.‘ ' — - ,I.’ a, C” -a.-.r:. _ ‘ .‘r . - "v.2 ' \I W9. \: 9:9,: .-. ._ ‘.' "“2“ \- ( ,1" n‘c- l"".|‘,“,' . +53 .....w WW” l\\‘:'|‘ |I.' ."‘., “NAIR ‘ . { n “ ‘ _ ‘ , ., I ‘_ .m U‘ n‘.' I"I\':., .4"’1. '1.“ 0‘ ;‘ ‘ 1‘ . .‘H‘ I‘ ( _" 1“ ‘, ":2 ' .‘3 .In H U. .;.“;| 1' Jf‘H-l: f:" r! . ' ‘ I: [WM-W ""II‘ ' ‘ I, n w. :‘ 41“.: t «M? a“ . f ‘ ' ‘ , ., wig-W1. LIBRARY Michigan 5 rate University This is to certify that the thesis entitled RELATIONSHIP OF YELLOW NUTSEDGE (CYPERUS ESCULENTUS L.) CONTROL TO PERSISTENCE AND MOBILITY OF SEVERAL ACETANILIDE HERBICIDES IN THE SOIL. presented by ALFRED JOSEPH CORNELIUS has been accepted towards fulfillment of the requirements for Ph.D. degree in Crop G 8011 Sc1ences Date of)" /- 7/ 0-7 639 —-_..— _.— A 4‘ RELATIONSHIP OF YELLOW NUTSEDGE (CYPERUS ESCULENTUS L.) CONTROL TO PERSISTENCE AND MOBILITY OF SEVERAL ACETANILIDE HERBICIDES IN THE SOIL BY Alfred Joseph Cornelius A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Crop & Soil Sciences 1978 DROW ABSTRACT RELATIONSHIP OF YELLOW NUTSEDGE (CYPERUS ESCULENTUS L.) CONTROL TO PERSISTENCE AND MOBILITY OF SEVERAL ACETANILIDE HERBICIDES IN THE SOIL. By ALFRED JOSEPH CORNELIUS The acetanalide herbicides alachlor [Z-chloro—Z',6'diethyl-N: (methoxymethyl) acetanilide], metolachlor [2-chloro-N:(2-ethyl-6-methyl- phenyl)-Ny(2-methoxy-l-methylethyl) acetamide], H-22234 [N-chloroacetyl- N:(2,6-di ethylphenyl)-g1ycine ethyl ester] and H-26910 [Nfchloroacetyl- N:(2-methy1-6-ethy1phenyl)-g1ycine isopropyl ester] at 3.5 x 10'6 M did not inhibit yellow nutsedge (Cyperus esculentus L.) tuber sprouting in petri dishes. The herbicides at 3.5 x 10-6 M and 3.5 x 10-7 inhibited growth of newly emerging shoots, and a dosage response was evident. The viability of yellow nutsedge sprouts decreased with increased exposure to the acetanilide compounds, however, after 192 h exposure, the tubers were not killed. In petri dish studies, there was no significant dif- ference in activity among herbicide treatments on yellow nutsedge sprouts. Treatments applied to the soil exhibited a significant difference in activity on yellow nutsedge. In the field, all acetanilide herbicides reduced the number of yellow nutsedge shoots per m2, compared to the untreated control. Visual control ratings, stand density measurements, shoot dry weights, and plant heights indicate the following order of ALFRED JOSEPH CORNELIUS activity on yellow nutsedge: metolachlor Z_alachlor :_H-26910 :_H-22234. Activity of all treatments was enhanced by incorporation into the soil and by increasing the rate. As soil organic matter and clay content levels increased, the activity of all herbicides decreased. The acetanilide compounds were effective on yellow nutsedge when applied to the soil, above or at the level of the tuber. Herbicide applied below the tuber had no significant effect upon shoot development. All treat- ments significantly reduced the number of yellow nutsedge shoots and con- sequently increased soybean yield compared to the untreated control. Acetanilide herbicide persistence and mobility were determined in the soil. The rate of dissipation in the 0 to 8 cm soil depth for the chemicals indicated the half life of metolachlor z_H-26910 Z_H22234 2. alachlor. The greatest soil persistence 8 weeks after application was exhibited by metolachlor and H-26910. Significant interactions for method of application indicated that the rate of dissipation was slower and persistence longer for soil incorporated treatments. The concentra- tion of herbicide applied to the soil did not effect dissipation rate. However, for all dates sampled, greater residues were detected in the treatments receiving 6.72 kg/ha. Trace amounts of herbicide were detected at the 8 to 16 cm soil depth. Movement of 14C-labeled acetanilide chemicals on silica gel plates indicated increased adsorption and lower water solubility for H-22234 as compared to the other herbicides. Mobility on soil thin layer chromato- graphy plates was as follows: metolachlor = alachlor > H-22234. All treatments exhibited a decrease in mobility as soil organic matter and clay content increased. To Lynn the love and strength in my life. To my mom and dad, who through their love have been my inspiration. ii ACKNOWLEDGMENTS The author wishes to express his sincere appreciation to his major professor, Dr. William F. Meggitt, for his guidance and encouragement throughout this project; and especially for the opportunity to be asso- ciated with the weed control program at Michigan State University. A special thanks to Dr. Donald Penner for his invaluable guidance in laboratory aspects of the project, and for his assistance in the arduous task of manuscript review. Thanks to Dr. Matthew Zabik, Dr. James Tiedge, and Dr. John Shickluna as members of the guidance committee, for their critical review and project assistance. The technical assistance provided by Dr. Homer LeBaron and the CIBA - GEIGY Corporation is gratefully acknowledged. To those research assistants responsible for the successful comple- tion of this project, John 'Whit' Whitmer, 'Crazy' Bob Rocchio, and Tory Shade, a very special and warm thankyou. iii TABLE OF CONTENTS Page LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . vi LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . vii INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 CHAPTER 1. COMPARATIVE EVALUATION OF SEVERAL ACETANILIDE HERBICIDES FOR THE CONTROL OF YELLOW NUTSEDGE (CYPERUS ESCULENTUS) . . . . . . . . . . . . . . . . . . 3 Abstract . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . Materials and Methods Results and Discussion . . . . . . . . . . . . . . . Literature Cited . . . . . . . . . . . . . . . . . . . . l NuMbM CHAPTER 2. ACTIVITY OF FOUR ACETANILIDE HERBICIDES ON YELLOW NUTSEDGE (CYPERUS ESCULENTUS L.) . . . . . . . . 20 Abstract . . . . . . . . . . . . . . . . . . . . . . . . 20 Introduction . . . . . . . . . . . . . . . . . . . . . . 21 Materials and Methods . . . . . . . . . . . . . . . . . 22 Results and Discussion . . . . . . . . . . . . . . . . . 24 Literature Cited . . . . . . . . . . . . . . . . . . . . 27 CHAPTER 3. PERSISTENCE AND MOBILITY OF SEVERAL ACETANILIDE HERBICIDES IN THREE MICHIGAN SOILS . . . . . . . . . . . 41 Abstract . . . . . . . . . . . . . . . . . . . . . . . . 41 Introduction . . . . . . . . . . . . . . . . . . . . . . 42 Materials and Methods . . . . . . . . . . . . . . . . . 43 Results and Discussion . . . . . . . . . . . . . . . . . 45 Literature Cited . . . . . . . . . . . . . . . . . . . . 51 CHAPTER 4. SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . 65 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . 68 APPENDICES A. Visual control rating of several acetanilide herbicides on yellow nutsedge 8 weeks after application . . . . . . 71 iv Effect of acetanilide herbicides on yellow nutsedge shoot density 8 weeks after application Yellow nutsedge stand density 2, 4, 8 weeks after application on a sandy clay loam soil 2. 5% organic matter . Yellow nutsedge stand density 2, 4, 8 weeks after application on a clay loam soil 4.1% organic matter . Yellow nutsedge stand density 2,4,8 weeks after application on a sandy clay loam soil 6. 0°o organic matter . . Effect of several acetanilide herbicides on yellow nutsedge plant height 8 weeks after application Effect of several acetanilide herbicides on yellow nutsedge shoot dry weight 8 weeks after application Effect of several acetanilide herbicides on soybean yield on a sandy clay loam soil 2.5% organic matter Yellow nutsedge development, 6 weeks after treatment with 3.36 kg/ha (A) alachlor, (B) metolachlor, (C) H- 26910, (D) H- 22234, applied to soil above the tuber, on the tuber, or below the tuber . . . . . Flow diagram of the analytical procedure for the determination of alachlor, metolachlor, H- 22234, H- 26910 parent residue in the soil . . . Acetanilide herbicide percent recovery from untreated soil after 30 minutes equilibration Gas chromatographic conditions . . Typical standard curve for acetanilide herbicides by flame ionization detection . Soil persistence of several acetanilide herbicides 0 - 8 cm depth on a sandy clay loam 5011 2.5% organic matter, 8 weeks after application Soil persistence of several acetanilide herbicides 0 — 8 cm depth on a clay loam soil 4.1% organic matter, 8 weeks after application . Soil persistence of several acetanilide herbicides 0 - 8 cm depth on a sandy clay loam soil 6. 0% organic matter, 8 weeks after application . Half life (t 1/2) of four acetanilide herbicides, applied at 2 methods of application, 2 rates, at 3 locations, over 2 years . Soil persistence of several acetanilide herbicides 0 - 16 cm depth on a sandy clay loam soil 2.5% organic matter, 8 weeks after application 8011 persistence of several acetanilide herbicides 8 - 16 cm depth on a clay loam soil 4.1% organic matter, 8 weeks after application Soil persistence of several acetanilide herbicides 8 - 16 cm depth on a sandy clay loam soil 6. 0% organic matter, 8 weeks after application . ll’C- acetanilide herbicide lateral diffusion on soil thin layer chromatography plates . . . V Page . 73 . 75 . 77 . 79 . 81 . 82 . 83 . 8S . 86 . 87 . 88 . 89 . 90 . 91 . 92 . 93 . 94 . 95 . 96 . 97 CHAPTER 1 1. 2. Accumulative precipitation (cm) for 8 weeks after herbicide application in 1975, 1976, and 1977 . . 3. Comparative evaluation of several acetanilide herbicides for the control of yellow nutsedge 8 weeks after application . 4. Activity of several acetanilide herbicides on yellow nutsedge at three locations in Michigan 8 weeks after application . . . 5. Yellow nutsedge stand density, shoots per square meter, 2, 4, and 8 weeks after application for 1976 and 1977 . 6. Effect of several acetanilide herbicides on yellow nut- sedge plant height, shoot dry weight, and soybean yield at Location I, 8 weeks after application CHAPTER 2 1. Effect of 3.5 x 10-6 M acetanilide herbicides on yellow nutsedge tuber sprouting after 7 days exposure 2. Effect of several acetanilide herbicides on yellow nutsedge shoot elongation after 5 days exposure . 3. Effect of exposure time of tubers and sprouts to 3.5 x 10 6 M acetanilide herbicides on yellow nutsedge sprout viability 4. Effect of exposure time of tubers and sprouts to 3.5 x 10‘6 M acetanilide herbicides on yellow nutsedge shoot length . . 5. Dry weight of yellow nutsedge shoots 6 weeks after treatment with 3. 36 kg/ha acetanilide herbicides applied to soils with various levels of organic matter 6. Yellow nutsedge shoot dry weight 6 weeks after treat- ment, when exposed to 3.36 kg/ha acetanilide herbicides at varied placement in the soil . CHAPTER 3 1. Characteristics of soils taken from the Ap horizon, O to LIST OF TABLES Soil characteristics, crops, and planting dates for the comparative evaluation of acetanilide herbicides at three locations in Michigan 16 cm, at three locations in Michigan for soil residue studies . vi Page . l3 . 14 15 16 . 17 . 18 . 29 . 30 . 31 . 32 . 33 . 34 . S3 Accumulative precipitation for 8 weeks after herbicide application during 1976 and 1977 Persistence of several acetanilide herbicides O to 8 cm in a sandy clay loam soil 2. 5% organic matter, location I, 8 weeks after treatment . Persistence of several acetanilide herbicides O to 8 cm in a clay loam soil 4. l°o organic matter, location II, 8 weeks after treatment . Persistence of several acetanilide herbicides 0 to 8 cm in a sandy clay loam soil 6. 0% organic matter, location 111,8 weeks after treatment . Herbicide persistence at the 8 to 16 cm soil depth, 8 weeks after application for three locations in Michigan during 1976 and 1977, averaged over four acetanilide herbicides . . . . . . . . . . ll‘C- acetanilide herbicide mobility on silica gel GP thin layer chromatography plates . . . . . . . . . ll*C- acetanilide mobility on soil thin layer chromatography plates . . . vii Page . S4 . SS . 56 . S7 . 58 . 59 60 LIST OF FIGURES Page CHAPTER 2 1. Yellow nutsedge shoot development, 6 weeks after treat— ment with 3.36 kg/ha (B) alachlor, (C) metolachlor, (D) H- 26910, (E) H- 22234, applied to soils with various levels of organic matter . . . . . . . . . . . . . 36 2. Yellow nutsedge development, 6 weeks after treatment with 3. 36 kg/ha acetanilide herbicide applied to soil above the tuber, on the tuber, or below the tuber . . . . . 38 3. Yellow nutsedge shoot, root, and rhizome development in the soil, 6 weeks after tuber germination . . . . . . . 40 CHAPTER 3 l. Radioautograph of ll‘C-alachlor, luc-metolachlor, 1“C— H-22234, movement on (A) silica gel GF, and (8) soil, thin layer chromatography plates, eluted with water . . . . 62 2. Molecular structure and water solubility of alachlor, metolachlor, H-22234, and H-26910 . . . . . . . . . . . . . 64 viii INTRODUCTION Yellow nutsedge (Cyperus esculentus L.) is a weed infesting all con- tinents and ranks as a major agronomic problem in the world (20). Once confined to low wet areas, yellow nutsedge has spread at an alarming rate into upland mineral soils. Contributing to its spread are the current agronomic trends toward earlier planting, fewer tillage operations, and reduced competition from annual weeds. Approximately 12.6% of the soybean acres, and 10.5% of the corn acres in the North Central States are infested with this weed (1). Yellow nutsedge reduces yields, escalates production and harvesting costs, and lowers crop quality. Biological, cultural, and chemical methods are employed in programs to control yellow nutsedge. However, no effective biological control is presently available; promising results have been reported with the insect Bactra veruntana Zeller (25). Cul- tural methods are a very important part of all weed control programs. Tillage operations alone can reduce the severity of the problem, but many viable tubers remain dormant in the soil and will germinate when tillage operations stop. Herbicide treatments are presently an instru- mental tool in the control of yellow nutsedge in agronomic crops. It has been reported repeatedly that the herbicide alachlor controls yellow nutsedge in corn (1) and soybeans (l). Alachlor preplant incorpor- ated delayed sprouting of tubers and provided 6 to 12 weeks control (24). Recent advances in acetanilide chemistry have resulted in new herbicides 1 with structures similar to alachlor. The acetanilide compounds metola- chlor, H-22234, and H-26910 were developed as selective herbicides for use in corn and soybeans. The objectives of these studies were: (1) to comparatively evalu- ate alachlor, metolachlor, H-22234 and H-26910 for yellow nutsedge con- trol and ascertain the effect of method of application, rate, and soil type on their activity, (2) to evaluate the activity of these acetanilide herbicides on yellow nutsedge tuber sprouting, sprout viability and shoot development, and (3) to evaluate their persistence and mobility in the soil. CHAPTER 1 COMPARATIVE EVALUATION OF SEVERAL ACETANILIDE HERBICIDES FOR THE CONTROL OF YELLOW NUTSEDGE (CYPERUS ESCULENTUS) ABSTRACT The acetanilide compounds alachlor [2-chloro-2',6'-diethyl-N: (methoxymethyl) acetanilide], metolachlor [2-chloro-N;2-ethy1-6-methly- pheny1)-Nf(2-methoxyl-methylethyl) acetamide], H-22234 (Nfchloroacetyl- N:(2,6-di ethylpheny1)-g1ycine ethyl ester] and H-26910 [Nrchloroacetyl- N;(2-methy1-6-ethylpheny1)-glycine isopropyl ester] are selective pre- emergence herbicides for use in corn (Ega_may§_L.) and soybean (Glycine max_(L.) Merr.). Field studies were initiated in 1975, 1976, and 1977 to comparatively evaluate these acetanilide herbicides for yellow nut- sedge (Cyperus esculentus L.) control and determine the effect of method of application, rate, and soil type upon their activity. All treatments evaluated reduced number of shoots per m2 compared to the untreated con- trol 8 weeks after application. Yellow nutsedge shoots emerged, late in the season in all treatments, for one or more locations, during at least one year. The break in control coincided with reduced precipita- tion for that location and year. Visual control ratings and stand densi- ty 8 weeks after application indicated that these herbicides have the following order of activity: metolachlor z_alachlor z_H-26910 3_H-22234, 3 4 depending upon location and year. Activity of all treatments on yellow nutsedge was enhanced by incorporation into the soil and by increasing the rate. As soil organic matter and clay content levels increased, the activity of all acetanilide herbicides decreased. After 8 weeks, the yellow nutsedge shoots which received the metolachlor treatments signi- ficantly shorter in height than all other treatments. Evaluating shoot dry weight reduction, herbicide activity was of the following order: metolachlor Z_alachlor :_H-26910 Z_H-22234. All acetanilide herbicide treatments significantly reduced the number of yellow nutsedge shoots and consequently increased soybean yield compared to the untreated control. INTRODUCTION Yellow nutsedge ranks as one of the major weed problems in the world (6). Once confined to low wet areas, yellow nutsedge can now be found in upland mineral soils. Within the past 5 years, the acres in corn and soybean infested by yellow nutsedge have significantly increased (2,5). Present agronomic trends toward earlier planting, fewer tillage operations, and reduced competition from annual weeds have contributed to its spread (2). Yellow nutsedge is a perennial sedge capable of reproducing by seed and tubers. The primary means of propagation in cultivated fields is by tubers formed at the tip of rhizomes (4,10). Tubers developed during the summer lie dormant in the soil until extended cold periods and leaching water break their dormancy. As a tuber germinates, one or more rhizomes elongate from the tuber buds, the rhizome then develops a basal bulb and subsequent parent plant. Each parent plant is capable of 5 producing 40 to 50 daughter plants and 300 to 500 tubers in 16 weeks. In 1 year this tuber has spread to an area containing 1900 plants and approximately 7000 tubers (11). It has been reported that alachlor controls yellow nutsedge in corn (1,3) and soybean (1,7,9). Preplant incorporated application of alachlor delayed sprouting of tubers and provided 6 to 12 weeks control, but failed to kill tubers (8). Tubers appeared to escape injury by failing to sprout until activity of the herbicide had substantially dissipated (8). Incorporation of alachlor just before planting effectively con- trolled yellow nutsedge, whereas preemergence applications were dependent upon rainfall and only moderately successful. Recent advances in acetanilide chemistry have resulted in new herbi- cides with structures similar to alachlor. The acetanilide compounds alachlor, metolachlor, H-22234, and H-26910 were developed as selective herbicides for use in corn and soybeans. The objectives of this study were to comparatively evaluate the acetanilide herbicides for yellow nutsedge control and ascertain the effect that the method of application, rate, and soil type have on their activity. MATERIALS AND METHODS For the comparative evaluation, the acetanilide herbicides alachlor, metolachlor, H-22234, and H-26910 were applied preplant incorporated or preemergence at 3.36 kg/ha and 6.72 kg/ha. Several locations in Michigan were selected for soil texture, soil organic matter content, and degree of yellow nutsedge infestation during 1975, 1976, and 1977 (Table 1). All locations were planted to corn or soybeans (Table l). Treatments 6 were applied with a tractor mounted sprayed delivering 215 l/ha to 3 by 12 meter plots. Crops were planted with rows spaced 76.2 cm apart with four rows per plot. The preplant incorporated treatments were incorpor- ated within 15 min after application with a spring tooth harrow, twice in opposite directions. Rainfall following herbicide application is shown in Table 2. A randomized complete block design was utilized with four replica- tions at Location I and three replications at Locations 11 and III. The major weed Species at all locations was yellow nutsedge and the infesta- tions were the result of natural selection. Field plots were hand weeded throughout the growing season to eliminate competitive effects from other weed species. Visual control ratings were taken 4, 8, and 12 weeks after applica- tion on a percentage basis with 0 = no control and 100 = complete control. The two middle rows of each four row plot were rated. Yellow nutsedge stand density was recorded 2, 4, and 8 weeks after application to evaluate the development of the yellow nutsedge population. Stand densi- ty counts were taken for 3 in2 between the two middle rows. Yellow nut- sedge shoot height and shoot dry weight were recorded for location I, 8 weeks after treatment. The yellow nutsedge shoots were harvested from 3 1112 between two middle rows, dried, and weighed. Soybeans from location I were harvested October 3 in 1975, October 5 in 1976, and October 10 in 1977. Six meters of the two middle rows were pulled, thrashed, dried to 13% moisture, and weighed. 7 RESULTS AND DISCUSSION Visual control ratings were used as a measure of treatment efficacy. At location I, alachlor and metolachlor provided equal control of yellow nutsedge and were more effective than H-22234 during 1975 (Table 2). In 1976, there was a significant herbicide by method of application inter- action. Preplant incorporated metolachlor and alachlor, and preemergence applied metolachlor, were the most effective treatments providing equal control of yellow nutsedge. During 1977, the most effective treatment was metolachlor with 92% control. Visual control ratings for location 11 during 1976 indicated that metolachlor was the most effective treat- ment. In 1977, metolachlor and alachlor provided equal yellow nutsedge control, and were more effective than H-26910 or H-22234. At location 111, during 1976 and 1977, metolachlor was the most effective treatment, with alachlor being equally effective during 1977. Treatments exhibited a decrease in herbicidal activity from 1976 to 1977 at locations 11 and III. The drop in yellow nutsedge control during 1977 corresponds to the low levels of rainfall received after application for both locations (Table 2). Evaluating the herbicides within all locations, metolachlor consistently provided the most effective yellow nutsedge control. Alachlor and H-26910 were intermediate in activity, while H-22234 was consistently poor. A comparison of the main effects for herbicides on stand density supported the conclusion obtained from visual control ratings (Table 3). At location I during 1976 and 1977, treatments that provided equally effective control of yellow nutsedge stand density were metolachlor, alachlor, and H-26910. At location 11 during 1976, reduction in stand 8 density by the herbicide treatments was in the order: metolachlor : alachlor Z_H-26910 Z_H-22234. Metolachlor and alachlor provided equal and effective control during 1977. At location 111 during 1976 and 1977, the greatest reduction in stand density resulted from metolachlor treat- ment; alachlor was equally effective during 1977. The level of organic matter of the soils varied from 2.5% at loca- tion I to 6.0% at location III. Clay contents of the soils were 27.8% at location I, and 35.8% at locations II and III. The herbicide's main effect was compared across locations (Table 4). All treatments were more effective at the lowest percent soil organic matter and clay con- tent; effectiveness significantly decreased as the percent organic matter and clay content in the soil increased. Visual control ratings at location 1 during 1975 and 1977 showed no significant difference between preplant incorporated or preemergence applications (Table 3). During 1976, there was a significant herbicide by method of application interaction, and it was observed that alachlor, H-26910, and H-22234 exhibited increased yellow nutsedge control when incorporated into the soil. The decrease in herbicide activity for pre- emergence treatments during 1976 corresponds with the low level of preci- pitation received 0 to 2 weeks after application (Table 2). At location 11 there was no significant difference between methods of application during 1976. However, in 1977, the soil incorporated treatments exhibited greater control of yellow nutsedge. The decrease in visual control rating for preemergence treatments during 1977 corresponds with low levels of precipitation received after application. At location 111, for both years, evaluated treatments showed increased activity when soil incorpor- ated. Visual control ratings indicated that soil incorporated 9 acetanilide herbicides consistently provided effective control within each location. The preemergence applications provided effective control on soil low in organic matter content, and when rainfall was received after application. Measurement of stand density provided information that reinforced visual observation. Incorporation of the herbicide into the soil increased yellow nutsedge control at all locations during 1976 and 1977. The visual control ratings indicated a significant increase in yellow nutsedge control from the higher application rates at locations I and II (Table 3). The rate effect was not observed at location 111. The stand density measurements indicated a significant rate effect for all locations and years. The 2x rate, 6.72 kg/ha, provided greater yellow nutsedge control than 3.36 kg/ha. From the visual control ratings and stand density measurements, it appeared that the activity of the acetanilide herbicides on yellow nut- sedge was enhanced by soil incorporation, higher application rates, or when the chemicals were applied to soils containing low levels of organic matter and clay. Yellow nutsedge stand density was monitored during the season to assess population development in the untreated control and to ascertain the effect chemical treatments exert on shoot emergence. The stand density data for the untreated control for all locations and years indicated that yellow nutsedge emerged rapidly during the 2 weeks after application and continued to emerge for the next 8 weeks (Table 5). Therefore, in order to provide effective control, treatments must exert activity throughout this time period. Following statistical analysis and evaluation of significant main effects, it was evident that all 10 herbicide treatments, for all locations and years evaluated, resulted in fewer shoots per m2 than the untreated control 8 weeks after application (Table 5). Metolachlor exhibited the most effective and consistent con- trol for all locations and years 8 weeks after application. Alachlor activity on yellow nutsedge was §_metolachlor and z_H—26910. H-22234 provided the least control of shoot density for all locations and years. H-22234 at location I during 1976 exhibited a break in activity as evidenced by the increase in number of shoots 2 to 8 weeks after applica- tion. During 1977, alachlor and H-22234 at all locations, H-26910 at locations 11 and III, and metolachlor at location 11, lost part of their effectiveness during the evaluation period as shown by the increase in shoots 2 to 8 weeks after treatment. During 1977, the yellow nutsedge population in the untreated controls at all locations exhibited an in- crease in stand density 4 to 8 weeks after experiment initiation. The herbicide treatments were unable to control this late season shoot emer- gence. The loss of activity in 1977 at location 11 and III corresponds with low initial rainfall, which may have facilitated herbicide dissipa- tion. Yellow nutsedge plant height and shoot dry weight were measured for location I to assess herbicide effect on yellow nutsedge plant growth. During 1976 and 1977, the yellow nutsedge shoots in the metolachlor treatments were significantly shorter in height after 8 weeks, 54 and 56% of control, than all other treatments (Table 6). Shoot dry weight reflected plant height (Table 6). There was a significant herbicide by method of application interaction for shoot dry weight during 1976. The treatments showing the greatest reduction in yellow nutsedge shoot dry weight were preplant incorporated metolachlor and alachlor, and ll preemergence applied metolachlor. The treatment resulting in the least shoot dry matter during 1977 was metolachlor. Yellow nutsedge plant height and shoot dry weight was significantly reduced when treatments were applied preplant incorporated during 1977 or when applied at higher rates during 1976 and 1977. Evaluating the acetanilide herbicides with visual ratings, plant height, and shoot dry weight indicated that yellow nutsedge control with metolachlor :_alachlor Z_H-26910 3_H-22234, at location I. The acetanilide herbicides were effective in reducing weed pressure and increasing soybean yield during 1975, 1976, and 1977 (Table 6). During 1976 there was no significant difference in soybean yield among the chemical treatments. However, H-22234, during 1975 and 1976, was less effective in controlling yellow nutsedge as reflected by lower soy- bean yields. Across the 3 years at location I, it appears that treat- ments providing 3_70% visual control of yellow nutsedge consistently in- creased soybean yield versus the weedy control, and that there was no significant difference among these treatments. 10. 11. 12. 12 LITERATURE CITED Armstrong, T.F., W.F. Meggitt and D. Penner. 1973. Yellow nutsedge control with alachlor. Weed Sci. 20:354-357. Armstrong, T.F. 1975. The problem: yellow nutsedge. Proceedings North Central Weed Control Conf. 30:120. Behrens, R. and M. Elakkad. 1973. Yellow nutsedge control in corn. Res. Rept. North Cntr. Weed Cont. Conf. 30:154-155. Bell, R.S., W.H. Lachman, E.M. Rahn and R.D. Sweet. 1962. Life history studies as related to weed control in the northeast. I Nutgrass. Rhode Island Agr. Exp. Sta. Bull. 364. Doane Research Report. Doane Agricultural Service, St. Louis, Mo. Holm, L.G., D.L. Plucknett, J.V. Pancho and J.P. Herberger. 1977. The Worlds Worst Weeds. The University Press of Hawaii, pp. 125-133. Kapusta, G., J.A. Tweedy and C.F. Strieker. 1974. Herbicidal con- trol of yellow nutsedge in soybeans. Res. Rept. North Cntr. Weed Contr. Conf. 31:144-145. Keeley, P.E., R.J. Thullen. 1974. Yellow nutsedge control with soil-incorporated herbicides. Weed Sci. 22:378-383. Ladlie, J.S., W.F. Meggitt and R.C. Bond. 1973. Preplant incor- porated, preemergence and postemergence applications on yellow nutsedge in soybeans. Res. Rept. North Cntr. Weed Contr. Conf. 30:112-113. Stoller, E.W., D.P. Nema and V.M. Bhan. 1972. Yellow nutsedge tuber germination and seedling develOpment. Weed Sci. 20:93—97. Tumbelson, M.E. and Kommedahl. 1961. Reproductive potential of Cyperus esculentus by tuber. Weeds 9:646-653. Wax, L.M., E.W. Stoller, F.W. Slife and R.N. Anderson. 1972. Yellow nutsedge control in soybeans. Weed Sci. 20:194-201. 13 om\m w\o 0mm cmmflnofiz :Hou 0.0 EmoH xmao zucmm coumm HHH Hm\m H\c uwflzm cmonxom H.v EmoH xmfiu coucflfiu HH e~\m e~\m mm\m Sufism emeexem m.~ Edda seed seeem seemeH H seed seed mama seeeee> deem flew edsexee Heem secseu seaweeds bump wcfiucmfim Hounds oficmmno .cmmflcoflz ca meoflpmuofi money we mmcflofinno: mowaflcmpoom mo :owumsaa>o 6>Humnmmeoo ecu pom moumu wcflucmam one .mmono .moflpmfiuouomnmco HHom .H magma 14 ~.ma N.mH o.HH N.m w.m w.m m.o w.o puma v.mH m.HH m.w H.w 0.5 m.v w.m n.~ onma HHH o.HH o.HH w.m m.o m.o o.v m.m o.o nnma c.0H m.m~ o.m~ m.mH m.m o.v m.o m.o mnmfi HH N.HH v.w v.w o.m o.m m.H m.H w.o nnma o.mH m.vH m.m~ o.oH m.v v.H o.H o.H onmfi v.HH n.m n.w N.n N.n o.o w.m o.H mnma H 23 w n o m v m N A use» coaumoog cowpmofiammm Houmm mxooz .nnma can .onmfl .mnma ca :oHumofiHmmm ovflofinno: Houmm mxooz w you mEov coaumufimflooam o>HumH35500< .m oanmh £15 .38. as». .333. m.:ao:=o An ~o>o~ am on» an acouomwfiv xaucmoamflcmflm no: can muouuo~ =OEEou an vozodaow uuommo coauuauoucm no :«aa one sundae a cwzuur acuoxo .aouucoo ouodmsou .Aouucou mo acouuom a mu Na\nuoonm connoumxo aw Auuncov veuum a u oo~ use Houucou o: u o now: «made omaucouuon a co commounxo one mucuuau “cana>a on me enuwwuz a an o~mo~-: 6 en uo~nuu~< 0 cm nouzoaaouo: oucouuoaooum a we cmw-uz vu mu camomuz 0 cm hogan: 6 mm hannoamouo: 63303005 2830.:— cowuuuwnmma mo vogue: x ovfiuwnuoz a mm 6 mm m mm m mv a vw a do 6 mm a me a w n on a mm a mm 5 Na as\ux Nn.o n we a mN a me a ov 2 mm m cm s ov 6 cm n mm a on n we a me a N5 mn\ux on.n can: a cm a mm a we 6 mm a mv a me 3 av m we a mm a as a me a nu oocomuoaooum a no 9 av m cm a em a ow a mo m am m "0 n m a an 6 mm a on voumuonuoucw usaumoum vozuoa ceauauwamm< a an 6 mm u me a mm 6 ov a me o «v 6 mm A an m me n on 6 mm vnmwmsz n on m ON 2 mm an em 9 mm m on on av pm No a o 5 mm m an o~mo~-: m cm 3 mm p cm n we a mm a no on mm n #0 a H” a an m mm 9 mm uo~suu~< a me a me a ON 0 mm 6 mm a me x mm 6 mu m o 6 mm a mm p cm Neanuuuouox ovwownuoz flay flag fiwv Awe flew flew awv flew Hwy flag may as“ flew xufimeov «canon Xufimzov mcfiuau xuwmcov mcfluwu xufimcov mcwpmu xuwmcou mcwumu xuflmcov ucwuwu mcflumu muoomwo venom «chucou venom Houucou venom Houucou venom “ouucoo ucmum Monacou nucmpm douucou Houucou cowuoauouca "mam«> Hmsmfi> Hmsmfl> Hmsmfl> ~w=mfi> Hmsmw> mamsmfi> can can: nnmu onmm nnma ohm" unmm onma mnmu HHH coflumooq HH :owumooq H :oflumuoq o.:o«umuw~mmm “mama mxooz m owwomusc zoaaox mo ~ouucou 629 how movfiuwnuo; ocwflwcmuoua ~auo>om mo :ofiumsam>o o>wuauamsou .n canny 16 Table 4. Activity of several acetanilide herbicides on yellow nutsedge at three locations in Michigan 8 weeks after application. Percent yellow nutsedge controlab Location 1 Location 11 Location 111 sandy clay loam clay loam sandy clay loam Treatment 2.5% OM 4.1% OM 6.0% OM Metolachlor ' 90 g 71 e 57 d Alachlor 80 f 62 d 38 b H-26910 75 ef 55 cd 30 ab H-22234 61 d 47 c 25 a aValues are mean of two years, two rates, two methods of application. bValues followed by the same letter are not significantly different at the 5% level by Duncan's Multiple Range Test. .umoh emcem onHpHsz m.ceo::o xn Ho>oH em ono we economme xHuceonflcme you one whoouoH :oEEoo nuwz :oHueooH one new» cHnon mceozn .HHH one HH m:0HpeooH how meowueoHHmou ooan one H :OHueooH pom mcoHueoHHmoH uzom nqu :OHoeoHHmme Ho moonooe 03p .moueu ozu mo :eoe one monHe>e 17 m mmm on nmm one mmH w mHN mo ovH on 55H Honocou o on non wnH eon moH eon am one mm on ow vmmmwim o omm oeo mew non me on on one He wo HOH onomiz eon me ne HoH e mm on Hm one mm one we HoHnoeH< eon noH won 05H one NNH e ow e mm one mu HoHnoeHouoz HHH e man no mwm o Hum e own o com o mam Houucou o 5mm n wvH e wHH o new on com on owH vmmmmiz o onm n an e mm n onH on mom on mnH chomiz n How e oNH e mm on an n HnH n ovH HoHnoeH< n moH e NoH e um e NHH ne oeH ne mNH uoHnoeHOHoz HH : one e eon e mm o Nam H mom e omm Heeeeeo H mm 6 mm eon Hm o an o How eon HmH vmmmmum eon om no em won Hm one oHH on NNH oeo an onomlz 6 mm non mH on 0H ne em one on ne Hm HoHnoeH< e 0 non NH ne NH ne mm eon mmH eon omH HoHnoeHooo: H neaNE\muoonmv nemme\muoonmv nsosoeoab :OHueoon coaueoHHmme Houme mxooz :oHoeoHHmme nouwe mneoz numH oan .nan one ommH How :oHueoHHmme Heume mxoez w one .v .N .Houoe onesvm Hem muoonm .qumeee ocean oweomusc onHo> .m oHneh 18 .umoh emcem onHuHsz m.:eo::o An Ho>oH em enu we acouom uHHv xHuceonH:MHm no: ope muouuoH :oEEoo xn voonHom uoomwo :oauoepoucfi no :Hee one aszHoo e :Hnuwz mosHe>e o Ne vmmmmu: n on onnNI: e 5H HoHnoeH< e mH HoHnoeHoooz womenomhoocfi pceHmon :OHueoHHmme Ho venues x ooHoHnHoI e weeH e w e me e ooom e we e me e oomH ee\en Ne.e e comH n em e an a sown e mm a me e oowH e:\mn em.» ouem e omen e eH a me e oomH e me e ooeH eeeemeegeeed e ome e NH e me e oowH e HA e oowH eeoeeompoocn oeeHmoHd nonpoe eonueoHHmm< e oonH e com o mm n ommH vmmmmuz on onom n vH n on n oewH n Hm onomim on omom n mH o om n ome o Hm o ommm HoHnoeH< o comm e N e om n ommH e em o ommm HoHnoeHoooz oeHoHnyoz Hee\mnv HHeeeeee we so He;\env HHeeeeee we no He;\mno eHon a: xgu on eHoH» p3 xne on eHon muoommo :eonxom noonm useHm seenxom uoonm oceHm :eonxom :oapoeuouefl nan oan man use :Hez d .:0HoeoHHmme youme exooz w .H coaueooH we nHon :eonxom wee .unMHoz zen noonm .panon uceHm omeomusc onHox :o mocHoHnnon onHHHceuooe Hene>om Ho ooomwm .n eHneH 19 on em vmmmmuz on em onomuz on an noHnoeH< e AH noHnoeHOpoz ooeemnoaooum Hee\wxv HHeeeeee no so Hee\mxv HHeeeeee me we Hee\mxv eHon p3 Hue on eHon p3 Age on eHon muoommo :eonxom uoonm oceHm neenxom poonm useHm :eonxom :oauoeuounH uan oan man one ewe: .meoscwoeoov .o oHneh CHAPTER 2 ACTIVITY OF FOUR ACETANILIDE HERBICIDES ON YELLOW NUTSEDGE (CYPERUS ESCULENTUS L.) ABSTRACT The acetanilide herbicides alachlor [2-chloro-2',6'-diethyl-N: (methoxymethyl) acetanilide], metolachlor [Z-chloro-Nfethyl-6-methy1- phenyl)-N;(2-methoxy-l-methylethyl) acetamide], H-22234 [Nfchloroacetyl- N:(2,6,-diethylphenyl)-glycine ethyl ester] and H-26910 [Nfchloroacetyl- N;(2-methyl-6-ethylphenyl)-glycine isopropyl ester] at 3.5 x 10"6 M did not inhibit yellow nutsedge (Cyperus esculentus L.) tuber sprouting in petri dishes. The herbicides at 3.5 x 10‘6 M and 3.5 x 10‘7 inhibited growth of newly emerging shoots. The viability of yellow nutsedge sprouts decreased with increased exposure to the acetanilide compounds, however, after 192 h exposure, the tubers were not killed. In petri dish studies, there was no significant difference in.activity among alachlor, metolachlor, H-22234, and H-26910 on yellow nutsedge sprouts. Treatments applied to the soil exhibited a significant difference in activity on yellow nutsedge. Metolachlor activity = alachlor 3_H-26910 Z.H'22234: depending on the percent organic matter in the soil. For all herbicides evaluated, activity decreased with increased levels of organic matter in the soil. For acetanilide herbicides to be effective on yellow 20 21 nutsedge they must be in the soil zone, above or at the level of the tuber. INTRODUCTION Herbicide treatments applied to corn (Egg may§_L.) for the control of yellow nutsedge include EPTC (Sfethyl dipropylthiocarbamate] (3), butylate [Sfethyl diidobutylthiocarbamate] (10), atrazine [2-chloro-4- ethylamino)-6-(isopropylamine)-§;triazine] (10), and alachlor [2-chloro- 2',6‘-diethyl-Nf(methoxymethyl)acetanilide] (2). Herbicides applied to soybean (Glycine max (L.) Merr.) which control yellow nutsedge are vernolate [Sfpropyl dipropylthiocarbamate] (12), bentazon [3-isopropyl- leZ,1,3-benzothiadiazin-4-(3H)-one 2,2-dioxide] (6,13) and alachlor. Several reports indicate that the thiocarbamates do not inhibit yellow nutsedge sprouting or kill the tuber (7,9). EPTC effectively suppresses and delays shoot emergence, the delay depending upon rate of application (7,9). The herbicide atrazine does not delay sprouting of yellow nut- sedge, but kills the shoots after emergence (9). Alachlor inhibits growth of newly emerging shoots, but fails to kill the tuber or inhibit sprouting (2,9). The placement of a herbicide in the soil has a significant effect upon its activity in the field. Knake and Wax (11) found that EPTC was lethal to green foxtail (Setaria viridis (L.) Beauv.) when placed in the soil shoot zone but not when placed in the root zone. Butylate placed in the tuber zone was effective in suppressing yellow nutsedge shoot growth and tuber sprouting, but was ineffective when incorporated in the soil above or below the tuber (8). Alachlor controlled yellow nutsedge 22 when applied above the tuber (1,8). The role of soil organic matter on the adsorption and reduction of phytotoxicity of herbicides has been reviewed (14,15). As soil organic matter content increased, higher rates of atrazine were necessary for effective weed control (4,5). Alachlor controlled yellow nutsedge in soil with less than 6% organic matter (2). Recently, new herbicides with structures similar to alachlor have been introduced. The acetanilide compounds metolachlor, H-22234, and H-26910 were developed as selective herbicides for use in corn and soy- beans. The objectives of this study were to evaluate and compare acti- vity of alachlor, metolachlor, H-22234, and H—26910 on yellow nutsedge tuber sprouting, sprout viability, and shoot development, to evaluate the activity of the acetanilide herbicides in the soil, and to determine the effect percent organic matter and soil placement have upon their activity. MATERIALS AND METHODS Yellow nutsedge tubers harvested from the field in East Lansing, Michigan were utilized for greenhouse and laboratory studies. The effect of acetanilide herbicides on tuber sprouting was evaluated in the labora- tory by placing ten tubers in a petri dish with 20 ml of 3.5 x 10'6 M alachlor, metolachlor, H-22234, and H-26910. Petri dishes were placed in a germination chamber at 22C in complete darkness. Seven days after treatment, tubers were examined for number of emerging shoots and rhizomes. Acetanilide activity on shoot elongation was evaluated by exposing one pre sprouted tuber to 3.5 x 10‘6 M, 10’7 M, and 10'8 M 23 concentrations of alachlor, metolachlor, H-22234, and H-26910 in petri dishes placed in a dark chamber at 22C. Shoot length was recorded after 5 days. The effect of exposure time on sprout viability and shoot development was determined by placing one pre sprouted tuber in a petri dish containing 3.5 x 10'6 M alachlor, metolachlor, H-22234, H-26910 for 0, 12, 24, 48, 96, and 192 h. After each exposure period shoot length was recorded; tubers were rinsed for 5 min with distilled water and placed in a petri dish containing only distilled water. Ten days after rinsing, sprout viability and shoot length were recorded. Sprout via- bility was assessed on the resumption of shoot growth. Treatments were maintained in a dark chamber at 22C throughout the duration of the study. The effect of percent organic matter in the soil on acetanilide herbi- cide activity was evaluated in the greenhouse with soil mixtures made with a Conover sandy loam soil 1.7% organic matter, 65.9% sand, 20.6% silt, 13.5% clay, and a muck soil with 81.4% organic matter. Quantities of each soil were mixed in volume ratios to obtain 1.7, 3.2, 5.6, 10.1, and 61.1 percent organic matter. Prior to treating the soil with herbi- cides, one pre sprouted tuber was planted 3.5 cm below the soil surface. Alachlor, metolachlor, H-22234, and H-26910 were sprayed at 3.36 kg/ha to the soil surface. After herbicide application, all treatments were surface irrigated and maintained in the greenhouse with supplemental flourescent lighting for a 16 h day. Soil placement studies utilized a charcoal barrier to separate herbicide treated soil from untreated soil. Alachlor, metolachlor, H-22234, and H-26910 were sprayed at 3.36 kg/ha on a sandy loam soil and incorporated as a batch mix with a portable cement mixer. One pre sprouted tuber was placed in a 1.5 cm band of charcoal for the above and below tuber herbicide treatments. The 24 charcoal barrier was absent for treatments placing the herbicide at the level of the tuber. Predetermined portions of the treated soil were used to establish a 2.5 cm layer of soil above the tuber, with the tuber, or below the tuber. All treatments were surface irrigated and placed in the greenhouse with supplemental lighting for a 16 h day. Yellow nutsedge plants in the organic matter and soil placement studies were harvested, dried, and weighed 6 weeks after application. All laboratory and greenhouse studies were in a randomized complete block design with four replications. All values presented are the means of two experiments with four replications each. RESULTS AND DISCUSSION Yellow nutsedge tuber sprouting was not significantly affected by 3.5 x 10‘6 M concentrations of alachlor, metolachlor, H-22234, or H-26910 (Table 1). Exposure of yellow nutsedge sprouts to 3.5 x 10'6 M, 10'7 M, 10'8 M concentrations of the acetanilide herbicides caused significant inhibition of shoot elongation (Table 2). A dosage response was evident. Yellow nutsedge sprouts exposed to the acetanilide herbicides from 0 to 192 h showed a decrease in sprout viability with increased exposure time (Table 3). However, after 192 h, more than 20% of the tubers were still alive as evidenced by shoot growth. All herbicide treatments inhibited shoot length after each exposure period (Table 4). However, after rinsing the tubers in distilled water, all treatments resumed growth. The shoot regrowth suggests that yellow nutsedge tubers can withstand exposure to the acetanilide herbicides over an extended period of time. Once chemical pressure was removed, the yellow nutsedge plants were 25 capable of continuing their development. There was a decrease in shoot length for all herbicide treatments as exposure time increased. The re- duced shoot length coincided with the lower number of viable sprouts fOllowing 192 h exposure (Table 3). There were no significant differ- ences among the acetanilide herbicides with respect to their activity on yellow nutsedge tuber sprouting, viability, or shoot elongation in petri dishes. All herbicide treatments showed a decrease in yellow nutsedge con- trol as the soil organic matter increased (Figure l). Metolachlor, alachlor, and H-26910 showed equal activity which was greater than H-22234 on the sandy loam soil with 1.7% and 3.2% organic matter (Table 5). As soil organic matter level increased to 5.6% and 10.1%, acetanilide herbicide activity on yellow nutsedge followed in the order: metolachlor = alachlor > H-26910 > H-22234. Herbicide treatments applied to the soil with 61.1% organic matter had little activity on yellow nutsedge, with metolachlor control 3_alachlor Z_H-26910 Z_H-22234 (Table 5). Treat- ments applied above or at the level of the tuber controlled yellow nut- sedge shoot growth (Figure 2). Herbicide treatments applied below the tuber had no significant effect upon shoot development (Table 6). As the yellow nutsedge tuber sprouted, it sent up a rhizome which formed a basal bulb below the soil surface from which originated vegetative shoots, roots, and rhizomes. During the 6 week period following application, yellow nutsedge roots grew but did not penetrate the treated soil zone (Figure 3). This development pattern for yellow nutsedge provided no intimate contact between plant and herbicide treatments applied below the tuber. Alachlor, metolachlor, H-22234, and H-26910 did not prevent yellow 26 nutsedge tuber sprouting or kill the tuber. However, they inhibited shoot elongation when in contact with the sprout. To be effective in the field, the acetanilide herbicides must be applied to soils low in organic matter and be present in the soil zone above, or at the level of, the tuber. To successfully inhibit yellow nutsedge shoot development, these herbicides must be present at a phytotoxic concentration for an extended period of time. 10. 11. 12. 13. 27 LITERATURE CITED Armstrong, T.F., W.F. Meggitt and D. Penner. 1973. Absorption, translocation and metabolism of alachlor by yellow nutsedge. Weed Sci. 21:357-360. Armstrong, T.F., W.F. Meggitt and D. Penner. 1973. Yellow nutsedge control with alachlor. Weed Sci. 21:354-357. Bell, R.S., W.H. Lachman, E.M. Rahn and R.D. Sweet. 1962. Life history studies as related to weed control in the northeast. I nutgrass. Univ. of Rhode Island Agr. Exp. Sta. Bull. 364. Day, B.E., L.S. Jordon and V.A. Jolliffe. 1968. The influence of soil characteristics on the adsorption and phytotoxicity of simazine. Weed Sci. 16:209-213. Hayes, M.H.B. 1970. Adsorption of triazine herbicides on soil organic matter, including a short review on soil organic matter chemistry. Residue Rev. 32:131-174. Hendrick, L.W., M.A. Veenstra and R.E. Ascheman. 1973. Canada thistle and yellow nutsedge control with split applications of bentazon. Proc. North Cent. Weed Contr. Conf. 28:64. Holt, E.C., J.A. Long and W.W. Allen. 1962. The toxicity of EPTC to nutsedge. Weeds 10:103-105. Ingle, E.L. and A.D. Worsham. 1971. Effect of soil placement of several herbicides on yellow nutsedge (Cyperus esculentus) tubers. Proc. Southeast Weed Sci. Soc. 24:188-192. Keeley, P.E. and R.J. Thullen. 1974. Yellow nutsedge control with soil incorporated herbicides. Weed Sci. 22:378-383. Kern, A.D., W.F. Meggitt and R.C. Bond. 1973. Yellow nutsedge con- trol with preplant incorporated and postemergence herbicide treat- ments in corn. Res. Rept. North Centr. Weed Contr. Conf. 30:167. Knake, E.L. and L.M. Wax. 1968. The importance of the shoot of giant foxtail for uptake of preemergence herbicides. Weed Sci. 16: 393-395. Ladlie, J.S., W.F. Meggitt and R.C. Bond. 1973. Preplant incorpor- ated, preemergence and postemergence applications on yellow nutsedge in soybeans. Res. Rept. North Centr. Weed Contr. Conf. 31:112-113. Stoller, E.W., L.M. Wax and R.L. Matthiesen. 1975. Response of yellow nutsedge and soybeans to bentazon, glyphosate and perfluidone. Weed Sci. 23:215—221. 28 14. Upchurch, R.P., F.L. Selman, D.D. Mason and E.J. Kamprath. 1966. The correlation of herbicide activity with soil and climate factors. Weeds 14:42. 15. Upchurch, R.P. and 0.0. Mason. 1962. The influence of soil organic matter on the phytotoxicity of herbicides. Weeds 10:9-14. 29 Table 1. Effect of 3.5 x 10'6 M acetanilide herbicide on yellow nutsedge tuber sprouting after 7 days exposure. Treatment Percent sproutinga Metolachlor 34.0 a Alachlor 36.3 a H-26910 40.0 a H-22234 41.2 a Control 41.3 a aValues followed by the same letter are not significantly different at the 5% level by Duncan's Multiple Range Test. 30 Table 2. Effect of several acetanilide herbicides on yellow nutsedge shoot elongation after 5 days exposure. Herbicide concentration (3.5 x) Treatment 10‘6 M 10“7 M 10'8 M (mm/shoot)a Metolachlor 3.2 a 12.1 b 28.8 cd Alachlor 3.6 a 12.3 b 30.9 cd H-26910 3.2 a 16.3 b 30.5 cd H-22234 3.6 a 15.3 b 28.1 c Control 36.4 d 33.0 cd 30.1 cd aValues followed by the same letter are not significantly different at the 5% level by Duncan's Multiple Range Test. 31 Table 3. Effect of exposure time of tubers and sprouts to 3.5 x 10‘6 M acetanilide herbicides on yellow nutsedge sprout viability. Exposure time (h) Treatment 0 12 24 48 96 192 (% viable)a Metolachlor 100 c 100 c 100 c 50 ab 38 ab 25 a Alachlor 100 c 100 c 100 c 75 be 50 ab 23 a H-26910 100 c 100 c 100 c 50 ab 63 ab 23 a H-22234 100 c 100 c 100 c 75 bc 37 ab 25 a aValues followed by the same letter are not significantly different at the 5% level by Duncan's Multiple Range Test. .umoe emcex onHoHsz m.:eo::o xn Ho>oH em on» we neonommno prceonmncme no: one nopnoH osem on» an ooonHom mosHe>o .nooez eoHHnnmno an mcnmcnn one enamomxo Eonm nonzu mnn>oEon nopwe oxen oH nnmcoH noonm mouecwnmoe mOm< 39 Figure 3. Yellow nutsedge shoot, root, and rhizome development in the soil, 6 weeks after tuber germination. 40 ‘l. _ ABOVE BELOW CHAPTER 3 PERSISTENCE AND MOBILITY OF SEVERAL ACETANILIDE HERBICIDES IN THREE MICHIGAN SOILS. ABSTRACT The acetanilide herbicides alachlor [Z-chloro-Z',6'-diethy1-§7 (methoxymethyl) acetanilide], metolachlor [2-chloro-E:(2-ethy1-6-methy1- pheny1)-N-(Z-methoxy-l-methylethyl) acetamide], H-22234 [§;chloroacety1- g:(2,6,-diethy1phenyl-glycine ethyl ester], and H-26910 [§;chloroacety1-‘ 5f(2-methy1-6-ethy1pheny1)-glycine iSOpropyl ester] were applied preplant incorporated or preemergence at 3.36 kg/ha and 6.72 kg/ha at three loca- tions in Michigan. The rate of dissipation in the O to 8 cm soil depth for the herbicides indicated the half life of metolachlor :_H-26910 :_ H—22234 z_alachlor. The greatest soil persistence 8 weeks after appli- cation was exhibited by metolachlor and H-26910 for all years and loca- tions evaluated. Significant interactions for method of application indicated that the rate of dissipation was slower and persistence was longer for soil incorporated treatments. The concentration of herbicide applied to the soil did not effect dissipation rate. However, for all dates sampled, greater residues were detected in the treatments receiving 6.72 kg/ha. Trace amounts of herbicide were detected at the 8 to 16 cm soil depth. Movement of the acetanilide chemicals on silica gel plates 41 42 indicated increased adsorption and lower water solubility for H-22234 as compared to the other herbicides. Mobility on soil thin layer chromato- graphy plates was as follows: metolachlor = alachlor > H-22234. All treatments exhibited a decrease in mobility as soil organic matter and clay content increased. There was no significant difference amont treatments with respect to their lateral diffusion on soil thin layer chromatography plates. INTRODUCTION The acetanilide herbicides alachlor, metolachlor, H-22234, and H-26910 were developed as selective preemergence herbicides for use in corn (Zea mays L.) and soybean (Glycine max (L.) Merr.). It has been reported that these compounds provide yellow nutsedge (Cyperus esculentus L.) control (1,3,8,13,19). Keely and Thullen (14) report that alachlor delayed sprouting of yellow nutsedge tubers and provided 6 to 12 weeks control, but failed to kill tubers. Tubers appears to escape injury by failing to sprout until activity of the herbicide had substantially dissipated. Alachlor inhibited shoot development; however, when its pressure was removed, shoots resumed growth (1,14). Knowledge of persistence and distribution of a herbicide in the soil is desirable for predicting its effectiveness. Herbicides should have sufficient residual activity to maintain weed control, then decompose to harmless products. The movement of chemicals in the soil is important because it results in their placement in the soil horizon. Movement of a herbicide in the soil may result in enhanced or diminished weed control, depending upon the nature of its movement. Soil applied herbicides should 43 have sufficient mobility to move into the soil, around germinating weeds. The acetanilide herbicides are used extensively in the United States, their effectiveness on yellow nutsedge being dependent on their presence in the soil (14). In the laboratory, alachlor degradation in the soil by microbial (4,5,6,16,l7) and physical (9) mechanisms has been evaluated. Chou (6,7) and Beestman and Deming (4) report the half life of alachlor to be 2 to 14 days. Information available on the persistence and mobi- lity of the acetanilide herbicides in the field is limited. The objec- tives of this study were to evaluate the persistence and mobility of alachlor, metolachlor, H-22234, and H-26910 in the field and to compare their movement in the same soil under controlled laboratory conditions. MATERIALS AND METHODS Field studies were designed to evaluate the persistence and mobility of several acetanilide herbicides in the soil. Alachlor, metolachlor, H-22234, and H-26910 were applied preplant incorporated or preemergence at 3.36 kg/ha and 6.72 kg/ha. Several locations in Michigan were selected for soil texture, soil organic matter content, and degree of yellow nutsedge infestation during 1976 and 1977 (Table 1). Location I, in Ingham county, was planted to 'Swift' soybeans and treatments applied May 26 during 1976 and 1977. Location 11, in Clinton county, was planted to 'Swift' soybeans and treatments applied June 1 in 1976 and May 21 in 1977. Location III, in Baton county, was planted to 'Michigan 396' corn and treatments applied June 8 in 1976 and May 20 in 1977. Treatments were applied with a tractor mounted sprayer delivering 215 l/ha to 3 by 12 meter plots. Crops were planted with rows spaced 76.2 cm apart with 44 4 rows per plot. The preplant incorporated treatments were incorporated, within 15 min after application, with a spring tooth harrow, twice in opposite directions. Precipitation data following application is pro- vided in Table 2. A randomized block design with three replications was utilized at all locations. Soil samples were taken from the 0 to 8 cm depth, 0, 2, 4, and 8 weeks after application. Fifteen samples per plot were taken between the two middle rows. Soil samples were prepared for extraction by thoroughly mixing and passing through a 2 mm screen. One hundred gram samples of soil were moistened with water to form a slurry and let equilibrate 12 h. Acetanilide residues were extracted by vigorous shaking for 30 min with 50 ml of hexanezacetone (9:1, v/v). After allowing the soil to settle, soil and extract was dried with 10 g of anhydrous Na2804, decanted, and evaporated to 1 ml. Metolachlor samples for location III required additional cleanup through an alumina column according to procedures received from the CIBA GEIGY Corporation. Gas liquid chromatography (glc) was done with a Tracor S60 gas chromatograph equipped with a flame ionization detector. Operating temperatures for injector, column, and detector were 210, 200, 230 C, respectively. Carrier gas flow rate was 40 ml/min. The column used was 2 m by 2 mm (i.d.) glass, packed with 3% OV-l on 100 to 120 mesh Gas Chrom Q. Re- covery from soil, after 30 min equilibration in the dark, for all acetanilide herbicides was greater than 85%. Detection limit in the soil was 0.03 ppm. Acetanilide mobility in three soils was determined according to the soil thin layer chromatography procedure described by Helling (10,11). The soils evaluated were the same as in the residue study (Table l). 45 Soil thin layer plates 20 cm by 20 cm were coated with 500 u thick layer of each of the soils using a thin layer chromatographic spreader. The plates were air dried then spotted 2 cm from the bottom with 0.2 uCi/spot and 0.02 mg/spot of 14C-alachlor, 14C-metolachlor, 14C-H-22234. Herbi- cide mobility was evaluated on a weight-weight and count-count basis to account for differences in specific activity among the chemicals (ala- chlor 1.7 mCi/mM, metolachlor 4.6 mCi/mM, H-22234 1.2 mCi/mM). The plates were chromatographed ascendingly 15 cm above the origin with dis- tilled water. The plates were air dried for 24 h and radioautographed. The RF value was measured at the front of the corresponding spot or streak shown on the radioautogram. RS values, as described by Rhodes (15), were determined as the distance moved by the bottom of the spot divided by the distance traveled by the eluant. Lateral diffusion of the herbicides was obtained by dividing the width of the spot at its 14C-labeled herbicides widest point by width of the applied spot (14). were spotted on silica gel GF plates, 0.2 uCi/spot, and eluted with dis- tilled water ascendingly. All thin layer chromatography studies were replicated four times and repeated twice. RESULTS AND DISCUSSION Soils at locations I, II, and III examined for herbicide residues at the 0 to 8 cm depth exhibited significant date by herbicide interac- tions during 1976 and 1977 (Tables 3, 4, S). Acetanilide herbicide resi- dues in the soil decreased from 0 to 8 weeks after application. The rate of dissipation, expressed as half life, varied amont treatments. At location I, metolachlor and H-22234 for both years, and H-26910 in 1976, 46 exhibited half lives of 2 to 4 weeks (Table 3). Alachlor for both years, and H-26910 during 1977, exhibited half lives of 0 to 2 weeks. At loca- tion 11, the half life of metolachlor was 4 to 8 weeks during 1976, and 2 to 4 weeks during 1977 (Table 4). H-26910 and H-22234 exhibited 0 to 2 week and 2 to 4 week half lives during 1976 and 1977, respectively. Alachlor showed rapid degradation during both years with a half life of 0 to 2 weeks. For location III, metolachlor and H-26910 during both years, and H-22234 in 1977, exhibited half lives of 2 to 4 weeks (Table 5). Alachlor for both years, and H-22234 during 1976, had 0 to 2 weeks (Table 5). Alachlor for both years, and H-22234 during 1976, had 0 to 2 week half lives. These results agree with laboratory results by Chou (6,7) and Beestman and Deming (4), who determined alachlor half life to be 2 to 14 days. There was little change in rate of dissipation between locations as soil type changes and organic matter increased. This supports the findings by Chou that organic matter additions fail to increase rate of alachlor degradation. Herbicide persistence in the soil was expressed as residue remaining in the soil 8 weeks after application. The most persistent compounds for all locations and years were metolachlor and H-26910 (Tables 3, 4, 5). Residues in the soil greater than 1.2 ug/g at location 1, 0.6 ug/g at location II, and 1.6 ug/g at location III were detected for metolachlor and H-26910. Although the half life of H-22234 was comparable to meto- lachlor and H-26910, the residue after 8 weeks was significantly less. The low levels detected for alachlor at the 0 to 8 cm depth 8 weeks after application corresponds to its rapid dissipation rate. There was a significant date by method of application interaction for all locations during 1976 and 1977 (Tables 3, 4, S). Residue samples 47 taken immediately after application indicated that acetanilide residues were greater in the 0 to 8 cm soil depth when applied preemergence. In- corporation served to distribute the herbicide below 8 cm, thus reducing concentration in the 0 to 8 depth immediately after application. Regard- less of method of application, all treatments for all years and locations showed a decrease in residue 0 to 8 weeks after application. The rate of dissipation between methods of application was not equal. Preplant incorporated treatments exhibited a 4 to 8 week half life for all loca- tions during 1977, and location III in 1976. The half life for incor- porated treatments was 2 to 4 weeks and 0 to 2 weeks at locations I and II, respectively, during 1976. Preemergence treatments for both years at locations I and III exhibited half lives of 0 to 2 weeks. Location II preemergence application showed a 0 to 2 week and 2 to 4 week half life during 1976 and 1977, respectively. The slower dissipation rate for preplant incorporated treatments is reflected in a longer half life and greater residue 8 weeks after application. For all locations and years, the acetanilide herbicides exhibited greater persistence in the soil when incorporated. The increased dissipation rate and decreased persis- tence for preemergence treatments was the result of their exposure to environmental influences on the soil surface. There was a significant date by herbicide rate interaction during 1976 and 1977 for all locations (Tables 3, 4, 5). Treatment rates of 3.36 kg/ha and 6.72 kg/ha showed a decrease in soil residue 0 to 8 weeks after application. However, fer each sample date, soil residues were greater for the 6.72 kg/ha rate. Eight weeks after application for all locations and years, the most persistent treatment was 6.72 kg/ha. Herbicide dissipation rate in the soil was not affected by herbicide 48 rate. The half lives for 3.36 kg/ha and 6.72 kg/ha were the same within each year and location. Persistence of the acetanilide herbicides was evaluated at the 8 to 16 cm soil depth for three locations. There was no significant differ- ence in residue level among metolachlor, alachlor, H-26910, and H-22234. However, for all locations, there was a significant main effect for weeks after application and herbicide rate (Table 6). All locations during 1976 and 1977 exhibited a decrease in soil residue 2 to 8 weeks after application. The acetanilide herbicides were present in the 8 to 16 cm soil depth for all sample dates in trace amounts. The low residue level detected at this depth correlates with low levels of precipitation re- ceived for all locations during 1976 and 1977 (Table 2). The significant rate main effect at 8 to 16 cm indicated greater residues for the 6.72 kg/ha treatments. The leaching of herbicides through the soil results in the placement of the chemical and may determine its efficacy (l8). Adsorption strongly influences movement while the depth of movement is dependent upon soil properties and rainfall received (12). Adsorption governs movement, whereas organic matter, clay, and pH effect adsorption. Increased solu- bility appears to correlate with decreased adsorption (12). The acetani- lide herbicides were spotted on silica gel thin layer chromatography plates and eluted with distilled water. The polysilicic gel was capable of hydrogen bonding and cation exchange. Movement of the herbicides on the silica gel provided information regarding structural differences and water solubility. Chemical movement on silica gel is primarily an adsorption-desorp- tion process. There were substantial differences in mobility among the 49 herbicides evaluated (Figure l). H-22234 exhibited the smallest RF and RS values (Table 7). Evaluating the structure of H-22234, an ester group is evidenced in the R-Z position (Figure 2). This additional carbonyl facilitated increased adsorption to the silica gel. Water competes with the chemicals for active sites on the silica. H-22234 was adsorbed the greatest and had the lowest water solubility, therefore, water did not displace it readily. This resulted in extensive tailing for the chemical on silica gel, as evidenced by a zero RS. Metolachlor exhibited the greatest mobility and least tailing on silica plates. The increased movement was the result of decreased adsorption. Therefore, this com- pound was displaced readily by water and moved as a compact band with the eluant. Alachlor has an ether group at the R-2 position, therefore, it will be adsorbed less tightly than H-22234. However, alachlor does not have methyl groups protecting its ether as does metolachlor. The RF value for alachlor was equal to metolachlor and greater than H-22234, while its RS value was intermediate between the two herbicides. Helling (10,11) and Rhodes (15) utilized soil thin layer chromato- graphy plates as a quantitative indication of herbicide mobility. The RF value is a measure of the maximum distance a chemical will move through the soil, when a given amount of water is applied. The mobility of a herbicide in the soil is governed by its adsorption.. Metolachlor and alachlor exhibited greater mobility than H-22234, in all soils evaluated (Table 8). The soil RF values of metolachlor = alachlor > H-22234 agree with the results obtained on silica gel. The carbonyl group, for H-22234, in the R-2 position, increases its adsorptive capacity to soil, subse— quently decreasing its mobility in the soil. All of the herbicides exhi- bited substantial tailing, as evidenced by a zero RS (Figure 1). This 50 distribution pattern in the soil was the result of herbicide adsorption to the organic matter and clay fractions. It has been reported that soil organic matter and clay content positively correlate with herbicide adsorption (12,18). All acetanilide treatments exhibited a decrease in mobility as the soil organic matter and clay content increased. Increas- ing the clay content or organic matter level in the soil increased the number of adsorptive sites. thereby decreasing herbicide mobility. Herbicides should have sufficient residual activity to accomplish control, then decompose to innocous products. Compounds with the greatest persistence are capable of affecting germinating weeds over an extended period of time. The movement of chemicals in the soil results in their placement in the soil and availability to germinating weeds. These studies indicate that metolachlor had the greatest persistence and mobility of the acetanilide herbicides evaluated. The effectiveness of metolachlor on yellow nutsedge was enhanced by the combination of greater persistence and greater mobility. H—26910 exhibited substantial persistence in the soil 8 weeks after application. The mobility of H- 26910 in the soil was not evaluated, however, based on its low water solubility and ester group at the R-2 position, its movement is suspected to be comparable to H-22234 (Table 7). Alachlor did not exhibit great persistence in soil, however, it was among the most mobile compounds in the soil. H-26910 and alachlor exhibited only one of the qualities of persistence or mobility, which may explain their effective but erratic activity on yellow nutsedge in the field. H-22234 did not exhibit either persistence or mobility in the soil, and provided poor yellow nutsedge control. 10. 11. 12. 13. 14. 51 LITERATURE CITED Armstrong, T.F., W.F. Meggitt and D. Penner. 1973. Yellow nutsedge control with alachlor. Weed Sci. 20:354-357. Bailey, G.W. and J.L. White. 1970. Factors influencing the adsorp- tion, desorption and movement of pesticides in soil. Residue Rev. 32:29-92. Behren, R. and M. Elakkad. 1973. Yellow nutsedge control in corn. Res. Rept. North Centr. Weed Contr. Conf. 30:154-155. Beestman, G.B. and J.M. Deming. 1974. Dissipation of acetanilide herbicides from soils. Agron. J. 66:308-311. Chahal, D.S., I.S. Bons and S.L. Chapra. 1976. Degradation of ala- chlor [-chloro-N;(methoxymethyl)-2',6'-diethy1 acetanilide] by soil fungi. Plant and Soil. 45:689-692. Chou, Sheng-Fu J. 1974. Biodegradation of alachlor [-chloro-Z',6- diethyl-Nf(methoxymethyl) acetanilide] in soils. M.S. Thesis, Michigan State University, Dept. of Crop and Soil Sci. Chou, Sheng-Fu J. 1977. Fate of acylanilides in soils and poly- brominated biphenyls (PBB's) in soils and plants. Ph.D. Thesis, Michigan STate University, Dept. of Crop and Soil Sci. Cornelius, A.J., W.F. Meggitt, R.C. Bond and R.E. Stearns. 1977. Response of yellow nutsedge to acetanilide herbicides in corn and soybeans. Res. Rept. North Centr. Weed Contr. Conf. 34:360. Hargrove, R.S. and M.G. Merkle. 1971. The loss of alachlor from soil. Weed Sci. 19:652-654. Helling, C.S. 1971. Pesticide mobility in soils I. Parameters of thin layer chromatography. Soil Sci. Soc. Amer. Proc. 35:732-737. Helling, C.S. 1971. Pesticide mobility in soils 11. Applications of soil thin layer chromatography. Soil Sci. Soc. Amer. Proc. 35: 737-748. Helling, C.S., P.C. Kearney and M. Alexander. 1971. Behavior of pesticides in soils. Advan. Agron. 23:147-240. Kapusta, G., J.A. Tweedy and C.F. Strieker. 1974. Herbicidal con— trol of yellow nutsedge in soybeans. Res. Rept. North Centr. Weed Contr. Conf. 31:144-145. Keeley, P.E. and R.J. Thullen. 1974. Yellow nutsedge control with soil incorporated herbicides. Weed Sci. 22:378-383. 15. 16. 17. 18. 19. 52 Rhodes, R.C., I.J. Belasco and H.L. Pease. 1970. Determination of mobility and adsorption of agrichemicals on soils. J. Agr. Food Chem. 18:522-528. Smith, A.E. and D.V. Phillips. 1975. Degradation of alachlor by Rhizoctonia solani. Agron. J. 67:347-349. Tiedge, J.M. and M.L. Hagedorn. 1975. Degradation of alachlor by a soil fungus, Chaetomium globosum. J. Agri. Food Chem. 23:77-81. Upchurch, R.P. 1966. Behavior of herbicides in soil. Res. Rev. 16:46-85. Wax, L.M., E.W. Stoller, F.W. Slife and R.N. Anderson. 1972. Yellow nutsedge control in soybeans. Weed Sci. 20:194-201. 53 Table 1. Characteristics of soils taken from the Ap horizon, 0 to 16 cm, at three locations in Michigan for soil residue studies. Organic Mechanical analysis Location Soil texture matter Sand Silt Clay pH (%) (%) I Sandy clay loam 2.5 60.2 12.0 27.8 6.3 11 Clay loam 4.1 40.2 24.0 35.8 6.6 III Sandy clay loam 6.0 46.2 18.0 35.8 6.7 S4 N.mH ~.mH o.HH N.n w.m w.m m.o w.o shad v.~H m.HH m.w H.w m.m m.v w.m m.m onmd HHH o.HH o.HH m.m m.o m.o o.v m.~ o.o 55mg o.o~ m.m~ o.m~ m.m~ m.m o.v m.o m.o cnma HH ~.~H v.w v.w o.m o.m m.~ m.H w.o unma o.m~ m.vH m.m~ o.oH m.v v.H o.H o.H onma H 23 w n o m v m m H new» :oflumooq cofiumoflwmmm youmm mxooz .nnma can ouma mcwnso :owumowammm ovfiofinho: nevus mxooz w you :ofiumpfimfiooum o>flumasa:oo< .N oHnmh 55 .mconneonnmon oonnn .=0nneonnmme mo moonnoe ozn .mneonEogo nsom mo ceoa on» one moane> v .m:0nneonnmon oongn .mouen ozu .mneunaocu nsom mo :eoe on» one moane>o .m:0nneonnmon ooncu .conueonnmme mo muonuoa ozu .mouen ozn mo :eoa one one moane> wm one we aconoMan xnnceonmncwnm no: one noommo :nea one a .umon omcem oamnnnsz m.:eo::o no ~o>on neox annunz nouuoa oaem ogu no vozonnom moane>e u mm.n o on.~ m mm.m e ne.n u eo.n e m~.n m oe.~ : nN.e ee\ex mn.e e oo.o a mm.n e ow.n o ne.m e vm.o n on.o o mm.n o n~.~ ee\ex om.m woug ovfluwnhoz X mama e en.o o He.n a em.~ m em.n e mo.o o em.o u ee.n o em.4 ooeomnoaoona a en.n e AH.N we me.m o om.~ n mm.o a om.o e a~.N o mm.n eouenoenooen unenmonm onenneonnmm< mo cacao: x open e ov.o a An.n woe o~.~ en ne.m e mm.o ea Hm.o eo en.n em ne.~ noneoen< e em.o oeu mo.~ we ne.~ an HA.4 e mm.o a Ne.o o ee.n m mn.m emNNN-: a 4N.n eu we.n moo me.~ fin eo.m ea Hm.n eon oo.n o mm.~ e mm.~ enme~-: o we.n em me.~ e em.m en nn.o e n~.n ea An.n we mn.m e mm.m noneuenoooz DOVMUHn—HQI X OHNQ emm\mnv enm\env m e N o e e N o pacemo conneonnmme nonme exooz conueondmmm nopme exooz conuoenoucn Anon enmn use enez .ncoaueonn nonwe mgooz m .H conneooH .nounee oncewno wm.~ anew EeoH xeno necem e an Eu w on o movnonnno: ovnnncenooe Heno>om mo ooaoumnmnom .m onneh S6 .mconpeonoaon oonon .:0nueonomme mo meooooe oz» .mneoneooo nsow mo :eos oon one moane>Ho .mconneunnmon oonon .monen oz» .mneonaooo nzom mo :eoa on» one moane>o .m:0nneonomon oonou .conneonnmme mo mooonoa oz» .mouen ozu mo :eoa oou one mo3He>o om oon we uaonommnw nnuceoancmnm no: one uoommo ones use .umoe oweem onmnnosz m.:eo:=o no Ho>on neon swoon: nonuon oeem oon no vozoooom moane>e o Hm.o o Hm.~ w vm.m o o~.o o no.o o oo.o o nm.n m wo.m eo\mx ~n.o e mm.o o HH.H e vo.o m Ho.m e mm.o o mn.o e no.n m no.~ eo\mx om.m wonem ounononoz x oueo e me.o o mm.~ o mw.~ m mo.m e mm.o o om.o e He.n o oo.v oocownoaoonm o Hw.o e eo.~ e mo.~ w no.m o wm.o v ov.o v on.n o on.m conenonnoocn unenmonm ozonueonnmm< mo econoz x one: e om.o o me.n ow -.~ m mc.e e no.o o om.o woo wn.c m mm.m noHooeH< e nv.o o mv.n ow Hm.m w on.e e mm.o v oo.o o om.~ m mo.m vmmmmnz o ww.o ow mH.N o oo.m m om.v oo No.o v mH.H o no.n w nm.v OnmoNu: o mm.o on on.n ow mm.m m mo.e we em.o mo no.~ m me.~ m ow.m noHooeHonoz ooononono: x open .33 .33 w v N o w e N o uoommo canneonnmme nopme exooz cenneonnmme noume moooz connoenonen nnmo onmo one one: .ocosneonn noume exooz m .HH conneooH .nonuee oncewno wo.v onom eeon neoo e :n so w on o movnunonoo ownnnceuooe neno>om mo oocoomnmnom .v onoeh S7 .mconneonnmon oonon .conueonnmme mo mooonoa oz» .mneonsooo noom mo :eos oon one mosne> .moonueonnmon oonou .conueonnmme mo mooonoa o3» .mouen 03» mo :eoa oou one mo=~e> v .mconneonnmon oonon .mouen ozu .mneonaooo noom mo :eoa on» one moone>o o .umoe omcmm onmnnnsz m.:eo::o no no>on em on» we poonoMMno nauseonmncwnm no: one noommo ones woe neon :nounz nouuon oeem oon no oozonnom moane>e o Nm.n o oo.m m em.v w em.n o oe.n o Hm.n w em.m o mn.o eo\wx Nn.o e ew.o o we.n o mN.N o mm.m e Nn.o o No.n o mn.N w eo.e eo\wx om.m eoped oononono: x oueo e em.o o oo.n eo nm.m o No.0 e nw.o o ne.n o mm.N o mm.n oocomnoEoonm o mm.n o nw.N o mN.m o mN.e o mN.H o Nm.n o m~.m o mw.N eonenomnoocn unenmonm oconneonnmm< mo ooonoz x oueo e oo.o oe mm.n oo mo.N o mw.o e Hm.o oe eo.n ooo mm.n Mm on.e nonooen< e mn.o o wn.n oo mo.m oo No.m e nn.o oe mn.n ooo on.N N nn.m vmmNNuz o mo.n oo No.m eo mo.e o Nn.m oo mo.n woo Nw.n mo mm.m m wn.m onoNu: o mm.n oo oo.N o me.m oo wm.m oo mm.n ooo Hm.n ow em.N mm oo.v nonooenonoz o non no x o e emm\mnv emw\mnv o o. .o I u o m e N o w e N o . poowmo conneonnmme nonme exooz conueoewmme nonwe moooz connoenouon nnmn onmn woe one: .ncoEueonp nonme exooz w .HHH :onneoon .nonuee onoewno No.0 nnom Eeon neno nocem e on so w on o moenononoo oeanoenooe neno>om mo oocoumnmnom .m oooee 58 .mfivwmmh QHDNHUQHMUIfiOd mQHMfiMflmOfl DZU .m:onneonnmon oonon o:e moneo o3n .:onneonnmme mo mooonoe ozn .mneonsooo noom mo :eoa oon one moone>o .m:onneonnmon oonon o:e monen 03n .:onneonnmme mo mooonoa o3n .mneonaooo noom mo :eoe oon one moane> om oon ne n:onoMMno nnn:eonmn:mnm no: o .nmoh om:e¢ onmnnnzz m.:eo:=o no no>on one noommo :nee o:e neon :nonnz nonnon oeem oon no oozonnom moone>e o oo.o o mo.o o mo.o o mo.o o oo.o o mo.o eo\ex on.o e mo.o e oz e no.0 e oz e vo.o e oz eo\mn em.m omumh OVHOHDHOI e oz e oz e oz e oz e oz e eoz o o on.o e oz o mo.o e oz o oo.o o mo.o v o on.o o on.o o oo.o o eo.o o no.o o eo.o N enm\mnv enw\mnu emw\m1v :onneonnmme nonme mxooz noon enon nnon onon nnon enon . nueooo HHH :onneooo HH :onneooo H :Onneooo :onnoenon:n o:e :nez m:onneoon oonon now :onneonnmme nonwe exooz w .onmoo anom go on on w oon ne oo:onmnmnom oononono: .moonononoo oonnn:enooe nsom no>o oomeno>e .nnmn o:e coon m:nn:o :emnoonz :n .o «noen 59 Table 7. l4C-acetanilide herbicide mobility on silica gel GF thin layer chromatography plates.a Treatment RFb RSC Metolachlor 0.79 b 0.55 c Alachlor 0.79 b 0.34 b H-22234 0.70 a 0.00 a aValues followed by the same letter within a column are significantly different at the 5% level by Duncan's Multiple Range Test. bRF value was measured at the front of the spot on the radioautogram. cRS value was measured at the bottom of the spot on the radioautogram. 60 Table 8. 14C-acetanilide mobility on soil thin layer chromatography plates.a Soil texture and organic matter sandy clay loam clay loam sandy clay loam Treatment 2.5% OM 4.1% OM 6.0% OM b (RF) Metolachlor 0.30 f 0.27 e 0.23 d Alachlor 0.29 f 0.27 e 0.21 cd H-22234 0.20 c 0.19 b 0.14 a aValues followed by the same letter are not significantly different at the 5% level by Duncan's Multiple Range Test. bRF value was measured at the front of the spot on the radioautogram. 61 Figure l. Radioautograph of 14C-alachlor, 14C-metolachlor, 14C-H-22234, movement on (A) silica gel GF, and (B) soil, thin layer chromatography plates, eluted with water. 62 onNNN.: IOJZU‘JOFU! 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Effect of several acetanilide herbicides on yellow nutsedge plant height 8 weeks after application. Plant Height Treatment 1976 1977 O 6 of control)a Preplant incorporated 3.36 kg/ha Metolachlor 62 52 H-26910 74 69 Alachlor 79 73 H-22234 89 80 Preemergence 3.36 kg/ha Metolachlor 56 61 H-26910 73 78 Alachlor 85 99 H-22234 86 99 Preplant incorporated 6.72 kg/ha Metolachlor 46 53 H-26910 70 63 Alachlor 79 69 H-22234 77 > 66 Preemergence 6.72 kg/ha Metolachlor 51 54 H-26910 68 71 Alachlor 83 77 H-22234 79 86 aValues are the mean of four replications. 82 APPENDIX C Table G-l. Effect of several acetanilide herbicides on yellow nutsedge shoot dry weight 8 weeks after application. Shoot Dry Weight Treatment 1976 1977 (% of control)3 Preplant incorporated 3.36 kg/ha - Metolachlor l7 2 Alachlor 27 12 H-26910 30 6 H-22234 53 44 Preemergence 3.36 kg/ha Metolachlor l7 3 Alachlor 38 33 H-26910 38 39 H-22234 41 45 Preplant incorporated 6.72 kg/ha Metolachlor 10 l Alachlor 8 4 H-26910 29 3 H-22234 33 25 Preemergence 6.72 kg/ha Metolachlor 18 l Alachlor 39 10 H-26910 39 8 H-22234 28 12 aValues are the mean of four replications. APPENDIX H Table H-l. Effect of several acetanilide herbicides on soybean yield on a sandy clay loam soil 2.5% organic matter. Soybean Yield Treatment 1975 1976 1977 (kg/ha x 1000)a Preplant incorporated 3.36 kg/ha Metolachlor 2.21 2.22 2.48 Alachlor 2.04 2.15 2.12 H-26910 1.93 1.75 H-22234 1.66 2.10 1.83 Control 1.09 0.90 1.58 Preemergence 3.36 kg/ha Metolachlor 2.27 1.81 ,l.95 Alachlor 2.31 1.78 2.07 H-26910 1.69 2.24 H-22234 1.57 1.74 2.03 Control 1.08 0.89 1.82 Preplant incorporated 6.72 kg/ha Metolachlor 2.16 2.01 2.07 Alachlor 2.17 2.30 2.01 H-26910 1.98 2.05 H-22234 2.02 2.03 1.75 Control 1.09 0.90 1.58 Preemergence 6.72 kg/ha Metolachlor 2.27 1.84 2.53 Alachlor 2.46 1.75 2.02 H-26910 1.76 2.21 H-22234 2.44 1.50 2.11 Control 1.08 0.89 1.82 aValues are the mean of four replications. 84 APPENDIX I Figure I-l. Yellow nutsedge development, 6 weeks after treatment with 3.36 kg/ha (A) alachlor, (B) metolachlor, (C) H-26910, (D) H-22234, applied to soil above the tuber, on the tuber, or below the tuber. .4...wa ZO 8S 3mm ZO ZO w>0m< m .. 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lateral diffusion on soil thin layer chromatography plates. Soil texture and organic matter sandy clay loam clay loam sandy clay loam Treatment 2.5% OM 4.1% OM 6.0% OM (mm) Metolachlor 24 27 26 Alachlor 25 26 26 H-22234 26 28 28