisoned bait spray
under town conditions even where summer rainfall is heavy.
We, therefore, decided to test the value of the poisoned sweet
as a means of combating the apple fruit fly in the residential
section of Orono, Maine. The residential district in the
experimental area contained 274 apple trees scattered in vacatit
lots and dooryards.

Some of the occupants informed us that certain varieties of
apples had been seriously infested by the apple maggot for ten
years. In some yards all of the infested fruit was allowed to
decay on the ground, and in others, some or all of the drops had
been gathered during previous years. Poultry was fenced off
in some of the back yards below the apple trees and in others,
the fowls were allowed to run at large.

The following table shows the results of two seasons’ spray-
ing in the residential district:

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 165

Results of Two Season's Spraying in Residential District.

Apples infested Apples infested

on sprayed tree. on check tree.
Varieties or Aprurs.|Map.| Picked, | Picked, |__ _
1914. 1915.
1914. 1915. 1914. 1915.

% v0 % %
McIntosh Red........ 1D Be ee atte icee Sept. 24]........ CRU RA eee ee tee
Coles Quincef......... C |Sept. 17|Sept. 17 34 PASSION a
Munson Sweett....... U1 |Sept. 8|Sept. 2 96 91 99 100
Alexander............ UNE A heigl aee Sept. 22). 500038. Gaing a se 4
Transcendent crab..... TAY sali a dcae oh Sept. 17]........ Sis talons etante b 100
McIntosh Red........ D4 |Sept. 14/Sept. 24 14 TUG ara eae Rae (0)
Bellfiower............ DCT Rain aed Sept. 27]........ BT oe ase irktuss ane emis ani
Tolman Sweet........ ERG IC Be sores Septic 2auccn ecm. PON eA Na 95
Tolman Sweet........ CBE abs stncereune Site 2looemoe on ROSE Wy ees sete 95
Tolman Sweet........ ERS aerecetsteneys Sept. 27]........ A Gime ete 95
Tolman Sweet........ oy OY | ean tea er Sore Sinlltieon oo LS Min Ly eae Are 95
Munson Sweetf....... U2 |Sept. 14/Sept. 2 99 COV Gh taal (iat 100
Transcendent crab.....| K2 |........ Sept. 9]........ SOW a ulete ere are 100
MamMeusee ee keene sees Sept. 14]........ Sey LAR benat eee en Eh | Pos Ene en Uae MEReeE a HARE
Hameusey 72 isc ieieiahnes si Maal Sacenae Sept. 14]........ Ese NE ase Bel et ate Nene Cesena epee aes MARR
A IME USE see ato cal iste ate Sept. 14]........ LTO crit (Rese See aL he MAUS aa Ra Ua
Golden Russet........|..... Sept. 14]........ TUB Seria HEN a oti HEAR ee related Caer ae
DW CHESS eta tale day tieereeclen Scone Sept. 14 : TES eS ane rr ene Sole a i ea
Seedling..............]..... Sept. 17|........ Cf SYicah cl Gen autres Haat) CSPI | RPENEN ye

*Agr. Jour. Union of South Africa, No. 25, pp. 1-7.

{ Indicates that the apples were picked from the same sprayed tree during 1914 and
1915, while the varieties not so marked were picked from different trees during the two
seasons.

It is evident from the results recorded in this table that the
control of the apple fruit fly with the use of the poisoned bait
has been a complete failure in the residential district, Two
Munson Sweet trees (Map, Ur and U2) showed an infestation
of 96 per cent and go per cent of the fruit after the first sea-
son’s spraying compared with 91 per cent and 98 per cent
after the second season’s treatment, In the case of a Coles
Quince (Map, C), however, there was a decided improvement
of the fruit, 34 per cent being attacked in 1914, and 4 per cent
in 1915. A comparison of the infestation of a treated McIn-
tosh Red and Alexander (Map, D3 and A) with the check
trees shows a higher per cent of maggoty fruit on the sprayed
trees. On the other hand, four Tolman Sweet trees (Map, T6,
T7, T8, and Tg) showed an infestation of 24, 46, 50 and 80 per
cent compared with 95 per cent on the check trees.

Attention must be called to the severe infestation of fruit on
treated trees situated in dooryards in close proximity to Pro-
fessor Woods’ orchard (Map, 84) in which there was prac-
tically no infestation during the past two seasons. Situated
within 450 feet of this orchard were the following varieties of
apple trees showing a high per cent of infested fruit: Tolman

166 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

Sweet (Map, Tg) 88 per cent; Munson Sweet (Map, U2) 99
per cent in 1914, and 98 per cent in 1915; Transcendent crab
(Map, K2) 80 per cent and Benoni (Map, L) 88 per cent on
August 19.

It is reasonable to suppose that when badly infested early
varieties are harvested, such as the Transcendent crab and Mun-
son Sweet, that the absence of apples on the trees will cause
the female flies to seek other fruit in which to oviposit. The
Transcendent crabs and the Munson Sweets were harvested by
the middle of September. It must be noted that the last appli-
cation of the spray in the orchards and residential district were
made between August 12 and 22, during the two seasons, The
bait was washed off by rains before the early varieties had
been harvested, leaving the fruit trees unprotected, at the time
when the dispersal of the flies probably occurs.

CONCLUSIONS.

In 1914, no conclusions could be drawn on the effectiveness of
the poisoned bait spray from any of the experiments that we
performed, due to the fact that the different soluble poisons
scorched the leaves and therefore insoluble arsenicals were
substituted in the later treatments. A series of experiments
with different amounts of soluble poisons, such as potassium
and sodium arsenate and sodium arsenite, show that as small a
quantity as one-quarter of an ounce of these insecticides dis-
solved in boiling water and then added to three gallons of water
with one pint of molasses will burn the foliage of the apple
trees.

In 1915, during a very rainy season, the results obtained
with three applications of the poisoned bait spray containing 4
soluble poison dissolved in diluted molasses, showed that the
infestation varied from 0 to 20 per cent in orchards situated
away from the margin of the experimental area, and from 32
to 57 per cent in orchards near untreated trees. An even dis-
tribution of the droplets over the foliage is more effective than
spraying the trunk, large limbs and foliage of the lower
branches. The number of applications necessary to insure good
results can not be stated with this work still in its experimental
stage. In orchards where tent-caterpillars have practically
stripped or partially defoliated the trees the poisoned bait with

SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 167

the use of a soluble poison can not be advocated. In orchards
where tent-caterpillars are controlled, defoliation caused by
spray injury is far less than the damage caused by these pests
in neglected orchards. Our experience shows that after fruit
growers have been convinced of the results obtained by the use
of the poisoned bait spray, many prefer sound fruit even if
burned foliage is the necessary price.

The fruit fly remedy has been a complete failure in the con-
trol of the pest under town conditions. With four applications
of the spray the infestation varied from 4 to 98 per cent.

EXPLANATION OF Map.

Map showing the location of the experimental area in which
an attempt was made to control the adult of the apple maggot
by means of the poisoned bait spray under orchard and town
conditions. The apple trees indicated by dots on the map were
isolated on one side by the Penobscot river and a bay of this
river. The location of six orchards are shown by the following
figures which represent the number of trees in each: 84, 3:,
40, 57, 47 and 38. The principal part of each orchard is sit-
uated above the figures. A series of dashes represents the
boundary between two orchards or separates an orchard from
trees present in adjacent dooryards. The residential district
contained 274 apple trees scattered in the different yards. The
entire area covered about one square mile and contained a
total of 571 apple trees.

A circle surrounding a dot shows the location of a sprayed
tree which was checked up with an untreated or control tree
situated on the outside of the experimental area. The follow-
ing is a list of varieties of apples that were used in checking up
the results:

A = Alexander. M1-M2= Milden.

B=Bells Early. P= Pyrus prunifolia (Hybrid Crab).
C= Coles Quince. A ed RGLEGs

Dz-D4= McIntosh Red. S = Large Red Siberian Crab.
F1-F2= Fameuse. T1-To= Tolman Sweet.
H=Hyslop Crab. U1-U2= Munson Sweet.

K1-K2= Transcendent. Crab. W = Wealthy.
*L = Benoni. X = Bellflower.

168 MAINE AGRICULTURAL EXPERIMENT STATION. 1916.

For Explanation of Map see Preceding Page

ae

ae

ickin$
so

ae? te
Ne

<i
ee