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
Publication Date:

Subjects

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

Notes

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

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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:
AA00018914:00002

Full Text
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U. S. DEPARTMENT OF AGRICULTURE,

BUREAU OF ENTOMOLOGY-BULLETIN No. 109, Part VI.

L 0. HOWARD, Entomologist and Chief of Bureau.




PAPERS ON INSECTS AFFECTING VEGETABLES.


THE SUGAW-BEET WEB WORMS


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BY



'H. 0. MARSH,


SEntomologcal Assistant.

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BUREAU OF ENTOMOLOGY.

L. 0. HOWARD, Entomologist and Chief of Bureau.
C. L. MIARLATT, Entomologist and Acting Chief in Absence of Chief.
R. S. CLIFTON, Executive Assistant.
IV. F. TASTET, Chief Clerk.

F. H. CHITTENDEN, in charge of truck crop and stored product insect in restigations.
A. D. HOPKINS, inll charge of forest insect investigations.
WV. D. HUNTER, in charge of southern field crop insect investigations.
F. M. WEBSTER, in charge of cereal and forage insect in restigations.
A. L. QUAINTANCE, in charge of deci-duous fruit insect investigations. i
E. F. PHILLIPS, in charge of bee culture.
D. M. ROGERS, in charge of presenting spread of moths, field work. :
ROLLA P. CURRIE, in charge of editorial work. ,
MABEL COLCORD, in charge of library.
:il
TRUCK CROP AND STORED PRODUCT INSECT INVESTIGATIONS.

F. H. CHITTENDEN, in charge. !

H. MI. RUSSELL, C. H. POPENOE, WM. B. PARKER, H. 0. MARSH, M. IM. HIGH, i
JOHN E. GR.AF. FRED A. JOHNSTON, entomological a-sistants.
I. J. CONDIT, collaborator in California.
W. N. ORD, collaborator in Oregon. !
THOS. H. JONES, collaborator in Porto Rico.
JMARION T. VAN HORN, PAULINE M. JOHNSON, ANITA M. BALLINGEB, preparatory t.















CONTENTS


Introduction......................................
General appearance of the sugar-beet webworm and
Life history and habits ............................
Character of injury ..............................
Natural enemies .................................
Other checks ...................................
Experiments with remedies........................
Spraying machinery.............................
Cost of spraying ...................................
Conclusion.......................................


nature of attack -........


I ILLUSTRATIONS.


FIG. 9. The sugar-beet webworm (Loxostege slicticalis): Moth.................
10. The garden webworm (Loxostege similalis): Moth, larva, pupa, details.
11. A medium-sized sugar-beet plant defoliated by the sugar-beet web-
worm in July ........................... ............................
12. Sugar beets defoliated by the sugar-beet webworm in July............
13. Large sugar-beet plants, showing defoliation and weakened roots due
to attack by the sugar-beet webworm in August......--........-....
14. Field of young sugar beets destroyed by the sugar-beet webworm in June.
15. Barrel sprayer suitable for use against the sugar-beet webworm.........
16. Barrel sprayer in action against the sugar-beet webwormn ..............
17. Four-row attachment for beet sprayer.................................
18. Four-row attachment for beet sprayer..............................
19. Four-row attachment for beet sprayer..............................
20. Geared traction sprayer suitable for use against the sugar-beet web-
worm ...........................................................
21. Geared traction sprayer in action against the sugar-beet webworm....
22. Filling a traction sprayer for spraying against the sugar-beet webworm..
23. Type of Vermorel nozzles suitable for spraying sugar beet3 against the
sugar-beet webworm.............................................


Page.
57
58
59
61
62
63
63
66
69
70


Page.
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60
61

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65
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T. C. & S. P. I. I., September 16, 1912.


PAPERS ON INSECTS AFFECTING VEGETABLES.


A REPORT OF PROGRESS REGARDING THE SUGAR-BEET
WEBWORM.
(Loxostege sticticalis L.)

By H. 0. MARsH,
Entomological Assistant.

INTRODUCTION.
During portions of the years 1909 and 1910 and nearly all of 1911
the writer, stationed in the Arkansas Valley of Colorado and Kansas,
was engaged in a study of the insects affecting sugar beets and truck
crops. Among the foremost of the species of insects studied was
the sugar-beet webworm (Loxostege sticticalis L.). Although the
investigation of this pest has not been completed, control measures
have been fairly definitely worked out, and this preliminary article
is presented with the hope that it will stimulate greater interest in
the subject among the beet growers, and thus render the completion
of the study more easily accomplished.
Sugar beets have been produced on a commercial scale in the
Arkansas Valley since 1900, and almost from the beginning this crop
has been infested by webworms. The injury produced by these in-
festations has varied greatly from year to year. During some seasons
little noticeable damage has occurred, while on a few occasions the
infested acreage has been extensive and the losses serious. As an
example it may be mentioned that in 1910 practically 4,000 acres of
beets grown for one of the sugar factories in the Arkansas Valley
were attacked. The serious nature of this outbreak was not realized
until too late, and although strenuous efforts were finally made to
control the "worms," the loss resulting from this infestation was esti-
mated at 20,000 tons of beets, which would have been worth approxi-
mately $100,000 to the growers. Such severe losses are rather excep-
tional, although nearly every year the loss occasioned by webworms
is far in excess of the amount imagined by the average beet grower.
To the progressive farmers in the Arkansas Valley the sugar-beet
webworm is generally too well known to require a detailed descrip-
tion, although a few notes regarding the life history when infesting
sugar beets may be of value.


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





PAPERS ON INSECTS AFFECTING VEGETABLES.


GENERAL APPEARANCE OF THE SUGAR-BEET WEBWORX AND
NATURE OF ATTACK.
The parent of this webworm (fig. 9) belongs to the lepidopterous
family Pyralidae, and is a tawny-brown, active moth, or "miller,"
with a wing expanse of about 1 inch.
It is larger and more conspicuously colored than the garden web-
worm which is shown in figure 10.
p The moths deposit their pearly-white
B eggs singly or in rows of from two to
five or more, usually on the under side
a Sof the leaf. When deposited in rows
they overlap more or less. Each female
moth is capable, under normal condi-
tions, of depositing at least 200 eggs.
\ From these eggs hatch the small larvae,
or "worms." When first hatched the
FIG. 9.-The sugar-beet webworm ,,9 a wi bl
(Loxostege sticticalis): Moth. worms are whitish, with black heads,
Twice natural size. (Reengraved but as they feed and increase in size
after Insect Life.) j
after Insect Life.) they become green, with dark markings.
The very young larvae eat small holes in the under side of the leaves
without, however, cutting through the upper epidermis, but as they
increase in size they consume almost the entire leaf, with the excep-
tion of the larger veins and the petioles. The "worms" prefer the
older leaves, and unless the food supply is nearly exhausted do not
eat the young leaves at the
center of the plant. When
full grown the "worms,"
which are slender and
about an inch in length, ,
leave the beets and burrow
in the soil, usually close
about the infested plants, 6
and spin tubelike cases in C
which they later pupate. FIG. 10.-The garden webworm (Loxostege sint,-
Thep p ari slender alis ; a, Male moth; b, larva, lateral view; c,
he pup arlender, larva, dorsal view; d, anal segment; e, abdominal
yellow-brown, inactive ob- segment, lateral view; f, pupa; g, cremaster.
jects, from which during a, b, e, f, somewhat enlarged; d, e, g, more en-
I large. (After Riley, except c, from Chittenden.)
the summer months the
moths issue within a few days. The moths, after issuing, feed on
the nectar in alfalfa or other blossoms and within a few days mate
and are ready to commence depositing eggs for another generation
or brood of wormsns"


58





PROGRESS REGARDING SUGAR-BEET WEBWORM.


LIFE HISTORY AND HABITS.
In rearing experiments conducted at Rocky Ford, Colo., the average
time required from the deposition of the eggs until the moths issued
was a little more than a month. The egg stage was observed to vary
from 3 to 5 days, the larva stage from 17 to 20 days, and the pupa
stage was usually 11 days. These variations were from records of
successive generations.
So far as the writer has been able to determine, there are three
generations or "crops" of webworms in the Arkansas Valley each
year. There may be a fourth generation, but if so it is not clearly
marked and possibly occurs early in the season on weeds such as
Russian thistle (Salsola tragus) and lamb's-quarters (Chenopodiurm
album). For the sake of convenience we may assume that only three
generations occur yearly. The periods during which the writer ob-
served the webworms of these successive generations in evidence on
sugar beets in the Arkansas Valley ranged from about the middle
of June until early July for the first generation and from about the
middle of July until well into August for the second generation,
while the third brood occurred in September.
In reality the generations are not sharply marked and considerable
overlapping may occur. In general the danger period extends from
shortly before the middle of June until well into September. The
first generation of webworms maybe expected at its height of destruc-
tiveness during the latter half of June, at a time when the beets are
comparatively small and least able to resist the attack. (See fig.
14.) At this season the infested beets may actually be killed by this
webworm, which, after eating all the leaves, may destroy the crown
of the plant. Whenever the crown is destroyed the beet dies. So
far as the writer has observed, the acreage destroyed in this way is
very small and ordinarily occurs only when the infested beets are
young and the available leaf surface limited. By the time the
"worms" of the later generation are present the beets have become
of good size and, although they may be completely stripped of all
but the youngest leaves, it is rarely that any are killed. (See figs.
11, 12.)
The larvte of the first generation, after maturing and burrowing
into the ground, pupate promptly and the moths issue within a few
days and deposit eggs for the second generation. The "worms" of
this next generation, on reaching maturity, likewise burrow into the
ground and spin their tubelike cases. However, only about half of
them pupate promptly, the others remaining unchanged in the tubes
until the spring of the following year. From the puprn which develop
in August, moths issue which deposit eggs for the third or September
generation, and these "worms" remain unchanged throughout the


59




*:ii
A
60 PAPERS ON INSECTS AFFECTING VEGETABLES.

winter. It will thus be seen that about half the webworms of the
second generation and all of those of the third generation, which
have not been destroyed by parasites or through artificial or natural
agencies, live through the winter in their tubes in the soil. These
"worms" pupate late in the spring and the moths which issue deposit
eggs for the first generation.
The moths when depositing eggs are often to be found in the beet
fields in enormous numbers, and when disturbed may be seen flying
close above the beet leaves in "clouds." When such numbers of moths
are observed in a beet field they should serve as a warning to the

4





















FIo. 11.-A medium sized sugar-beet plant defoliated by the sugar-beet webworm In July.
(Original.)

grower that a "crop" of webworms may be expected within the next
week or 10 days.
As a rule the first and second generations are the most destructive,
the third generation, which is actually only a partial one, rarely
causing serious damage. It seldom happens that the "worms" of
successive generations infest the same patch of beets to a serious ex-
lenrt. Thus a certain field may be infested by the webworms of the
first generation, while the moths which develop from them may drift
to adjoining fields to deposit eggs for the next generation.
The webworms often appear very suddenly and apparently with-
out warning in certain fields, and it is not uncommon for the growers
to express the idea that they have migrated from adjoining fields.





PROGRESS REGARDING SUGAR-BEET WEBWORM. 61

This, however, is not the case, but their apparently sudden appear-
ance is explained by the fact that the young webworms are easily
overlooked and that during the last few days before they reach
maturity their growth is very rapid. It frequently happens that
from 50 to 300 eggs are deposited on single beet plants, and in ex-
treme cases as many as 500 eggs may be so placed. The worms hatch-
ing from these eggs remain upon the beet on which they hatched
until they reach maturity, unless all the leaves are destroyed and they
are thus forced to crawl -- .
to another beet to obtain .
food.

CHARACTER OF INJURY.

It is impossible to state I-
definitely the damage to
sugar beets that an infes-
tation of webworms may v
catuse, as this may vary
from almost no percepti-
ble loss to the complete
destruction of the infested i
plants, the extent of the
injury depending on the
number of webworms
present, the size of the
infested beets, and various
other factors, such as cli-. .
matic conditions, soil fer- .. ... .
utility, and water supply. ,
As previously mentioned. "
small beets may be killed : .
outright (see fig. 14) ... ^,. ... ...
while larger beets may .
be completely stripped FIG. 12.-Sugar beets defoliated by the sugar-beet
of foliage. With large webworm in July. (Original.)
of foliage. With large
beets new leaves will usually be put out promptly and their
apparent recovery will take place quickly, especially if they are
irrigated as soon as possible after the defoliation. Although new
leaves are soon put out, defoliation retards the growth of the beet
roots. (See fig. 13.) The writer has seen beet roots which at the
time the tops we're defoliated, in early July, were more than an inch
in greatest diameter that made absolutely no gain in weight or
size for three weeks after the leaves were destroyed. It might be
added that these beets were in good, fertile soil and were watered
51094-Bnll. 109. pt 6-12--2




PAPERS ON INSECTS AFFECTING VEGETABLES.


'ven while the webworms were destroying the foliage. Judging. .
from personal observations and from the statements of many growers,
the writer may state that when sugar beets have been defoliated
by webwormns during the growing season a loss of from 1 to 5
tons of roots to the acre may be apparent at harvest time. The
decrease in tonnage is not the only damage, as analyses of such :
beets have indicated losses of both sugar content and purity, which
in some cases have reduced the price $1 a ton. Another injurious q
feature which follows defoliation is that the soil about the beets is
exposed to the direct rays of the sun, allowing the moisture to
__________________________ evaporate rapidly, and
if the supply of irriga-
\t ftion water is limited"
This may become a seri-
ous matter.
^yIt will be seen that
t \the sugar-beet webworm
y -is a pest capable of
causing extensive dam-
^ *age and that measures
fitending toward its con-
Si : trol are worthy of care-
: : fiful consideration.
:/' : : *NATURAL ENEMIES.

,..,i il t cies has natural one-
''':::":' .. ..... mies, among the most
.... .. ... .
']Atl:*"'-7"''--*" ** ,* .": .....efficient of which are
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blackbirds. Thesebirds
_________________________ often gather in enor-
FIG. 13.-Large sugar-beet plants, showing defoliation mous flocks in the in- '
and weakened roots due to attack by the sugar-beet tested beet fields and
webworm in A\ugust. (Original.) feed on the webworms.
Unfortunately the webworms are not thus attacked until they have .
become nearly full grown and attain a size that renders them more
conspicuous. As a result, it generally happens that the infested beets
are partially or completely defoliated before the birds have corn-
pleted their good work. The destruction of the "worms," however
lessens the possible number of the succeeding generation. The web-
worms are also reduced in number by true parasites, and in some
cases the writer has found fully 50 per cent of the overwintered larvae
killed in this way. One of the most common parasites is a little
wasplike insect known scientifically as Diosphyrus vulgaris Cress.,
a braconid. :


62





PROGRESS REGARDING SUGAR-BEET WEBWORM.


OTHER CHECKS.
As previously noted, the webworms burrow into the soil about
the infested plants, and when the beets are plowed out at harvest
time many of the worms are crushed or are so deeply buried that
the moths, if they succeed in developing, are unable to leave the
tubes, and consequently perish. In spite of these checks there will
be every year some areas of greater or less extent where the web-
worms will occur in injurious numbers and where spraying or other
artificial control measures will be necessary.


FIG. 14.-Field of young sugar beets destroyed by the sugar-beet webworm in late June.
(Original.1
EXPERIMENTS WITH REMEDIES.
During the time the writer has been stationed in the Arkansas
Valley he has given special attention to means of controlling this
webworm, and in his opinion spraying with Paris green has proven
by far the most effective and satisfactory remedy. The writer has
made many experimental tests with a variety of insecticides and
has also supervised a considerable amount of practical work against
this species, as a result of which study he considers the following
formulas as most efficient:
Formili Kro. 1.
Paris green ---------------------------------------pounds
Whale-oil soap ---------------------------------------do---- 6
Water --------------------------------------------gallons-_ 100


Formula Yo. 2.
Paris green ---------------------------------------pounds--
Lime ----------------------------------------------do- --
Water --------------------------------------------ga lions-_


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0
0
100


63





PAPERS ON INSECTS AFFECTING VEGETABLES.


These mixtures have been applied to sugar beets with various tyes J
of sprayers (figs. 15-22) at the rate of from 80 to 125 gallons per c .i1f-
and the results have been uniformly successful in controlling the web&::::"..:
worms. As a rule, 100 gallons per acre should be applied and tih'nI
spraying commenced as soon as possible after the webworms ha":....
hatched. Where possible the spray should be applied at about b,
pounds pressure, although the writer has observed good results where i
only 40 to 50 pounds pressure was maintained. The leaves of sugar .
beets are quite smooth, and in order to apply an even coat of poison it :i
is necessary to add some adhesive to the spray mixture. In the :
writer's experience nothing has proven more satisfactory for this i
.. .. ... :L..."-J





















FIG. 15.-Barrel sprayer suitable for use against the sugar-beet webworm. (Original.)

pLurpose than whale-oil soap. If it is not obtainable, ordinary laun-
dry soap may be used with about equally beneficial results, although .
it is more expensive. Lime, as recommended in formula No. 2, serves
to an extent as an adhesive and has the additional effect of neutraliz-
ing any free arsenic which may be present in the Paris green. Lime, ..
however, renders the mixture somewhat caustic, and this formula is !
less pleasant to use than is one in which soap is used as the adhesive .
agent. l
Refuse molasses from the beet-sugar factories was given extensive :
tests as a substitute for soap, and when used at the rate of from 3
to 6 gallons in 100 gallons of mixture it served as an effective ad- .
hesive. The molasses, however, contains a considerable amount of i


64





PROGRESS REGARDING SUGAR-BEET WEBWORM.


alkali and other impurities which tend to make soluble some of the
arsenic and copper in the Paris green. The soluble arsenic burns the
beet foliage, and on account of this injury refuse molasses is not
recommended. It may be interesting to add that in experiments
which the writer made with Paris green against other species of in-
sects, using as an adhesive refuse molasses from cane mills, which was
less highly charged with impurities, the results were satisfactory,
and no burning of the sprayed foliage occurred.
Several standard brands of arsenate of lead have been tested
against the sugar-beet webworm in the Arkansas Valley, and with-


FIG. 16.-Barrel sprayer in action against the sugar-beet webworm. (Original.)
out exception the results have proven unsatisfactory. The arsenate
was used at the rate of 6, 8, and 10 pounds in 100 gallons of water,
and 100 gallons per acre applied, but the webworm was not con-
trolled. In these experiments a large traction sprayer and an ordi-
nary barrel sprayer were used.
Zinc arsenite, when used at the rate of 4 pounds in 100 gallons of
water and applied at the rate of 125 gallons per acre, was effective.
It was, however, noticeably slower in its killing effects than Paris
green as recommended in formulas Nos. 1 and 2, and when used at
this strength was equally as expensive as an effective application of
Paris green.


65





66 PAPERS ON INSECTS AFFECTING VEGETABLES.
Paris green will kill the sugar-beet webworm when used at the rate
of 2 pounds in 100 gallons of water, but its action is comparativdely '
slow. It can also be safely used on sugar beets at the rate of 4
pounds in 100 gallons of water, although this amount is excessive aiind
unnecessarily expensive. All things considered, either formula Np.,
1 or formula No. 2 can be depended on for the most satisfactory :,:
results....
Many beet growers deman'l that an insecticide to be used against
webworms shall be immediately effective. It is of course unreason- '
able to expect immediately fatal results from a stomach poison.
When Paris green is properly applied against this webworm at the
rate of 3 pounds in 100 gallons of water, a fairly large number of
dead webworms will be found about the sprayed beets at the end of
24 hours, and at the end of three days practically all webworms
should be dead.
Dusting with Paris green and lime has also proven effective against
this webworm when used at the rate of from 2 to 4 pounds of the
poison in 100 pounds of air-slaked lime. The "dust" may be ap-
plied by shaking it from a coarse sack or with a "powder gun."
This method is slow, would increase the cost of application more than
50 per cent, and is difficult to apply in an even coating. .
Occasionally a field of beets may have been irrigated just before
an infestation of webworms becomes apparent, and in such a case
the soil is likely to be so wet that the prompt use of a sprayer will
prove impracticable and dusting may then be employed to advantage. '
SPRAYING MACHINERY.
For spraying large areas of sugar beets a geared traction sprayer :
of 125 gallons' capacity (figs. 20-22) will prove profitable; but for
the average grower, whose planting does not exceed 20 acres, this
type of machine is too expensive and unnecessarily large, and a
smaller, much cheaper sprayer, which can be assembled at home, will
give satisfactory results. Such a sprayer may be fitted up by mount-
ing a spray pump in a 50-gallon barrel on an ordinary one-horse,
two-row beet cultivator, from which the "handles" and "shoes"
have been removed. This arrangement will be readily understood
by referring to the accompanying illustrations (figs. 15, 16). The ;
four-row attachment is connected with the pump by a rubber hose
and is fastened to sections of plank which are bolted to the culti-
vator frame and extend out behind the wheels. The row attachment '
is made of k-inch and J-inch iron pipes and can be put together by a .
plumber. Three types of row attachments are illustrated. Number :;l
1 (fig. 17) is the simplest and will give satisfaction under ordinary A
conditions. This may be built to cover eight rows of beets instead i
of four. The eight-row attachment, however, is rather cumbersome ::j

*1






PROGRESS REGARDING SUGAR-BEET WEBWORM.


and may cause some trouble by catching in fences, etc., when turn-
ing at the end of the field. Number 2 (fig. 18) is so arranged that
two nozzles are above each row of beets. This is desirable, but not


Fr -- f

F. 17o t20

Pie. 17.--Four-row attachment for beet sprayer. (Original.)


absolutely necessary, when large beets are to be sprayed. Number 3
(fig. 19) is so made that both the surface and the underside of the
beet leaves are reached by the spray. By using this attachment


FIG. 18.-Four-row attachment for beet sprayer. (Original.)


beets can be very thoroughly sprayed and young webwormns on the
underside of the leaves will be more quickly killed than when only
the surface of the foliage is wet by the spray. A nozzle arrange-


20---


b'tt

trA/le ar/NOZZLer-
Ztt


FIG. 19.-Four-row attachment for beet snrayer: Nozzles arranged so that both the upper
and lower sides of the leaves may be wet by the spray. (Original.)
meant such as is obtained with this type is necessary when Bordeaux
mixture is applied for the leaf-spot disease (Cercospora beticola
Sacc.).


W


67






PAPERS ON INSECTS AFFECTING VEGETABLES.


4A
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4 4 ... k .2 .
I !


FIu. 20.-Geared traction sprayer suitable for use against
(Author's illustration.)


the sugar-beet webworm.


Fiu, 21.-Geared traction sprayer in action against the sugar-beet webworm.
illustration.)


68





PROGRESS REGARDING SUGAR-BEET WEBWORM.


In fitting up a sprayer a strong, heavily built pump provided with
an agitator should be used, and the necessity of using first-class
nozzles is imperative. The nozzles should be of the Vermorel type


FIG. 22.-Filling a traction sprayer for spraying against the sugar-beet webworm.
(Original.)
(fig. 23), which delivers a fine, mistlike spray. This type of nozzle,
together with the pump, hose, and other fittings, can be purchased
from any reliable dealer, and the entire sprayer can be fitted up at
an expense not ex-
ceeding $25. _
With this sprayer
and a horse it is
easily possible for .
one man to spray 5n
acres of sugar beets
a day. With a large
traction sprayer a
much greater acre-
age may be treated *IMI
in the same length
in theme lg. 23.-Type of Vermorel nozzles suitable for spraying
of time.- sugar beets against the sugar-beet webworm.


COST OF SPRAYING.


The cost of labor, materials, etc., for spraying sugar beets will
vary under ordinary circumstances from $1 to $2 an acre. The
price received for sugar beets by the growers in the Arkansas Valley


69




70 PAPERS ON INSECTS AFFECTING VEGETABLES.

usually exceeds $5 a ton. As previously mentioned, a defoliation by
the sugar-beet webworm may reduce the yield of sugar beets 1 to 5
tons to the acre and also cause a loss in sugar content and purity.
As this damage can be absolutely prevented at a cost not exceeding $2
an acre, the profits from spraying infested beets are apparent.
CONCLUSION.
An easily accessible supply of water will aid materially in keeping
down the cost of spraying. Water from the irrigation laterals
may be used, but in all cases it should be carefully strained to pre-
vent dirt and other material from getting into the pump and clogging
the no es. Water that is highly charged with alkali should be
avoided.
After a sprayer is used it should be carefully washed with clean
water and all the working parts thoroughly oiled. It is a mistake to
allow a sprayer to stand in the field exposed to sun and weather, and
it will pay to keep it housed when not in actual use.
As a final word, it may be well to state that webworms, and with
few exceptions most other insects which affect sugar beets in the
Arkansas Valley, can be easily and cheaply controlled. When this
fact is more generally accepted by the beet growers it is safe to say
that sugar beets will produce still better profits.









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











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