Comparative values of new insecticides for use against Lygus spp. and the Say stinkbug

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Material Information

Title:
Comparative values of new insecticides for use against Lygus spp. and the Say stinkbug
Physical Description:
19 p. : ; 27 cm.
Language:
English
Creator:
Hills, Orin A., 1903-
McKinney, K. B
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
United States Department of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Insecticides -- Testing   ( lcsh )
Lygus -- Control   ( lcsh )
Stinkbugs -- Control   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
by Orin A. Hills and K.B. McKinney.
General Note:
Caption title.
General Note:
"E-648."
General Note:
"April 1945."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030289928
oclc - 779850951
System ID:
AA00025123:00001

Full Text
Li~~
STATE LN AR
April 19145 E-64e8

UNITTED STATES DEPAPTvIERT OF AGRICULTURE AORICUILTURAL RESEAARCH ADMINISTRATION BUREAU OF ENTOMOLOGY AM PLANT QUARANTINE

COM4PARATIVE VAUES OF NEW INSECTICIDES FOR USE AGAINST IYGUS SPP.
AND THE SAY STINEJBUG

By Orin A. Hills and K. B. McKinney Division of Truck Crop and Garden Insect Investigations

Incidental to the development of a control program against hemipterous insects affecting sugar beets grown for seed, a considerable
number of laboratory tests of various insecticides have been made at
Phoenix Ariz... to determine their comparative value as contact insecticides against Lyu app., primarily Lyu oblineatus (Say), and the Say stinkbug (Chlorocbroa, sayi Sta'0). It is the purpose of this
circular to make available additional information regarding the value
of some of these new materials as contact insecticides.

The results of these tests, made in small laboratory cages, are
not always indicative of the value of an insecticide under field conditions. Most of the insecticides that produced high insect mortalities in laboratory cages have been tested in the field with good
results ybut in some instances materials have shown considerable promise in laboratory tests and have not given good results under field
conditions.

Methods

The laboratory tests were made by confining the insects on
branches of suitable food plants In small cylindrical screen-wire or
cloth-covered cages. Applications were made either by applying liberal and uncalibrated quantities of the insecticides directly to the insects
and plants through the cage covering or by applying calibrated quantities to the plants only before the introduction of the insects.

The cages used in these experiments were approximately 321 inches
in diameter by 7 inches high. They were built onto the lids of 1-pint
ice-cream cartons, and the stems of the food plants in most cases extended through a hole in the floor of the cage into the carton below, which contained water. In some of the later experiments branches of
one of the fig marigolds, Mesembryanthemum sp., were used as a food plant, and it was found unnecessary to place the sterns of this plant
in water.

Insects for all experiments except those involving nymphs of the
Say stinkbug were gathered from the field and put in the cages on dusted
plants, or were put on clean plants and dusted later. The variously






2

treated cages of insects were then placed on laboratory shelves in randomized blocks for further observation. In the case of nymphs of the Say stinkbug the test insects were reared in a constant-temperature cabinet in the laboratory at a constant temperature of 82"F. Most of these nymphs were in the third and fourth instars at the time of treatment. The insects were put in the cages on predusted plants and the
cages placed on shelves in a second constant-temperature cabinet. They were arranged in randomized blocks each shelf constituting a block, and carried at a temperature of 826.

Tests Against Lgus Bugs

The predominant species of Lqju occurring in the Salt River Valley of Arizona are L. oblineatus Say) and L. hesperus Knight; these species occur intermixed, although at certain seasons of the year and on certain plants one or the other often predominates. The following tests were made with field-run insects which were predominantly L. oblineatus. Both adults and nymphs were used, and in most cases the two forms were placed in separate cages.

Experiment No. l.--Six organic compounds furnished by the Division of Insecticide Investigations were tested in this experiment. Each material was furnished mixed with equal parts of talc or sulfur. Each mixture was applied directly onto the insects through the walls of the cages, eight lots of adults and six of nymphs being used in each case. Twigs of Atriplex semibaccata R. Br. were supplied as food. The mortalities after 1, 2, and 3 days, as shown in table 1, were inappreciable except in the lots dusted with phthalonitrile.






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A mixture containing 13.3 percent off phthalonitrile and 86.7
percent of sulfur was later tested in small field plots against Lyu on sugar beets grown for seed. Satisfactory reductions in insect populations were obtained, but there were some indications that this material might be damaging the flowers since there was a lower percentage of viable seed than was expected.

Experiment No. 2j---Previous laboratory and field experiments had indicated that mixtures of sulfur with py'retbrua extract-impregnated dusts were effective against Lyus Other workers in the Bureau had used magnesium oxide with certain materials to give additional toxicity. Experiment No. 2 was made to determine the value of "heavy" and "light" magnesium oxide as an insecticide, and also to determine the insecticidal value of mixtures of magnesium oxide and sulfur, and magnesium oxidepyreth2rua extract-sulfur dusts. S,-veral dusting sulfurs as well as wettable sulfurs used as dusts were also included in this experiment. Each material was applied to 11 cages containing adults and to 12 cages containing nyrmphs. The food plant used in each case was Chenopodium murale L. The powders were applied liberally to the insects and plants through the meshes of the cages with a hand dust gun. The results are given in table 2.














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As in past experiments, low mortalities of adults are indicated for the dusting sulfurs. The pyrethrum extract-sulfur dusts diluted with magnesium oxide (3:1) gave equally as good results as the undiluted pyrethrum extract-sulfur, and the sulfur-phenoxathiin compound was almost as good as the pyrethrum extract-sulfur. Little differences were indicated for the various dusting sulfurs, but the wettable sulfurs, used as dusts, gave slightly better results, and still better results were obtained with magnesium oxide in combination with sulfur. Magnesium oxide alone, particularly the "light" form, showed considerable promise, as did dry lime-sulfur. The phenoxathiln-sulfur compound was later tried against L in small field plots of sugar
beets grown for seed, but it did not give a satisfactory kill. A mixture of 20 percent of dry lime-sulfur and 80 percent of sulfur was also tried later in the field. It was found to be somewhat better than sulfur alone, but not enough so to Justify the additional expense.

Experiment No. 3.--In this experiment adults and nymphs of L s
were introduced together in the cages. The insecticides tested consisted of two proprietary dinitro compounds, 2-chlorofluorene, and DDT, the
last two materials furnished by the Division of Insecticide Investigations in the dilutions indicated. In 10 cages for each material the dust mixture was applied to the insects as in previous experiments, whereas in 10 other cages the mixture was applied to the plants within the cages before the insects were introduced. Atriplex semibaccata was used as the food plant in the first series and Chenopodium mural in the second.

As shown in table 3, the results were not materially different
for the dinitro-o-cresol and the DDT. High mortalitieL with 10-percent DDT in cage tests have previously been reported by .ilh. 1/ and Stevenson et al. 2/ reported good kills of L in cages using 2-percent
DDT. The dinitro-o-cyclohexylphenol showed good results where applications were made directly to the insects, but poor results where the applications were made to the plants only. Fie-d tests of this material have shown it to be a weak insecticide against Lygus although it is more promising against the Say stinkbug. Results obtained with 2-chlorofluorene were not quite so good where plants only were dusted, as is evidenced particularly by the early examinations.






I/ Hills, 0. A. DDT and other insecticides for the Say stinkbug and the tarnished plant bug. (Scientific Note) Jour. Econ. Ent. 37: 142-143. 1944.

Stevenson, W. A., Sheets, L., and Breazeale, J. M. Tests with DDT
against pentatomids, airids, the bollworm, and the cotton aphid. (Scientific Note) Jour. Econ. Ent. 37: 143. 1944.






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Experiment No. 4. --This test included two of the dinitro compounds commonly used as insecticides, one dinitro compound (4,6-dinitro-2-tolyl acetate) the insecticidal value of which was unknown, DDT, and a dust impregnated with secondary terpene-alcohol thiocyanyl acetate. In this experiment these materials were tested in rather dilute form and also in concentrations considered suitable for field use. The conditions of the tests with the dilute and concentrated materials were as nearly the same as possible. Five cages containing LZgs adults and five cages containing nymphs were used for each material in each case, Chenopodium marale being used as a food plant. The materials to be tested were all in powder form and were applied to the plants within the cages before the insects were introduced. Definite quantities were applied by removing the tops from the cages containing the plants and placing the encaged plants in a settling chamber. Here the materials were applied as a dust at the rate of 0.5 grea per square foot, which is the equivalent of approximately 50 pounds per acre.

Results obtained from the use of the dilute materials (table 4)
indicate that only dinitro-o-cresol was effective in the weaker dilutions. Later a pyrethrum e;tract-sulfur dust (table 5) was substituted for one of the 4,6-dinitro-2-tolyl acetate dusts, since there seemed to be no difference in the results obtained from the two methods of preparing this material. Good results have been obtained with the pyrethrum extractsulfur dust both in laboratory and field tests, and it was included here for comparison with the other materials. Results shown in table 5 indicate that 5-percent DDT and 1-percent dinitro-o-cresol were equally as good as the pyrethrum-sulfur dust although somewhat slower in their action.








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Dusts containing 4.5 and 5 percent of DDT ~re later tried against gue in field plots of seed beets, with excellent results. Seed harvested from plots receiving one application of this material was at least as good as seed from plots receiving two appliaticn of the pyrethrum extract-impregnated sulfur dust recommended for gu control in seed beets. A 1-percent dinitro-o-cresol dust was also tested on sugar beets grown for seed in field plots. Good kills of LgE were obtained, but such severe burning occurred that this material cannot be recommended for use on seed beets.

Experiment No. 5. --This test included sabadilla, DDT, and 2-chlorofluorene dusts; the pyrethrum extract-impregnated sulfur dust used in previous experiments was also included here for comparison. Two proprietary sabadilla insecticides were tested. Each was labeled by the manufacturer as containing 20 percent of sabadilla seed. Each of these
materials was tested in 20-percent and 5-percent concentrations. In addition one of the materials was tested in the 5-percent strength in combination with sulfur. Three DDT preparations were tested, all of which contained 3 percent of DDT. The first was DDT in pyrophyllite; the second DDT, pyrophyllite, and sulfur; and the third a DDT-sulfur preparation made up by fusing DDT in sulfur and regrinding. The last was an experimental preparation made up by one of the commercial insecticide manufacturers. Three 2-chlorofluorene dusts were tried; the first containea 20 percent of 2-chlorofluorene in talc, the second 10 percent of 2-chlorofluorene in talc and pyrophyllite, and the third 10 percent of 2-chlorofluorene in talc and sulfur.
Mesembryanthemum sp. was used as a food plant, and calibrated quantities (0.5 gram per square foot) of the dusts were applied to the encaged plants in a settling chamber before the introduction of the insects. Only yg adults were used, and each treatment was replicated eight times.

The results of this experiment are presented in table 6 and show that both sabadilla and DDT were effective against bu adults. The sabadilla killed much more rapidly both at the 20-percent and 5-percent strengths than did the DDT. These data also indicate that the sabadilla insecticide from one source of manufacture was slightly superior to the other. Differences between 20-percent and 5-percent concentrations were small, and sulfur as a diluent was little if any better than pyrophyllite. DDTI dusts containing sulfur gave somewhat better results than DDT in pyrophyllite, and the material prepared by fusing DDT and sulfur and regrinding was slightly better than the mechanical mixture of DDT, pyrophyllite, and sulfur. Dusts containing 10 percent of 2-chlorofluorene gave better results than the 20-percent material, probably owing largely to an improvement in the physical qualities of the dust by the addition of the diluent. The 10-percent dust containing sulfur did not give such good results as the 10-percent dust containing only talc and pyrophyllite.






12

Table 6.--Mortality of L adults in laboratory insecticide tests.
October 30 to November i, 1944


Material tested Insects Mortality after -(percent by vt. Of used 1 day 2 days 3 days 4 days 5 days
final mixture) gor Percent Percent Peroent Percent eroen
Sabadilla:

20% plus unknown
inert 80% 1/ --- 117 74 86 88 90 91

5% plus unknown
inert 20% plus pyrophyllite 75% 1/-- 119 82 89 92 94 95
20% plus hydrated
lime 20% plus
talo 60% g/ 122 100 100 100 100 100

5% plus hydrated
lime 5% plus
talc 15% plus pyrophyllite 75% 2/ -- 119 86 93 96 97 98
5% plus hydrated lime
5% plus talc 15%
plus sulfur 75% 2/ 118 99 99 99 99 100

DDT 3%:

Plus pyrophyllite
97% .....------------- 110 33 68 81 84 92
Plus pyrophyllite
27 plus sulfur 70% (mechanical
mix)-------........------ 121 45 74 89 95 96
Plus sulfur 97%
(fused and reground) 128 62 84 95 98 100






Table 6. --(Continued)


Material tested Insects Mortality after -(percent by wt. of used 1sd
final mixture) 1dayj2 days 3days14days15days

Number Percent Percent Percent Percent Percent
2-Chlorofluorene:

20% plus talc 80% --- 119 6 13 16 22 29

10% plus talc 40%
plus pyrophyllite
50% ---------------- 118 56 70 81 90 92

10% plus taloc 40%
plus sulfur 50% --- 118 20 28 34 36 42

Pyrethrum extract dust V: Plus sulfur 50% plus pyrophyllite (0.2%
pyrethrinp) ------- 120 100 100 100 100 100

Untreated check ------- 121 0 0 5 16 23


/ Supplier No. 1 2 Supplier No. 2
3 See table 2, footnote 1.







13

Experiment No. 6. -In this experiment the insect icidal value of sabadilla and DDT dusts containing sulfur was compared with similar dusts in which pyrophyllite was used as the diluent. The value of adding a small amount of petroleum oil to these dusts was also tested, as was the insecticidal value of a sulfur dust containing a dithiocyanate. When the oil-impregnated dusts were being made up, the dry ingredients were first thoroughly mixed, the oil was then atomized onto the dust a little at a time, and the dust was remixed until no more oil could be added without impairing the physical qualities of the dust'. Sulfur does not absorb oil so readily as some of the other powders used as insecticide diluents, and therefore not so much oil could be put into materials containing sulfur. An automobile lubricating oil having an S.A.E. rating of 10 was used for this work. Both the DDT and the sabadilla were used in 1-percent strengths in all these dusts. At these concentrations these materials were considered weak insecticides, but~ these strengths were used to accentuate an~y differences which might occur from the addition of the sulfur or oil. The dithiocyanate dust was made up at a strength considered suitable for field use (3.6 percent).

The conditions of this experiment were similar to those of experiment No. 5. Mesembryanthenim sp. was used as a food plant, Lyu adults were used as test insects, and before introduction of the insects 0.3 gram of each material was applied to the plants in a settling chambr covering an area of 1 square foot. Each material was applied to seven replicate cages.

The results of this experiment, given in table 7, indicate that neither the DDT nor the sabadilla was improved: by the addition of the petroleum oil. Sulfur as a diluent seemed to improve the DDTE dusts, but
not the sabadilla dusts. Good kills resulted from the use of the dithiocyanate and sulfur dust, but no increased ms~rtalit~y was indicated after the first 214 hours. This dust was later tried in field plots of seed beets for Lygu control,, with fairly good results; it warrants further trial.






14

Table 7.--Mortality of gue adults in laboratory insecticide tests, November 1325, 1944


Material tested (percent by :Insects: Mortality after -vt. in final dust mixture) : used :
: :1 day : 2 days: 3 days: 4 days: 5 days
Number Percent Percent Percent Percent Percent

DDT, 1% in pyrophyllite plus:
Sulfur 89% plus petroleum
oil 2% --------------------- 102 33 51 57 66 76
Petroleum oil 3% -------------- 103 18 29 38 50 57
sulfur 90o% -------------------- 10l6 21 47 57 69 79
Alone ------------------------ 107 16 34 47 58 73

Sabadilla 1% plus:
Sulfur 94% plus hydrated lime
1% plus talc 3% plus petroleum oil 1% ----------------- 102 17 30 43 43 45
Hydrated lime 1% plus talc 3%
plus pyrophyllite 91% plus
petroleum oil 4% ----------- 106 18 29 39 44 47
Sulfur 95 % plus hydrated lime
1% plus talc 3% ------------ 104 12 26 34 38 52
E ydrated lime 1% plus talc 3%
plus pyrophyllite 95% -------104 8 17 24 32 39

Dithiocyanate dust 28% plus
sulfu.r 72% ------------------- 105 95 96 97 98 99
Untreated check -----------------105 1 8 15 25 36


A proprietary material containing 13.5% of beta-beta'-dithiocyanodiethyl ether, 80% of talc and 5% of magnesium carbonate.







Tests Against the Say Stinkbug

The results of tests against adults of the Say stinkbug have already been reported in part by Hills. 1/ Stevenson et al. 2/ have also reported the results of cage tests with 2-percent DDT against
adults of Chlorochroa sayi and two other species of stinkbugs as well as s sp.

Experiment No. 1. --This experiment included two of the commercial dinitro insecticides, 10-percent DDT, and 20-percent 2-chlorofluorene. Adults of the Say stinkbug were used as test insects. Ten cages of insects were used for each material. Atriplex elegens (Moq.) D. Dietr. was used as a food plant. Liberal quantities of the materials were applied as dusts to the plants and insects tLh-ough the meshes of the cages.

The data from this experiment (table 8) show that the 1-percent dinitro-o-cresol and DDT were equally effective against this insect, but that the bugs were killed much more rapidly with the dinitro-ocresol than with the DDT. Twenty-percent 2-chlorofluorene was shown to be ineffective against this insect, and mortalities obtained with the 1-percent dinitro-o-cyclohexylphenol dust were somewhat lower than had been obtained in previous tests. The dinitro-o-cyclohexylphenol dust used in this experiment, however, was 1 year old, which may have been at least partly responsible for the comparatively low mortalities accompanying its use.

Table 8.--Mortality of Chlorochroa sai adults in laboratory insecticide tests, August 17 to 23, 1943


Material tested Insects Mortalit after-(percent by vt.) used 1 day 2 days 14 days 6 days

Number Percent Percent Percent Percent

Dinitro-o-cyclohexylphenol 1%
in special volcanic ash -- 100 46 60 65 72

Dinitro-o-cresol 1% in
special volcanic ash 100 89 90 92 92

DDT 10% in pyrophyllite ----- 100 14 53 86 98

2-Chlorofluorene 20% in talc- 99 5 12 22 46

Untreated check ------------- 100 1 7 15 30





16

Experiment No. 2. --This experiment included proprietary dinitro compounds and DIDT. Since the 20-percent 2-chlorofluorene dust did not give good results with the Say stinkbug in experiment No. 1, it was omitted from these tests. A fresh supply of the dinitro-o-cyclohexylphonol dust was obtained and its toxicity compared with that of the 1-yearold material used in experiment No. 1. The conditions of this experiment were similar to these of experiment No. 1, as 10 cages of insects were used for each material and Atriplex elegans was the food plant. Insecticides were applied liberally as dusts to the plants and insects through the meshes of the cages.

The results are given in table 9 and indicate that a freshly prepared dinitro-o-cyclohexylphenol dust is superior to 1-year-old material. These data also show that dinitro-o-cresol is much more prompt in its
action than dinitro-o-cyclohexylphenol, but that the end results of these two materials are not significantly different. Results obtained with the DDT in this experiment were very similar to those of experiment No. 1. Plant-tolerance tests indicated that the dinitro-o-cresol caused much
more foliage burn than did the dinitro-o-cyclohexylphenol.

In limited field trials of dinitro-o-cyclohexylphenol against the Say stinkbug in seed beets fairly good results were obtained.


Table 9. --Mortality of Chlorochroa sayi adults in laboratory insecticide
tests, September 1 to 6, 1943


Insects Moribund Mortality after-Material tested used at
l houre 1 day 2 days 3 days 4 days 5 days
1 hoursIIII

Number Percent Percent Percent Percent Percent Percent
Dinitro-o-cyclohexylphenol 1% in
special volcanic
ash:

Material 1 year old 90 0 27 53 60 62 66




Fresh material---- 88 0 94 97 98 98 98

Dinitro-o-cresol 1%
in special
volcanic ash 99%--- 93 65 88 90 90 90 90


DDT 10% in pyrophyllite 90 0 13 43 75 93 95

Untreated check------....... 89 0 1 2 6 9 10







17


Experiment No. 3.--This was the first experiment against nymphs of the Say stinkbug. Five insecticides were selected which had given good results against adults of this species or against gus. Six replicate cages were used for each insecticide. Branches of Chenopodium murale were used as food plants, and the insecticides were applied to the plants in a settling chamber at the rate of 0.5 gram per square foot, before the introduction of the insects. The stinkbug nymphs used in this experiment were reared specimens and after introduction on the dusted plants
the cages were held in a constant-temperature cabinet at 820 F.

The results, which are given in table 10, indicate that all materials were fairly effective against nymphs of the Say stinkbug except the 2chlorofluorene. The kills obtained with dinitro-o-cyclohexylphenol were not quite so good as those obtained with the pyrethrum extract-sulfur, dinitro-o-cresol, or DDT. However, field tests with these two materials have shown that dinitro-o-cresol causes considerable foliage burn and is not safe to use on sugar beets grown for seed, whereas dinitro-ocyclohexylphenol can be used with safety. The results obtained with DDT indicate that this material is slow in its action against the nymphs of the Say stinkbug, which corroborates results of previous experiments with adults of this insect and also with gus where lower concentrations of DDT were used. The 20-percent 2-chlorofluorene was shown to be ineffective against the Say stinkbug nymphs.


Table 10.--Mortality of Chlorochroa sayi nymphs in laboratory insecticide tests, January 24 to 29, 194
Material tested
Matern ywfial tested fInsects Mortality after -(percent by wt. of finalday days daysJ5
dust) used Iday 2 3 4 days

Number Percent Percent Percent Percent Percent

Pyrethrum extract dustli
plus:

Sulfur 50% plus pyrophyllite (0.2% pyrethrins) 60 87 92 95 97 98

Dinitro-o-cresol 1% in special volcanic ash --------- 57 61 77 83 88 93

Dinitro-o-cyclohexylphenol
1% in special volcanic
ash ---------------------- 60 43 63 70 75 78

DDT 10% in pyrophyllite ---- 59 20 66 83 90 95

2-Chlorofluorene 20% in talc 58 4 10 10 20 28

Untreated check ------------ 56 7 12 16 18 27

1. See table 2. footnote 1.





18


Experiment No. 4. --In this experiment comparisons were made of dusts containing a dithiocyarate,pyrethrum extract, and both of these insecticides. The conditions of this experiment were similar to those of Experiment 3. Chenopodium morale was used as the food plant, insecticides were applied t6 the plants only in a settling chamber at the rate of 0.5 gram per square foot before the introduction of the insects, nymphs of the Say stinkbug were used as the test insect, and five replicate cages were used for each treatment.

The results of this experiment are given in table 11 and indicate that only fair results were obtained with dusts containing the dithiocyanate. Excellent results were obtained with the dust containing pyrethrum extract, even when the pyrethrins content was reduced to 0.1 percent. This dust was more effective than one containing both insecticides.

Tests in field cages as well as in test plots against adults of the Say stinkbug have shown that pyrethrum extract-sulfur dust containing
0.2 percent of pyrethrins knocked down a high percentage of the insects but a large number recovered.

Table ll.--Mortality of Chlorochroa sayi nymphs in laboratory insecticide tests, February 7 to 12, 194

Material tested Insects Mortality after -(percent by wt. in final used
dust mixture) 1 day 2 days 13 days 14 days days

Number Percent Percent Percent Percent Percent

Dithiocyanate dust 30%2plus:

Pyrophyllite 70% ---------- 50 62 74 78 80 84

Sulfur 70% ---------------- 51 44 56 66 68 72

Pyrethrum extract dust 5%t
plus:

Dithiocyanate dust 30%
plus sulfur 50% plus
pyrophyllite (0.1%
pyrethrins, 3.6%
dithiocyanate) --------- 50 88 90 94 98 100

Sulfur 50% plus pyrophyllite
(0.1% pyrethrins) 50 100 100 100 100 100
Sulfur 50% plus pyrophyllite
(0.2% pyrethrins) 50 100 100 100 100 100

Untreated check ------------- 49 10 15 26 33 37

1/ See table 7, footnote 1.
2/ See table 2, footnote 1.






19

Summary and Conclusions

Twenty-seven new materials were tested as insecticides in laboratory cages against Igus app. and the Say stinkbug. Some insecticidal value was indicated for the following:

Against Lygue spp.: *Phthalonitrile, magnesium oxide (alone and
Jr EcoEnation with sulfur and pyrethrum extract-sulfur dusts),
*phenozathiin-sulfur,*lime-sulfur, 2-chlorofluorene, *dlnitroo-cresol, *DDT, sabadilla, dithiocyanate dust.

Against the Say stinkbug: *Dinitro-o-cyclohexylphenol, dinitro-ocresol, and *DDT.

The materials starred (*) were later tried in the field against
these insects on sugar beets grown for seed. Phthalonitrile satisfactorily reduced Lgu populations but apparently damaged the sugar beet flowers and caused a reduction in the percentage of viable seed produced. The phenoxathiin-sulfur compound on small field plots did not give satisfactory kills of Ljgus. A dust containing lime-sulfur and sulfur gave somewhat better results against Igus than dusting sulfur alone but was not enough better to justify the additional expense. Dinitro-o-cresol gave very good kills of Lygus but caused a severe foliage burn. DDT produced the highest Igus mortality of any of the materials tried in the field and produced no detrimental effect on the plants. Plots treated with this material produced a better quality of seed than any plots
treated with the pyrethrum extract-sulfur dust, recommended for Lygu control on seed beets. Dithiocyanate-sulfur dusts gave fairly good results in the field against gus, and this material should be given further trial. Dinitro-o-cyclohexylphenol produced satisfactory kills of the Say stinkbug and did not damage the foliage or flowers. DDT gave fair results against the Say stinkbug in experimental plots, although these data are limited.







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