Beet Sugar Development Foundation web worm control

THE BEET SUGAR DEVELOPMENT FOUNDATION

P.

o.

Box

531

FT. COLLINS, COLO.

WEB WORM CONTROL.

(

THE BEET SUGAR DEVELOPMENT FOUNDATION SENT OUT A QUESTIONNAIRE ON FEBRUARY

9,

194

8,

TO OBTAIN INFORMATION FROM SCATTERED AREAS ON WEB WORM CONTROL. THE FOL-L,wlNG OUTLINE WAS SET UP AS A GUIDE FOR THE INFORMATION DESIRED:

10 [NUMERATE THE INSECTICIDES USED (STATE WHETHER USED AS A OUST OR LIQUID)•

2.

GIVE RESULTS OBTAINED FROM EACH.

3.

WHAT INSECTICIDE OR COMBINATION OF INSECTICfDES WAS USED COMMERCIALLY. GIVE APPROXIMATE ACREAGES FOR EACH.

4.

IF INSECTICIDES WERE COMBINED, WHAT FORMULATION WAS USED.

5•

GIVE METHODS OF APPLICATION, WITH YOUR COMMENTS ON LIMITATIONS AND MERITS OF EACH. IN YOUR WORK WHAT TYPE OF EQUIPMENT DID YOU USE AND WHAT PRESSURES.

6.

010 YOU NOTICE WHETHER RESULTS WERE DIFFERENT WHEN USED ON DIFFERENT KINDS OF WEB WORM (SUGAR BEET WEB WORM, ALFALFA WEB WORM, GARDEN WEB WORM) •

7.

IN YOUR OPINION, WHAT IS THE BEST AVAILABLE INSECTICIDE (oR COMBINATION OF INSECTICIDES) AND WHAT RATE PER ACRE ANO STRENGTH OF SOLUTION DO YOU SUGGEST FOR:

A

.

SUGAR BEET WEB WORM,

6,

ALFALFA WEB WORM,

C

.

GARDEN WEB WORM, D. CLOVER LOOPER.

8

0 WHAT RECOMMENDATION HAVE YOU AS TO TIME OF DAY WHEN APPLICATION SHOULD BE MADE; ALSO AS TO SIZE OF WORM WHEN INSECTICIDE IS MORE EFFECTIVE.

9.

GIVE LIST INCLUDING ADDRESSES OF AIRPLANE CROP DUSTING INDIVIDUALS AND

COMPANIES IN YOUR AREA.

THE RESPONSE WAS GOOD. SOME SUGAR COMPANY AREAS REPORTED NO OUTBREAKS OF W:B WORM IN THEIR AREA, HENCE, NO RECENT EXPERIENCE IN THE CONTROL OF THEM.

GENERAL COMMENTS FROM WEB WORM CONTROL REPORTS:

1. A

COMBINED INSECTICIDE CONTAINING FROM

.0

6%

TO • 12% PYRETHRINS AND

1.

0

%

TO

5.0%

DDT APPEARS TO GIVE CONSISTENTLY ACCEPTABLE KILLS OF SUGAR BEET W~B WORM. THE MATERIAL SHOULD BE APPLIED AT THE RATE OF

25

POUNDS PER ACRE. THIS COMBINATION PROVIDES FOR A QUICK KILL AS WELL AS AN EFFECTIVE RESIDUAL OF DDT.

2.

THE MORE COMMON INSECTICIDE, PARIS GREEN, STILL GIVES GOOD KILLS IN MOST OF THE REPORTED CASES, WHEN APPLIED IN SPRAY FORM AT THE RATE OF

4

TO

7

POUNDS PER ACRE.

3.

THE LATE EVENING HOURS ARE THE BEST FOR DUST APPLICATION, SoME REPORTS INDICATE THAT SPRAYINGS HAVE CONTINUED UP TO MIDNIGHT, THE WORMS TEND TO DO MOST OF THEIR EATING AT NIGHT,

4,

COMMERCIAL APPLICATIONS WERE GENERALLY MADE WITH GROUND DUSTERS ANO SPRAYERS.

5•

THE CARRIER USED FOR AN INSECTICIDE SHOULD BE OF THE SAME DENSITY AS THE INSECTICIDE SO AS TO INSURE MORE UNIFORM DISTRIBUTION, THIS IS PARTI-CULARLY TRUE IN AIRPLANE DUSTING WHERE THE TENDENCY IS TO USE SMALLER QUANTITIES OF DUST,

6.

BENZENE HEXACHLORIDE HAS GIVEN GOOD KILL ON WEB WORMS,

7,

CHLORDANE DOES NOT APPEAR TO BE TOO EFFECTIVE IN CONTROLLING WEB WORM INFESTATION,

8,

THE BEST KILL OCCURS WHEN WORMS ARE LESS THAN ONE INCH IN LENGTH, ONE REPORT MENTIONED THAT ALL OF THE WORMS LEFT AFTER DUSTING WERE LARGE WORMS ANO THAT IF DUSTING IS DONE WHILE WORMS ARE SMALL A LARGE PERCENTAGE OF KILL CAN BE EXPECTED BUT IF WORMS ARE LARGE IT WOULD BE BETTER TO USE PARIS GREEN SPRAY OR STRENGTHEN THE POISON IN THE DUST,

9,

IT WOULD BE DESIRABLE TO OBTAIN AN EFFECTIVE SELECTIVE WEB WORM INSEC-TICIDE ONE WHICH WOULD Kill THE WEB WORM BUT WOULD NOT KILL THE NATURAL PARASITIC ENEMIES OF THE WEB WORM,

10,

THERE APPEARS TO BE SOME SYNERGISTIC ACTION RESULTING FROM COMBINING INSECTICIDES (TOTAL EFFECT OF INSECTICIDE MIXTURE IS GREATER THAN COM-BINED EFFECT OF EACH MATERIAL WHEN CONSIDERED SEPARATELY), THIS IS MOST EVIDENT WHEN PYRETHRINS ARE COMBINED WITH DDT.

THE FOLLOWING REPORTS WERE RETURNED TO THIS OFFICE:

E,

P, PATTISON, MECHANIZATION SUPERVISOR oF HoLLY SUGAR CoRPORATION, CoLo-RADO SPRINGS: COLORADO, (THE NUMBERED PARAGRAPHS REFER TO THE ORIGINAL QUESTION -NAIRE SENT OUT BY THE FOUNDATION)

1 AND 2, DUST:

WORLAND - PYROCIOE, RATE

20

TO

25

LBS. PER ACRE, RESULTS, GOOD.

SHERIDAN

SIDNEY

-DDT

5%,

RATE

20

LBS, PER ACRE, RESULTS, POOR,

DOT

10%,

RATE

20

LBS, PER ACRE, RESULTS, SHOWED SOME RESULTS, CALCIUM ARSENATE

20%,

RATE

20

LBS, PER ACRE. RESULTS, IN

DE-FINITE.

PARIS GREEN

10%,

DEHYDRATED LIMES

20%,

PYRAX

70%,

RATE

40

LBS, PER ACRE, No DATA ON RESULTS.

TORRINGTON - SODIUM ARSENATE, RATE

8

Les. PER ACRE. RESULTS FAIR. HARDIN -SWINK DELTA -LIQUID WORLAND -SHERIDAN SIDNEY

-PYROCIDE, RATE - NO INFORMATION, RESULTS FAIR, PYRETHRUM

25%,

PYROPHILLITE

75%,

RESULTS

30%

Kill, DDT PYRETHIN, RESULTS - NO VALUE AT ALL.

MULTICIDE

No,

1

0

,

FORMULA··

1

P. M,,

.06%

PYRETHRINS,

.05%

DDT. RESULTS, NOT SATISFACTORY

PYROCIDE

10%,

VARIOUS RATES, - RESULTS

8o

TO

100%

Kill,

PYROCIDE

10%,

RESULTS, STOPPED MOVEMENT BUT ONLY

20%

KILL, DDT

1

0

%,

RESULTS, STOPPED MOVEMENT BUT ONLY

2

0

%

KILL,

PARIS GREEN, RATE

3/3/4

LBS, PER ACRE, RESULTS, FAIR TO GOOD. PARIS GREEN, RESULTS, GOOD.

PARIS GREEN,

7

LBS, -

21

LBS, HYDRATED LIME MIXED IN

50

GALS. WATER, RATE

50

GALS, PER ACRE. RESULTS,

1

00

%

KILL,

TORRINGTON - PARIS GREEN, RESULTS, G00D, HARDIN -SWINK DELTA

-.3.

WORLAND -SIDNEY

-PARIS GREEN. RESULTS EXCELLENT, RATE

6

LBS. PER

1

0

0

GALS, WATER,

PARIS GREEN, RESULTS, GOOD,

ARSENATE OF ZINC, RESULTS, UNSATISFACTORY,

PARIS GREEN. RATE

8

LBS, PER

10

0

GALS, WATER, RESULTS, STOPPED MOVEMENT BUT ONLY

20%

KILL •

PARIS GREEN PYROCIDE DDT

5

%

DDT

1

0

%

CALCIUM ARSENATE ToXIPHENE PAR Is GREEN

245

AC RES

310

ACRES

65

ACRES

~~

ACRES ACRES

500

ACRES

350

ACRES TORRINGTON - SODIUM ARSENATE

PAR Is GREEN

50

1

0

ACRES ACRES SWINK DELTA -PYRETHRUM

25%,

PYROPHILLITE

75%

DDT PYRETHIN MuLTICIDE DusT

#10

PYROC I DE

10%

PARIS GREEN ARSENATE OF ZINC

PYR0CIDE

{2

APPLICATIONS ON) PARIS GREEN DDT

-3-394

ACRES

1

00

ACRES

5

00

POUNDS

32

0

ACRES

8!+

ACRES

53

ACRES

25

ACRES

15

ACRES

2

0

ACRES

(No.

7

CONTINUED) SWINK

-DELTA

-8.

10% DRY PYROCIDE APPLICATION OF 30 LBS. PER ACRE, APPLIED

WITH TRACTOR DRAWN OUSTERS AS WELL AS THE AIRPLANE.

25% DDT, 25 LBS. PER ACRE, BUT TOO EXPENSIVE

10% PYROCIDE DUST 25 LBS. PER ACRE, NOT QUITE AS GOOD, BUT

MUCH LESS EXPENSIVE.

TORRINGTON - Do NOT BELIEVE THE TIME OF DAY HAS ANY BEARING ON EFFICIENCY

OF APPLICATION, WHEN WORM IS SMALL, BEST RESULTS WERE

OB-TAINED. SIDNEY HARDIM SWINK DELTA

-.2.

SHER I DAN -Sw1 NK ·· DEL TA

-SPRAY OR DUST WHEN WORM LESS THAN 3/411

, OR JUST AFTER HATCHING.

EARLY IN THE MORNING, WORMS HALF GROWN,

DAWN TO 8:00

A. M.

WORMS SHOULD BE ABOUT 3 DAYS OR!" LONG.

EARLIEST POSSIBLE IN THE MORNING WHILE THERE IS STILL DEW, No DIFFERENCE ON SIZE,

THE SHERIDAN AIRPLANE SERVICE, SHERIDAN, WYOMING, RATE 5¢ PER

POUND,

COLORADO DUSTERS,

INC.,

MUNICIPAL AIRPORT, PUEBLO, COLORADO

JACK BETHEL FLYING SERVICE, MONTROSE, COLORADO

DRAPELA FLYING SERVICE, GRAND JUNCTION, COLORADO

ROCKY MOUNTAIN AIR SERVICE, RIFLE, COLORADO

DR.

A.

R. DOWNIE, PLANT PATHOLOGIST, AMERICAN CRYSTAL SUGAR COMPANY, ROCKY

FoRD' COLORADO. ( PARAGRAPH NUMBERS REFER TO OUTLINE SENT OUT BY FoUNDAT I ON) •

1. ALL MATERIALS WERE USED AS DUSTS,

RATE PER

USED COMMERCIALLY

Ac. -

LBS.

PYROCIDE #10 - 0.20% PYRETHRINS

DDT 5%

DDT 10%

P.M. -

0.5%DDT, 0.06% PYRETHRINS

USED EXPERIMENTALLY (HAND DUSTER)

BENZENE HEXACHLORIDE 10% GAMMA ISOMER

METHOXY CHLORDANE 5% CHLORC:ANE 10%

-5-20-30 30 30 30-40 PERCENT Kr LL 85-100 20 20 85-90 85-90 85-95

65

65

2.

ANSWERED UNDER

~1.

J.

4

.

5.

6

.

l·

8

.

DusT PYROCIDE

#10

DDT

5%

ACRES TREATED DDT

10%

P. M.

5%

DDT - PYROCIOE

#10

740

10

15

20

10

ONLY COMBINATION USED WAS A MIXTURE OF

5%

DDT DUST WITH PYROCIDE #10

OUST IN A RATIO OF

3:1 •

THIS MIXTURE WAS APPLIED BY PLANE AT

30

LBS.

PER ACRE ANO GAVE USS THAN A

60%

KILL.

APPROXIMATELY

90%

OF THE DUSTING WAS DONE SY PLANE AT

30

LBS. OF DUST PER ACRE, THE REMAINDER OF THE ACREAG£ WAS DUSTED WITH GROUND RIGS. NONE OF THE FARMERS CONTACTED WERE INTERESTED IN WET SPRAY METHODS,

PLANE OUSTING

MERITS LIMITATIONS

1 • CAN COVER LARGE AC~EAGES IN

1.

REQUIRES

1/f

AS MUCHDUST AS USED SHORT PERI OD OF TIME. IN GROUND EQUIPMENT TO DO AN

2. CAN BE EMPLOYED WHEN GROUND IS EQUAL JOB.

TOO WET TO USE GROUND EQUIP-

2.

RESTRICTED DAY-LIGHT DUSTING, MENT,

3.

DusT CAN ALL BE LOCATED AT AIR STRIP AND DOES NOT HAVE TO BE HANDLED SO OFTEN,

VERY LITTLE ATTENTION WAS PAID TO THE KINDS OF WEB WORM PRESENT,

MOST SATISFACTORY RESULTS WERE OBTAINED WITH THE PYROCIDE

#10

DusT, HOWEVER

P.

M. DOES SHOW SOME PROMISE ESPECIAi.LY WHEN USED IN GROUND RIGS, DUE TO THE OILY NATURE OF THIS DUST, A SATISFACTORY KILL WAS

NOT OBTAINED WHEN IT WAS APPLIED BY PLANE. BENZENE HEXACHLORIDE

AND METHOXY SHOULD BE INVESTIGATED FURTHER,

A.

SuGAR BEET WEB WORM

----·

-PYROCIOE

#10

DUST,

30

LBS, PER ACRE APPLIED BY PLANE,

PYROCIDE #10 DUST, 20 LBS, PER ACRE APPLIED BY GROUND EQUIPMENT. P. M.,

30

LBS, PER ACRE APPLIED BY GROUND EQUIPMENT,

EXPERIENCES IN THE ARKANSAS VALLEY THIS LAST YEAR SECTICIDES PYROCIDE #10 AND P. M. INDICATE THAT IVE WHEN DONE BETWEEN

9:00

A

.

M. AND

5:30

P.

M,

BOTH PLANE AND GROUND DUSTING,

WITH THE CONTACT IN-OUSTING WAS INEFFECT•

THIS HELD TRUE FOR

BEST KILLS WERE OBTA INED WHEN THE LARGEST WORMS WERE APPROXIMATELY ONE INCH LONG.

-6-DOYLE KEELING

COLORADO DUSTERS, fNC. MUNICIPAL AIRPORT

PUEBLO, COLORADO

WESLEY SMITH, AGRICULTURAL SUPERINTENDENT, CANADIAN SuGAR FACTORIES, LTD., TABER, ALBERTA, CANADA. (PARAGRAPH NUMBERS REFER TO OUTLINE SENT OUT BY FOUNDATION) •

1 •

INSECTICIDES USED:

COMMERCIAL DERRIS PREPARATIONS GARDEN GUARD

Arox

COMMERCIAL PYRETHRUM PREPARATIONS PYROCIDE

PYROCIDE DP-514 - - 5-7% PYRETHRUM, 1!% DDT. ALL ABOVE INSECTICIDES USED AS DUST.

2. RESULTS:

GARDEN GUARD)

A TOX ) GooD CONTROL

PYROCIDE - VARIED, MOSTLY POORj OLD STOCK PYROCIDE

D.

P.-514 - NOT USED.

_3.

COMMERCIAL CONTROL GARDEN GuARD AToX PYROCIDE PYROCIDE D.P.-514 4. No INSECTlr.lDES COMBINED. 152 ACRES 225 ACRES 2b ACRES

Nor RECEIVED IN TIME TO USE •

j.

ALL INSECTICIDES USED AS DUST. A NUMBER OF GROWERS HAVE 4 OR

6

ROW MESSENGER OUSTERS WHICH ARE ATTACHED TO BEET CULTIVATORS OR MOUNTED ON CARTS. Two LARGE MACHINES USED; 16 ROW JOHN DEERE AND 16 ROW NIAGARA. ALL DUSTERS SHOULD HAVE A LONG TRAIL SHEET.

6. No DIFFERENCE NOTED ON DIFFERENT KINDS OF WEB WORMS.

]• ON HEAVY INFESTATIONS WHICH REQUIRE AN IMMEDIATE KILL, PYROCIDE HAS BEEN FOUND QUITE EFFECTIVE AT 15 LBS. PER ACRE IF NOT DETERIORATED DURING STORAGE.

PYROCIDE

D.

P.-514 IS SUPPOSED TO BE EQUALLY EFFECTIVE BUT WE HAVE NOT USED IT. COMMERCIAL PREPARATIONS OF DERRIS, GARDEN GuARD AND AToX

WERE SLOWER IN ACTION THAN PYROCIDE. SOME APPLICATIONS OF 10 LBS. PER ACRE WERE SATISFACTORY. A NUMBER OF GROWERS USED 30 LBS. PER ACRE. ABOVE TREATMENTS ARE FOR SUGAR BEET WEB WORM. WE HAVE NO OB-SERVATIONS OF THE OTHER WEB WORMS.

8.

ONE OF OUR DIFFICULTIES IS WIND WHICH IS MORE PREVALENT AT OR NEAR NOON.

EARLY MORNING OR LATE EVENING TREATMENTS, IF THERE IS NO WIND, HAVE BEEN MORE EFFECTIVE THAN DURING OTHER PARTS OF THE DAY •

.2

•

WE ARE NOT AWARE OF ANY AIRPLANES ENGAGED IN CROP OUSTING IN THIS REGION.

-7-HARRY G. W!LL1AMS OF C. S, WILLIAMS COMPANY, ROCKY FORD, COLORADO.

(PARA-GRAPH NUMBERS REFER TO OUTLINE SENT OUT BY FOUNDATION,)

1,

(A)

N

o,

7½

DRY PYROCIDE DUST

2.

.3.

4.

j.

(B)

No. 10

DRY PYROCIDE - - DUST

{ c) PARIS GREEN SPRAY

( D) py R ETH RU M OU S T ( AN A L Y S J S UN KN OWN) •

7½

PYROCIDE GAVE SATISFACTORY CONTROL ON SMALL TO MEDIUM SIZED WORMS.

10

%

DRY PYROCIDE GAVE SATISFACTORY CONTROL OF ALL SIZED WORMS, WHEN

APPLIED AT BETWEEN

20

TO

30

POUNDS PER ACRE, PROPER TIME OF DAY,

BOTH BY GROUND MACHINES AND AIRPLANE OUSTERS.

No

COMBINATIONS Of INSECTICIDES WERE USED TO OUR KNOWLEDGE •

(No

ANSWER) ,

DURING WEB WORM 11

SEIGE11

SPRAYERS, TRACTOR DUSTERS, AND AIRPLANE DUSTERS

WERE USED, BECAUSE OF LACK OF ENOUGH SPRAYERS FEW APPLICATIONS OF LIQUID PARIS GREEN WERE MADE, THESE BEING SATISFACTORY. SOME CASES

REPORTED USE OF

7½

AND

10

DRY PYROCIOE NOT GIVING RESULTS BUT WERE FOUND TO BE APPLIED AT RATE OF

10

AND

12

POUNDS PER ACRE AT ALL TIMES

OF DAY WHEN HEAT, GROUND TEMPERATURE WERE NOT ADVISABLE FOR GOOD

AP-PLICATION, WHEN PROPERLY APPLIED THESE SEEMED TO HAVE GIVEN HIGHLY SATISFACTORY CONTR0L BY AIR AND GROUND,

6.

RESULTS SEEMED ABOUT SAME ON ALL WORMS.

1·

Nor

KNOWN IF WE HAVE ALL THESE WORMS BUT

10%

DRY PYROCIDE AT

20

TO

30

LBS. PER ACRE, BEST TIME SEEMINGLY EARLY IN MORNING RATHER THAN IN HEAT Of DAY, SPRAY ALMOST ANY TIME Of DAY,

8.

_2,

COLORADO DUSTERS, INC,, MUNICIPAL AIRPORT, PUEBLO, COLORADO

E. L.. WILKINS, JR., LAS ANIMAS, COLORADO W.

J,

BLACK, LA JUNTA, COLORADO

c.

s.

WILLIAMS Co., (DUST MIXERS)' ROCKY FoRo, COLORADO

McLAUGHLIN GORMLEY KING COMPANY,

1715

FIFTH STREET,

S. E.,

MINNEAPOLIS

14,

MINNESOTA:

"THE BEST RESULTS HAVE BEEN OBTAINED IN THE LAST TWO YEARS WITH "PM" OUST CONTAINING

1%

DDT AND

.12

%

PYRETHRINS, SucH A DUST IS MADE FROM OUR PM DUST

CON-CENTRATE WHEN DILUTED 1 PLUS

9.

"THIS DUST HAS GIVEN RESULTS ABOUT EQUAL T0 "PYROCIDE"

Dusr

No.

10

MADE FROM

OUR DRY "PYROCIDE" DILUTED 1 PLUS

9,

THE PM DUST IS AVAILABLE AT A FRACTION OF THE COST OF THE DRY "PYROCIDE11

DUST,

"A

LOWER CONCENTRATION Of THESE OUSTS IS EFFECTIVE AGAINST THE EARLY

INFES-TATIONS OF WEB WORMS, BUT NOT QUITE EFFECTIVE ENOUGH AGAINST THE LATER STAGES. foR

THIS REASON, \.JE RECOMMEND THE CONCENTRATION ABOVE DESCRIBED, f'M DUST IS LIKEWISE EFFECTIVE AGAINST ALFALFA WEB WORM",

-8-VERNAL JENSEN, THE AMALGAMATED SUGAR COMPANY, OGDEN FACTORY, OGDEN, UTAH.

"WE HAVE HAD SOME LOCALIZED OUTBREAKS OF YELLOW-STRIPED ARMY-WORM AND

25

TO

30

POUNDS PER ACRE OF

5%

DOT HAS BEEN VERY EFFECTIVE IN THEIR CONTROL.

INAS-MUCH AS THE U.S. BUREAU OF ENTOMOLOGY HAS BEEN VERY CAUTIOUS IN THE USE OF DDT ON FORAGE CROPS THAT ARE FED TO ANIMALS, STRIP APPLICATIONS WERE MADE AROUND BEET FIELDS,

"FOR THE MOST PART, THE ARMY-WORM PUPATED ANO DEVELOPED IN ALFALFA FIELDS. As SOON AS THE ALFALFA WAS HARVESTED, THE WORMS MIGRATED TO ADJACENT CROPS ANO

WITH THE USE OF THESE STRIP APPLICATIONS, A VERY EFFECTIVE CONTROL WAS OBTAINED",

H, W. DAHLBERG, DR. H. E. BREWBAKER, DR. R. T. NELSON,

H.

L. BUSH,

LAMAR

HENRY, GREAT WESTERN SUGAR COMPANY:

OBSERVER'S COMMENT: THE GREAT WESTERN SUGAR COMPANY SUBMITTED A

CHRONOLO-GICAL DISGEST OF NUMEROUS TESTS ANO SINCE THIS REPORT 15 Too LONG TO REPRINT IN

ITS ENTIRETY ONLY A FEW SUMMARIZATIONS WILL BE NOTED HERE:

SOME MATERIALS USED WHICH GAVE ACCEPTABLE KILLS WERE: 1.

2.

10%

PM,

15%

PM,

.06%

,09%

PYRETHRINS AND PYRETHRINS AND

0.5%

0,75%

DDT DDT

20%

PM,

,12%

PYRETHRINS AND 1

,0%

DDT

10%

PM FORTIFIED WITH DDT TO

5,5%

10%

PM FORTIFIED WITH DDT TO

1

0%

BENZENE HEXACHLORIDE

50%

CONCENTRATE WETTABLE CONTAINING

5%

ACTIVE

ISOMER

10% PM

PLUS

3%

ORY PYRACIDE

10%

DRY PYRACIDE

10% DOUBLE STRENGTH

PM

(.12%

PYRETHRINS AND 1

,

0

%

DDT WITH ENOUGH DDT

TO BRING UP THE CONTENT TO

5%

OR EVEN 10%.

THE ABOVE MATERIALS WERE APPLIED AT RATES WHICH VARIED FROM

20

TO

35

POUNDS

PER ACRE WITH

25

TO

3

0

POUNDS BEING THE MOST COMMON,

SUMMARY AND CONCLUSIONS FROM REPORT,

SuGAR BEET WEB WORM

"THE MANY VARIABLES THAT ENTER INTO THE PREPARATION OF A DUST AND ITS USE MAKE IT DIFFICULT TO GENERALIZE WITH ANY DEGREE OF CERTAINTY FROM THE LIMITED DATA

GIVEN IN THIS REPORT, HOWEVER, AS ALTERNATIVES TO PARIS GREEN SPRAY FOR THE

CON-TROL OF SUGAR BEET WEB WORMS THE FOLLOWING TWO DUSTS ARE SUGGESTED ON THE BASIS

OF COST AND EFFECTIVENESS BASED ON THE

1947

TESTS:

1. 10% DOUBLE STRENGTH "P-M" CONCENTRATE, AND

9

0

%

PYRAX (PYROPHYLLITE),

2,

10%

"P-M" CONCENTRATE,

3%

PYROC I DE AND

87%

PYRAX

J

A FURTHER CONCLUSION SEEMS TO BE JUSTIFIED - NAMELY, THAT AN INSECTICIDE

DUST APPLIED IN THE EVENING IS GENERALLY MORE EFFECTIVE THAN AT ANY OTHER TIME OF THE DAY",

-9-GARDEN WEB WORM

"1.

THE GARDEN WEB WORM DIFFERS STRIKINGLY FROM THE SUGAR BEET AND ALFAL-FA WEB WORMS IN FEEDING HABITS AND ALSO IN APPARENT SUSCEPTIBILITY TO

INSECTICIDES,

2, A

5%

DDT DUST APPEARED TO BE AS EFFECTIVE AS ANY OTHER TREATMENT USED

IN KILLING THE GARDEN WEB WORMS, MORE OR LESS, REGARDLESS OF SIZE.

3.

NATURAL ENEMIES OF THE GARDEN WEB WORM, PRESENT IN RELATlVELY LARGE

NUMBERS ESPECIALLY IN CONNECTION WITH THE LATER BROOD OF WEB WORMS, WERE READILY KILLED BY DDT, THIS PROVIDES SOME ARGUMENT FOR A SEARCH FOR SOME NEW INSECTICIDE WHICH IS SELECTIVE IN ITS KILL,

4

.

THE GARDEN WEB WORM IS PROBABLY LIMITED IN ITS HABITAT

10

AREAS

CHAR-ACTERIZED BY HIGHER TEMPERATURES,"

ALFALFA WEB WORMS.

"1. ALFALFA WEB WORMS WERE PRESENT IN SMALL NUMBERS IN VARIOUS TESTS AND THE GENERAL OBSERVATION WAS MADE THAT THEY APPEARED MORE TOLERANT TO BOTH PYRETHRIN ANO DDT THAN THE OTHER TWO WORMS. FURTHER STUDIES AP•

PEAR NECESSARY TO DETERMINE THE MOST EFFECTIVE LETHAL MATERIALS AND

DOSAGES FOR THE ALFALFA WORM, FROM SPECIFIC OBSERVATIONS RELATIVELY HEAVY DOSAGE OF PYRETHRIN APPEARS MORE LIKELY TO BE EFFECTIVE THAN TREATMENT WITH DDT."