INTEGRATED MANAGEMENT OF RHIZOCTONIA ON SUGARBEET WITH VARIETAL RESISTANCE, SEED TREATMENT, AND POSTEMERGENCE FUNGICIDES

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1 INTEGRATED MANAGEMENT OF RHIZOCTONIA ON SUGARBEET WITH VARIETAL RESISTANCE, SEED TREATMENT, AND POSTEMERGENCE FUNGICIDES Json R. Brntner n Ashok K. Chn Reserh Fellow n Assistnt Professor, respetively University of Minnesot, Northwest Reserh n Outreh Center Crookston, MN Rhizotoni mping-off n rown n root rot (RCRR) use y Rhizotoni solni AG 2-2 hve een the most ommon root iseses on sugreet in Minnesot n North Dkot for severl yers (2-4). Disese n our throughout the growing seson n reues plnt stn, root yiel, n qulity. Wrm n wet soil onitions fvor infetion. Control options inlue rotting with non-host rops (erels), plnting prtilly resistnt vrieties, plnting erly when soil tempertures re ool, improving soil ringe, n pplying fungiies s see tretments, in-furrow (IF), or postemergene. An integrte mngement strtegy shoul tke vntge of multiple ontrol options to reue Rhizotoni rown n root rot. OBJECTIVES A fiel tril ws estlishe to evlute n integrte mngement strtegy onsisting of resistnt n suseptile vriety with new ville see tretments ompre with in-furrow zoxystroin lone n in omintion with postemergene zoxystroin pplition for 1) ontrol of erly-seson mping-off n RCRR n 2) effet on yiel n qulity of sugreet. MATERIALS AND METHODS The tril ws estlishe t two lotions, one t the University of Minnesot, Northwest Reserh n Outreh Center, Crookston n nother in grower s fiel ner Bker, MN. Both lotions were fertilize for optiml yiel n qulity. At eh lotion, omintion of resistnt n suseptile vriety trete with metonzole + rizolex (= Metlok Suite), penthiopyr (Kin ST), metonzole + rizolex + penthiopyr, sexne, or untrete or zoxystroin in-furrow ws plnte in four replite plots in rnomize omplete lok esign. See tretments n rtes re summrize in Tle 1 n were pplie y Germins See Tehnology, Frgo, ND. Infurrow zoxystroin ws pplie own the rip tue in 6 gllons totl volume A -1. Eh vriety y t-plnting tretment omintion ws plnte in uplite, so tht t 5 weeks fter plnting, one plot of eh vriety y tplnting fungiie tretment omintion reeive postemergene 7-inh n pplition of zoxystroin (14.3 fl oz prout A -1 ) while one ws left s stn-lone tretment. Controls for eh vriety inlue no see or infurrow fungiie tretment t plnting with n without postemergene Quris. Two-yer verge Rhizotoni rtings in Amerin Crystl Sugr Compny tests for the resistnt n suseptile vrieties were 3.5 n 5.2, respetively (5). NWROC site. Prior to plnting, soil ws infeste with R. solni AG 2-2-infeste whole rley (35 kg h -1 ). The tril ws sown in six-row plots (22-inh row sping, 3-ft rows) on My 21 t 4.5-inh see sping. Counter 2G (9 l A -1 ) ws pplie t plnting for ontrol of sugreet root mggot n 3 gllons A -1 strter fertilizer (1-34-) ws pplie ross ll tretment omintions. Glyphoste (4.5 l prout e/gllon) ws pplie on June 4, June 23, n Septemer 3 (22 oz A -1 ) for ontrol of wees. Postemergene zoxystroin ws pplie in 7-inh n in 1.5 gllon/a using iyle spryer with 415 nozzles n 26 psi on June 25 (5 weeks fter plnting). No fungiies were pplie for ontrolling Cerospor lef spot s the folir isese ws not oserve in plots. Bker site. The tril ws sown in six-row plots (22-inh row sping, 3-ft rows) on My 3 t 4.5-inh see sping. Glyphoste (4.5 l prout e/gllon) tnk-mixe with AMS (8.5 ls A -1 ) n Fusile DX (12 oz A -1 ) ws pplie on June 13. This wee ontrol pplition ws repete gin on July 1 (less the grminiie). Postemergene zoxystroin ws pplie in 7-inh n on June 24 (3.5 weeks fter plnting). Cerospor lefspot ws ontrolle y seprte pplitions of Inspire (7 oz A -1 ) on August 1 n

2 Tle 1. Applition type, prout nmes, tive ingreients, n rtes of fungiies use t plnting in fiel tril for ontrol of Rhizotoni solni AG 2-2 on sugreet. Eh t-plnt tretment ws use in omintion with Rhizotoni resistnt (213 rting = 3.3) n suseptile (213 rting = 5.2) vriety, n ll tretment omintions were uplite, with one set reeiving postemergene 7-inh n pplition of zoxystroin (14.3 fl oz A -1 ). Stnr rtes of Apron + Mxim n 45 g/unit Thigren were on ll see. Infurrow Quris ws pplie own the rip tue in totl volume of 6 gl/a. Applition Prout Ative ingreient Rte None See Metlok Suite Metonzole + Rizolex g.i./unit see See Kin ST Penthiopyr 14 g.i./unit see See Metlok Suite + Kin ST Meton + Rizolex + Penthio g.i./unit see See Sexne Sexne 2.5 g.i./unit see In-furrow Quris Azoxystroin 9.5 fl oz prout A -1 TPTH/Topsin (5 & 7.6 oz A -1, respetively) on August 15. All fungiies for CLS ontrol were pplie utilizing UTV-mounte spryer ispersing the prouts in rost pttern t wter volume of 15 GPA with TeeJet 82 flt fn nozzles t 8 psi. Stn ounts were one eginning 3 weeks fter plnting through 11 weeks fter plnting. The tril ws hrveste Septemer 3 t the NWROC n Septemer 25 t Bker. Dt were ollete for numer of hrveste roots (NWROC only), yiel, n qulity. Twenty roots per plot lso were ritrrily selete n rte for severity of RCRR using to 7 sle ( = helthy root, 7 = root ompletely rotte n folige e). Root rot rtings t Bker reflet srring n mlformtions from erlier infetions with Aphnomyes ohlioies whih ws severe in the fiel. Dt were sujete to nlysis of vrine using SAS Pro GLM (SAS Institute, Cry, NC) for min effets of vriety, t-plnt tretment, postemergene zoxystroin pplition, n ll possile intertions. RESULTS NWROC site: There were signifint vriety y t-plnting tretment intertions for stn t, illustrte in Fig. 1. Emergene n stn estlishment were higher with the resistnt vriety (Fig. 1A) thn with the suseptile vriety (Fig. 1B). In oth vrieties, see trete with Kin, Metlok Suite + Kin, or sexne, or with infurrow Quris pplition resulte in higher emergene n stn estlishment over 11 weeks thn the untrete ontrol n see trete with Metlok Suite lone. The intertion is ue to the reltive effet of in-furrow Quris on stn. In the resistnt vriety (Fig. 1A), stn in plots trete with Quris in-furrow ws lower thn the top see tretments, ut higher thn the untrete ontrol. With the suseptile vriety (Fig. 1B), however, plots trete with Quris in-furrow were equl to the top see tretments. These stn t trens ontinue through hrvest so tht the numer of hrveste roots ws higher thn the untrete ontrol in plots trete with Quris in-furrow n ll see tretments exept Metlok Suite lone (Tle 2). Postemergene Quris pplition i not signifintly ffet stn t. Rhizotoni rown n root rot rtings were signifintly lower with the resistnt thn the suseptile vriety (Tle 2). Similr to stn t, plots trete with Quris in-furrow n ll see tretments exept Metlok Suite lone resulte in RCRR rtings signifintly (P =.5) lower thn the untrete ontrol (Tle 2). Postemergene Quris pplition i not ffet RCRR rting. There ws sttistil vriety y t-plnting y postemergene tretment intertion for RCRR rting (Tle 2). For ll tretment omintions, the resistnt vriety h lower RCRR rting thn the suseptile with the exeption of Metlok Suite lone with no postemergene Quris, where resistnt n suseptile vrieties h the sme rting (t not shown). There were no signifint intertions for hrvest prmeters, n min effets re summrize in Tle 2. The mile n lter portions of the growing seson were ry, llowing plnts tht survive to proue eent yiels. Perent surose n pouns of surose ton -1 were not signifintly ifferent mong ny tretments (Tle 2). Yiel n reoverle surose A -1 were signifintly (P =.5) higher for the resistnt thn the suseptile vriety (Tle

3 25 A. Resistnt vriety B. Suseptile vriety e e Non-infeste ontrol Untrete ontrol Metlok Suite Kin ST Metlok + Kin Sexne Quris IF Dys fter plnting Fig. 1. Emergene n stn estlishment for A.) resistnt n B.) suseptile sugreet vrieties trete with fungiies on see or Quris infurrow n sown My 21, 214 in fiel tril infeste with Rhizotoni solni AG 2-2 IIIB (35 kg/h) or not infeste (non-infeste ontrol); non-infeste ontrol shown only for omprison, ut not inlue in the sttistil nlysis to keep tretments lne; there ws signifint (P =.5) vriety y t-plnting tretment intertion; t points represent men of 8 plots (4 replite plots ross postemergene Quris n no postemergene tretments); for eh stn ount te, vlues shring the sme letter re not signifintly ifferent (P =.5) Dys fter plnting Tle 2. NWROC site: Min effets of vriety, t-plnting (see or in-furrow), n postemergene fungiie tretments on Rhizotoni rown n root rot n sugreet yiel n qulity. Min effet No. hrv. RCRR Yiel Surose (Apron + Mxim on ll see) roots/ ft T (-7) U ton A -1 % l ton -1 l A -1 Vriety V Resistnt Suseptile ANOVA p-vlue <.1 <.1 < <.1 At-plnting tretments W Untrete ontrol Metlok +.5 g.i./unit X Kin g.i./unit Metlok Y + 7 g.i./unit g.i./unit fl. oz./a ANOVA p-vlue <.1 <.1 < <.1 LSD (P =.5) NS NS 845 Postemergene fungiie Y None fl. oz./a ANOVA p-vlue Intertions Z Vty. x At-plnt trmt. * NS NS NS NS NS Vty. x PE fung. NS NS NS NS NS NS At-plnt x PE NS NS NS NS NS NS Vty. x At-plnt x PE NS * NS NS NS NS T U V W X Y Z Numers followe y the sme letter re not signifintly ifferent; LSD = Lest Signifint Differene, P =.5. RCRR = Rhizotoni rown n root rot; -7 sle (juste rting), = root len, no isese, 7 = root ompletely rotte n plnt e. Vlues represent men of 48 plots (4 replite plots ross 6 t-plnting tretments n 2 postemergene tretments) Vlues represent men of 16 plots (4 replite plots ross 2 vrieties n 2 postemergene tretments) Metlok suite = metonzole g.i./unit. Vlues represent men of 48 plots (4 replite plots ross 2 vrieties n 6 t-plnting tretments) * = signifint t P =.5, NS = not signifintly ifferent

4 2). Among t-plnting tretments, yiel n reoverle surose A -1 were highest for plots trete with Quris infurrow, with Kin, sexne, or Metlok Suite + Kin see tretments, intermeite for see trete with Metlok Suite lone, n lowest in the untrete ontrol (Tle 2). Postemergene pplition of Quris i not signifintly (P =.5) ffet hrvest prmeters. Bker site. There were no signifint (P =.5) intertions for stn or hrvest t (t not shown). Stn ws reue for ll tretments erly in the seson ue to high rinfll mounts n severe Aphnomyes mping-off. Aphnomyes ws isolte from oth root n soil smples rought k to the lortory t the NWROC. The impt of Aphnomyes ws similr for oth vrieties (whih hve similr Aphnomyes rtings) n similr ross ll t-plnting n postemergene tretments. DISCUSSION At the NWROC site, lte plnting (My 21) into wrm n wet soils tht h een inoulte with R. solni long with 6.8 inhes of rinfll in June omine for very severe isese pressure. Most of the mge to the rop ws from stn loss n erly-seson infetions. Rinfll in July n August ws 2.17 n 1.65 inhes, respetively, oth elow verge. Therefore, the ifferenes ue to t-plnting tretment were tremenous, while postemergene Quris i not provie ny enefit. Among t-plnting tretments, see tretments ontining penthiopyr (Kin or Metlok Suite + Kin) or sexne resulte in the est stn with the resistnt vriety, while the sme see tretments n Quris in-furrow resulte in the est stn on the suseptile vriety. Overll, the est isese ontrol n sugr yiel ws with omintion of resistnt vriety with n effetive t-plnting see tretment or Quris in-furrow. Uner severe isese pressure, growers nnot expet to protet suseptile vriety, even with the est ontrol options. For exmple, the verge reoverle surose for the three effetive see tretments n Quris in-furrow ws 8159 pouns A -1 with the resistnt vriety ompre to 72 pouns A -1 with the suseptile vriety, ifferene of 1139 pouns A -1. Interestingly, the enefit of the resistnt vriety ompre to the suseptile ws pprent s erly s the first stn ount (19 ys fter plnting). Although emergene in the 213 Amerin Crystl Sugr Compny oe vriety trils (5) ws lower for the resistnt (66%) thn for the suseptile (73%) vriety, uner severe erly-seson Rhizotoni pressure t the NWROC, emergene n erly-seson stn estlishment were higher in the resistnt vriety, even without ny t-plnting (see tretment or in-furrow) fungiie (Fig. 2A). When this sme see ws plnte t the Bker site, where there ws erly Aphnomyes isese pressure ut no erly Rhizotoni pressure, emergene n stn estlishment were higher for the suseptile vriety (Fig. 2B). This suggests either some erly expression of resistne in the fiel or some other soil or environmentl ftor fvore emergene of the resistnt vriety t the NWROC. We lso hve oserve stn ifferenes etween resistnt n suseptile vrieties within the first four weeks fter plnting uner Rhizotoni pressure in our 213 inoulum ensity fiel tril (1). In previous trils uner growth hmer onitions, however, we typilly o not see ny expression of plnt resistne in the first few weeks fter plnting. ACKNOWLEDGEMENTS We thnk the Sugreet Reserh n Eution Bor of Minnesot n North Dkot for funing this reserh; Mitsui Chemils Agro, In., Syngent, n Vlent for proviing prouts; Hilleshog for proviing see; Germins See Tehnology for treting see; Mike Metzger n Ly Wulfekuhle, Minn-Dk Frmers Coopertive for plot mintenne n hrvest t the Bker site; Dennis n Bry Butenhoff, Bker site grower oopertor for proviing ln; the University of Minnesot, Northwest Reserh n Outreh Center, Crookston for proviing ln, equipment n other filities; Jeff Nielsen for plot mintenne; Hl Mikelson, Constntin Aelkoun, Tim Cymluk, Ktie Sheetz, n Irwin Sylvh for tehnil ssistne; Minn-Dk Frmers Coopertive, Whpeton, ND for the Bker site sugreet qulity nlysis; n Amerin Crystl Sugr Compny, Est Grn Forks, MN for NWROC site sugreet qulity nlysis.

5 A. NWROC high Rhizotoni pressure B. Bker, MN no Rhizotoni pressure 18 Res Sus Dys fter plnting Dys fter plnting Fig. 2. Emergene n stn estlishment for resistnt n suseptile sugreet vrieties sown with no t-plnting fungiie tretment for Rhizotoni ontrol in fiel tril A) t the NWROC infeste with R. solni AG 2-2 IIIB (35 kg/h) n B) ner Bker, MN with erly Aphnomyes isese pressure, ut no Rhizotoni pressure; t points represent men of 8 plots (4 replite plots ross postemergene Quris n no postemergene tretments); for eh stn ount te, vlues shring the sme letter re not signifintly ifferent (P =.5). LITERATURE CITED 1. Brntner, J.R., H.R. Mikelson, n E.A. Crne Effet of Rhizotoni solni inoulum ensity n sugreet vriety suseptiility on isese onset n evelopment. 213 Sugreet Res. Ext. Rept. 44: Brntner, J.R. n C.E. Winels Plnt pthology lortory: summry of fiel smples. 21 Sugreet Res. Ext. Rept. 41: Brntner, J.R. n C.E. Winels. 29. Plnt pthology lortory: summry of fiel smples. 28 Sugreet Res. Ext. Rept. 39: Crne, E., Brntner, J.R., n Winels, C.E Plnt pthology lortory: summry of fiel smples. 212 Sugreet Res. Ext. Rept. 43: Niehus, W.S Results of Amerin Crystl s 213 Offiil Coe Vriety Trils. 213 Sugreet Res. Ext. Rept. 44: