LIBRARY STATE PLANT BOARD May 1947 E-72*. United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine SUMMARY OF EXPERIMENTS WITH DDT TO CONTROL THE JAPANESE BEETLE By Walter E. Flemingl/ Division of Fruit insect Investigations Studies with technical DDT for the control of the immature stages of the Japanese beetle (Popillia japonlca Neman) in the soil and for the protection of fruit and foliage from attack by the adult beetle ware conducted in Maine, Massachusetts, Vermont, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, North Carolina, and ohiOe This re- port summarizes the results obtained during the period from 1943 through 1946. Formulation of DDT Dusts and Sprays When this study was undertaken, few commercial preparations of DDT were available, and it was necessary to prepare special dusts and sprays. Later commercial formulations were used, in general, it was found that the effectiveness of the treatment was dependent more upon the amount of DDT applied than upon the formulation* Dusts.— The dust formulated at the laboratory far the treatment of turf and cultivated land contained 10 percent of technical DDT, 87 percent of pyrophyllite or talc, and 3 percent of tricalolum phosphate. The DDT was micro nized2/ with an equal weight of pyro- phyllite or talc and then mixed with additional diluent and 'JIW 1/ Personnel of the New Jersey Agricultural Experiment Station, the Connecticut Agricultural Experiment Station, the North Carolina Department of Agriculture, and the Divisions of Japanese Beetle Control, Insecticide Investigations, and Forest Insect Investigations of the Bureau of Entomology and Plant Quarantine assisted in certain phases of this investigation. The assistance of various members of the staff of the Japanese Beetle Laboratory in conducting this in- vestigation is acknowledged. 2/ This material was micronized through the courtesy of the Micronizer Processing Company, Inc., Moorestown, N. J. 1 1 1947 - 2 - tricalcium phosphate. This dust flowed freely in the mechanical seeder and spreader, and when 250 or more pounds were applied per acre a uniform distribution was obtained. Later it was found that commercial dusts containing pyrophyllite or talc were satisfactory, but that those made with a clay were too adhesive to flow properly in this equipment. The amount of DDT required for the treatment of potting soil is very small* For this treatment the 10-percent dust was diluted further so that it contained 2 percent of DDT, or a commercial dust of this concentration was used, in order to have the material of sufficient bulk that it could be mixed uniformly throughout the mass of soil* For dusting foliage the amount of DDT in the dust was governed by the type of equipment. A 10-percent dust was used in the small hand dusters, and a 1-percent dust was used when the treatment was applied by airplane. Water-dispersible DDT.— In the early tests with sprays the technloal DDT was mlcronized with an equal weight of pyrophyllite, and fish glue equivalent to 1/16 of the weight of the solids was added as a wetting agent while the material was being prepared for spraying. Later it was found that the commercial water-dispersible DDT was equally as effective as the foregoing spray and much easier to handle in the field. Sprays prepared from 25 to 50 percent water- dispersible powders to contain the same amount of DDT per 100 gallons were equally effective in protecting plants from attack by the adult beetle, but when the powder contained much less than 50 percent of DDT an objectionable conspicuous deposit was left on the fruit and foliage. Throughout this paper, wherever mention is made of the use of DDT in water suspension, the quantity indicated refers to the quantity of actual technical DDT, in the form of a water-dispersible powder, unless otherwise stated. In the earlier experiments summer- oil emulsion was used with the water-dispersible powder as a sticker; later it was found that the addition of a sticker was not necessary and that it tended to leave an excessive residue of DDT on the fruit. DDT emulsions.— Two commercial DDT emulsions were applied by an airplane. One contained 30 percent of DDT with a methylated naphtha- lene as a solvent, and the other contained 25 percent of DDT with an aromatic petroleum derivative. DDT solution. — A solution of DDT was applied by airplane and also from the ground by a mist blower. This solution contained - 3 - 1 pound of DDT in 1 quart of xylene and 3 quarts of deodorized kerosene. Protection of plants from Attack by Adult Beetles Since adult Japanese beetles usually attack the upper portion of a plant and then work downward and inward until they have consumed all the fruit and foliage, in applying experimental sprays and dusts care was taken to cover all portions, particularly the extending branches at the top* The sprays and dusts killed many of the beetles that were hit during the application, and the residue on the plants afforded pro-* tection against beetles that came subsequently to them* DDT does not seem to be a strong repellent, since the residue did not pre- rent beetles from alighting on the sprayed or dusted plants* However, the beetles that walked over or started to feed on these plants soon became paralyzed and died* DDT was used under many conditions to protect various crops and ornamentals from injury by the adult beetles. The tests conducted and the results obtained may be auniaarized briefly as follows; Apple. — In 1944, 1945, and 1946 at Bridgeton, N. J., one ap- plication of a spray containing 1 pound of DDT per 100 gallons of water to yellow Transparent and Williams Early Red apple trees early in July, Just as the beetles were beginning to attack them, afforded complete protection to the fruit, which was harvested by the middle of July, and to the foliage throughout the summer. An application of this spray to Williams Early Red apple trees on May 31, as a sub- stitute for the last arsenioal cover spray for the codling moth, was inadequate for control of the Japanese beetle, because new growth during June and July was not protected from attack* Nectarine. — a few nectarine trees at Dayton, N. J.» were sprayed with DDT, 1 pound per 100 gallons of water, in 1943 after the beetles had become established on them and were causing severe damage to the fruit. All the beetles on these trees were destroyed and no further injury ocourred. The adjacent trees, whioh were not sprayed, were completely defoliated, and all the fruit was consumed by the beetles* Peach. — in New Jersey peaches ripen from the middle of July until late in September. The foliage of all varieties is subject to - 4 - attack by the beetle, and the fruits of the early-ripening vari- eties are often severely damaged. In 1943 through 1946 blocks of bearing trees in commercial orchards at Cranbury and Bridgeton, N. J., were sprayed with water-dlspersible DDT* Iks following varieties were In these blocks: Cumberland J. H. Hale N. J. 135 Sunhlgh ELberta Newday Raritan Rose Triogem Goldeneaat N. J. 109 Redrose Goldenglobe N. J. 118 Summer crest Sprays containing 1/4, 1/2, 3/4, and 1 pound of DDT p^r 100 gallons were applied early in July as the beetles were beginning to invade the trees. All these sprays killed many of the beetles on the trees at the time of application, but only the spray containing 1 pound of DDT afforded complete protection to the fruit and foliage throughout the summer. Plum*— At Dayton, N. J*, in 1943, a few nonbearing young plum trees were heavily infested and partially defoliated by the beetles* Spraying with DDT at the rate of 1 pound per 100 gallons destroyed all the beetles and no further Injury occurred. Grape. — Japanese beetles attack the foliage of all varieties of grapes and damage the berries of those varieties which ripen dur- ing August. Most of the vines grow rapidly during July, so that more than one application of a spray is required to protect the foliage. From 1943 through 1946 experiments with DDT were conduct- ed in a commercial vineyard at Holmdel, N. J. When 1/2 to 1 pound of DDT was added to 100 gallons of bordeaux mixture in the pre- blossom, petal-fall, and pea-stage sprays for control of the grape berry moth (Polychrosls vlteana (Clem.)), the last spray being ap- plied late in June, an additional spray 2 to 3 weeks later with 1/2 pound of DDT in 100 gallons of water to cover the new growth afforded complete protection* When DDT was not used for control of the grape berry moth, protection against the Japanese beetle was obtained by spraying with 1 pound of DDT per 100 gallons of bordeaux mixture late in JUne and 2 to 3 weeks later with 1 pound of DDT per 100 gal- lons of water. These sprays proteoted the following varieties from injury by the beetles: - 5 - Butler Etta Massasoit Portland Caco Fredonia Missouri Riesling Regal Catawba Herbert Muscat Salem Champion iona Niagara Sheridan Concord Janesville Ontario Telegraph Cottage Lindley Perkins Wilder Delaware Martha Pocklington Woodruff Red Worden Occasional feeding occurred on the sprayed foliage of Brighton, Brilliant* Clinton, Lutle, Urbana, and Vergennes. Hungarian was the only variety that was not adequately pro- tected by these sprays; extensive feeding occurred on the sprayed foliage, and the beetles attacked the fruit. Blueberry * — in recent years the Japanese beetle infestation in most of the commercial plantings of blueberries in New Jersey has been so light that no special spray has been required* How- ever, some plantations, particularly those adjacent to general farm- ing areas, have invasions which cause damage to fruit and foliage* A heavily infested block, including the varieties June, Ranoooas, Scammell, and Stanley, was found at New Brunswiok, N. J*, in 1943* Early in July these plants were sprayed with 1 pound of DDT per 100 gallons of water. This spray protected the fruit and foliage for 2 weeks. Then the beetles began to attack the terminal growth which had developed after the application of the spray. The plants were resprayed and no further damage occurred. Ornamental trees and shrubs.— During 1944, 1945, and 1946 several hundred ornamental trees and shrubs at Bridgeton, N. J*, Rye, N. Y., and Blowing Rock, N. C** were sprayed with DDT at the rate of 1 pound to 100 gallons of water. The following species were in- cluded: Trees Fagus grand 1 folia Quercus montana palustris Tills amerlcana europaea nlmus amerlcana American Beech Chestnut Oak Pin Oak American Linden European Linden American Elm - 6 - Shrubs and Vines Acer japonica palmatum Azalea calendulacea " mollis Berber Is thunbergl Buddlela davidil Chaenomeles lagenarla Cotoneaster sp. Lespedeza sp. Malus florlbunda Parthenoclssus qulnquefolia Prunus serrulate triloba Rosa spp. Fullmoon Maple Japanese Maple Flame Azalea Chinese Azalea Japanese Barberry Butterflybush Flowering Quince Cotoneaster Lespedeza Japanese Flowering Crab Virginia Creeper Oriental Cherry Flowering Plum Various hybrid tea roses and the climbing roses Dorothy Perkins and Paul's scarlet The DDT protected the foliage, but did not prevent the beetles from damaging the blooms. When the plants did not make much growth, one spray, applied late in June or early in July, was sufficient to protect the foliage. The plants that grew considerably during July required a second application 2 weeks later. Late in July 1945 ornamental trees and shrubs at Fort Schuyler, N. Y. , were sprayed with a solution of DDT in xylene and kerosene by means of a mist blower. The infestation in the trees and shrubs was destroyed, and no further injury occurred during the summer. Flowering garden plants.— During 1944 and 1945 several beds of flowering garden plants, including marigolds, snapdragons, and zinnias, at Bridgeton, N. J., were sprayed with DDT at the rate of 1 pound per 100 gallons. A spray applied early in July protected the plants for 2 weeks. A second spray, applied 2 weeks later, af- forded protection to the plants throughout the summer. Field crops. — Soybeans, including the varieties Chief, Earlyana, Gibson, illini, Lincoln, Macoupin, Mingo, Patoka, Richland, and Viking were sprayed with DDT, 1 pound per 100 gallons, at Dover, Del., in 1945. The spray killed many of the beetles on the plants and af- forded protection for about 1 week. As the plants made considerable growth during this period, it was necessary to repeat the application at weekly intervals. - 7 - On July 25, 1945, a plot of soybeans and several plots of corn at Beltsville, Md., ware dusted with 10-percent DDT* Most of the beetles on the soybeans were killed, and a week later only an occasional beetle was seen on the plants. When the dust was applied to the corn, beetles were feeding on 10 to 50 percent of the silks. Two days later no beetles were present, but after a week many were feeding on the old and newly formed silks. About half of a 30-acre field of hybrid corn near Lebanon, Fa., was sprayed or dusted with DDT on August 2, 1946. The following formulations were used: A solution prepared by dissolving 1 pound of DDT In 1 quart of xylene and 3 quarts of kerosene. A commercial emulsion containing 30 percent of DDT dissolved in methylated naphthalene and an unknown emulslfier, diluted 1:3 with water. A commercial emulsion containing 25 percent of DDT dissolved in an aromatic petroleum derivative and an unknown emulslfier, diluted 1:1 with water. A dust containing 1 percent of micronized DDT* All treatments were applied by an airplane, which flew low over the field. The dust was applied at the rate of approximately 45 pounds per acre and the solutions and emulsions at about 1-1/3 gal- lons per acre. Shortly after the application of these treatments the beetles showed evidence of poisoning, and within an hour many of them had fallen to the ground. Three days later there were 65 percent fewer beetles on the dusted corn and 93 percent fewer beetles on the corn sprayed with the solutions than in the adjacent untreated plot. Seven days later, although the population in the treated plots had not changed, the beetles were feeding on the newly formed silks. It was evident that more than one application of DDT would be required during the silking period to control the beetles on corn. Control of the Immature Stages in the Soil In the tests for control of the Immature stages in the soil, adult beetles were able to burrow into soil treated with DDT at rates up to 50 pounds per acre without any detrimental effeot. Furthermore, eggs hatched and pupae developed normally in treated soil. The only stage susceptible to poisoning by DDT was the larva. - 8 - Pound for pound, DDT is about 100 times as toxic to the larvae as is lead arsenate, the material used most extensively in the past for their control. Newly hatohed larvae succumb more quickly than do fully grown third instars. DDT is not effective at 40° ?., when the larvae are dormant, but the speed of toxic aotion increases progressively with the rise of the temperature above this point. The rate of toxic action was the more rapid in sands than in other types of soil, but there was no significant difference in the rates in gravelly loams, sandy loams, loams, and silt loams. DDT poisoned the larvae more rapidly in well-drained soils than in poor- ly drained, inadequately aerated soils. The rate was retarded by the addition of organic matter, such as peat, but was not inhibited by inorganic fertilizers, such as lime, calcium phosphate, potassium nitrate, ammonium sulfate, and calcium cyanamide, or by aluminum sulfate, ferrous sulfate, or sulfur. In laboratory studies the effectiveness of DDT in representative soils from the Piedmont Plateau, the Appalachian Mountains, and the Coastal Plain did not change in 3-1/2 years. It appears that DDT will remain insect icidally active in the soil for a long period. The most effective control of the larvae was obtained when DDT was in the soil at the time the eggs were hatching. Treatments were applied to established turf and to cultivated land in the spring of 1944, 1945, and 1946 with the object of destroying the brood which hatched during the summer. The tests conducted and results obtained may be summarized briefly as follows: Turf. — In May 1944 DDT was applied as a dust at the rate of 25 pounds per acre to infested turf at Totawa, N. J. The treatment killed one-third of the larvae before pupation. It reduced the 1944-45 brood 90 percent by September and 96 percent by the following May. The 1945-46 brood was reduce? 98.9 percent, and the 1946-47 brood 99.8 percent, by September 1945 and 1946, respectively. In May 1945 DDT was applied to turf at Blowing Rock, N. C.» at the rate of 25 pounds per acre. Most of the area was treated with the 10-percent dust, but a small portion was sprayed with a suspension of DDT, at the rate of 25 pounds of DDT in 1,000 gallons per acre. In the dusted area the 1945-46 brood was reduced 78.6 percent by September and 91.6 percent before pupation in June. In - 9 - the sprayed area the reduction was 67.4 percent and 90,2 percent, respectively. By October 1946 the DDT dust had reduced the density of the 1946-47 brood by 97.4 percent, and the spray by 64.4 percent. In May 1946 DDT was applied to turf at the rate of 25 pounds per acre as a dust at Blairstown, N. J., Orange, Conn., and North- ampton, Mass., and as a spray at Blairstown, N. J., and New London, Conn. The treatment killed 25.8 percent of the 1945-46 brood at New London and 71 percent of this brood at Orange before pupation. By mid-September the dust had caused a reduction in the 1946-47 brood of 99.7 percent at Blairstown, 84.0 percent at Orange, and 98.5 percent at Northampton, and the spray had killed 99.5 percent at Blairstown, and 82.7 percent at New London. In July 1946, before most of the eggs had hatohed, DDT was ap- plied both as a dust and as a spray to turf at Orange at the rate of 25 pounds per acre. By mid-September the dust had reduced the 1946-47 brood by 88 percent and the spray had reduced it by 83 percent. One application of DDT as a dust or spray to the surface of established turf at the rate of 25 pounds per acre before the eggs hatched, reduced the larval population to negligible proportions, and from the present indications the treatment will be effective for several years* Cultivated land in commercial nurseries.— To determine the possibilities of DDT for eradicating the larvae in the soil in beds and plots in commercial nurseries, to satisfy requirements of the quarantine, in the spring of 1944, 1945, and 1946 treatments were applied at the following commercial establishments in New Jersey where various types of ornamental stock were being grown: Browns Mills, Chatsworth, Kingston, Magnolia, Pemberton, Ridgewood, Riverton, Rutherford, Shiloh, Vincentown, Wayne, and woods town. DDT was applied as a water-dispersible powder to established beds at rates ranging from 10 to 50 pounds of DDT per acre, 1,000 gallons of the spray being used per acre. The material was not mixed into the soil. There was a pronounced reduction in the density of the larval population by mid-September in all treatments, but complete elimination was not obtained even with 50 pounds of DDT per acre. - 10 - The DDT was also applied as a dust at rates ranging from 10 to 55 pounds per acre and mixed by cultiration with the upper 3 to 4 inches of soil. When less than 25 pounds per acre was applied, few of the plots were entirely free of infestation by mid-September, but at the higher dosages only an occasional larva was found. 'Vith the 25-pound treatment 99.9 percent of the population *»3 eliminated. Results equally as good were obtained with the water-dispersible DDT, applied as a spray and mixed with the upper 3 to 4 inches of the soil* Plots at Riverton and Woodstown, which were treated by applying DDT at the rate of 25 pounds per acre and mixing it *lth the upper 3 to 4 inches of soil, were left undisturbed for 2 years. This treatment eliminated two success! to annual broods. The results indicate that DDT applied to nursery beds and plots in the spring at the rate of 25 pounds per acre and mixed with the upper 3 to 4 inches of soil will practically eliminate the larvae by mid-September. The indications are that the treatment will be effec- tive for several years. DDT appears very promising for the treat- ment of beds and plots to satisfy the requirements of the quarantine. Potting soil.-- To determine the possibilities of DDT for the treatment of soil used in commercial greenhouses for potting plants, to satisfy requirements of the quarantine, DDT was mixed with dif- ferent soils at rates ranging from 2.7 to 108 grams per cubic yard. At 80° F. complete mortality of newly hatched larvae was not ob- tained with 2.7 grams in 2 weeks, but all the larvae were killed with 5.4 grams in 5 days, with 10.8 grams in 4 days, with 27 grams in 3 days, and with 54 or more grams in 2 days. Third-instar lar- vae were much more resistant; to obtain complete mortality required 7.2 weeks with 10.8 grams, 4 weeks with 27 grams, and 2.7 weeks with 54 grams. Twenty-seven grams per cubic yardp which is equivalent to 25 pounds per acre, seemed to be about the optimum amount for the treat- ment of potting soil. Greater amounts of DDT did not accelerate very much the rate of poisoning and increased the hazard of injuring plants; lesser amounts prolonged the time required to eliminate the infestation too much to be practical. During the summer, if proper allowance is made for the incubation of the eggs, a period of 3 to 4 weeks would be required from the time the eggs are laid in soil treated with this dosage until it was free of infestation. - 11 - There is a close correlation between the temperature of the soil and the rate of poisoning. To kill third-instar larvae in soil treated with 27 grams of DDT per cubic yard required 4 weeks at 80° F., 6 weeks at 70°, 8 weeks at 60°, and 16 weeks at 50°. The type of soil influenced the velocity of poisoning with 27 grams of DDT per cubic yard. At 80° F. to kill third-instar larvae required on an average 2.8 weeks in the sands, 4.4 weeks in the sandy loams, 4.1 weeks in the loams, and 3.9 weeks in the silt loams. The addition of ammonium phosphate, ammonium sulfate, calcium cyanamide, calcium phosphate, calcium sulfate, and sodium nitrate to potting soil at rates up to 2.5 pounds per cubic yard did not inhibit the inseoticidal action of DDT. Hydrated lime at rates up to 40 pounds per cubic yard did not modify the toxicity of the DDT to the larvae. The addition of organic matter tended to retard the velocity of poisoning. The effectiveness of DDT in the different soils did not change significantly during 3-1/2 years. The addition of the fertilizers and organic matter to the soils did not modify the duration of the effectiveness. Effect of DDT Treatments for Japanese Beetle Control on Other Insects and Invertebrates In studying the effectiveness of DDT dusts and sprays for con- trol of the larvae and the adults of the Japanese beetle, it was the practice to make general observations on the effect of the treatments on other insects and invertebrates. When DDT was ap- plied as a spray to fruit and ornamental trees and shrubs, all dead and dying invertebrates beneath the plants were collected and classified. Some representatives of the following groups were af- fected by DDT: Arachnida: Araneida, Phalangida Crustacea; Oniscoida Chilopoda Diplopoda Hexapoda; ■ Coleoptera: Buprestidae, Carabidae, Cerambycidae, Chrysomelidae, Cicindelidae, Coccinellidae, Curculionidae, Elateridae, Lampyridae, Mordellidae, Scarabaeidae - 12 - Hexapoda (cont.): Diptera: Calliphoridae, Larvaevorldae, Muscilae, Rhagionidae, Sarcophagidae, Syrphldae, Tephritidae Hemiptera; Cicadelliae, Mirldae, Pentatomldae, Reduviidae Hymenoptera: Andrenidae, Apidae, Braoonidae, Eumeninae, Formlcidae, Ichneumonidae, Tanthredinidae Lapidoptera: Geometeridae, Lasiooampodae, phalaenidae, Pyralidldaa Odonata: Agrionldaa Orthoptera: Gryllldae, Mantidae Many inaacts, inoluding beneficial forms, war a killed by DDT! either by being wattad by the spray or by coming in contact with deposits on the foliage or on the ground beneath the trees. There is still much to be done to establish the effect of DDT on the beneficial insect parasites and predators, as well as on insects that assist in the pollination of important crops. In general, DDT appears to be somewhat less injurious to pollinating insects than is lead arsenate. Spraying the foliage for protection against the Japanese beetle seemed to be of some value in controlling certain other pests. When applied to peaches, the spray reduced the injury to fruit by the oriental fruit moth (Grapholltha molests (Busck))3/ and seemed to give some control of the peach tree borer (Sannlnoldea exitlosa (Say))4/. Substituting DDT for lead arsenate in the last arsenical cover spray for early apples gave better control of the codling moth (Qarpocapaa pomonella (L.)). When applied to grapes, DDT practically eliminated the grape leaf folder (Desmia funeral is (Hbn.)) and the grape leaf hoppers ( Brythroneura spp.), and gave better con- trol of the grape berry moth (Polychrosls viteana (clem.)) than did lead arsenate. American holly (Ilex opaca Alt.) in a group of shrubs sprayed with DDT had few holly leaf miners (Phytomyza ilicls (Curtis)), but adjacent unsprayed plants had many miners. The spray also con- trolled the elm leaf beetle (Galeruoella xanthomelaena (Schr.)) and the rose chafer (Macrodactylus subspinosus (F.))» 3/ Driggers, B. F. Laboratory test on the oriental fruit moth with special reference to DDT. (Scientific Note) Jour. Econ. Ent. 37: 120-121. 1944. 4/ ____________ Field tests of DDT to control the peach borer, (scientific Note) Jour. Econ. Ent. 37: 657. 1944. - 13 The spray seemed to have no effect on full-grown larvae of the bagworm (Thyridopteryx ephemeraeformls (Haw.)), the grape mealybug (Pseudococcus maritlmus (Ehrh.)), or the Comstock mealy- bug (P. comstocki (Kuw.)), and did not control the grapevine aphid (Aphis illinoisensis Shimer), the rosy apple aphid (Anur aphis rosaus Baker), or the apple aphid (Aphis pomi Deg.). It seemed to have no effect on galls on grape vines. Mites increased markedly on plants subject to attack by this a pest following applications of DDT. On azaleas a spider mite (Tetranychus sp., probably bimaculatus Harv. or althaeae Von Haust.) increased rapidly after the spraying, and caused mottling of the foliage. The European red mite ( Paratetr anychus pilosus (C. and F.) increased rapidly on apples, peaches, and lindens sprayed with DDT, and in August it caused many of the leaves to drop prematurely. It was evident from these results that the control of mites is a problem that must be considered when DDT is used as a spray on foliage. The application of DDT as a dust to the ground killed large num- bers of insects which are found frequently on the surface of the soil or on low-growing vegetation, Including many of the ground beetles, particularly of the family Carabidae, blister beetles, grasshoppers, crickets, leafhoppers, and leaf bugs. Sowbugs and crayfish in low spots were killed. Cutworms were usually absent from soil treated with DDT, but wireworms and earthworms seemed to be as abundant as in untreated soil. The effect of DDT on the many species of ants is uncertain; sometimes ants were absent, but in other cases they seemed to be as numerous as in untreated soil. Some garden slugs were killed by coming in contact with the dust, but after the residue had been washed from the blades of grass by rain, the treatment seemed to have no effect on them. Effect of DDT on Plants There have been very few cases where spraying the foliage with DDT at the rate of 1 pound per 100 gallons of water has caused any direct damage to the plants. No injury was observed on the follow- ing plants; Deciduous fruits (all varieties that were sprayed) : Apple Grape Peach Blueberry Nectarine Plum - u - Ornamental 8: Azalea calendulaoea mollis Berberls thunbergi Buddlela davldli Chaenomeles lagenarla Fagus grandlfolia Lespedeza sp. Malus florlbunda Parthenocioeus quinquefolla Prunus serrulata triloba Quercus montana palustrl8 Tllia americana europaea Ulmus americana Flame Azalea Chinese Azalea Japanese Barberry Butterflybush Flowering Quince American Beech Lespedeza Japanese Flowering Crab Virginia creeper Oriental Cherry Flowering Plum Chestnut Oak Pin Oak American Linden European Linden American Elm Flowering garden plants: Marigold Snapdragon Zinnia Spraying with water -dispersible DDT may have caused some chemical burning on the foliage of Japanese maple (Acer palmatum) and fullmoon maple (A. Japonica) , but this is uncertain because these varieties are very susoeptible to scalding by the sun during the summer. It injured slightly the blooms on roses and on petunias and definitely retarded the growth and reduced the yield of soybeans. Applying DDT dissolved in xylene and kerosene with a mist blower did not damage the foliage of various deciduous trees and shrubs. Corn was not injured while in silk by dusting or spraying emulsions and solutions of DDT from an airplane. Preliminary tests were made at the laboratory and conducted cooperatively with 54 commercial establishments in a number of eastern States to determine whether various plants could be grown satisfactorily in soil containing 25 pounds of DDT per acre, or 27 grams per cubic yard. The plants were grown in treated soil and compared with those in untreated soil. The results are indicated below. - 15 - Plants Not Noticeably Affected by DDT in Soil Vegetables: Beta vulgaris Brassica chinensis " oleracea acephala " capitate rape Capsicum sp. Cucumia melo " sativus Cucurbita maxima Daucus carota sativa Lactuca sativa Pastinaca sativa Pisum sativum Raphanus sativus Solanum melongena tuberosum Zea mays Common Beet Chinese Cabbage Kale Cabbage Turnip Pepper Muskmelon Cucumber Squash Garden Carrot Garden Lettuce Garden Parsnip Garden Pea Garden Radish Garden Eggplant potato Corn Cereals and grasses: Agrostis alba palustri3 tenuis tenuis as tori ana Avena sp. Cynodon dactylon Dactylis glomerate Festuca elatior rubra commutata Hordeum vulgar e Lolium perenne Poa compressa pratensis trivialis Secale cerale Stenotaphrum secundatum Triticum sp. Red top Creeping Bentgrass Colonial Bentgrass Astoria Bentgrass Oats Bermudagrass Orchardgrass Meadow Fescue Chewings Fescue Barley Perennial Ryegrass Canada Bluegrass Kentucky Bluegrass Rough-stalk Bluegrass Rye St. Augustinegrass Wheat - 16 - Ornamentals: Acalypha hlspida Acanthus montanus Acer pal ma turn Achillea ptarmica Aechmea calyculata caudata fasclata fulgens weilbachia Aeschynanthus pulcher Ageratum sp. Aglaonema commutatum " costatum simplex Allamanda cathartlca hendersoni Alpinla sanderae Althaea rosea Amomum car damp n Ananas comosus Anthemls tlnctorla Arabia alplna Araucaria excel sa Ardisia crenulata Aregelia marmorata spectabilis trlsti8 Arenaria verna caespitosa Armaria sp. Aronia arbutlfolla Aspidistra elatior variegate Aster subcoeruleus thomsonl frlkarti Azalea indica " kaempferi kurume mollis rosmarlnifolla rutherfordiana sanderl Begonia coooinea x olbla foliosa heracleifolia imperialis maculata argentea manicata aureo-maculata Chenille Copperleaf Acanthus Japanese Yaple Sneezewort Yarrow Scarlet Basketvine Ageratum Chinagreen Henderson Common Allamanda Banded Galangal Hollyhock Cardamon Amomum Pineapple Golden Camomile Alpine Rockcress Norfolk! sland Pine Ardisia Airplant Aregelia Showy Aregelia Bitter Aregelia Moss Sandwort Thrift Red Chokeberry Striped Aspidistra East indies Aster Frikart Aster Indica Azalea Torch Azalea Kurume Azalea Chinese Azalea Snow Azalea Rutherford Azalea Sander Azalea Imperial Begonia Spotted Begonia - 17 - Ornament al s ( cont . ) : Begonia metallica nitlda odorata rex semperflorens Berber! s mentorensis verruculosa Billbergia albertl * beucker distachya nutans pyramidalis guintitissima sander iana zebrina Buddleia sp. Buxus sempervlrens semper virens suffruticosa Calathea makoyana ornata roseilineata vandenheekei Calceolaria sp. Calendula sp. Camellia japonlca Campanula oarpatica persiclfolia rotundifolia superba Carina sp. Catananche caerulea Cerus candelarls Chamaecyparls lawsoniana nootkatensis glauca obtusa gracilis pisifera Cblorophytum el a turn Chr y san themum sp. Clbotium schledel Cis8us discolor rhomb if olia sicyoldes Clerodendron thomsonae Codiaeum varietgatum Coleus sp. Cordyline termlnalis Coreopsis tinctoria Steel Begonia Glossy Begonia Assamking Begonia perpetual Begonia Mentor Barberry Warty Barberry Albert Airbrom Bleurim Airbrom Violetrim Airbrom Sander Airbrom Zebra Airbrom Butterflybush Common Box Truedwarf Box Makoy Calathea Roseline Bigleaf Calathea Vandenheck Calathea Calceolaria Cal endula Common Camellia Carpathian Bel If lower Peachleaf Bell flower Bluebells of Scotland Carina Blue Cupidsdart Candle Cactus Lawson Falsecypress Blue Nootka Falsecypress Slender Hinoki Falsecypress Sawara Falsecypress Bracket plant Chrysanthemum Mexican Cibotium Begonia Treebine Venzuela Treebine Waterwithe Treebine Bleedingheart Glorybower Leafcroton Coleus Common Dracena Calliop8is 18 - Ornamentals (cont.): Cornus florlda Cotoneaster aoutlfolia Crassula arbor esc ens Croton punctatus Cryptanthus acaulls terminal! 8 Cryptomerla japonlca lobbi Ctenanthe oppenhelmlana Cyclamen sp. Daphne cneorum DaYallia fl jlensis plumosa Delphinium sp. Plan thus caryophyllus plumarlus Dlcentra spectabllls Dleffanbachla bausel leonl plcta splendens Doronlcum caucaslcum Dracaena deremensls warnecki fragrans massangeana vlctorlae godseffiana kellerl goldleana gracilis long! Eplsloa cooclnea Srlgeron speolosus Euonymus fortunel vegetus Eupatorium coelestinum Euphorbia pulcherrlma Flcus elastlca radlcana varlegata Flttonla verschaffeltll Fuchsia sp. Ginkgo blloba Gypsophlla repens Hedera canarlensls helix Hellopsls sp. Hellotroplum sp. Heml graph Is colorata Herniarla glabra Heuchera rosmundi Flowering Dogwood Peking Cotoneaster Crassula Lobb Cryptomerla Cyclamen Rose Daphne Fiji Davallia Larkspur Carnat ion Grass pink Common Bleed ingheart Bause Tuf troot Leon Tuf troot Variable Tuf troot Whitespot Tuftroot Caucasian Leopardbane Mas sang e Dracaena Victoria Dracaena Keller Dracaena Goldie Dracaena Oregon Fleabane Bigleaf Wintercreeper Euonymus Mi stf lower Eupatorium Oakleaf Poinsettla Indlarubber Fig Variegated Rooting Fig Tall Flttonla Fuchsia Ginkgo Creeping Gypsophlla Algerian Ivy English Ivy Heliopsis Heliotrope Common Burstwort Rosamund Alumroot 19 - Ornamentals ( cont • ) : Hoffmannla ghiesbreghti refulgens Homalocladlum platycladum Homalomena walllsi Hoya carnosa Hydrangea macrophylla Hypericum sp. Iberia sempervirens Ilex glabra opaca Impatiens sultani Jaaminum officinale aff ine sambac Juniperus chinensis communis excelsa horizontalis scopulorum squamata virginiana Xalancnoe blossf eldiana laburnum anagyroides Lonicera henryi Magnolia soulangeana stellate Mahonia aqulfolium Maranta arundinacea bicolor leuconeura kerehoveana Matricaria tchihatchewi Medlnilla magnif ica Myosotis scorpioidee Nepeta mussini Nephrolepis exaltata boatoniensis Nephthytis afzeli Nidularium amazonica " fulgens innocenti purpureum Ophiopogon japonicus Pachysandra terminalis Pa nd anus baptisti veltchi Papavsr orient ale Parthenocissus tricuspidata Ribbonbush Common Waxplant Bigleaf Hydrangea St. Johnswort Evergreen Candytuft Inkberry American Holly Sultan Snapweed Arabian Jasmine Chinese Juniper Common Juniper Greek Juniper Creeping Juniper Rocky Mountain Juniper Singleseed Juniper Eastern Redcedar Kalanchoe Goldenchain Laburnum Henry Honeysuckle Saucer Magnolia Star Magnolia Oregongrape Bermuda Arrowroot Redspot Banded Arrowroot Silver Ball Turf ingdaisj True Forgetmenot Persian Nepeta Bostonfern Lilyturf Japanese pachysandra Veitch screwpine Oriental Poppy Japanese Creeper - 20 - Ornamentals (cont.): Pasalflora alatocaerulea racemoaa Pelargonium sp. Pellionia daveauana Penstemon garretti Peperomla obtusifolla senders! Petunia sp. Philodendron cordatum " dubium hastatum phlox divaricate " glaberrima nivalis Phyllitis scolopendrlum crlstatum Picea glauca pungens Pierls japonica Piles muscosa Pinus mugo Polystichum ap. Potentilla fruticosa Primula veris paeudotauga taxifolia Pteria eretica tremula Pulmonaria saccnarata Pyracantha coccinea lalandl Rorippa nasturtium-aquaticum Rosa sp. Rub us reflexus plctus Salv ia sp. San8evieria zeylanica Saxifraga sarmentosa Scindapsus aurens Scirpus cernuua Spiraea sp. Taxus baccata brevifolia cuspidate hunnewelllana media Teucrium chamaedrys Thalictrum glaucum White Passionflower Garden Geranium Garrett 8 Pen3temon Ovalleaf Peperomla Sanders Peperomla Petunia Heartleaf Philodendron Sweetwilliam Phlox Smooth Phlox Trailing Phlox Hartstongue Fern White Spruce Colorado Spruce Japanese Pieris Clearweed Swiss Mountain Pine Hollyf ern Bush Cinquefoil Cowslip primrose Douglasfir Cretan Brake Australian Brake Bethlehem Lungwort Laland Firethorn Watercress Rose Sage Ceylon Sansevieria Strawberry Saxifrage Solomonislands Ivyarum Weeping Bulrush Spirea English Yew Pacific Yew Japanese Yew Hunnewell Yew Anglo Jap Yew Chamaedrys Germander Dusty Meadowrue - 21 - Ornamentals ( cont • ) : Thuja occidentalis " orlentalis Tillandsla linden! ana Tolmiea menzlesl Trachelo spermum jaamlnoldee Tradescantia flualnensls Tropaeolum sp. yacclnium sp. Veronica sp. Viburnum burkwoodi carlesi dilatatum setigerum t omen to sum Vinca sp. Viola cornuta " odorata tricolor hortensis Vitis sp. Vriesia erecta " favorlta magnifiea Weigela sp. Xianthosoma lindeni Zinnia sp. Eastern Arborvitae Oriental Arborvitae Lindens Tillandsia Pick-a-Back Plant Chinese Star jasmine ??anderingjew Nasturtium Blueberry Speedwell Burkwood Viburnum Koreanspice viburnum Linden Viburnum Tea Viburnum Doublefile Viburnum Periwinkle Horned violet Sweet Violet Garden Pansy Grape Poelrex Vriesia Weigela Linden Malanga Zinnia Plants Definitely Retarded by DDT in Soil Vegetables: Allium flavum Glycine soja Lycopersicon esculentum Phaseolus limensis vulgaris humilia Spinacia oleracea Yellow onion Soybean Common Tomato Lima Bean Bush Bean Spinach Ornamentals: Alyssum saxatile cltrinum Fragaria sp. Gaillardia sp. Lobelia sp. Scabiosa sp. Goldentuft Alyssum Strawberry Gaillardia Lobelia Scabious UNIVERSITY OF FLORIDA _ 22 - 3 1262 09239 1365 There ia some evidence that the detrimental effect of technical DDT in the soil on some plants is not caused by the compound, but by impurities and certain isomers in the technical material. 3ush beans, lima beans, and tomatoes did not tolerate 25 pounds per acre of the technical, DDT but grew normally in soil containing 200 pounds of purified DDT per acre. Effect of DDT on warm-blooded Animals In the experimental work with DDT for control of the Japanese beetle, some birds, principally robins and catbirds, were killed, probably by feeding on poisoned insects. When DDT was applied as a dust to the ground, it was urged that horses, cows, goats, chick- ens, ducks, and other animals be excluded from the treated area until rain had removed most of the dust froj the foliage. No harm to stock was observed when this procedure was followed, but much more information is desired on the reactions of various animals after feeding on plants treated with DDT. Residue of DDT on Food Crops Fruit picked immediately after being sprayed with water-dis- persible DDT, 1 pound per 100 gallons, with summer-oil emulsion added as a sticker, had a residue of metre than 7 mg. per kilogram. Apples picked 6 days after spraying and passed through a wiper had a residue which approached this amount; apples picked 2 weeks after spraying and wiped in the same manner had a residue well below this. Peaches picked 2 weeks after spraying and passed through a "defuzzerr had a residue less than 7 mg. per kilogram. When more than one application of this spray was made to peaches and grapes during the summer, the residue on the fruit at harvest was definitely above 7 mg. per kilogram. When the sticker was omitted, apples picked 3 weeks after one application of the spray had a residue of 2.5 mg. per kilogram, and peaches picked 3 to 4 weeks after spraying had 4.7 to 6 mg. per kilogram. Grapes sprayed three times with 1 pound of water - dispersible DDT and once with 1/2 pound of the material per 100 gal- lons had a residue of 3.8 mg. per kilogram at harvest.