Greenhouse Assessment of Differences in Clomazone Tolerance among Sweetpotato Cultivars. H. F. Harrison, Jr. and D. M. Jackson*

Transcription

1 Weed Technology : Notes Greenhouse Assessment of Differences in Clomzone Tolernce mong Sweetpotto Cultivrs H. F. Hrrison, Jr. nd D. M. Jckson* Differences in clomzone tolernce mong sweetpotto cultivrs were first oserved in April 2007 fter use of the hericide for weed control in fields contining the sweetpotto reeding project t the U.S. Vegetle Lortory. Susceptile cultivrs nd experimentl clones exhiited severe folir chlorosis nd reduced growth, wheres the most tolernt were not injured. Twelve cultivrs nd experimentl clones were included in greenhouse experiment to quntify the differences in clomzone tolernce. In the greenhouse, the clomzone concentrtion tht cused moderte injury or reduction in shoot growth to the most tolernt clones ws pproximtely 10 times the concentrtion tht cused similr response in the most susceptile clones. Two older cultivrs, Excel nd Sumor, tht were developed efore the registrtion of clomzone for use in sweetpotto were susceptile. Clomzone is n importnt component in sweetpotto weed mngement, nd susceptiility is n undesirle trit tht should e voided in new sweetpotto cultivrs. Nomenclture: Clomzone; sweetpotto, Ipomoe tts (L.) Lm. Key words: Hericide tolernce, injury, susceptiility. Ls diferencis de l tolernci l clomzone entre los cultivres de cmote se oservron por primer vez en ril de 2007, después del uso del hericid pr el control de mlezs en cmpos donde se relizó el proyecto de mejormiento del cmote en el U.S. Vegetle Lortory. Los cultivres susceptiles y clones experimentles mostrron clorosis folir sever y crecimiento reducido, mientrs que los más tolerntes no se dñron. Doce cultivres y clones experimentles se incluyeron en un ensyo de inverndero pr cuntificr ls diferencis en l tolernci l clomzone. En el inverndero, l concentrción de clomzone que cusó un dño moderdo o reducción en el crecimiento de los rotes en los clones más tolerntes, fue proximdmente 10 veces l concentrción que cusó un respuest similr en los clones más susceptiles. Resultron susceptiles dos de los cultivres más ntiguos, Excel y Sumor, que fueron desrrolldos ntes del registro de clomzone pr usr en el cmote. Clomzone es un componente importnte en el mnejo de mlezs en el cultivo de cmote y su susceptiilidd es un rsgo no desele que dee evitrse en los nuevos cultivres de cmote. Sweetpotto is minor vegetle crop in the United Sttes; however, it rnks mong the top 10 food crops in totl worldwide production. Approximtely 106,500,000 metric tons were produced in 2009 (FAO 2010). In recent yers, pproximtely 80% of sweetpottoes hve een produced in Chin. In the United Sttes, sweetpottoes were plnted on pproximtely 42,300 h in 2009 (North Crolin Sweetpotto Commission, 2010). Weed mngement in U.S. sweetpotto production is difficult ecuse reltively few hericides re registered, nd they do not control ll weed species common in sweetpotto production regions. Cultivtion nd hnd weeding re used extensively to prevent losses to weeds. For exmple, in North Crolin, in ddition to hericide ppliction for weed mngement, sweetpotto fields re cultivted n verge of three times, most re hndweeded t lest once, nd mny re mowed to control weeds tht grow ove the crop cnopy (USDA 2005). Dt for hericide use in sweetpotto production re incomplete; however, severl reports indicte tht clomzone is used extensively. North Crolin is the leding sweetpottoproducing stte, with pproximtely 18,800 h plnted in 2010 (North Crolin Sweetpotto Commission 2010). A DOI: /WT-D *Reserch Agronomist nd Reserch Entomologist, U.S. Vegetle Lortory, U.S. Deprtment of Agriculture, Agriculturl Reserch Service, 2700 Svnnh Highwy, Chrleston, SC Corresponding uthor se-mil: howrd.hrrison@ rs.usd.gov stte crop profile from 2005 (USDA 2005) stted tht clomzone ws used extensively in North Crolin sweetpottoes. Similr reports indicte tht clomzone ws used on 70% of Louisin nd Mississippi sweetpotto crege (USDA 1999, 2001), 75% of crege in Texs (USDA 2003), nd 90% of crege in Virgini (USDA 2001), nd it ws used y nerly ll sweetpotto growers surveyed in New Jersey (USDA 2005). Porter (1990) reported tht injury ws minor nd yields of Beuregrd nd Centennil sweetpottoes were not different from hoed control with preplntincorported nd posttrnsplnting pplictions of clomzone t up to 3.4 kg i h 2 1. The effective control of nnul grsses tht he oserved hs contriuted to the extensive use of clomzone in sweetpotto production. It lso controls severl nnul rodlef weeds (e.g., common cockleur [Xnthium strumrium L.], dyflower [Commelin communis, L.], Florid eggrweed [Desmodium tortuosum, (Sw.) DC.], redweed [Melochi cochorifoli L.], nd velvetlef [Autilon theophrsti Medik.]) tht re not controlled y other selective sweetpotto hericides (Anonymous 2005). Clomzone pplied with flumioxzin is considered to e very effective preemergence hericide comintion for sweetpotto (Kelly et l. 2006). Although differentil tolernce hs not een reported in sweetpotto, vrition mong cultivrs in clomzone tolernce hs een found in severl other crops, including common en (Phseolus vulgris L.; Sikkem et l. 2006), cge (Brssic olerce L.; Hopen et l. 1992), corn (Ze mys L.; Hrrison nd Jckson: Sweetpotto clomzone tolernce N 501

2 Keifer 1989), pumpkin [Cucurit mxim Duchesne, C. moscht Duchesne (Poir.), C. pepo L.; Hrrison nd Keinth 2003], nd rice (Oryz stiv L.; Mudge et l. 2005; Scherder et l. 2004; Zhng et l. 2004). Sweetpotto is vegettively propgted crop, nd ecuse ll cultivrs nd genotypes originte s single plnt, they re often clled clones. In this report, sweetpotto clones tht hve een grown commercilly re clled cultivrs, nd those tht hve only een grown experimentlly re clled experimentl clones. The crop is propgted commercilly from vine cuttings of plnts grown in field plnt eds or greenhouses. Plnt eds re usully formed y densely plnting storge roots (sweetpottoes) into rised eds in erly spring. The 2007 plnt eds for the U.S. Vegetle Lortory sweetpotto reeding project contined pproximtely 300 geneticlly unique cultivrs nd experimentl clones tht were plnted in seprte plots. Clomzone ws rodcst over the plnt ed field t 0.84 kg h 2 1 fter plnting ut efore shoot emergence with 3.4 kg i h 2 1 npropmide included in tnk mixture tht ws used for weed mngement. Npropmide ws included to control crpetweed (Molugo verticillt L.), common purslne (Portulc olerce L.), nd horse purslne (Trinthem portulcstrum L.), which re common on the reserch frm ut re not controlled y clomzone. After the shoots emerged, severe clomzone injury, expressed primrily s extensive folir chlorosis, ws oserved on some cultivrs nd experimentl clones. Others in the field exhiited no chlorosis. Ech plot in the plnt ed field ws rted for clomzone injury, nd these rtings were used to select 12 clones with pprent differences in clomzone tolernce. Susequently, greenhouse concentrtion response experiment ws used to quntify differences in clomzone tolernce mong the 12 clones. Mteril nd Methods The 12 sweetpotto clones selected for the experiment consisted of cultivrs (Beuregrd, mericlone B-24, Crolin Bunch, Excel, Ruddy, nd Sumor ) nd experimentl clones ( 04-N01, 04-N02, SC , 00-99, , , nd ). The greenhouse ws locted t the U.S. Vegetle Lortory, Chrleston, SC. Tempertures rnged etween 20 nd 32 C, supplementl lighting ws not provided, nd humidity ws incresed from mient y n evportive cooling system. The greenhouse potting mixture ws 1 : 1 (v/v) lend of commercil potting mixture 1 nd wshed river snd. Powdered limestone nd controlled-relese fertilizer 2 t 1.1 g L 2 1 were dded, nd the mixture ws lended in portle cement mixer for 5 min. Clomzone 3 ws incorported into the potting medium y dding the pproprite volume of the commercil formultion to 500 ml of wter, sprying directly onto the potting mixture in concrete mixer with hnd-held spryer, followed y mixing for 10 min. Clomzone concentrtions of 0, 1.0, 2.0, 4.0, 8.0, nd 16.0 mg kg 2 1 dry potting mix were selected on the sis of the results of preliminry experiment tht indicted this concentrtion rnge would cuse injury similr to tht oserved in the field. The clomzone-treted potting mixture ws used to fill 946-ml plstic cups. On the sis of the surfce re of the cups nd the weight of potting medium they contined, the 1.0 mg kg 2 1 concentrtion is equl to 0.21 kg h 2 1 rodcst to the soil surfce. However, the uniform concentrtion of clomzone in the potting medium throughout the 13 cm depth of the cups might not occur with field pplictions. Sweetpotto vine cuttings pproximtely 18 cm long were tken from greenhouse-grown plnts, trnsplnted into cups contining clomzone-treted soil, nd plced in the greenhouse. Strting dtes were Decemer 11, 2007, nd Jnury 21, Plnts were wtered lightly twice dily if necessry to mintin moist potting mixture. Cre ws tken to wter plnts uniformly nd to void overwtering, which could cuse leching of the hericide. After 3 wk, sweetpottoeswere evluted for clomzone injury on scle of 0 to 10, where 0 is no chlorosis, 3 is chlorosis of pproximtely 30% of lef re, 7 is chlorosis of pproximtely 70% of lef re, nd 10 is complete chlorosis of shoots or plnts ded. Shoots were excised t the soil surfce, nd shoot fresh weights were determined. Excised shoots were plce in forced-ir drying oven t 50 C for 96 h, nd shoot dryweightsdetermined. The experiment ws rrnged in rndomized complete lock design with five replictions nd ws repeted. Shoot weights for the clomzone tretments were converted to percent control efore nlysis. Injury rtings nd shoot weights from the two repetitions of the experiment were pooled, nd dt within clomzone concentrtions were sujected to two-wy ANOVA, which indicted no tretment y experiment interctions. Cultivr mens were seprted y using Fisher s protected ( ; CoStt version ). Liner regression nlyses of men injury rtings nd shoot fresh nd dry weights s percent control on clomzone concentrtion were performed. Results nd Discussion The greenhouse experiment demonstrted tht there re mrked differences in clomzone tolernce mong the 12 sweetpotto clones. Injury rtings mong clones were different t ll concentrtions (Tle 1). Injury rtings for the most susceptile experimentl clone, 04-N01, were 7.0 t 2.0 mg kg 2 1 nd higher t greter concentrtions, wheres injury rtings for severl tolernt cultivrs nd experimentl clones were elow 7.0 t 16 mg kg 2 1. Correltion coefficients for liner regression of injury rting on concentrtion were significnt for ll cultivrs nd experimentl clones except 04- N01, which did not exhiit liner response ecuse injury ws high t ny concentrtion. Shoot fresh nd dry weights of untreted plnts were different mong the 12 sweetpotto clones included in this study ecuse of morphologicl differences (stem thickness, lef size, etc.; Tles 2 nd 3). Thus, shoot weights were converted to percent control to llow comprison of the reltive effect of clomzone on the shoot growth of clones. Reltive fresh weights were different mong clones t ll clomzone concentrtions (Tle 2). Fresh weights with 1.0 mg kg 2 1 were different only ecuse of the pprent incresed growth of three clones, resulting in fresh weights greter thn the control. Lower concentrtions of clomzone hve cused similr increse in shoot weight of highly tolernt pumpkin cultivrs (Hrrison nd Keinth 2003) in 502 N Weed Technology 25, July Septemer 2011

3 Tle 1. Injury rtings for 12 sweetpotto clones grown for 3 wk in potting medium contining clomzone t 1, 2, 4, 8, nd 16 mg kg 2 1. Injury rting Liner regression r Clone Slope () Intercept () Beuregrd ** Crolin Bunch ** Excel * Ruddy ** Sumor * 04-N ns 04-N * SC ** ** * ** * Fisher s Protected t for compring mens within column. the greenhouse. Correltion coefficients for liner regression of shoot fresh weight on concentrtion were significnt for ll cultivrs nd experimentl clones, except Ruddy, Sumor, nd (Tle 2). These did not exhiit liner response, ecuse Ruddy nd fresh weights were not reduced y the lower concentrtions, nd Sumor hd similr fresh weights of 64 to 69% of the control with 2 through 16 mg kg 2 1. Shoot dry weight reduction ws greter thn shoot fresh weight reduction in response to clomzone (Tle 3). Averged over ll cultivrs nd concentrtions, fresh weights were 82% of control, wheres dry weights were 69% of control. Dry weights of severl tolernt cultivrs nd experimentl clones Beuregrd, Crolin Bunch, nd 04- N02 were reduced less thn 30% with 8 mg kg 2 1 clomzone. Dry weights of the most susceptile experimentl clones, 04- N01 nd 97-22, were reduced more thn 30% t 1 mg kg 2 1. Correltion coefficients for liner regression of shoot dry weight on concentrtion were significnt for ll clones except Ruddy, Sumor, 04-N01, nd The response for these ws nonliner ecuse only 16 mg kg 2 1 reduced Ruddy shoot dry weight, nd Sumor, 04-N01, nd dry weights were gretly reduced y most concentrtions. The clomzone concentrtions required to cuse injury rtings of 3.0 or 30% reduction in fresh nd dry weights were estimted from the liner regression eqution for ll clones, with correltion coefficients significnt t the 0.05 level. These levels of injury nd growth reduction were chosen, ecuse they fell within the liner section of the response curve more often thn the 50% growth reduction (I 50 ) tht is commonly used. Concentrtions cusing injury rtings of 3.0 rnged from 1.6 mg kg 2 1 for to 7.5 mg kg 2 1 for Beuregrd. Although 04-N01did not exhiit liner response to clomzone concentrtion, its injury rting ws 5.0 t 1 mg i kg 2 1 nd greter t the other concentrtions (Tle 1). Clomzone concentrtions estimted to cuse 30% reduction in shoot fresh weight rnged from 4.2 mg h 2 1 for to 22.4 mg kg 2 1 for 04-N02. The clomzone concentrtions estimted to cuse 30% reduction in shoot dry weight rnged from 4.1 mg i h 2 1 for SC to 11.0 mg i h 2 1 for Crolin Bunch. Although the Tle 2. Shoot fresh weights for 12 sweetpotto clones grown for 3 wk in potting medium contining clomzone t 0, 1, 2, 4, 8, nd 16 mg kg 2 1. Shoot fresh weight Liner regression Clone Control Slope () Intercept () r g % of control Beuregrd * Crolin Bunch * Excel ** Ruddy ns Sumor ns 04-N * 04-N ** SC ** ** ns ** * ( ) for compring mens within column. Hrrison nd Jckson: Sweetpotto clomzone tolernce N 503

4 Tle 3. Shoot dry weights for 12 sweetpotto clones grown for 3 wk in potting medium contining clomzone t 0, 1, 2, 4, 8, nd 16 mg kg 2 1. Shoot dry weight Liner regression Clone Control Slope () Intercept () r g % of control Beuregrd * Crolin Bunch ** Excel ** Ruddy ns Sumor ns 04-N ns 04-N ** SC ** ** * ** ns ( ) for compring mens within column. susceptile clone, 04-N01 did not exhiit liner response to concentrtion, its dry weight ws reduced y more thn 30% t ny concentrtion (Tle 3). These dt demonstrte tht the clomzone concentrtion required for moderte injury or shoot growth reduction for the most tolernt cultivr ws pproximtely 10 times the concentrtion required to cuse similr response for the lest tolernt cultivr in these greenhouse experiments. Only moderte injury ws oserved on the most susceptile cultivrs y midseson, 7 to 8 wk fter plnting in the plnt ed field (personl oservtion). The hlf life of clomzone vried from 16 d in sndy lom soil to 36 d in silt lom soil (Sensemn 2007); thus, the pprent recovery from injury y the susceptile clones could e due to dissiption of the hericide in the silty snd soil t the U.S. Vegetle Lortory reserch frm. Further studies re needed to determine the clomzone tolernce of severl importnt sweetpotto cultivrs tht were not included in these experiments nd to ssess the effect of injury on yield nd qulity. The high level of injury oserved with the most susceptile cultivrs is undesirle ecuse it reduces erly shoot growth. The most susceptile cultivrs in this study, Excel nd Sumor, were developed efore the registrtion of clomzone for sweetpotto. These nd other U.S. Vegetle Lortory cultivrs hve een used in sweetpotto reeding s genetic sources of insect nd disese resistnce. Becuse clomzone is n importnt component in sweetpotto weed mngement, cre should e used to ensure tht experimentl clones with these cultivrs in their ncestry re not susceptile. A simple screening procedure, like the greenhouse experiment descried ove, could e useful for testing new experimentl clones erly in the sweetpotto reeding cycle to ensure tht susceptile clones re not dvnced. Also, older cultivrs tht hve een reintroduced to commercil production s heirloom vrieties nd imported cultivrs tht re produced for specilty mrkets should e tested for tolernce efore using clomzone. Cultivr tolernce should e considered when determining the pproprite clomzone ppliction rte. Additionlly, the lrge differences in clomzone tolernce oserved in this study wrrnt investigting the potentil for reeding sweetpotto cultivrs with incresed tolernce. If clomzone tolernce is quntittively inherited like mny other trits in sweetpotto (Jones 1986), then progeny resulting from crosses of reltively tolernt cultivrs like Beuregrd, Ruddy, nd SC could hve greter tolernce thn either prent. Sources of Mterils 1 Metro-Mix 360, Sun Gro Horticulturl Distriution Inc., Bellevue, WA Osmocote plus, The Scotts Co. LLC, Mrysville, OH Commnd 3 ME, FMC Corp., Phildelphi, PA Literture Cited Anonymous Commnd 3ME hericide product lel. EPA Reg. No Phildelphi: FMC Corp. 19 p. CoStt version CoHort Softwre. Monterey, CA. [FAO] Food nd Agriculture Orgniztion of the United Ntions FAO Sttistics. Accessed Dec 16, Hrrison, H. F., Jr. nd A. P. Keinth Glsshouse ssessment of clomzone response in US pumpkin cultivrs. Crop Prot. 22: Hopen, H. J., R. L. Hughes, nd B. A. Michelis Selectivity mong cge cultivrs to clomzone. Weed Technol. 7: Jones, A Sweet potto heritility estimtes nd their use in reeding. Hortscience 21: Keifer, D. W Tolernce of corn (Ze mys) lines to clomzone. Weed Sci. 37: Kelly, S. T., M. W. Shnkle, nd D. K. Miller Efficcy nd tolernce of flumioxzin on sweetpotto (Ipomoe tts). Weed Technol. 20: Mudge, C. R., E. P. Wester, C. T. Leon, nd W. Zhng Rice (Oryz stiv) cultivr tolernce to clomzone in wter seeded production. Weed Technol. 19: North Crolin Sweetpotto Commission Home Pge. ncsweetpottoes.com. Accessed Decemer 16, Porter, W. C Clomzone for weed control in sweetpotto (Ipomoe tts L.). Weed Technol. 4: Scherder, E. F., R. E. Tlert, nd S. D. Clrk Rice (Oryz stiv) cultivr tolernce to clomzone. Weed Technol. 18: N Weed Technology 25, July Septemer 2011

5 Sensemn, S. K., ed Hericide Hndook. Lwrence, KS: Weed Science Society of Americ. Pp Sikkem, P. H., C. Shropshire, nd N. Soltni Effect of clomzone on vrious mrket clsses of dry ens. Crop Prot. 26: [USDA] U.S. Deprtment of Agriculture Crop Profile for Sweetpottoes in Mississippi. Office of Pest Mngement Policy nd Pesticide Impct Assessment. pdf. Accessed Decemer 14, USDA Crop Profile for Sweetpottoes in Louisin. Office of Pest org/cropprofiles/docs/lsweetpottoes.pdf. Accessed Decemer 14, USDA Crop Profile for Sweetpottoes in Virgini. Office of Pest org/cropprofiles/docs/vasweetpotto.pdf. Accessed Decemer 14, USDA Crop Profile for Sweetpottoes in Texs. Office of Pest org/cropprofiles/docs/txsweetpottoes.pdf. Accessed Decemer 14, USDA Crop Profile for sweetpottoes in North Crolin. Office of Pest org/cropprofiles/docs/ncsweetpottoes.pdf. Accessed Dec. 14, USDA Crop Profile for Sweetpottoes in New Jersey. Office of Pest org/cropprofiles/docs/njsweetpottoes.pdf. Accessed Decemer 14, Zhng, W., E. P. Wester, D. C. Blouin, nd S. D. Linscome Differentil tolernce of rice (Oryz stiv) vrieties to clomzone. Weed Technol. 18: Received Octoer 5, 2010, nd pproved Ferury 3, Hrrison nd Jckson: Sweetpotto clomzone tolernce N 505