March 1945 E-645
United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine RESULTS OF TESTS MADE WITH DDT AGAINST THE TAPANESS MEMTLE IN 1944
By C. H. Hadley and W. E. Fleming Division of Fruit Insect Investigations
Pfelizinary tests with technical DDT by workers at the Tapanese
beetle laboratory of the Bureau of Intomology and Plant Quarantine at
Moorestown, N. 3., during the summer of 1943 indicated that this material was the best protective agent ever tested against the adult
lapanese beetle (Popillia 1a2onioa Newm.) and that it appeared very
toxic to beetle larvae in the soil. There seemed to be no significant difference in effectiveness between the imported material and that of
The investigation was continued in 1944 on a much larger scale.
All the DDT used was of domestic origin, and was the technical grade obtained from Geigy Company, Inc. This technical DDT Was mixed with
an equal weight of pyrophyllite, and then micronized.Effect of DDT on Adult Beetles
Laboratory tests were made to ascertain whether the presence of
such materials as bordeaux mixture, wettable sulfur, lime-sulfur,
tank-mix copper phosphate, or Fer ate (containing 70 percent of ferric dimethyl dithiocarbamate) in the spray tank would modify the effectiveness of the DDT. Groups of plants were sprayed with DDT alone and in
combination with these materials. Some of the plants were placed in the testing chamber shortly after the application of the sprays, and others after the spray deposits had been exposed to various periods
of weathering. As rains were very infrequent, all the sprayed plants
were sprinkled daily with a garden hose.
The laboratory tests indicated that the duration of effectiveness
of DDT may be reduced when it is used with bordeaux mixture, wettable
sulfur, lime-sulfur, or tank-mix copper phosphate. Fermate did not
seem to modify the effectiveness of the DDT.
V/These materials were micronized tlirough the courtesy of the
Micronizer Processing Co., Inc.
In the field tests the composition of the DDT spray used was as follows:
DDT ...,.... .1 lb.) mitronized together
Pyrophyllite . ...... 1 lb.)
Fish glue solution . . . 1 pt.
(1 lb. liquid glue per gal.)
Summer oil emulsion . . . 1 qt.
Water to make . . . . 100 gal.
In the preparation of the spray the DDT-pyrophylit. mixture was
placed in a pail and the glue solution added. Water was added gradually, with constant stirring, until a thin paste, or slurry, was obtained. This solution was poured through a screen into a spray tank, as it was being filled, until the tank was about three-fourths full; then the oil was added, and the tank was filled with water to its capacity. No difficulty was encountered in preparing the spray in the field.
Peaches.--One experimental block at Cranbury, N. 3., included 228 bearing peach trees. The varieties in this block--Triogen, Sunhigh, Goldeneast, Elberta, 3. H. Hale, Sumercrest, Redross, Goldenglobe, Cumberland, and Raritan Rose--ripen from early in August to late in September and thus are especially susceptible to Tapanese beetle attack. On Tune 17, in anticipation of the second brood of the oriental fruit moth (Grapholitha molests Busck), the block was sprayed with the DDT spray. On 3uly 14 the northern half of the block was sprayed a second time.
Japanese beetles invaded the peach orchard in large numbers during Tuly and August. In the northern and southern parts of the orchard, where only the regular sprays, without DDT, had been applied, both the fruit end foliage were severely damaged. A few beetles were observed on the foliage of trees sprayed once with DDT, but the beetle injury was very light. Almost no beetles were observed on trees receiving two applications of DDT. Complete protection of the fruit throughout the season was obtained with one application of the DDT spray.
Tests were also made at Shiloh, N. 3., in a peach orchard that contains over 1,000 bearing peach trees. In this orchard the early varieties--Summercrest, New Day, and Raritan Rose--have been severely damaged by the Japanese beetle for several years. On 3une 30, when beetles were beginning to invade the orchard in large numbers, a band two trees wide on the north and east sides of the orchard, the sides most susceptible to beetle attack, was sprayed with DDT. The summeroil emulsion was omitted from this spray, as the trees had been dusted with sulfur 2 days previously, and it was feared that the oil might cause some injury. The spray afforded complete protection to the fruit and foliage of the trees in this band. The fruit and foliage on trees throughout the remainder of the orchard were severely damaged.
Z~ies.--In a large orchard of Yellow Transparent apple trees at
;Shiloh DDT2 was substituted for lead arsenate in a block of 68 trees when the last arsenical cover spray for the codling moth was applied to the rest of the orchard on May 30. During June,2 nicotine-oil sprays were applied to ell the trees for codling moth control. When the beetles Invaded the orchard early in July they attacked the young growth not protected by DDT,, and just before harvest they attacked the ripening fruit. No additional spray was applied. It was evident that to obtain complete protection a DMT spray would have had to be applied just prior to invasion of the orchard by the beetles.
Another block of Williams Early Red apples, given the same treatment through June, was resprayed with DDr on July 3, as beetle injury to unprotected terminal growth began to be evident on Tune 30.
As a result of this application no additional injury occurred to the terminal growth,, and no ripening apples were damaged by beetles. Throughout the remainder of the orchard both fruit and foliage were
Ora --Ina large vineyard near Holmdel, N. T., several experimentaREba~e were sprayed with DDT for control of the Japanese beetle and the grape berry moth (oycrois viteana (Clem.)). This vineyard Includes a large number of varieties,, and the control of these two insects has been a serious problem for several years. Nine sprays of bordeaux mixture, with and without lead arsenate,, were applied to the vineyard during the season. In the experimental blocks sprayed with DDT, lead arsenate was not included after the first DDT application, but the bordeaux mixture was used for black rot control. Ecept In the experimental blocks, a comercial derri s preparation was applied late In July and in August for control of the Japanese beetle,, the berry moth,, and leafhopper.
One block of about 1 1/2 acres, containing 36 varieties,, was sprayed with DDT and bordeaux on June 13 and 29, and July 31. The first spray was primarily for the berry moth, but the last two sprays
were applied to protect the rapidly developing foliage from beetle attack. Complete protection from the Japanese beetle was obtained throughout the beetle season on all varieties except two, Clinton and Hungarian. Somne of the small, dense foliage on these varieties was injured. No DDT injury was observed on the foliage of any of the 36 varieties.
About 3/4 acre of Niagara grapes and an equal acreage of Delaware grapes were sprayed with MDT on Tuly 17, when beetles were beginning to dage the foliage. The spray was repeated on August 3 to cover the new foliage growth. These sprays afforded complete protect ion throughout the beetle season, while the remainder of the block, which was sprayed with a comrcial derris preparation, showed considerable beetle injury,
Another 3/4-acre block of Niagara grapes was sprayed with WDT on June 13 for protection against the berry moth. Additional DDT sprays were applied on June 29, July 17, end August 3 for the J1apanese, beetle. The remainder of this vineyard received the regular sprays, without DDT. The vines sprayed with DDT were protected against beetle injury throughout the season; in the remainder of the vineyard the foliage showed considerable beetle injury. Xquelly good results were obtained from four DDT sprays applied to about 3/4 acre of Jersey Muscat grapes on June 13 and 29, July 17, and August 3.
Blueberries.--Cultivated blueberries on the grounds of the New Jersey Agricultural Experiment Station have been severely damaged by Japanese beetles for several seasons. A small block containing six varieties of bearing plants, which the beetles were beginning to attack, was sprayed with DDT on July 8. The summer-oil mulsion was oAitted, to avoid the possibility of imparting an undesirable flavor to the ripe fruit. At the same time the remainder of the planting was sprayed with derris.
The DDTIE afforded protection to the fruit and foliage for about
2 weeks, the derris for less than 1 week.
Linden trees.--For a number of years Japanese beetles have completely defoliated many linden trees on the grounds of a large country club near Rye, N. Y. On June 27, mhen the beetles were beginning to attack the foliage, about 80 of these trees were sprayed with DDT; the remaining trees were not sprayed. The spraying equipaent, available was not fully adequate for the job, and it was impossible to spray the tops of the taller trees.
The sprayed trees, except near the tops where coverage was poor. were protected from beetle feeding throughout the beetle season. Dead and dying beetles were picked up under the trees shortly after the treatment and throughout July and August. The unsprayed lindens were completely defoliated as in previous years.
Ornamentals. --Miscellaneous ornamental trees and shrubs at the
country club near Rye,, and on the grounds of a large nursery at Shiloh, were sprayed once with DDT at the beginning of the beetle season. The shrubs and trees included azaleas, roses, rhododendrons, cotoneaster, flowering crab, flowering quince, flowering cherry, Japanese plum, elms, pin oaks, various maples, and some annuals such as marigolds and zinnias, all very susceptible to attack. Complete protection
throughout the season was obtained on the portion* of these plants which were covered by the spray. The new growth and blooms that developed later were attacked by beetles end damaged considerably. It was evident, however, that practically complete protection could have been obtained if the spraying had been repeated often enough to cover the new growth.
In connection with these experiments dealing with the Tapanese beetle there was opportunity to observe the effect of the DDT sprays on several other insects. On apples, poaches, and ornamental azaleas the red mite populations invariably were greatly increased wherever DDT was used. On grapes good control of leafhoppers was obtained with the DDT sprays. on Niagara grapes 15.6 percent of the grapes were Infested with the berry moth where MDT was used as compared with 41.7 percent where the regular sprays were used. However,, on Jersey Muscat grapes there appeared to be no difference between these sprays In the control of this insect.
Effect of DDT on Yapsnese Beetle Larvae in Soil
Laboratory tests indicated that in soil treatmenlts DDT functioned,, not am a fumigant, but as a contact or stomach poison. The larvae must came into contact with the solid material in order to be killed. In experiments with 28 soils, including sands, sandy loamn, silt loams, gravelly loarns, and loams,, which have been in progress for more tham a year, 25 pounds of DDT per acre was found to be more effective against third'.instar larvae than 1,000 pounds of lead arsenate, and the effectiveness of the DDT in the soil was not changed during this period. The toxicity of the DDT was not modified by the addition to the soil of fertilizers and soil conditioners, such as
aluminu sulfate, monoamonium phosphate, ammonium sulfate, calcium cyanamide, calcium sulfate, ferrous sulfate, tripotassiwn phosphate. sodium nitrate, sulfur,, tannic acid, or lime.
rn the field tests turf and nursery plots were treated with DDT applied as a spray or dust. When applied as a spray, the 50-percent micronized DDT-pyrophyllite mixture was used at a strength of 2 pounds to 100 gallons of water. Several dust mixtures were used, one of the best being of the following composition;
DDT * * . .10 percent) micronized together
Pyrophyllite . . .10 percent) Talc .. .. .. 78percent fricalcium phosphate. 2 percent
In tests Involving about 3 acres of treated turf MDT was applied In May as a dust to the surface at rates of 25 and 35 pounds of DIYT per acre. Two weeks after treatment large numbers of dead and dying larvae were observed on the surface of the plots. An intensive survey made in September, on the succeeding larval generation, showed that the 25-pound treatment had caused 82 percent reduction and the 35pound treatnt 90 percent reduction in the larval populations. Indications are that none of the surviving larvae will be alive to pupate in the spring.
In nursery treatments DDT was applied dry at rates of 20, 30, and 50 pounds per acre to three 1/4-acre plots in M~ay. The DDT was then worked into the upper 3 inches of the soil by cultivation, and azaleas
wore set out in the plots. In Septemuber larvae of the Japanese beetle, the Asiatic garden beetle (Autoserica castanet (Arrow)), and native white grab species were found generally distributed throughout the untreated portion of the nursery, the average population being about four larvae per square foot. A survey of the plots Indicated that the 20-pound-per-acre treatment had caused a reduction of 99 percent in the larval populat ion. No living larvae were found In either of the other two plots.
Early in July DDT~ was applied as a spray at rates of 10, 25, and 50 pounds per acre in 2,500 gallons of water to the surface of established beds of azaleas. After application of the spray there was no cultivation of the beds for the remainder of the season. A survey made in September showed that the 10-pound treatment caused a reduction in the larval population of 95 percent whereas in the plots treated with 25 and 50 pounds per acre only one very sick grub was found in each plot, a reduction of better than 99 percent for each treatment. At present it appears that a dosage of 25 pounds per acre,, applied either as a dust or as a spay, will be effective for two and possibly more years,
Although outworms were common in other parts of the nursery, none were found in the treated plots. However, MDT did not seem to have any effect upon earthworms, for they were equally abundant in the treated and untreated parts of the nursery.
The results of preliminary tests with MDT for the control of the Japanese beetle have been very favorable, but more information is needed before this material can be recommended for general use. Additional knowledge is needed on (1) the formulation of dusts and sprays;
(2) the compatibility of DDT with other insecticidal, fungicidal, end conditioning materials; (3) the dosage requirements for the adult and imture stages of the Japanese beetle; (4) the effect of DDTI on beneficial insects; and (5) the tolerance of different types of vegetation to DDT. More information is also required on the factors influencing the permanence of MDT when applied to foliage and to soil.
In addition to these problem further information Is also required on the amount of DDT residue which may be permitted on fruits intended f or human consumption, and on methods for removing excess DDT residues. Recommendations will be made as soon as they are justified by experi-. mental evidence.
In field tests conducted against the Japanese beetle (Popiliia, Japonica Nem.) during the summer of 1944, one spray of DDT at the rate of 1 pound per 100 gallons, applied at or just prior to the
beginning of the beetle season, gave complete or satisfactory protection to the fruit and foliage of early ripening peaches and apples,
blueberries, and a miscellaneous group or ornamental and shade trees and shrubs. As many as three applications wore necessary to give satisfactory control on grapes on account of the develojuept of new growth during the beetle season, Flowering plants and ornamentals producing blooms and new growth while the beetles are flying mill also usually require up to three applications to insure satisfactory protection,
The DDT spray gave excellent control or leaf hoppers on grapes,
and fair control of the grape berry moth (Polyobrouis viteana (Clem.)). However, a marked Increase in red mite populations was generally noted in blocks of apples and peaches, and on ornamental azaleas sprayed with DDT, in contrast to very low populations in comparable blocks not receiving the spay.
The results with MDT for control of Japanese beetle larvae In
soil indicate that this materiel is more toxic then lead arsenate, and that a dosage of 25 pounds per acre, applied either as a dust or as a spray* will practically eliminate the larval population.
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