Papers on insects affecting vegetables ..

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Title:
Papers on insects affecting vegetables ..
Series Title:
U.S. Dept. of agriculture. Bureau of Entomology Bulletin ;
Physical Description:
v, 84 p. : illus., pl. ; 23 cm.
Language:
English
Publisher:
Govt. print. off.
Place of Publication:
Washington
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Subjects

Subjects / Keywords:
Vegetables -- Diseases and pests   ( lcsh )
Insecticides   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Bibliographies interspersed.
General Note:
Papers pub. separately, 1911-1913 and numbered consecutively.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029622798
oclc - 32687280
lccn - agr16001045
System ID:
AA00018914:00001

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U. S. DEPARTMENT OF AGRICULTURE
U. S. DEPARTMENT OF AGRICULTURE,


BUREAU OF ENTOMOLOGY-BULLETIN No. 109, Part V.
L. 0. HOWARD, Entomologist and Chief of Bureau.


PAPERS ON INSECTS AFFECTING VEGETABLES.



ARSENITE OF ZINC AND LEAD CHRO-

MATE AS REMEDIES AGAINST THE

COLORADO POTATO BEETLE.



BY

FRED A. JOHNSTON,
Entomological Assistant.


[In cooperation with the Virginia Truck Experiment Station.]



ISSUED APRIL 5, 1912.


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1912.





















BUREAU OF ENTOMOLOGY

L. 0. HOWARD, Entomologist and Chief of Bureau.
C. L. MARLATT, Entomologist and Acting Chief in Absence of Chief.
R. S. CLIFTON, Executive Assistant.
W. F. TASTET, Chief Clerik.


F. H. CHITTENDEN, in charge of truck crop and stored product insect
A. D. HOPKINS, in charge offorest insect investigations.
W. D. HUNTER, in charge of southern field crop insect investigations.
F. M. WEBSTER, in charge of cereal and forage insect investigations.
A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.
E. F. PHILLLPS, in charge of bee culture.
D. M. ROGERS, in charge of preventing spread of moths, field work.
ROLLA P. CURRIE, in charge of editorial work.
MABEL COLCORD, in charge of library.


investigations.


TRUCK CROP AND STORED PRODUCT INSECT INVESTIGATIONS.

F. H. CHITTENDEN, in charge.

H. M. RUSSELL, C. H. POPENOE, WM. B. PARKER, H. 0. MARSH, M. M. HIGH,
FRED A. JOHNSTON, JOHN E. GRAF, entomological assistants.
I. J. CONDIT, collaborator in California.
P. T. COLE, collaborator in tidewater Virginia.
W. N. ORD, collaborator in Oregon.
THOS. II. JONES, collaborator in Porto Rico.
MARION T. VAN HORN, PAULINE M. JOHNSON,preparators.
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CONTENTS


Page.
Spraying experiments with arsenite of zinc and lead chromate in comparison
with other arsenicals .................................................... 53
Spraying experiments with arsenite of zinc at different strengths ............ 55
In









































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T. C. & S. P. I. I., April 5, 1012.


PAPERS ON INSECTS AFFECTING VEGETABLES.


ARSENITE OF ZINC AND LEAD CHROMATE AS REMEDIES
AGAINST THE COLORADO POTATO BEETLE.

By FRED A. JOHNSTON, Entomological Assistant.
[In cooperation with the Virginia Truck Experiment Station.]
I
SPRAYING EXPERIMENTS WITH ARSENITE OF ZINC AND LEAD
CHROMATE IN COMPARISON WITH OTHER ARSENICALS.

In May, 1911, a series of experiments for comparing the insecti-
cidal value of arsenite of zinc and of lead chromate with that of other
arsenicals in controlling the Colorado potato beetle (Leptinotarsa
decemlineata Say) was undertaken under the direction of Dr. F. H.
Chittenden at the Virginia Truck Experiment Station, at Norfolk, Va.
The season was later than usual, making it unnecessary to spray for
the potato beetle until about May 9. At this date no larve were
present on the plants, though beetles and egg masses were abundant.
On May 9 six plats were sprayed. Table I gives the insecticides
and strengths used.

TABLE I.-Sprays used against the Colorado potato beetle, Norfolk, Va., May, 1911.

plat Insecticide used.
No.

I Lime-sulphur, 2 pounds to 50 gallons of water and 3 pounds of arsenate of lead.
II Arsenate of lead, 3 pounds to 50 gallons of water.
III Lead chromate, 2 ounces to 4 gallons of water.
IV Arsenite of zinc, 1I pounds to 50 gallons of water.
V Bordeaux mixture (4-6-50 formula) and 1 pounds of Paris green.
VI Bordeaux mixture (4-6-50 formula) and I4 pounds of arsenite of zinc.

On May 22 all of the potatoes were resprayed, the same proportions
of the different materials being used with the exception of the lead
chromate in which case the strength was doubled. (One ounce to a
gallon of water.)
At this date the larve were exceedingly numerous and doing much
damage in unsprayed potato fields.
21142a-12 53


U. S. D. A., B. E. Bul. 109, Part V.






PAPERS ON INSECTS AFFECTING VEGETABLES.


On the day following the second application of the sprays a count
of the infested plants in each plat was made and the following figures
obtained:
TABLE II.-Results of spray applications against the Colorado potato beetle, Norfolk,
Va., May, 1911.

Number Number
Plat Insecticide used. of in- of unin- Infesta-
No. Jested tested tion.
plants, plant.

Per cent.
I Lime-sulphur (2-50 formula) and 3 pounds of arsenate of lead....... 37 347 9.6
II Arsenate of lead, 3 pounds to 50 gallons of water.................... 118 622 15.9
III Lead chromate, 2 ounces to 4 gallons of water, and 1 ounce to 1 gal-
lon of water...................................................... 216 169 +56.0
1V Arseniteof zinc, 1 pounds to 50 gallons of water .................... 206 1,048 16.4
V Bordeaux mixture (4-6-50 formula) and I1 pounds Paris green.... 152 741 +17.0
VI Bordeaux mixture (4-6-50 formula) and 1 pounds arsenite of zinc... 225 555 28.

It will be seen that the results obtained from the use of lead
chromate were very unsatisfactory as compared with those in the
case of other insecticides used. The lead chromate employed was in
the form of a powder, and great difficulty was experienced in making
it mix well with water, it having a tendency to settle quite rapidly,
requiring constant agitation to keep it in solution. It adhered well
to the foliage, and its color stood out quite prominently in contrast
to the other plats. However, the young larvae seemed to be able to
feed on plants that were thoroughly covered with the material without
receiving much injury.
The arsenite of zinc employed was also in the powdered form. It is
much lighter than lead chromate and remains in suspension in water
much better. It adheres to the foliage very well and does not, so far
as could be observed, burn or injure the plants in any way.
The percentage of infested plants in the plat that was treated
with Bordeaux mixture and arsenite of zinc was somewhat greater
than in the plat in which the arsenite of zinc alone had been used.
This was no doubt due partly to the fact that the Bordeaux-arsenite
of zinc plat was in a different field, one which had been in potatoes the
previous year and was thus subject to the attack of a greater number
of beetles. Also, many of the plants which were counted as infested
were only slightly injured, and it is doubtful if the yield of potatoes
would have been much lessened.
On June 29 the potatoes were dug, and following are the weights
. of one row of potatoes in each of the first four plats.


54




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ARSENITE OF ZINC AGAINST POTATO BEETLE. 55

TABLE III.- Yields of potatoes from one row from each of Plats I, II, III, and II.
sprayed as indicated in Table I.

One
row Number Weight Weight
from Insecticide used. of plants of No. 1 of No. 2
Vlat in row. potatoes.' potatoes.'
0o.

Pounds. Pounds.
I Lime-sulphur and arsenate of lead ............................384 1881 251
II Arsenate of lead.................................................. 368 1721 26
III Lead chrom ate .................................................... 385 128 19j
IV Arseniteofzinc................................................... 374 1431 18

SExcellent to good. Fair to indifferent.

By taking the yield of the same number of plants from each row the
contrast between the different rows will be more marked. Table IV
represents the yield of 374 plants from each row:

TABLE IV.- Yields of potatoes from 374 plants from one row from each of Plats I, II,
III, and IV, sprayed as indicated in Table I.

One
row Number Weight Weight
from Insecticide used. of plants of No. 1 of No. 2
plat in row. potatoes.' potatoes.'
No.

Pounds. Pounds.
I Lime-sulphur and arsenate of lead ................................ 374 183.26 25.05
II Arsenate of lead................................................... 374 175.401 26.18
III Lead chromate.................................................. 374 124. 168 19. 07
IV Arseniteof zinc ........................................... ....... 374 143.5 18

1 Excellent to good. Fair to indifferent.

SPRAYING EXPERIMENTS WITH ARSENITE OF ZINC AT VARIOUS
STRENGTHS.

An experiment with the three following strengths of arsenite of
zinc in controlling the Colorado potato beetle was begun at the Vir-
ginia Truck Experiment Station, Norfolk, Va., on May 31, 1911.
No. I, arsenite of zinc, 1 pound to 50 gallons of water.
No. II, arsenite of zinc, 1 pounds to 50 gallons of water.
No. III, arsenite of zinc, 2 pounds to 50 gallons of water.
On the day the spraying was done (May 31) the rows sprayed with
No. I, No. II, and No. III had 47, 86, and 88 infested plants, respec-
tively.
On June 2 the row treated with No. I had 33 infested plants, a
decreased infestation of 14 plants, or 29.8 per cent. The row treated
with No. II had 57 infested plants, a decreased infestation of 29
plants, or 33.7 per cent, while the row treated with No. III had 38
infested plants, a decreased infestation of 50 plants, or 56.8 per cent.




mmumm


UNIVERSITY OF FLOM

56 PAPERS ON INSECTS AFFECTING I
1262 089214 -8

On June 3 the count was again taken, and the row treated ..l
I had 15 infested plants, a decreased infestation of 32 plants, '............
per cent. The row treated with No. II had 23 infested
decreased infestation of 63 plants, or 73.2 per cent, while the.
treated with No. Ill had 13 infested plants, a decreased infestati
75 plants, or 85.2 per cent. l
The following table shows the number of infested plants in i
plats before and after spraying:

TABLE V.-Results of applications of arsenite of zinc at different strengths agabi':si
Colorado potato beetle.

Solu. Decrase In, ^|
Date. iSon- Number of number of
Date. o. infested infested
No plants, plants. "

1911. P .e.'
M ay 31.................................................... I 47 ............ ..
Do. ................................................... ......... .... ..32
Do ..................................................... II 868 ......... ... .. a
June 2..................................................... I 8.33
D o ..................................................... II 57 ::
Do ..................................................... 138 50i
June3..................................................... I 15 32
Do ..................................................... 11 23 63
Do..................................................... III 13 75

On June 3 the number of larve on the plants which wo4erel
infested was much smaller than the number present when thMin|
was first applied. The extent of infestation of some plants ami..
to but one or two larvae; these plants, however, were counted .:::i
infested. "
Results.-From the preceding table it will be seen that far a"
results were obtained where 2 pounds of arsenite of zinc to 50 gaq
of water were used. i
The results were obtained more quickly, and a larger percentage :'
larvae was killed. At this strength arsenite of zinc did not bur A
injure the foliage in any way, and without doubt an even greai"t
amount of the arsenical might be used without injury to the pJal
and with correspondingly greater efficiency in killing the beetles.



ADDITIONAL COPIES of this publication
may be procured from the SUPWrnTD-
ENT OF DOCUMENTS, Government Printing
Office, Washington, D. C., at 5 cents per copy


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