LIBRARY STATE PLANT BOARD June 1952 E-839 United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine EFFECT OF DDT AND CHLORDANE APPLIED TO CONTROL JAPANESE BEETLE LARVAE ON THE YIELD OF GRASS, RYE, SOYBEANS, AND CORN By W. E. Fleming and W. W. Mainesl' Division of Fruit Insect Investigations DDT at the rate of 25 pounds per acre or chlordane at 10 pounds per acre, mixed intimately with the upper 3 inches of soil, is authorized for the treatment of beds and plots in commercial nurseries that are under quarantine because of the Japanese beetle (Popillia japonica Newm.). These toxicants are recommended also for application to the surface of established turf to protect it from damage by this insect.— Large areas of turf are treated with these toxicants, and rye, soy- beans, and corn are used by commercial nurseries in rotations for soil improvement. In 1947 an experiment was undertaken to simulate these applications of chlordane and DDT to large areas, maintaining them according to accepted procedure, to determine the effect of the toxicants on growth of the crops. This experiment was concluded in 1951 after four growing seasons and the results are presented in this report. Establishment of Field Plots A 3-acre field at Moorestown, N. J., that had not been under cultiva- tion for several years was selected for this experiment. The soil in this field is sassafras sandy loam, which is used in the production of general farm crops and nursery stock in southern New Jersey. A light- brown sandy loam about 6 inches deep, with a scattering of well-rounded quartz gravel throughout, rests on a sandy clay subsoil. Drainage is well established. Analysis^' of this soil showed that the pH was 5.0 and that it was relatively low in organic matter, magnesium, phosphorus, and potassium, 1/ The writers acknowledge the assistance of L.W. Coles, C. A. Perkins, H.W. Strabel, and A. R. Whitcraft, of the Japanese Beetle Laboratory, Moorestown, N.J., in conducting this investigation. 2/ Fleming, W. E. 1950. Protection of turf from damage by Japanese beetle grubs. U.S. Dept. Agr. Leaflet 290, 8 pp. 3/ Made by the Soil Testing Laboratory, New Jersey Agricultural Experiment Station, New Brunswick, N.J. -2 During the summer of 1947 an area 330 by 340 feet in this field was plowed, harrowed, and graded. It was kept relatively free of weeds by frequent cultivation. In September, in order to have established turf available for treatment the following spring, a mixture of grasses and clover was sown at the rate of 190 pounds per acre by means of a 10-foot tractor-drawn spreader to a strip 330 feet long and 100 feet wide on the southerly side of the area. This mixture, recommended by the New Jersey Agricultural Experiment Station, contained 45 percent of Kentucky blue grass, 25 percent of redtop, 10 percent of Colonial bent, 15 percent of rye grass, and 5 percent of white clover. After the seed was sown, the ground was rolled lightly to compact the soil and stimulate germina- tion. A deficiency of rain that fall was not favorable to the new grass, but by the spring of 1948 the turf was well established and ready for application of insecticides. The problem was how to lay out the experimental plots so that the spreader could be used to apply the insecticides in the same manner as used in commercial nurseries and on large turf areas. Accordingly, the field, including both turf and cultivated portion, was divided into 11 strips, each 30 feet wide and extending northward 340 feet. By trial and error over a distance of 435 feet, the spreader was adjusted to deliver approximately 250 pounds of 10-percent DDT or 200 pounds of 5-percent chlordane per acre. The DDT dust was applied once to strips 1 and 7 and twice to strips 2 and 8; the chlordane dust was applied once to strips 4 and 10 and twice to strips 5 and 11. Strips 3 and 9 were left untreated as checks, and strip 6 was left untreated to serve as a barrier between the replicated plots. The pattern of each application was in the form of parallel ribbons of material, about 2 inches apart, across the field. When two applications were made these ribbons tended to merge. It appeared that a uniform distribution was obtained with all treatments. With each application the amount of dust put into the hopper was recorded, and when the operation was completed the material remaining in the hopper was removed and weighed. The amount of toxicant applied in each treatment was calculated and expressed as pounds per acre. It was found that the equivalent of 25 pounds of DDT per acre had been applied to strips 1 and 7, and of 60 pounds per acre to strips 2 and 8. The equivalent of 10 pounds of chlordane per acre had been applied to strips 4 and 10 and of 19 pounds per acre to strips 5 and 11. The toxi- cants applied to established turf were left on the surface of the ground; in the cultivated area the toxicants were mixed immediately by cultiva- tion with the upper 3 inches of the soil. The arrangement provided for duplicate plots, each 30 by 100 feet, on turf and for two pairs of plots, each 30 by 40 feet, for each treat- ment in the cultivated areas. These plots are referred to as A, B, C, and D in the tables. It seemed to be the only arrangement possible for - 3- use with the tractor-drawn equipment, but it had the disadvantage that without randomization of the treatments proper compensation could not be made for variations in the soil throughout the plots. It is believed, however, that from a practical viewpoint this experimental design was adequate to determine whether these treatments had any serious effect on the crops. Planting and Rotation of Crops The rye, soybeans, and corn were each planted in two adjacent strips, each 40 feet wide, extending across the strips of the treatments described previously. The adjacent strips of a crop were separated by a noncount row, or swath. The seed bed was prepared for each crop by disking to a depth of 3 inches to avoid distributing the toxicants mechanically to a lower level. Spring rye, a grain-producing type not so tall or so plump as the common winter rye, was broadcast at the rate of 100 pounds per acre on April 19, 1948, April 12, 1949, and May 11, 1950. In 1948 and 1949 good stands were obtained, but in 1950 the planting was so delayed by the cold wet spring that the crop was a failure. It was decided to use the common winter rye in 1951. This seed was sown on October 10, 1950, and a good stand v/as obtained. Soybeans of the Black Wilson type were broadcast at the rate of 2 bushels per acre on May 10, 1948. A good stand was obtained, but so many weeds developed that the crop could not be harvested in a satis- factory manner. Thereafter the soybeans were sown in rows 36 inches apart, the seed about 3 inches apart in the rows, so that the plants could be cultivated. Twenty-five rows, including the middle barrier row, were sown on May 12, 1949, June 6, 1950, and June 4, 1951. The hybrid field corn, Funk G-94, was planted in rows 42 inches apart, the seed about 15 inches apart in the rows. Twenty-one rows, including the middle barrier row, were sown on May 10, 1948, May 13, 1949, June 6, 1950, and June 4, 1951. The rotation of these field crops was rye, soybeans, corn, and rye, so that, except for the first and the fourth years, each crop was planted in a different strip across the treated plots. Soil- Fertility Program Although sassafras sandy loam is one of the important agricultural soils, it is necessary to add organic matter, lime, and commercial fertilizers to grow crops or grass in a satisfactory manner. The organic matter in the cultivated area has been built up gradually during the 4 years by shredding and disking the crops into the soil and by incorpo- rating a cover crop into the soil in the spring. Rye grass was used as the cover crop over the winter of 1948-49, but because of the difficulty - 4- of killing this crop and mixing it with the upper 3 inches of soil by disking, the use of rye grass was discontinued. Winter wheat was found to be more satisfactory under these conditions. Each spring lime was applied to the established turf and to the culti- vated area. In 1948 hydrated lime was used at the rate of 800 pounds per acre. In subsequent years ground limestone was used, 500 pounds per acre in 1949, 1,000 pounds in 1950, and 800 pounds in 1951. With this program of liming, the pH of the soil was maintained between 6.0 and 6.5. A commercial 5-10-10 fertilizer was applied twice each year, the first treatment in the spring to the turf and cultivated area, and the second later in the season as a side-dressing to the corn and soybeans in the following amounts: Pounds per acre Spring Later in season 1948 1,000 500 (corn only) 1949 600 250 1950 and 1951 500 250 Harvesting of Crops When the rye had made full growth and the heads were maturing, the plants were cut at the surface of the ground in 4-foot swaths with a tractor-powered sickle bar. The swaths in each plot were collected and weighed. Then the cuttings were spread over the plot and disked into the soil. The soybeans were cut at the surface of the ground when they had made good growth and the pods had formed. Each 30 -foot row in each plot was cut and weighed. These cuttings were then spread over the plot and incorporated into the soil. The weight of the husked ears of corn was used for comparison between plots. When the corn matured, late in September or early in October, the ears were removed, husked, counted, and weighed. The stalks were then shredded and incorporated into the soil. Periodically as required the grass on the turf plots was mowed with a power mower and the clippings were left on the ground. During June of each year, when the turf was in its best condition, the grass was cut and the clippings were collected by means of an 18-inch hand mower equipped with a grass catcher. The clippings were then weighed. Discussion of Results The green weights of the rye, soybeans, grass, and of the mature ears of husked corn in the plots to which the different treatments had been applied are summarized in tables 1 and 2. - 5- In 1948 the rye in all plots germinated normally but the seedlings in the plots treated with DDT had an abnormal purple color. Although this color gradually disappeared, the growth of the rye was visibly retarded. At harvest it was evident that the application of DDT to the soil had definitely reduced the green weight of the crop. In 1949 and 1951, although some discoloration and retardation of the seedlings were evident, there was nothing to indicate that the application of DDT up to 60 pounds per acre had modified the green weight at harvest. During the 4 years there was nothing to indicate that applications of chlordane up to 19 pounds per acre had any detrimental effect on the growth of the rye. The application of DDT at rates up to 60 pounds per acre and of chlordane at rates up to 19 pounds per acre appeared to have no signifi- cant effect on the growth of soybeans, corn, or mixed grasses. This experiment should not be considered as a study of the photo- toxicity of these insecticides to these plants. As the chemical analyses of the soil-2 showed that practically all the DDT and chlordane had re- mained within the upper 3 inches during the 4 years following the appli- cation, it would be expected that when the roots penetrated below this layer the plants would grow fairly normally. Summary DDT or chlordane mixed with the upper 3 inches of soil is authorized for the treatment of beds and plots in commercial nurseries that are quarantined because of the Japanese beetle ( Popillia japonica Newm.). Applied to the surface, these toxicants are recommended also for the protection of turf from damage by this insect. A 4-year study was made of the effect of these toxicants applied in this manner on growth of grass, rye, soybeans, and corn. The green weights of the crops in the treated plots were compared with the weights in the untreated plots. It was found that, except for a retardation in the growth of rye with DDT the first year, the application of DDT up to 60 pounds per acre, or of chlordane up to 19 pounds per acre, had no detri- mental effect on these crops. Since the roots of these plants penetrated below the treated layer of soil, this experiment should be considered as a study of the reactions of crops under this special condition rather than a general study of the phytotoxicity of DDT and chlordane to these crops. 4/ These analyses were made by R. D. Chisholm and L. Koblitsky, of the Division of Insecticide Investigations. -6 - Table 1. --Effect of applying DDT for control of Japanese beetle larvae on green weight of rye, soybeans, corn, and grass Crop Year Pounds DDT per acre Green weight in pounds per plot Plot A Plot B Plot C Plot D Average Rye 1948 25 60 None 1949 25 60 None 1951 25 60 None Soybeans 1949 25 60 None 1950 25 60 None 1951 25 60 None Corn 1948 25 (ears) 60 None 1949 25 60 None 1950 25 60 None 1951 25 60 None 42 40 42 40 41.0 24 29 34 29 29.0 85 72 84 68 77.3 173 223 167 152 178.8 223 221 165 150 189.8 210 229 191 172 200.5 146 91 106 97 110.0 130 85 76 81 93.0 124 121 91 91 106.8 262 297 237 254 262.5 281 297 234 207 254.8 291 295 260 251 274.3 194 217 194 197 200.5 205 194 200 202 200.3 223 221 210 202 214.0 135 180 164 192 167.8 125 156 109 164 138.5 113 177 130 177 149.3 225 232 199 222 219.5 252 245 219 221 234.3 230 226 185 236 219.3 139 138 136 152 141.3 124 143 117 153 134.3 111 124 124 142 125.3 185 168 169 168 172.5 195 184 169 156 176.0 191 189 180 160 180.0 129 189 128 132 144.5 183 200 140 145 167.0 208 207 130 172 179.3 Table 1. — (Continued) -7 Crop Year Pounds DDT per acre Green weight in pounds per plot Plot A Plot B Plot C Plot D Average Grass 1948 1949 1950 1951 25 76 60 87 None 60 25 80 60 98 None 80 25 34 60 41 None 31 25 75 60 73 None 84 95 89 78 68 65 40 36 36 32 79 73 75 85.5 88.0 69.0 74.0 81.5 60.0 35.0 38.5 31.5 77.0 73.0 79.5 -8 - Table 2. --Effect of applying chlordane for control of Japanese beetle larvae on green weight of rye, soybeans, corn, and grass Crop Year Pounds chlordane per acre Green weight in pounds per plot Plot A Plot B Plot C Plot D Average Rye 1948 11 19 None 1949 11 19 None 1951 11 19 None Soybeans 1949 11 19 None 1950 11 19 None 1951 11 19 None Corn 1948 11 (ears) 19 None 1949 11 19 None 1950 11 19 None 1951 11 19 None 74 79 82 62 74.3 69 64 74 64 67.8 85 72 84 68 77.3 207 211 173 163 188.5 172 175 178 181 176.5 210 229 191 172 200.5 103 147 96 103 112.3 147 140 92 118 124.3 124 121 91 91 106.8 285 306 280 276 286.8 312 345 269 312 309.5 291 295 260 251 274.3 236 199 198 196 207.3 205 211 211 210 209.3 223 221 210 202 214.0 133 137 144 165 144.8 164 175 155 168 165.5 113 177 130 177 149.3 216 238 173 246 218.3 208 237 185 233 215.8 230 226 185 236 219.3 126 106 149 142 130.8 132 116 149 144 135.3 111 124 124 142 125.3 192 193 184 170 184.8 198 206 190 194 197.0 191 189 180 160 180.0 141 173 110 153 144.3 130 137 120 174 140.3 208 207 130 172 179.3 9 - Table 2. --(Continued) Crop Year Pounds chlordane per acre Green weight in pounds per plot Plot A Plot B Plot C Plot D Average Grass 1948 1949 1950 1951 11 66 19 74 None 60 11 63 19 61 None 80 11 38 19 41 None 31 11 80 19 72 None 84 86 93 78 32 26 40 32 24 32 82 74 75 76.0 83.5 69.0 47.5 43.5 60.0 35.0 32.5 31.5 81.5 73.0 79.5 UNIVERSITY OF FLORIDA I I I I II III III 3 1262 09239 6430