CIRCULAR 165 JANUARY 1969 WEED CONTROL in SERICEA LESPEDEZA ~t~:-~"li ~ ~;g~ -31'. :~~:: " ,: :-. Agricultural Experiment Station AUBURN UNIVERSITY E V. Smith, Director Auburn, Alabama CONTENTS Page EXPERIMENTAL PROCEDURES 4 4 11 RESULTS AND DISCUSSION SUMMARY AND CONCLUSIONS LITERATURE CITED_ 13 15 APPENDIX FIRST PRINTING 3M, JANUARY 1969 WEED CONTROL in SERICEA LESPEDEZA G. A. BUCHANAN, Asst. Professor of Agronomy and Soils E. R. BURNS, Instructor of Agronomy and Soils ERICEA LESPEDEZA (Lespedeza cuneata L.) is a summer perennial legume grown in the Southeast for hay, pasture, and soil conservation (6). It is valuable in this area because of its ability to make substantial growth on relatively poor soil (1). Studies at Auburn University Agricultural Experiment Station of fine-stem lines of sericea have led to the development and release of the Serala variety (2,3,4). Serala offers promise for increasing sericea acreage in Alabama. Sericea seed are small and produce weak seedlings. Also, stands are usually established during early spring when conditions favor rapid growth of weeds. Because of the poor competitive ability of sericea seedlings, weed control is a major problem during establishment. Although better stands of sericea can be obtained by broadcast seeding than by drill seeding (8), weeds still offer severe competition during the first year. Considerable research has been directed toward controlling weeds in clover and other small-seeded legumes. Lee (7) and Schrieber (9) reported that ethyl N, N-dipropylthiocarbamate (EPTC) gave good control of grasses and some broadleaf weeds in establishing stands of legumes when applied preplant and incorporated. Phenoxy herbicides are used for postemergence control of weeds in annual lespedeza. Freeman (5) reported that N-(2-mercaptoethyl) benzenesulfonamide S-(0,0 -diisopropyl phosphorodithioate) (bensulide) did not injure Korean lespedeza when applied at rates as high as 8 pounds per acre. However, N-butyl-N-ethyl-alpha,alpha,alpha-trifluoro-2, 6- dinitro -p- toluidine (benefin) was injurious to Korean lespedeza at rates above 3/4 pound per acre. Review of literature failed to provide reference to chemical weed control in sericea. S The objective of this study was to compare several herbicides for preemergence control of weeds and injury to sericea lespedeza. EXPERIMENTAL PROCEDURES Weed control experiments were conducted in sericea during 1966 on a Cahaba sandy loam soil at the Plant Breeding Unit, Tallassee. In 1967, experiments were also included on Susquehanna clay loam soil at Tuskegee Experiment Field, Tuskegee. Experiments were located on areas known to be infested with many common weeds. Preplant herbicides were incorporated with a double-section disk harrow. Each plot was disked twice. Recleaned Serala sericea was planted with either a conventional planter or with a Planet Junior hand planter. About 30 to 80 seed were planted per foot of row at a depth of about 1/4 inch. All experiments were started within the period March 24 to April 5. Counts of grass and broadleaf weeds and sericea seedlings were made 8 to 15 weeks after herbicide application. Visual ratings of weed control and crop injury were also made at various times during the growing season. Seed were combine harvested from one experiment in 1967 and yields expressed as unhulled seed per acre. One experiment was conducted in 1967 on established sericea. In this experiment, sericea had been established the previous year. The experimental area was mowed, raked, and treated with herbicides before the sericea started growing in the spring. Herbicides evaluated during this investigation are listed in the Appendix. RESULTS AND DISCUSSION In 1966, vernolate gave acceptable control of annual grasses and some broadleaf weeds when applied at rates of 2.0 pounds per acre or more, Table 1. No reduction in stand of sericea occurred at rates as high as 8.0 pounds per acre. Although there was some early stunting, it persisted for only 2 to 4 weeks. Results of both experirents with vernolate in 1967 were similar to those in 1966, Tables 2 and 3. Vernolate was effective at rates of 2.4 pounds per acre or greater. No crop injury or reduction in stands of sericea was detected at rates as high as 9.6 pounds per acre. None of the vernolate treatments caused a reduction in yield of sericea seed. Average plant height of sericea on plots treated with vernolate was similar to that on untreated checks. [41 TABLE 1. EFFECT OF VERNOLATE ON GRASS AND BROADLEAF WEED CONTROL SERICEA STANDS, AND INJURY TO SERICEA LESPEDEZA, PLANT BREEDING UNIT, 1966 Stand Herbicide Rate Grass weeds Broadleaf weeds Sericea Crop Injury' Lb./A vernolate-----------1.0 vernolate-----------2.0 vernolate-----------3.0 4.0 vernolate _-__-_-_-vernolate-----------8.0 Check----------------1 2 --_ 5/30/67 Plants! 100 ft.' 405 55 43 40 6 586 5/30/67 Plants! 100 ft.' 261 168 42-25 30 27 1,312 5 Plants/ft. Pet. 21 23 26 23 0 5 37 23 45 Pet. 0 0 0 0 1 19 0 0 Per cent injury to sericea; 0 = no injury, 100 complete kill. Number of grasses or broadleaf weeds per 100 feet of row, 12-inch band. TABLE 2. EFFECT OF VERNOLATE ON GRASS AND BROADLEAF WEED CONTROL AND SEED YIELD OF SERIGEA LESPEDEZA, PLANT BREEDING UNIT, 1967 Stand Herbicide Rate Crass weeds 6/14/67 Broadleaf weeds 11/3/67 Lb./A 770 562 Seed yield 6/14/67 Lb./A vernolate-------------vernolate-------------- 1.2 2.4 Plants/ 100 ft.1 181 82 Plants/ 100 ft.' 21 26 vemnolate-------------vernolate-------------vernolate -------------- Check 3.6 4.8 9.6 138 74 15 303 25 30 18 86 627 641 898 652 ' Number of grasses or broadleaf weeds per 100 feet of row, 12-inch band. TABLE 3. EFFECT OF VERNOLATE ON GRASS AND BROADLEAF WEED CONTROL, SERICEA STANDS, AND INJURY TO SERICEA LESPEDEZA, TUSKEGEE EXPERIMENT FIELD, 1967 Stand Herbicide Rate Lb./A veirnolate 144 331 1.2 313 2.4 88 mnolate-----3.6 175 281 ve rnolate------e rnolate------4.8 25 131 0 9.6 256 rnolate-----eCh ------769 ieck --175 'Number of grasses or broadleaf weeds per 100 feet ------ 8/13/67 Plants! 100 ft.' Grass weeds Broadleaf Crap injury weeds 8/13/67v rvv Plants!l Plants/ft. Pet. 100 Sericea 8/13/67 Crp height of sericea Av. ft.' In. 15 17 15 15 18 15 71 0 of row, 12-inch band. 80 90 76 90 75 0 0 0 0 0 [5 ] Weed control in all experiments for both years with EPTC was comparable to that of vernolate, Tables 4,5,6. Although EPTC did not reduce the stand of sericea in 1966, treatment with the two highest rates did cause considerable stunting that persisted throughout the growing season, Table 4. Early injury was observed in the experiment conducted on the sandy loam soil at the Plant Breeding Unit in 1967; however, no injury was evident after 6 weeks, except at the 9.6 pounds per acre rate, Table 5. Only slight, early injury was observed at any rate in the experiment conducted on the sandy clay loam soil, Table 6. Average height of sericea on plots treated with EPTC was similar to that on untreated plots. None of the EPTC treatments caused a significant reduction in yield of sericea seed, Table 5. TABLE 4. EFFECT OF SERICEA STANDS, ON GRASS AND BROADLEAF WEED CONTROL, INJURY TO SERICEA LESPEDEZA, PLANT BREEDING UNIT, 1966 AND EPTC Stand Herbicide Rate Lb./A EF?TC-------El ?TC-------ElETC-------Chieck ........ 1 Per Crop injury' / 6 Sericea 4/28/66 6/24/66 5/30/67 4 Grass weeds 5/30/67 Plants/ 2 100 ft. 26 9 23 Broadleaf weeds 5/30/67 Plants/ 100 ft.2 137 40 107 1,312 Plants/ft. 2 2 16 19 Pct. 33 47 57 0 Pct. 5 35 40 0 3.0 5.0 7.0 .586 2Number cent injury to sericea; 0- no injury, 100= complete kill. of grasses and broadleaf weeds per 100 feet of row, 12-inch band. EFFECT OF TABLE 5. EPTC ON GRASS AND BROADLEAF WEED CONTROL, CnoP INJURY, AND SEED YIELD OF SERICEA LESPEDEZA, PLANT BREEDING UNIT, 1967 Stand Herbicide Rate Lb./A Grass weeds 6/14/67 Plants/ Broadleaf weeds 6/14/67 Crop injury' Seed yield 11/3/67 6/14/67 8/18/67 100 ft.' 58 3.6 EP?TC ----------- . 74 4.8 EF'TC 58 9.6 El 'TC-------303 Chieck 0= 1 Per cent injury to sericea; 2Number of grasses or broadleaf Lb./A Pct. Pct. 100 ft.' 648 0 12 123 809 0 27 99 572 27 45 64 652 0 0 86 complete kill. no injury, 100 weeds per 100 feet of row, 12-inch band. Plants/ In general, EPTC was more injurious to sericea than vernolate, Figure 1. Injury was more pronounced in 1966 than in 1967 and was greater on sandy soil than on clay soil. [6] i ~ ~I;~~-- _; '-~:::~ ., _ j ,P ~ ~ ~~ . .ai i S _: 5 / 1z ~j#; 4% V; 4a $ . t1 ~~ - 1 C rp -- ; FIG. 1 Scricea lespedeza plots showing degree of injury from EPTC and vernolate. The severe stunting shown in the upper photo was on a plot that had been treated with 7 lb. A of EPTC. The uninjured sericea in the lower photo was on a plot that had been treated with 8 lb. A of vernolate. TABLE 6. EFFECT OF EPTC ON GRASS AND BROADLEAF WEED CONTROL, SERICEA STANDS, AND INJURY TO SERICEA LESPEDEZA, TUSKEGEE EXPERIMENT FIELD, 1967 Stand Herbicide Rate Lb./A EPTC________________. EPTC-....--......... EPTC________________ Check-............... 1 2 3.6 4.8 9.6 Grass weeds 8/13/67 Plants/ 100 ft.' 50 13 13 769 Broadleaf weeds 8/13/67 Plants/ 100 ft." 419 469 606 175 SericeaCrop 8/13/67 inju Plants/ft. 75 75 74 71 Pct. 0 10 3 0 height of sericea In. 15 18 14 15 Per cent injury to sericea; 0 = no injury, 100 = complete kill. Number of grasses or broadleaf weeds per 100 feet of row, 12-inch band. Benefin gave acceptable grass control at all rates that were evaluated, Tables 7,8, and 9. Control of broadleaf weeds, such as pigweed and carpetweed, was acceptable; however, ragweed, morningglory, and sicklepod (coffeeweed) were not controlled. Stands of sericea were not reduced by any benefin treatment in 1966 and only by the highest rate at one location in 1967, Tables 8 and 9. Although early stunting of sericea occurred on some of the plots treated with benefin in 1966 and at one location in 1967, this was not reflected in a decrease in height when measured at the end of the growing season, Table 9. Injury was more severe on the sandy soil than on the sandy clay soil where no height reduction was evident after 6 weeks, Tables 8 and 9. The lower yield of sericea seed on plots treated with benefin is attributed to late season competition from broadleaf weeds. Plots treated with the lowest rate of benefin had a higher population of broadleaf weeds at the end of the growing season than did the cultivated check. Bensulide and siduron both gave effective grass control in each experiment during the 2-year period, Tables 10,11, and 12. Broadleaf weed control was poor in all cases. Where observed, crop injury was slight and of short duration. Neither bensulide nor siduron reduced crop height in the experiment conducted on the sandy clay soil in 1967. Bensulide did not cause a reduction in yield of sericea seed at any rate tested, Table 11. Control of early season weeds in established stands of sericea is sometimes a problem. If a herbicide that would give control for the first 5 to 8 weeks of the growing season were used, competition from sericea would probably eliminate most late-germinating weeds. [8] TABLE 7. EFFECT OF BENEFIN ON GRASS AND BROADLEAF WEED CONTROL, SEBICEA STANDS, AND INJURY TO SERICEA LESPEDEZA, PLANT BREEDING UNIT, 1966 Stand Herbicide Rate Grass weeds 5/30/67 Broadleaf weeds 5/30/67 Plants/ 1 00 Crop injury' Sericea4/8662/6 5/30/674/8662/6 Plants/ft. Pct. Pct. Lb/A Plants/ 100 ft.' ft.- 2 5 23 344 70 0.75 benefin.------21 7 5 304 171 1.0 benefin .------3 0 26 352 36 1.5 benefin-------20 15 18 350 49 2.0 benefin-------0 0 19 1,312 586 -Check .------1 Per cent injury to sericea; 0= no injury, 100= complete kill. 2 Number of grasses or broadleaf weeds per 100 feet of row, 12-inch band. TABLE 8. EFFECT OF BENEFIN ON CRASS AND BROADLEAF WEED CONTROL, CROP INJURY, AND SEED YIELD OF SERICGEA LESPEDEZA, PLANT BREEDING UNIT, 1967 Weed control Herbicide Rate Crass weeds 6/14/67 Broadleaf weeds 6/14/67 Crop injury' Seed yield 6/14/67 8/18/67 11/3/67 Lb. /A benefin________ benefin Plants/ 100 ft.2 3 Plants/ 36 0.9 100 ft.'2 33 Pct. 17 Pct. 17 Lb/A 413 541 22 42 32 4 2.4 benefin________ 652 0 0 86 303 Check ---------1 Per cent injury to sericea; 0= no injury, 100 = complete kill. 2 Number of grasses or broadleaf weeds per 100. feet of row, 12-inch band. __ ------- 1.2 0 47 27 444 TABLE 9. EFFECT OF BENEFIN ON GRASS SERIGEA STANDS, AND AND BROADLEAF WEED CONTROL, SERICEA INJURY TO LESPEDEZA, TUSKEGEE EXPERIMENT FIELD, 1967 Herbicide Rate Grass weeds 8/13/67 Stand Broadleaf weeds 8/13/67 8/13/67 Plants/ft. 74 Sericea Crp Pct. Crp Av. height of sericea injury Lb./A Plants/ 100 ft.' Plants/l 525 206 be nefin--------- 0.9 256 169 1.2 ------nefin be] 569 106 nefin--------2.4 be, 175 c1 eck_-___------ -769 1 Per cent injury to sericea; 0 = no injury, 100 100 ft.' In. 14 16 14 15 0 83 17 10 59 0 71 complete kill. 2 Number of grasses or broadleaf weeds per 100 feet of row, 12-inch band. 19] TABLE 10. EFFECT OF.BENSULIDE AND SIDURON ON GRASS AND BROADLEAF WEED CONTROL, SERICEA STANDS, AND INJURY TO SERICEA LESPEDEZA, PLANT BREEDING UNIT, 1966 Stand Herbicide Rate Grass weeds 5/30/67 Broadleaf weeds 5/30/67 Sericea Crop injury' 5/3067 4/28/66 6/24/66 Lb./A bensulide___________ 4.0 bensulide___________ 8.0 siduron_______________ 4.0 siduron--------------8.0 siduron_______________ 12.0 Check 1 Plants/ 100 ft.' 4 2 91 5 4 586 Plants/ 100 ft. 2 430 369 320 212 275 1,312 Plants/ft. 16 28 21 23 Pct. 5 3 5 7 Pct. 0 0 0 0 -------- 20 19 15 0 0 0 Per cent injury to sericea; 0= no injury, 100= complete kill. Number of grasses or broadleaf weeds per 100 feet of row, 12-inch band. TABLE 11. EFFECT OF BENSULIDE ON GRASS AND BROADLEAF WEED CONTROL, CROP INJURY, AND SEED YIELD OF SERICEA LESPEDEZA, PLANT BREEDING UNIT, 1967 Weed control Herbicide Rate Grass weeds 6/14/67 100 bensulide-----bensulide------ Crop 1 injury S 11/3/ Broadleaf weeds 6/14/67 6/14/67 8/18/67 Lb/A Plants/ 2 ft. Plants/ 100 ft.2 Pct. Pet. Lb/A 662 720 652 Check --------- 4.8 9.6 __ 3 0 303 31 22 86 1 Per cent injury to sericea; 0 2 Number of grasses or broadleaf no injury, 100= complete kill. weeds per 100 feet of row, 12-inch band. TABLE 12. EFFECT OF BENSULIDE AND SmuRoN ON GRASS AND BROADLEAF WEED CONTROL, SERICEA STANDS, AND INJURY TO SERICEA LESPEDEZA, TUSKEGEE EXPERIMENT FIELD, 1967 Stand Herbicide Rate Grass weeds 8/13/67 Broadleaf weeds 8/13/67 81/7ijr Sericea 8// Crop ijy Av. height of eie ec Lb./A Plants/ 100 ft.2 Plants/ 100 ft.2 Plants/ft. Pct. In. bensulide ---------4.8 25 194 67 10 16 bensulide_________ 9.6 63 644 69 0 15 siduron._______ 9.6 106 538 75 0 16 Check_____________ 769 175 71 0 15 1Per cent injury to sericea; 0 no injury, 100 - complete kill 2 Number of grasses or broadleaf weeds per 100 feet or row, 12-inch band. [10] Preemergence herbicides such as atrazine, prometryne, turon, diuron, and linuron gave effective control of most annual grasses and weeds when applied in early spring to dormant lespedeza, Table 13. OF HERBICIDES ON WEED CONTROL AND SERICEA TABLE 13. LESPEDEZA WHEN APPLIED TO DORMANT SERICEA, PLANT BREEDING UNIT, 1967 Herbicide Rate fluome- EFFECT control Weed' 4/8/67 Crop injury' 7/8/67 Lb./A Rating Pct. 12 Pct. 0 10.0 2.5 atrazine-----------------------------5.0 atrazine ----------------------------- 9.5 10.0 2.5 prom etryne-----------------------prom etryne-----------------------fluometuron 8.0 1.5 ---------------------9.0 5.0 10.0 57 07 17 12 05 25 20 0 0 0 0 20 2.0 fluometuron----------------------- 10.0 3.0 fluometuron ----------------------diuron .------------------------------diuron -------------------------------- 25 5.2 1.0 00 8.7 2.0 07 10.0 2.0 linuron ------------------------------17 10.0 4.0 linuron ------------------------------0.0 00 -C heck ---------------------------1 0 0 0 0 0 2 Per complete control. Per cent weed control; 0 = no control, 10 cent crop injury; 0 = no injury, 100 = complete kill. SUMMARY AND CONCLUSIONS Various herbicides were evaluated in a 2-year period for con- trol of weeds during stand establishment and in established stands of sericea lespedeza. Of the herbicides evaluated, vernolate appeared to offer the greatest promise. Vernolate gave acceptable control of grasses and some broadleaf weeds at rates of 2.0 pounds per acre or higher. Sericea was tolerant to 9.6 pounds per acre of vernolate. Weed control with EPTC was comparable to that of vernolate; however, EPTC caused more injury to sericea. This was particularly true on sandy loam soil. Benefin, siduron, and bensulide gave acceptable control of annual grasses and some broadleaf weeds. Most rates of these herbicides caused little or no injury to sericea. Atrazine, fluometuron, prometryne, diuron, and linuron gave control of annual grasses and broadleaf weeds when applied to an established stand of dormant sericea. [ 11)] LITERATURE CITED (1) BAILEY, R. Y. 1951. Sericea in Conservation Farming. No. 2033. USDA. (2) DONNELLY, E. D. 1965. Serala Sericea. Crop Sci. 5:605. (3) DONNELLY, E. D. and J. F. FERRY. 1957. An Analysis of the Anatomy of Three Stem Types of Sericea Lespedeza (L. cuneata). Proceedings of Assoc. of Sou. Agr. Workers. p. 59. (4) DONNELLY, E. D. and G. E. HAWKINS. 1959. The Effect of Stem Type on Some Feeding Qualities of Sericea Lespedeza (L. cuneata) in a Digestion Trial with Rabbits. Agron. J. 51:293-294. (5) FREEMAN, J. F. 1966. Pastures and Hay Crops Section of Research 1953. Report, Southern Weed Conference. 19:105. (6) (7) HUGHES, H. D., MAURICE E. HEATH, and DARREL S. METCALFE. Forages. The Iowa State College Press. Ames, Iowa. pp. 190-205. LEE, W. O. 1959. Preplant Soil-Incorporated Herbicides for Control of Annual Weeds in the Establishment of Alfalfa, Birdsfoot Trefoil, and Red Clover. West. Weed Control Conf. Res. Prog. Report 29. (8) PATTERSON, R. M., E. D. DONNELLY, and C. W. GANTT. 1967. Broadcast Seed for Best Sericea Stand. Highlights of Agr. Res. Vol. 14, No. 1. Auburn Univ. (Ala.) Agr. Exp. Sta. (9) SCHRIEBEaR, M. M. 1960. Preemergence Herbicides on Alfalfa and Birdsfoot Trefoil. Weeds. 8:291-299. [13] APPENDIX COMMON AND CHEMICAL NAMES OF HERBICIDES INCLUDED IN VARIOUS EXPERIMENTS Common name vernolate EPTC benefin bensulide Trade name Vernam Eptam Balan Betasan Method of Application preplant incorporated preplant incorporated preplant incorporated preemergence Chemical Name S-propyl dipropylthiocarbamate ethyl N, N-dipropylthiocarbamate N-butyl-N-ethyl-alpha, alpha, siduron f'uoneturon atrazine linuron diuron Tupersan Cotoran Atrazine Lorox Karmex preemergence preemergence postemergence postemergence postemergence 2,6-dinitro-p-toluidine N- ( 2-mercaptoethyl) benzenesulfonamide S-( O,O-diisopropyl phoSphorodithioate) 1- ( 2-methylcyclohexyl )3-phenylurea 3- ( m-trifluoromethylphenyl )-1,1-dimethylurea 2-chloro-4-ethylamino6-isopropylamino-s-triazine 3- ( 3,4-dichiorophenyl) 1-methoxy-1l-methylurea 3- ( 3,4-dichiorophenyl )1,1-dimethylurea alpha,-trifluoro- [15] AGRICULTURAL EXPERIMENT STATION SYSTEM OF ALABAMA'S LAND-GRANT UNIVERSITY \V'ith an agricultural resear ch unit in every major soil area, Auburn UniverisitN' serves the nieeds of field crop, livestock, foretstry , and horticiiltiiial produ1ce~rs inl eachl r egioni in Alabamna. Ever i izeni of the( State has a stake in tis rxesear ch programn, since any~ advl\antage f1rom niews and( more economllical \%-a vs ofD produc~inlg arid handling fairm producets (directly lhiiifits the consuming publllic. ® 0? ~ ( Research Unit Identification 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11 . 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Tennessee Volley Substotion, Belle Minao Sond Mountain Substation, Crossville. North Alaboma Horticulture Substation, Cullmon. Upper Coostol Plain Substation, Winfield. Forestry Unit, Foyette County. Thorsby Foundation Seed Stocks Form, Thorsby. Chilton Area Horticulture Substation, Clanton. Forestry Unit, Coosa County. Piedmont Substation, Camp Hill. Plant Breeding Unit, Tallossee. Forestry Unit, Autouga County. Prattville Experiment Field, Prattville. Black Belt Substation, Marion Junction. Tuskegee Experiment Field, Tuskegee. Lower Coostal Plain Substation, Camden. Forestry Unit, Barbour County. Monroeville Experiment Field, Monroeville. Wiregrass Substation, Headland. Brewton Experiment Field, Brewton. Ornamental Horticulture Field Station, Spring Hill. Gulf Coast Substation, Fairhope.