THS “I.“ r“ _ a mm... d 737.“ LIBRAR Y ‘" Michigan State “v— This is to certify that the thesis entitled INTERACTION 0F BENTAZON (3-lSOPROPYL-IH-2,I,3- BENZOTHIADIAZIN-lI(3_H_)-0NE 2,2-DIOXIDE) WITH DICLOFOP (2-(ll-(2,lI-DICHLOROPHENOXY) PHENOXY) PROPANOATE) AND SEVERAL ORGANOPHOSPHATE INSECTICIDES presented by James Robert Campbell has been accepted towards fulfillment of the requirements for Master of SCienCUegreein Crop and Soil Science Major professor ( 0-7639 v\-' wilfefim .' ‘s‘RRflf OVERDUE FINES: 25¢ per day per item RETURIIIKE LIBRARY MATERIALS: Place In book return to remove charge from circulation records INTERACTION OF BENTAZON (3—TSOPROPYL—lflf2,l,3—BENZOTHIADIAZIN ~4(3g)—0NE 2,2—DIOXIDE) WITH DICLOFOP (2—(4—(2,4—DICHLOROPHENOXY) PHENOXY) PROPANOATE) AND SEVERAL ORGANOPHOSPHATE INSECTICIDES By James Robert Campbell A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crop and Soil Sciences 1980 ABSTRACT INTERACTION OF BENTAZON (3-ISOPROPYL-lflf2,1,3-BENZO- THIADIAZIN-4(3E)-ONE 2,2—DIOXIDE) WITH DICLOFOP (2-(4—(2,4—DICHLORO- PHENOXY) PHENOXY) PROPANOATE) AND SEVERAL ORGANOPHOSPHATE INSECTICIDES By James Robert Campbell The organophosphate insecticides malathionQQSQfdimethyl §f(1,2- dicarbethoxyethel)posphoridithionate), parathion(9)97diethyl 97p- nitrophenyl phosphorothioate and diazinon (9)93diethyl.Q-(Z—isopropyl- 4—methyl-6-pyrimidinyl)phosphorothioate) combined with bentazon (3-iso propyl-lflfZ,1,3—benzothiadiazin-4 (3§)—one 2,2 dioxide) caused severe injury to soybean (Glycine max (L.) Merr. ‘Corsoy') and navy bean (Phaseolus vulgaris L. 'Seafrer') as a postemergence spray. Postemer- gence tankmixture applications of bentazon with organophosphate or carbamate insecticides, or soil applied organophosphate insectiCides prior to bentazon treatments did not interact with bentazon to injure corn (Egg m§y§_L. 'Great Lakes Hybrid 4122'). Technical grade malathion interacted with bentazon similar to formulated malation. Malathion applications 48 hours before or after bentazon applications injured . soybeans to the same extent as tankmixtures of the compounds. Bentazon reduced the activity of diclofop (2—(4—(2,A-diclorophenoxy) phenoxy)propanoate) on annual grasses in tankmixtures. Bentazon did not reduce the activity of BAS 9052 (2—(1—(ethoxyimino)—butyl)—5-(2- James Robert Campbell (ethylthio)propyl)f3~hydroxy—2—cyclohexene~l-one) in controlling annual grasses in greenhouse and field experiments. The wettable powder formulation of bentazon as well as higher temper- atures slighly reduced the antagonistic interaction of bentazon and diclofop. In greenhouse studies soybeans were injured by the diclofop bentazon combination. However, in field studies this injury was not sufficient to reduce soybean yield. TABLE OF CONTENTS Page LIST OF TABLES .... ..... ... ........ - ..... . . . . ... . ..... .. iii INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . 1 CHAPTER 1: Enhanced Phytoxisity of Bentazon with Several Organo- phosphate Insecticides. . . . . . . . . . . . . . . . 3 ABSTRACT. . . . . . . . . . . . . . . . . . . . . . . . . . 3 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . 4 MATERIALS AND METHODS. . . . . . . . . . . . . . . . . . . 4 RESULTS AND DISCUSSION... . . . . . . . . . . . . . . . . . 6 LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . 13 CHAPTER 2: Factors Influncing the Compatability of Diclofop and BAS 9052 OH (2-(1-(ethoxyimino)-butyl)-S-(2—(ethylthio)- propyl)—3—hydroxy-2-cyclohexene—l—one) with Bentazon.. 15 .ABSTRACT. . . . . . . . ... ... . . . . . . . . . . . . . 15 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . 15 MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . 16 RESULTS AND DISCUSSION. . . . . . . . . . . . . . . . . . 19 LITERATURE CITED. . . . . . . . . . . . . . . . . . . . ; 31 CHAPTER 3: Summary and Conclusions ..... . . . . . . . . . . . 33 LIST OF RERERENCES. . . . . . . . . . . . . . . . . . . . . . . 35 ii' LIST OF TABLES Page CHAPTER 1 1. Effect of insecticides and bentazon of the fresh weight of soybeans, corn and navy beans 14 days after application... . . . . . . . . . . . . . . . . 9 2. Calculations of expected interaction responce by Colby's formula on soybean, navy bean and corn. . . 10 3. Effect ofinalathion formulation On the interaction with bentazon on soybeans 7 days after harvest. . . 11 4. The effect of split applications ofnmlathion and bentazon on the fresh weight of greenhouse—grown soybeans 7 days after application. . . . . . . . . . 12 CHAPTER 2 1. Effect of diclofop and bentazon on barnyardgrass and soybean 14 days after application under green- house conditions. . . . . . . . . . . . . . . . . . 23 2. Effect of diclofop and bentazon on yellow foxtail moisture content and fresh weight 7 days after application under greenhouse conditions. . . . . . 24 3. Effect of BAS 9052 and bentazon on barnyardgrass fresh weight 14 days after application under greenhouse condtions. . . . . . . . . . . . . . . . 25 4. Effect of bentazon formulation on the interaction with diclofop applied to barnyardgrass 14 days application under greenhouse condtions. . . . . . . 26 5. Effect of light intensity on herbicides on the moisture content of barnyardgrass 14 days after application. . . . . . . . . . . . . . . . . . . . . 27 6. Effect of temperature during growth and herbi- cides on the moisture content and fresh weight of barnyardgrass 10 days after application. . . . . 28 7. Effect of bentazon,adiclofop and BAS 9052 on annual grass control, soybean injury and grain yield. . . . . . . . . . . . . . . . . . . . . . . 29 8. Effect of bentazon, diclofop and BAS 9052 on barnyardgrass fresh weight at two leaf stages under field condtions. . . . . . . . . . . . . . . 30 iii INTRODUCTION Modern agriculture requires increased economic efficiency in all areas of production. Pest management is an important aspect of crop production, the use of insecticides and herbicides have increased yields and decreased production cost. Application of pesticide combi— nations can further increase production effiCiency, resulting in reduced fuel and labor costs, decreased soil compaction and more effecient equipment use. Bentazon [3—isopropyl—lH-2,l,3-benzothiadiazin—4(3H)-one 2,2—dioxide] is a postemergence herbicide effective in controlling a number of broadleaved and sedge weeds including Compositae, Ambrosiaceae, Convol— vulaceae, Polygonaceae and Cyperaceae (19). The control of grass weeds or insects could be facilitated by tank mixing other pesticides with bentazon. But indiscriminate mixing of pesticides is illadvised since many combinations have shown synergistic injury to the crop or antagonism of weed contrél (1,6,7,10,ll,l3,l7). Bentazon has been reported to exibit increased soybean injury when combined with the grass killing herbicide diclofop [2-(4-(2,4—dichloro phenoxy)phenoxy propanoate] (22). Increased crop injury has been reported when various organophosphate and carbamate insecticides were combined with a herbicide (l,6,10,ll,l7,21). In view of these interaction it would be desirable to know the extent of bentazon interactions with other pesticides. Our objectives were to a) evaluate the potential interaction of bentazon with several organophosphate and carbamate insecticides b) determine any interaction of bentazon with grass killing herbicides such as diclofop and BAS 9052 [2-(1-(ethoxyimino)—butyl)— 5-(2-(ethlthio)-propyl)-3—hydroxy—2-cyclohexene-l—one] and evaluate CHAPTER 1 Enhanced Phytotoxicity of Bentazon with Several Organophosphate Insecticides ABSTRACT The organophosphate insecticides malathion [9,Qfdimethyl §T (l,2—dicarbethoxyethel)phosphorodithionate], parathion (9,9fdiethyl'gfp- nitrophenyl phosphorothioate) and diazinon [QJOfdiethyl 9f(2 isopropyl- 4—methy1~6—pyrimidinyl)phosphorothioate] combined with bentazon [3~isopropyl— le2,l,3—benzothiadiazin-4—(3H)—one 2,2-dioxide] caused severe injury to soybean (Glycine max (L.) Merr. 'Corsoy') and navy bean (Phaseplus vulgaris L. 'Seafarer'). Postemergence tank mixture applications of bentazon with organOphosphate or carbamate insecticides, or soil—applied organOphOSphate insecticides prior to bentazon treatments did not interact with bentazon to injure corn (Zea_may§_L. 'Great Lakes Hybrid 4122'). Technical grade malathion interacted with bentazon to the same extent as formulated malathion. Malathion applications 48 h bafore or after bentazon applications were as injurious to soybean as tank mixtures of the two compounds. INTRODUCTION One of the management practices that allows for greater economic savings and production efficiency is the application of several pesticides at once as tank mixtures. Of potential interest would be the postemergence application of bentazon—insecticide combinations. However, there are numerous reports showing that certain herbicide—insecticide combinations may increase phytotoxicity to the crop (l, 3, 5, 6, 8, 9). Bentazon has been reported to interact with the herbicide diclo— fop—methyl [methyl 2—(4(2,4-dichlor0phenoxy)phenoxy)propanionic acid] when applied to soybean (11). Often these pesticide interactions are due to a change in uptake or metabolism of the herbicide (4, 10, 12). The present study evaluates the potential interaction of bentazon with several organophosphate and carbamate insecticides. MATERIALS AND METHODS 'Corsoy' soybean, 'Great Lakes Hybrid No. 4122' corn, and 'Seafarer' navy bean were seeded, five seeds per 946—ml wax cup, into greenhouse soil (1:1:1, v/v/v, soilzsandzpeat). Seedlings were thinned to three uniform plants per pot 10 days later. Pesticides were applied with a link belt sprayer at 2.5 kg/cm2 pressure with 280 L/ha spray volume. The plants were at the following leaf stage at application: the first trifoliolate leaf of soybean was one-half to fully expanded, the second leaf of the corn plant was emerging from the whorl, the second trifoliolate leaf of navy bean was fully expanded. Initial experiments 5 with soybean and navy bean were placed in a greenhouse at 25 i 5 C without supplemental lighting. Subsequent experiments with soybean and corn plants were grown out—of—doors. Commercial formulations of the insecticides malathion emulsifiable concentrate (EC) at 1.12 kg/ha, parathion EC at 0.56 kg/ha, diazinon wettable powder (WP) at 2.24 kg/ha, carbaryl WP or carbaryl (l-naphthyl .meethylcarbamate) flowable liquid (FL) at 1.12 kg and carbofuran (2,3- dihydro—Z,2—dimethyl—7-benzofuranyl methylcarbamate) FL at 1.12 kg/ha were applied. Herbicide—insecticide combination treatments were applied as tank mixtures. Due to the similarity of plant response of greenhouse and outdoor grown plants, the following experiments were conducted under greenhouse conditions. Commercial granular formulations of terbufos [§f(((1,1 dimethylethyl) thio)methyl) 9,9fdiethylphosphorodithioate] at 1.12 kg/ha, carbofuran at 0.84 kg/ha and fonofos (Qjethyljgfphenylethylphosphonodithioate) at 1.12 kg/ha were incorporated into the top 5 cm of a mixture of sand and soil (1:l, sandy loam:beach sand, v/v). Postemergence treatments of bentazon at 1.68 kg/ha were applied at two stages of growth, either as the first leaf or the fourth leaf was emerging from the whorl. To determine whether the active ingredient in an insecticide formulation was interacting with bentazon, formulated malathion (Malathion 50 Chevron Corporation) and technical grade malathion at 1.12 kg/ha were applied with and without bentazon at 1.68 kg/ha to soybean plants when the first trifoliolate leaves were expanding. The technical malathion was kept in suspension with water by constant agitation, application was with a thin layer chromatography plate sprayer. In a split application study formulated malathion was applied 48 or 3 h before as well as 3 or 48 h after an application of bentazon. All plants were fertilized with a solution containing 100 ppm (w/v) of N, P205 and K20. All experiments were in a completely randomized design, rerandomized several times throughout the experiment, having four or five replications per experiment and repeated at least once. RESULTS AND DISCUSSION Postemergence applications of bentazon or any of the insecticides alone did not result in injury to soybean measured as a reduction in soybean fresh weight (Table 1). Severe injury resulted from combination treatments of the organophosphate insecticides, malathion, parathion and diazinon combined with bentazon, as indicated by reduction in fresh weight. This injury appeared within 24 h as an interveinal water soaking, necrosis, followed by leaf abscission within a few days. The onset of injury was more rapid on soybeans grown outside than those grown in the greenhouse. Only the combination of malathion and bentazon resulted in a corn fresh weight reduction from that of the control (Table 1). However, this combination treatment was not significantly different from malathion alone and the corn rapidly recovered from the injury. Navy bean treated with bentazon or any of the insecticides alone were not injured (Table 1). Combination treatments of malathion, parathion, or diazinon with bentazon resulted in large reductions in fresh weight and severe leaf injury. This injury was either a rapid necrosis of the leaf tissue or a chlorosis which was not restricted to any veinal or interveinal portion of the leafo It is noteworthy that with both the soybean and navy bean the phosphorothioate or phosphorodithioate type insecticides, parathion, diazinon and malathion, interacted with bentazon but the car— bamate type insecticides, carbofuran and carbaryl did not, although all have been shown to be esterase inhibitors (7). The interaction of the insecticides studied with bentazon was evaluated using Colby's (2) multiplicative model for interactions and the statistical significance between the expected and actual combination value calculated as outlined by Hamill and Penner (4). The analysis indicated significant synergism for the interaction with the number of insecticides showing significant synergistic decreases in plant fresh weight in the following decreasing sequence: soybean, navy bean, and corn, respectively (Table 2). Soil application of the insecticides terbufos, carbofuran or fonofos followed by a postemergence application of bentazon to corn did not exhibit a significant reduction in fresh weight (data not presented). Yellow nutsedge (Cyperus esculentus L.) shoots treated with malathion at 1.12 kg/ha and bentazon at 1.12 kg/ha were not injured more severely than yellow nutsedge shoots treated with bentazon alone (data not presented). The mixtures of formulated malathion or technical malathion with bentazon resulted in the same degree of injury to soybean. This indicated that the synergistic injury of malathion with bentazon was a result of the active ingredient in the malathion formulation (Table 3). Although bentazon alone caused a significant reduction in fresh weight the injury resulting from the combination treatment was much more severe. Split application treatments of malathion and bentazon resulted in severe reductions in soybean fresh weight (Table 4). This response occurred when the malathion was applied 48 or 3 h before as well as 3 or 48 h after bentazon was applied. The split applications did not differ or differed only slightly from the malathion bentazon tank mixture. This injury indicates that the interaction was not in the spray solution but on or within the leaf itself. Hmva H. 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