AllelopathyJournatT(l) l-55 (2000) O Inrernationa,^,,r,':'r::;:';::::,:rt;SS

Juglansspp., juglone and allelopathy

R.J.WILLIS

Schoolof Botany.L.iniversity of Melbourre,Parkville, Victoria 3052, ALrstr.alia

(Receivedin revisedform : February 26.1999)

CONTENTS

1. Introduction 2. HistoricalBackground 3. The Effectsof walnutson otherplants 3.i. Juglansnigra 3.1.1.Effects on cropplants 3. I .2. Eft'ectson co-plantedtrees 3. 1 .3 . Effectson naturalvegetation 3.2. Juglansregia 3.2.1. Effectson otherplalrts 3.2.2.Effects on phytoplankton 1.3. Othel walnuts : Juglans'cinerea, J. ntttlor.J. mandshw-icu 4. Juglone 5. Variability in the effect of walnut 5.1. Intraspecificand Interspecific variation 5.2. Seasonalvariation 5.3 Variation in the effect of Juglansnigra on other.plants 5.4. Soil effects 6. Discussion

Ke1'rvords: Allelopathy,crops, history, Juglan.s spp., juglone. phytoplankton,walnut, soil, TTCCS

1. INTRODUCTION

The"rvalnuts" are referable to Juglans,a genusof 20-25species with a naturaldistribution acrossthe Northern Hemisphere and extending into SouthAmerica. Juglans is a memberof thefamily Juglandaceae which contains6 or 7 additionalgenera including Cruv,a, Cryptocctrva and a total of about 60 species. Walnuts are corrunerciallyimportant as the sourceof the ediblewalnut, the highly prizedtimber and as a specimentrees. Eating walnutsare usually obtarnedfrom -/. regia (the colrunonor Persianwalnut, erroneousll'known as the English walnut)- a nativeof SEEurope and Asia, which haslong been cultivated, but arealso sometin.res availablelocally from other speciessuch as J. nigra (back walnut) - a native of eastern North America andJ. ntajor, J. calfornica andJ. hindsii, native to the u,esternu.S. ILillis

Grafting of supcrior fnrit-bearing scions of J. regia onlo rootstocksof hlrdier spccics. strclras J' ltind'sii or.I. nigra is cornruonpractice. The speciesof ualnnts are in necd of relis-ion.particularly thosefrom South and Central America, and frorn East Asia. as more than 60 specieshave been recognisedin the past. At preseut about 20-25 speclcsand ntttnerous varieties are recognised:the better knorln speciesare listecl in Table L

ihbleL Majorspccies ol Jttglart.s(contpiled lionr varioussourccs)

Species Common name Distribution

Europe/Asia

.1.regio L. pcrsian Conrr.nor.ror rvalnut S.E .Eulope.Asia: rvidelv planted .J. ntotrd.slturica Maxinr. Manchurian rvalnut N.I:. Asia .1.oilatrrltifolirrCarriere .Iapaneses,alnut .lapan.Russia ,J. cotha|ert,si,s Dode China North America'SoLrthArncrroa

.1. rrigro L. Black lalnut E.IIS: rvidclvplantcd J. citrereu L. Ilutternutor uliite rvalnut E.LISand Canad:r .L trrttjrtr (1brr.) Ileller ArrzonaualtrLrt S.WtlSi. Mcrico J. rticrocttrpo '",r'alrr. Berl. Lillle tt or Texasblack vu,altut S WUS .1. ltin.l.sii (.Ie pson) .Iepson Claroor N.Calilbrnial,alnut Calilbrnia J. c'olifonrica S. Wats. Calilbrrrialralnut Caliibrrria

,J olorcluno Shndl. & Williarns CenlralArtrcrir:an r.r,alnut Mesico.Ceulr'al Anrcrioa .J. rnolli.s Engclrn. er llenrsl Mcrico. Guatcllala ,1. pv'ifitrnti.s Liebntan Mexico J. .jorttaicensi.sC. DC Nogal or WestLrdies u,alnut West Irrdics

.J. d tt.t It.dI i.\ Griseb. Argentrna.Rolivia

J. ttt'otropico Dicls Lcuador.Colornbia

Hvblids Juglans spp.,juglone ancl allelopathy

.1. intcrnrcdio = J. nipya x J. regia

J. quttdrungulota - J. cinerea x J. regio Since antiquity',the walnul tree is knou'n as a sourcc of substanccshannlul 1o other lir.ing things. For example. rotting fruits wcre usedbl' native North Atnericaus to stun fish and decoctionsof leal'eshave long been used b.vfisltertncu to drive \\'onlts to the soil surface. Many American folk uses for u'alnut. including foliagc as a repellentfor ants and flies. have been described(313). Such uas the balcful rcputatiouof the n'alnut in parts of Itall'. that it is called "s'itchcs' trec" (3()2). Holq,cr. u'ahlut also providesamongst the earliestrecorded suggcstions of allelopalhr and to this da1'u'alnut provides tlre best paradigm of allelopathv.r.r hich has attractcd nluchatlention froln the popularpress (3-1.63. 9-5.215. 251) and conrmuuitrscnicc prograrns(99. 126,138.. 139).

2. HISTORICAL BACKGROUND

Earlr nritings aboul the ualnul concernthe Old World spccics.luulunsregitr- thc courmonor Persianwalnut. The earliestrecordcd statcmenl rcgitrding thc harmful effeclsof the rvalnuttrces came frorn the Rolnanauthor Varro (309). uriting in about "1.f, 36 B C.. Jbr itlstance,/re [your neighbourJho.s ott ook-sntvc ort llrc (()nu)ton hounrlor.t,,rou vould be wrong to planl olive lree,sott tha edgc rtf suclt o votttl,.fitt^ tha,setree,s have a natural atrtipath.vto il ,srtgreat lhat, not onl.v,dttlhe.r.,heor vttrlt', but even, itt their efforts to escope,bend avo.v itttt'onlstoworrl lhe /ontr preci.sel.r'u.s tloe,stlte vine i.[planlecl neor cabbage. Like oak lree.s,trolnul lrac.srreur.r'our fitrrtr. i.f of lorye size ond stdtlding at little distance.fronrone onolht:r,make il.: nrar.gin.slfir to louchott.v plont vhatever i.t uncloubtedl.vpoison." Hc also notcsthal. "'llte ook uutl the olive are partecl b.vsuch inveterote hated thal i.f ona be plonlctl itr tlte holt,.frottr rrhtch the olher hasbeen tlug out, lhe.r,tlie.lhe ook intleed ol.vt tl.r.,ingif planlctl ttt'rrr the walnLrt."

These notions were courmonll'reiterated and sourclinrcsaugurenled in subsequentnatural historl' and agricultural lracls in thc Mcdicral period. Of pa(icular intercst is tlte Andalusianregiou rvhich had a rich historr of agricullural uriters beginning rvitlt Columella. The Arab rvorld had a numbcr of grcat libraries as thc Arabs.unlike tlte Europeans.ltad accessto paper:holever" thc \ast urqoritr of lhc booksuere bumt during the Christianpurges of the l-5thand l(rllr ccnlrrrics. Alabic science.maiulv under the influence of Jabir ibn Hai1"am.developed a con-rplexsJstelr of antipathiesand s1'rnpathies,based largelv on supposedcornpositions of tltings fronr tl'iilis the elements of water, air, earth and fire (l6l). The few surviving agricultural rvritings frorn this era seem to have a rnore practical basis. The writings of the l2th centur)' Andalusian rvriter Ibn Al-Arvlarn rvere largell' based on a number of predecessorsbut theservorks. notably that of the lOth celtury Persian. Ibn Waltsltii'va have printed been recently. al-Filaha al l,iabati.v.traor Nabathean Agricdlture. cornpiled by Ibn Wahshilya, may owe its origins to ancient Babylonian lritings and. thus. predate Grcek and Roman rvritings. but the earliest knou'n r,ersion in Arabic dates to the 8th century'. Ibn WahshiS'a (137) statesnumerous plant s1mpathiesand ar(ipathiesbut thesecomrnonll'retain an occultinfluence. In describingthc rralnut he sa1-sthat it is "the opposite o.f the pomegranote vith respecl tfruit is intens<:nncl the heat cattsespirnples anel black morks." Ibn Al-Arvlarn's rvork. u'hile importanl in his cra. rvas effectir,'el1'lostuntil the l9th centurv rvhen translatiousappeared rn Spanish(135) and French(136). althoughit rvasevidentlvknoln to the l(>thcenlur.\ u'riter, Herrera (129). Ibn Al-Awwam wrote of the n'alnut (translaledfrom l36): ".,1// treesplanted in the viciriitll dernonstrateantipathy, tritlt tlte exc:eptiono.[lhe.lig, rhich is.fountlto have severalp

Hadj of Grenada says "That the walnut is antipathetic to nto.i trees tllat one vishes to plant in its vicinit.v',except thefg attd the ntul.berr.t',because the volnut is of' excessivescorching and drytress,which is harmful to allwhich cotne neor it and thiclt Qre not s.vttrpatheticto il. It destro),sever.vthingv,hich grov,.t^berteatlt it, ex(:eptcertoitl winter plants, orfern.v pla,'tts,v,hich one can grov beneothir,y bronche.s y,hen it is bore of ils leaves; when one wa,tl,t to ossociate u'ith cliubing grapevine.s.tlte.t'do tr

The l3th centurv rvriter Albertus Magnus (2) described thc n'alnut as unfavourable to surrounding cultivated plants becauseof lts "indvelling exlretne loxic bitternes,i'. Pietro di Crescenziin his rvork Agricctltura Cotnm

The writings of Pliny and other Latin authorswere compiledaud augln€lltcd rvith information from lbn Al-Awrvan and other Hispano-Arabic u'ritcrs b1-Herrera (129). He recordsthat the Castiliannalne for l'alnut hasthe mearing of "to hann"- although it is norv generally regardedthat Romance langrngc uanles for u'illuut such as nogal(Spanish), no.ver(French) and noce (Italian) are derived frour the Lati[ rrr,r for nut. This etyrnologicalmisconception is paralleled in English. *'ith thc ternr ,/uglon,s.spp., luglotte and alleiopathr

"roxiorrs" derived fronr the Latin noxa. meaning hann. Curiouslr. Fuchs (94) in l-550 cleirnedthat the unrelated Greek trord for u'alnut kar\.,onuas llso derircd frour a uord nteaningcausing lteadache. The first indication of controvers,vconcenling the hannful cffccts of lalnttl appcars in l(16{ in thc writings of Erelvn (86). Evell'u r\;ts a grcal proponenl of plauting nalnut in England and he dcscribcd hou. in Burgundr. uitcre ualuut is plrttttcd itt rrlreat helds bv fartners. "lt i,t sofar.fntn hurtirtg tha r:ntp. that the.r' lottk rtt tltcrrt a.t o greot l)re.terver. hv keeping, the grorrnd \rur,tt. IJouclcr. lanttcrs in 13urgrrnd'r'ar oid plartting S,rapcsbeneath ualuul ( lti.l ).

A significant adlance on rvalnul to\icit] appcars in thc rrritings of Wbrlidgc (.110)ru 1677. as hc prorides a statenrcntol the urcclrauismof injrrrr. son)c t\\o hundred 1'ears prior to thc oftcn quotcd statements of Stickno and Hor (2til) Worlidge nrites: "|'here is o svnpoth.t' ond ontipath.t' itt plotrt.t. .lntl tttatt.r'.fahulou.s trorliliott.t !here are concerning tJten, but thi,s i,s c:erloinl.y'ohsen't'rl thel sonre trae.r till not thrive under the shacleor rlrip of'artothey o.sth<, tlrip rt.i'otrulntrt trec ontl ttf'tr c:herr.r,ere injuriou,s to other tree,s. bec:ouse the leaf is hi!ter antl rlrt'rlrtTt tlt,.;tnt.t'etlr .ruchtrte.s or plattt.s Ihot are ttnder tl."

Wcll indicatire of knorllcdge of thc ualnut rn Europc in tlrc scrcntcctlr ccnlun'. and thc l'a1 in n'hich Plinr"s infomration \\'as augnlcntcd. is the account of Estieltne(85)" u'lto rcgards tlte French ternr for ualnul as:llso rrrcanirrg"hannfrrl'". "['he v'olnut is'tt species conlntot'tenottgh in all ports, &'kttotLn lo heor,tttclt a natttt' lno.t'erf because it i.s rtoxiou.s Io others rhich ore neighhtturittg. itt tltr ltloct:t rhere it i.:plontt't/. ,{ and trtpe

Llr tltc closco[ the l8th cenlun ne\\'infonnatioubcgan to bc :rddcd. For lli ll is

exrtrnple"in Phillips' PomariumBritannicunt (2201" in additionto urcntionof Plinr. it ''1l7(l is slated that a n'ell knorvn London stralberry-grou'er. Mr. Kccn. has llotcd thal woltttrI i.s.soinjurious to slrav'herrv beds, that the.r-,seltlcttthear.fruil in the nerghbotrrhood o.f that tree." The harmful effect of the w'alnul \\'as couunou knonlcdgc in Europe and for exarnple.appcars in de Stcndahl'snovcl of lti3 l. 1.c Ilouge el le '\'oir'. "Each of these cur,yedvalnuts, said ll. de Rtnql vlterr ltis wife athrriretl fhern, cosls nte the harvest of a demi-arpent, y'l1eatcotltlot gnnr under it,s .shade."According to Crozicr (64). the secretaryof the Central HorticulturalSocictr of Frar-rcc\\'rote.' "Shrub.sand untlenroocl vill generall.t, thrit,t, otttl .flourish then plonretl under beech trees, but will n

During the latter half of the l9tlr centun il bccamcapparcut lhat Anrcrican species-tnosl notabll'the black lalnut (.1.nigra). also \r'ereiniurious to other plan(s Tltis sccnrsto be first recorded in Ihc Transaclion,sof tlte Illinoi.t ,\tote Horticulttrrul ,\rrclclt'. Firsllr'"Galusha (l0l). in discussingtltat"certain kind.so,l trtr.\ ure p(,i,\(,ttt(' on rtrc:ltortf'.rccorded that his neighboLrr.in planting a ro\\' of black ualuul lrccs oll onc stde of ltis :tpplc orchard"found after l2 vearsthat alnost all thc ud.iaccnlapplc lrccslutd dicd. Iu 187-1.thcre las a livell discussional thc IllinoisStalc HorlicullLrrrrl Socielr ll93) and Mr. McWhortcr and Mr. Douglasagrccd that black uirlnrrl allcctccl thc palatabilitr,of grassfor stock. Mr Bn'ant tddcd that hc hacluitncssecl blltck rutlltut killing applc trees s'ithin a radius of about 2-5uretcrs and hc thouglrt (ha( italnut rools \\ere in sornerva\ poisonous. Ho$cvcr. othersat thc urccti0g$erc in disagreetncn{and. $hen Dr. Sclrroedercomrnenled that rr,ahrutlqlves "c/)rilaitra gt'cul pntprtrtiotr o.[ bitter slu./fantl the.t'enhitter the grourtd anl nrakt:it stck". hc uls conlrontcdrr ith laughtcr.

Rentarkabh'sirnilar comrnents appcar clsor'hcre in the Amcricanagricultunrl prcss. A Pennsrlr.'anianfarnrer. Mr. O. Snolbcrger.\\'rote to a Famlcrs' Clrrbin Nctr York (7): "1./ael.satisfiecl lhat I hot'eseen three ctpple trce.r de.stnt)etl ht hlacA'taltrtrt.: and I heliere the.t'desto)' grape rines. I lutlge it i.s the vater dr()ppins.,/irttttthc valnur leave.slhat cloe,sthe v'ork.". In a discrrssiolbefore lhc WisconsinStittc HortictrlturalSocictt'in 188 1. Stickner,andHo1'(281.1 concludcd that "the tnain r((l.\ott vh.t'vegerotit'tnloes not lltrive under tltese lrecs Iblack s'aluutl r.t the poi.soutttr.t cltorocteroI the drip."

In l8ft.l.an Autericanreporl similar to that br Galusha(l{)l) las publishccl ",Sblre itt att Errglishforcstn'Jounral 18): lhirl.t t'aars ogo I 1t1s1711,'tlrrn rtrchurul rtl ohotrt 200 opple tr<'e.ron otte o.fnt.t'Jarms - open prairie. lloving a lot of three to litru' -.r'eot' old Ilalnut lree,sgnnring.[ron seetl.I plantetl a /bv ntu'.sol rltenron thc n()rrll .sidett.t a ttntlhreak. Both ,lid vcll t'in'.rttnretintt,. atttl n()t'.\'()rnetti Iltt, vrtlntrtIrt't,.t havt rt'ocherla lteight of J0 feet. The.fir.st rotr of ,lpplc trec.thu.s lrtn{ sittre bct'tt Juglans spp.,juglone and allelopath.v,

killed out. The rest of tlte orcharcl is tloing v,ell; hat,irtg a large c:rop o/'.fruit rluring thepa,st season and is generallv.fruitfirl. lI'ith nr)'experience,Lthoultl a,r,soonthink of feeding poisott to nr.t,stockos planting such trees near enoueh tt>,lpplc trees to suhjectthe latter to their influence. ,\'Iv grove o.f llalnut trees i.\ rttur:hathniracl hv passer,s-h.v.Thi.s tvrtuld seen, to deprive orhoricultural schenre,sof'the rcmance vrlh nhichthe.t, have heeu surroundecl in lheor!'."

Horvevcr.despite the apparentuidesprcad erpcricncc of thc so-callcd"ualnrrl toricitl"" Crozier((r.l) dismissed all suchclailns as unsupported.

3. THE EFF'ECTSOF WALNUTS ON OTHER PLANTS

3.1 Juglans nigru

J.l.l Effcctson crop plants

I.Grapcvine: In the carll'tu'cnticthccntury Hcdrick (12-5)slatcd rhat grapcvires \\crc harlltcdby"rvalnut trecs. Tlte injuriouseffccls of ualnut ucrc knoun,to Schrcincr andRccd (261.265) at thc USDA BurcauolSoils. bul ucrc nol invcstigulcdbr tlrcur lI. Tomato: The urrfoldingof tlrc u'aluut slory rcalll bcginsin thc 1920s.as bot'lrlhc svmptomalologl'andchetnistrv of u'alnut toxicitv ucrc clucidatcdal lhc Virginra AgriculttrralExpcrirncnt Station. Cook ((rl). in a bricl nolc.dcscribcd lhc urltirrgof torrratopllrtls as afltc(ed by ,luglans nisra. M:rsscr ( I tt5. ltl(r) collatccltrurrn 'flrc obscn:tliortsof ltis collcagucsol thc cfleclsof black tvlrlnutotr lonltto. rcsrrlts frottta spra.v-iltgexperimenl uerc parlicularh'strikiltg(ltt6): a scl ol surallsqrrarc plotsof tomatoplants happcncdto be bordcrcdbl lu'o black rralrrul trccs.all tollrto planlsuitltin l-5rtt and l2 tn rcspectivclr'.otlhe trvotrecs \\crc injurcd. Masscrnotcd that"in a largc allalfa field rvhich contaiucdl solitan black u'alnrrltrce. alfalfiruas gencralh'absentand replacedb1'grass uithin the vicinitr of thc trec and that tlre danagcsecnted root-related. Massev obsen'ed that black rvalnulinjrrred toruato plauts and potatoplanls. to a lcsserc\tellt. but not bcets.snap bcansor corn in his honrc gardclt He subsequentlvscl up lltrec simplc erpcriurcnls. Hc establishcdlhat u.irlnrrt rootbark addedto \\'aterculturc would causcuilting and bro\\'ningof rootsof totnato uithin {8 lt. that root bark addedto soil rvouldalso cnuse poor groulh. but that.rlalnut soilalone caused no effect. Massel'concluded that tlrerernust bc soutcloxic principlc nhich nral be initiallv insolublcin rvatcr" or mai'altcr chcmicalhoncc it lclrresllrc root. He srrrrnisedlhat the cheuricalu'as likelr.the hvdroquinonc.juglonc. lII. Applc : Schneiderhan(258. 259.260) rcportedthe dcrniscof apple treesuhiclr \\'erellcar black u'alnttt(rees. appareutll'a comnronlv knoln problcrnin Mrgilia tlc addedthat onlv J. nigro and.l. cinerea appearedinjurioLrs. as./. hindsil and,,/. Il'illis

califitrnico supported intercrops. he also regarded./. regia as not inprrious. ln lhc courseof a curson'Sun'eyin FrederickCounty. Virginia. Schneidcrhanfound cightccn instancesof 'n'alnutin;ur-v to apple trees. The averagedistance of -18dead apple lrees u'asabout ll.9 nr from a rralnut lree and the averagedistancc of l-l inirrredapplc trccs u'asabout 1.1.3m. Schneiderhanspeculated that the relatir,ell'cou.llllonoccurrence of u'ahruttoxiciq' in FrederickCountl" mar.be relatcdlo thc shallo$ soil iurd consequcnt inlermingling roots. He also spcculatedthal arnongthe local applcrarictics. Stavnlan mat'be llrore resistantto rvalnultosicitr'. Schneiderhan'sobscrvltions \\crc confinllcd br'lhe experienccsof Smith (272) rvhoservitlnul trecs \r'ere on rarioirs grlficcl stock Srrith also lound that alfalfa sufferedon his propertr' Diflcultics uitlr black rvrluul l'cre ulso reportedfrour West!'irginia (2 l(). 2l I )

In 1928 Dar.'is.rvorking at the !irginia Agnculturll Erpcrinrent Slaliorr isolatedjuglone frorn both hulls and roots of black ualnut (70) Jugloneuas adrninistcredto both tonate and potatoplants br inleclionrnto the stenr.carrsing severeeffects. Both rtaturaland s1'ntheticalh'preparcd -luglonc causcd similar effects Thc apparentidentifrcation of the causeof u'alnuttoxicitl' rlas consrrlcredsufTicientlv inportant to \r'arrantmention in thc,\'arr'I'nrk'i'inte,t(lt) aud to gilrn scrlicc:ts u scruroniclnctaphor ( 20:l).

The various reportson u'alnul tosicitv rr,hichappeared in thc 192()'scuuscd sortredcgree of panic in certain quarters.as fanners l,ho had uol c\pcrienccd an\ problemsrvith ualnut trees imnrediatelvfelt threalened. Millcr (19-i) attcurplecllo rebut Schneiderhart'scolnnlents in describingan old appleorchard containing l'alnu{. in nhiclt injured or dead tresswere not near n'alnut lrces. An editorial in thc Ila.thingtonStar (9) ridiculed thc idea lhat the n'alnut tree $'as toric trncliu alannist lulanner.attcnlpted lo blame ant'scicntist [Schnciderh:rnlfor anl loss of rralnut lrees due 1o their fclling. Others (28) courparedthe effectof n'alnut sirnph to that ol anl 'o1her "Ihc Ltrge trec c\crling a stroug compctilivceffect. confirrnationof .jugloucin $alnut toxrcifr thctr gencrateda vigorousconlro\rersl'rr'hich $as staqcdor'cr sc|cftrl 1'earslargeh'at the annual meetirrgsof the Northcrn Nut Groucrs Association. Scepticisrnabottl u'alnut toxicitt rr'asled b1.'Grecne(110. lll) lto citcd a nunrbcrof rcportsb1'farnters claitning that plants grov aclurirablrundcr their lainut trccs Hersher'(130)tvas outraged at souleofthc discussionsat the 1929nrectinll ofthe Northern Nut Grou'crsAssocialion and rcspondedu'ith a facetior"rsltolc bl,tming illl\ plant injun'on "inlangible poisons"aud there was A rnoveto suppfcssncgutrrr. inforurationabout black s,alnut( l2).

During thc l9-l0s and l9-l0s there ucre contirrucd.largclr unccclotlrl.rcpofis coucerniusthe effectsof black$alrrul on crthcrcrops (175. i9l. 223. 237. llti. 2(r2. 271.212. 28+. 32i) but oftenthe infornratiourras conlradicton. N{acDanicls.rrho Itad a long associationuitlt the Norlhcrn Nut Grou.crs,4ssociation.rras cridcntlv Juglons spp.,juglone anclallelopotht

spurrcdbv the Association(69) and reportedon solnepot e\periurcnlsrn uhich lonrato and alfalfa plants lcre plantcd in'nalnut soil but there appcarcdlrttle er.idenccof inhibition(175). Walnut hulls placedaround a grape vine seentedonlv to enhance gronlh. Tonratoplants plauted close to a black u'alnuttree shorred little adr.crsceflccl until late iu the scason..This uork nas continuedb1'Broun (-13).lho sltoled that allallaand tonlato in contactlith ualnut root bark sere retardcdin germinationand slrongh'inhibitcd in seedhnggrollh. Tomatoseedlings grorin irt nutrient solutiolls riith uddedu.allmt root bilrk uerc significantll inhibitede\eu \\hcn gilen full rurrtricntsbirt. particularlr.uhcn nitrogendcficient. There uas er.iclcntllconflict alnongualnut grol\'crs over the issue of n.alnut toxicitl-" parlicularlr as California sro\\crsnith plantationsof ,/. regia on their o$11roots or on gralied stock could not offeranv clidence suppor{inga to\ic effects117,5). and. in l9-ltt. lhc USDA (.](X)t atlcrupted1cl defusc thc situationtlrrough the extraordinan'nrcaus of a prcss rcleasc rciissuringthe public of the hamrlessuature of $alnut trees.in paflicular.to loulalo.

Curiousll. thc first detailede\pcrimenlal uork on the effectsof black ualrrrrt oli lornatonas conductedin Gerrnaur'.bv Bodc (12: 279.28t)) Wheu tornato scccllings\\'ere gro\r'11 in the nutrient solulionsupl-lorting tuo vclr-old ualnut sccdiings.Bodc could fiud no oidence of injun. concludingthat root excrctionol lriglouc\\'as l'lot a srgnificantfactor This is not surprisinglll \.le\\'of the lirnitcd solitbililrof.juglone irt ua1cr.but Bodeuas alsouuil\\itrc that.prglone produclion nrar bccontentore significallt \f ith nraturationof thc irce. He foLrndthat -jugloncrcachcd tlie soil through leaI leachate.leaf litter and also through thc littcr crcatcdbr nralc clttk!ns.

Thc rnlcractionultich has attractedthe mostdetailed studr is thc pronorrnccd effcclof l'ahnlt on tomato. Originallr'.this uas describedbv Masscr 1185)and Brooks (12)as a uilting phcnomenon.Bode 132)obsen'ed marked cptnits{\ of 1hc lcalcs. prelllitlurcrcllou'ing of the leaves.shorteucd internodal grolth ancldecreased lalcrll Ioot loriilalion. N'IacDaniclsand Pir-urou(176) rcrrcucd knouledge concerning rtalnuttoxicitr-and confirntedthat black rvalnut callseddauragc to both tonralound peonvplauts. printarih-through root contact. N{acDaniclstl72l dctailedtltc s\nptomatologvof tolnatoplants grouu nearblack ualnut. The first sign uas uilting. sontetimesin a strtglebranclt and especralll'duringda1 tirnc. Sourcaffccted plants evcntuallrproduced ueu groulh frorn the base. Esarninatiorof lhc slent tissuc ret'ealeddiscoloured zones. brouning ofthe lascular tissucand thc prcsenceofx1lcnr tlloses.uhiclt ural erplain the wilting. In ahnostall casesof uilted toulato plants. MacDanielsu'as able to find one or rnoreualnut rootsin contactuith tltc touratoroot ball Furtherirork 1177)attempted to assessualnu1 darnagc to othcr Solanaccac plants.potato and capsicum(pepper). Potaloplants did lilt. but to a much lesser crtentthalt tolnatoand no trlosesu'ere found: the capsicuurplants shoued no obvious elfccts. l0 IIi llis

Tomato plants are unusually sensitive to juglone: l0 ppttt luglonc carl causc 50% reductionof seedlinggrowth. rvhereas100 ppm juglonc is lcthal (31.1). Tltc interaction of walnut rvith tomalo plants rvas also investigaledbv DePalma (71. 75). n'ho usedone-year old seedlingsof J. nigra in glasshouseand field (rials: holevcr. thc only inhibition recorded rvas when rvalnut root exlract was applied to tontato plants and in field e.rperirnents.thc tomato plants colunonlv showedcnhanced grouth lltert adjacentto $'alnut plants.

It has been reported that walnut mat, affect lhe lastc o[ beets but no{ affect yield (22 l). The interaction of J. nlgra u'ith crops such as corn and bcan plauted iu alley cropping systemshas been demonstratedin lrcnching cxpcrimeuts(l{(r- l{7) Wtile competition, particularly for rvater"is of priuc irnportancein such svstcrlls.il appearsthat minirnising the contact of crop roots n'ith juglonc is also significant Kipkcch (155) found that lcaf vegetablesvaried in sensitiritr to bcing allo'croppcd with J. nigra: lhe order of sensitivity was Slviss chard (Beto vulgaris) > kale (l3ro.s.sico oleracea) > lettuce (Lactuca sativa) > parsley (Pelroselinluncrisputn). Nutricuts such as nitrogen. pltosphorusaud potassiurn\\'ere gcnerallr highcr in plantation soil. er.'identlvdue to increased inputs of organic lnatter b1' ualntrt bul. pcrhaps. compensatedby diminished grouth due to inhibition bv uahrul.

3.1.2. Effects on co-;llantedtrees

Black n'alnut may establishpoorlv on sitesrrhich lack tree corcr (-19). The use of "nurse spccies". rvhiclt eitlter prolect the voung u'alnut trccs fronr rncclralical damage or. lnore iurportantlv. enhance thc soil conditions" has becn reconrnrcrrdcdto accclcrateand irnprovervalnut grorvth (6, 16, 56, 73.93. 98. 106.2 13. 25+. 30i" i()7). Much of this pioneering rvork rvas done at Forestry ScienceLaboratory. USDA North Central Esperiment Station. Carbondalesouthcrn Illinois.

Nurse speciesmav also decreasethc gros'th of compc(ingor allclopathic r.rrrdergron'tltspecies such as the Fe.s'tucagrass (120. 2-t3. 217. 3t)(t).notablr /,. orundinacea.itselfan allelopathicspecies and reducethe incidcnccofualnu( discascs suchas lficrosphaerellaleaf spot and anthracnose(152. 153). Comnronnrrrse specics arePintts spp..Robinia pseucloacacia.Eleagnus tonhellota and ^'llnu.sg/allno.sa. Whilc pines are generally sensilive tojuglone it ural'takc tcn vearsor so before the effectsof juglone are apparent and. b1'this time. rvalnt( trees are rvell established((r). Thc usc of legunressuch as black locust (Robinia pseudoacacia)has prored problematic as ils rapid groutlt overtoppedcoplanied rvalnuts. lespedeza failcd altogether(5(r). fueneld (2.{5) testedthe ellectsof luglone(10't rt to l0-6\I;on l-l hcrbsand shrubspotentiallr' uscful as covercropsor nrlrse speciesarrd found that all uere scnsilire tojuglonc. Gcnninationand radicle exlensiol'lrvere qeneralh' less affecled than shootelonsatiorr .|ttglansspp., juglone and allelopath.t, ll anddn' n'eight accuurulation. The speciesmost affectedin bioassal sere Lonic:era maackii,Lespetleza cuneato, TriJitliunrincantaturtr, .4lnu,s glutino.sa aud I',leagnu.s unhcllola. Hou'ever.Ponder et ol. (22(t)found that soil frorn $alnut plantations"u'ith andnithout ,4ltru.sglulitto^rr/.r or Elaeagnus umbellata^had no significant effcct on the gronlh or Rhizobitmrnodulation of the covercropI,icia villo,sa,although inhibition couldbc demonstratedthrough appfication of luglonein sandculturc.

Eleagnusumbellata and.4lnusglutinosa are actinorrhizaland arc capablcof increasingsoil nitrogen through the action of the actinornycelef;rankio. Hou'cvcr" il l'as found thal nursc specieslnay prospcrfor a period of 8-13 1'cars.aflcr uhich lhc rncreasedroot svstelnof u'alnut and,/orthe apparentaccurnulation of .jLrglonein the soil causesthc decline of the nurse irees (2{6). Contran to thc findings abole (2-15). juglonc is reportcd to have little direct effect on ,{lra.r grou'lh but affccts nodulation and the aclivitl of Frankia. Curiouslr,.of five I;rankia isolalcstested. thc onc associateduitlt,J/rr^s crispo"a speciesrclatir,clv rich in lhc phcnolic pinosr:lvirr.rurs tltc nost rcsistantto juglone (3ll. 312). It u'as found that the groulh of f;rankio iu 1,11ft)\\'as reduced cxponentially as juglonc concentrationincrcascd frorn l()oM to l0-r M (71). At a conccnlrationof l0{M juglone had a selere cflect ou thc grouth. il ritro. of thc nitrogen firilg srrnbionlsl;'ronkia and llhizohiurl and conccntrationsas lorr as l0'6M causcdsignificant inhibition in I?hizohiunr,ahlrough Rhizobium nas sliglttlrtt-tore tolcrant at iuglone concentratrionof l0-r M ('72). In frrrthcrerperirnetrts (205.206). seedlingso;f ,4lnus glutittctsa \\'ere grown hrdropouicallr and it uas found that.jugloncat concentrationsof 2 r l0-s and 2 x l0-nM inhibitcd nilrogcnascacti\it\ afteronc dav and after fir'e dar.s.respectir.eh'. Jnglonc at 2 x l()-5M causedrcduccd roolrcspiration and plant grolth. Hor.,evcr..jugloncaddcd to soil onlr had an cffcct at a concentrationof l0'3Mand this cffect ceasedafler 22 dars cridcntlv duc to detorificationbv the soil. Contran'to thc rcsultso[Fisher (tt9).thc aulhorsfound that a ttel soil regintedid not increasethe longo'it1'of the juglonc rn thc soil. Work br Hcckrnarrand Kluchinski (l2l) suggestedthar lcaf litter of J. nigro did not contribulc signilicantll'to inhibition of nodulatiouor nitrogen fixation in lcguutcs. Pondcrand Tadros(227) cxarnincd tlte role of juglone ir-ra l-1-lcar old rlalrrut plantation containingthe nurse specics.4,lnu.s glututo,rus and !:,leagnu.sunrhe llatu.s on an upland sitein southcrnIllinois. Thel found that juglonc lcvcls.nhiclr nerc significantlr grealcritt l'alnut-black alder planiings llian in purc ualnut or \\alnut-autumuolivc planlings.could be thc causeof thc relatrveh'earh dcnriscof black aldcr trccs rrr rralnulplantations. Ponder (22-5) also exaurined thc interactionofblack \\alnul \\ith .1lnu.sglutint,.srr rlnd lileagnus utnhellotain a l5-rcar old boltornlultdplantation in sottthcrnIllinois and. similarl1,.found that louer conccutrationsof lrrgloncin topsoil tvcrcassociatcd nith plantationscoplanlcd u'ith /f. utnhellctta.likclrduc to cuhancccl mtcrobtaldegradalion. Pondcr also reportcdthat thcre uere dillercnccs in thc soil nilrificrstn diffcrentplantings. Hotvo,cr.these differcnccs \\crc nol dirccth corrcllrlcd utth.ittglone.btrl *erc likclv causedthrough changes to thc undcrstorc\\egctulrolr ll'i ll i.s

Uttdcrstandingthe dvnarnicsof juglone can bc inrportirntiu ualnut plantation lllallagculcnt.particularll,' u'here tlre trecs are han'cstcdfor liurbcr. The hancsliug proccsscarr result in the releaseof substantialquantities of juglone iu debrisancl throughdarnagcd roots (58). If it is desirableto nraintlin intcrcroppeclspccics. il uulr bc prcfcrlblc lo harvestlatcr in thc vcar llhcn juglone lo'cls arc lorr or. if rcplan(ccl tritltttttsccdlings rcquire a conrpc(itivccdg,c. thcu harvcslirrgin strrnrrrerrrrrar [rc advautagcorrs.Oftcn. thc allelopathiceffccts of rvalnutarc unforcsccn.for e\illuplc. Gabricl (100) dcscribcshou an arborcturnfor u,hilc birclrcs(scrics E.rcclsac) uus cs{ablishcdort a silc *hiclr rvaspartlr occupicdbv l2 sr:niving lrccs frorn a lirilcd blttcklaltrtrl pluutalion.Within orlcvcar l-5ou( of 2(X)rurious rrhitc birclics had dicd and of lltcsc.li u'crcuciir lr blacks'aluul Deadbirchcs rrcrc rcplaccdnith nol birch platttingsand a[ter J vcars. I I of thc li trorrblcdrralnrr( sitcs again cirrrse'd[rirclr tttortalilvartd a lurthcr8 birchcsltad srrccrrnrbcd ncar lalrrLrt lrccs. \\hcrclrs tlrcrc ncrc onlr { olhcr losscsauar' lrorn thc ualnrrls.

Tltc rrcgativccffcct of blackultlnLrt on conifcrspllrntcd nclrrbr rs rrcll kuonn Itttd sttpportcdbv nutucrousobscrvatious. u'hcrc it has contrrronlrbccn lbrrndlhirl coniltr plitntlttious.cspcciallv tlrosc of /)rrrrr.rspp.. cstablishcd nc\l to ualurrt (rccs slrorrltiglt nlorlalitvucar (hc conulou bordcr(5" +2. -l-).87. l ltt. 2 l 8. 2-11.262. 263. 321) Rcsc:trcltrrilh -jrrglonchirs dcrnonstratcd llr:rt sccdling g,ro\\lll of l'irtrr.t.\tr(,htt.\' cltrtbciltltibitcdbritslittlclsl0-TMjuglonc(5l). Sccdlingsof/'lrrir.\//1)l)r/.\gro\\n for fi-10rrccks irt ltrdropotticcrtlltrc u'crcirt-jurcd b\ l()-()M.jrrglorrc. I trt'trlt,ptola'1t1', l'ttt'rt tthre.sittld l)it1tt.\',r1,/1s,,17r',.t bv l0-5 M juglonc. l0--+Nl .luglorrckillccl /.rrrlr It'lttttl4Sti.sattd 1'lnrr.r .rt'/r'c.r'/r'r.r arrd l()-l M.luglonckillcd lrll lbrrrspccics (,)7) Fislrcr (ll9) clctttortstratcdlltitt lhc rtllclopalhiccflccl ol bllck uirlnul olt 1',rrr,srr,.s/rro,srr l)lr(l l'irtu.tstntbtrs uits linkr'duith poor soil drairragcarrd assrrrrrccllr longcr rctclltion of .irrgloncin thc soil Vtn Sarnbcck(l0l) concludcdthirl salurrt rurs lr supe.r'ior' cortlpctitoron bc((cr si(cs and undcr conrpctilionslrcss. probtrblt prodrrccd rnorc .itrgloncnlticlt ttllcctcdpinc. ltoucvcr.on dccp ucll clruiuctlsi(cs. co-crisIcncr: \\il\ possrblclrs jrrglonc lllitv rlol buildrrp in lhc soil.

J. 1..]. Efk'cts on natural vcgctltion

Althotrglr.ltr.slon.s' sllp. arc cortsidcredto be amongstthc trcslcqurppcd platrts to Itflccto(ltcr plttltts via allclopalln.lhcrc are surpnsirrglr,[cuclltttr rrri lhc cffcctsol- ualrttttotl sttrrottnding'iegctalionundor natural conditions. llonclcr. rt u;rs nol rrntrl 195I thill Brooks(-12) attclllptcd to docuurcntthc elTcctsof ullnrrt on srrrrouudirrs \cgclittloll itt a broad conlc\1. although urostof thc trecs sludicclucre iu arr agrtcttltttralscttltlg. ln vicrvof lhcseuell knou'ncffccts. Corrrad f-i9) irtreslrgatcd l|c c-ffcctof leitf ltrtdhrtli crlracls of black u'alnuton lhc gcrnriuationirrrd scecllin!, g,rorrth of cight dccrdLrottstrccs tnclrtdirre blirck utluut ilsclf.brrt fburrcl no sisnificunt,-.t'lccts .Iuglatt,ssytp., juglone ontl allelopathr li

Thc effcclsof frcsh leaf ;rnd hull crtracls on lhc earl\ genltillllllollstitg,cs of L,iquitlattthurst.t'raci.flua, ]'latanus ttccitlt:tttali,:and Rohittitr 7t.;t'rrtloo<:a(/o\\erc cramincdulorc closeh: but anv inhibitor-r'effecl proved tcllrponrr\. Brallou (ltt) e\anrincdthc effcctsof .1.nigro on old hcid srrcccssrouand foundllt:tt it nas itthibilon to []/rrrrr.somericana and Froxittt.r,spenn.;.vlvanica. Dc Scisciolo et al. (-17)coltlparcd theunderstore)' \'cgetation in scr,cralplanted mixcd hardu'oodslancls con{aiuing ,.I. nigro,.lr:cr.sacchctnrnand ()uercu,sruhrct and could dclcct no qualilirlirc dillcrcnccs. Tlrcdcnsih of rrndcrstorc-\'\egetationrras acluallv srgnificautll higltcr il1dcr.J. nigra. Thc onll significanlinleractions recordcd ucrc posilirclrssociirlrons uillt I?uhu.' rtccitlentoli:.('irr.oi:u tlttttdri.sulcotaitnd Dryrtptcri.:.rpruulo.srrAlt(l iur llnc\pcclccl 'fullo rrcgrtilcintcraclron u ith . l ,taccharutttsccdlings. Rcccnth. r'r c/. (2tiu) founcl thatthc root-clinrbinglianc Rir,s ratlictttt.sis lcssabundant lhan crpcctcd otr.L nigt'd andthat bark estract can inhibit the genuinationof /i. rcttlicclt.s.Thc ubscnccof lhc hcrbdittarrr' (Cunila origcltoicle,slunder certain hardrrood speclcs lcd rln Saurbccker o/. (10-l)to inlcsligatc the cffcct of root- foliage and dccaring lcavcs lcachlrtcsof scvcralspccies. including.). nigra'.hosocr. tlrc authorscould not fincllnr srgnificant elfectattributablc to lrllclopathr'.

3.2. ,lugluns rcgiu

3,2.1, Ellcctson other plants

Tltc Pcrsianualnut Juglansregia is uidcll grou'uthroughoLrt lhc uorld as an ornatnenlalor crop lrcc. Its inhibiton, effcct on undcrston Vcgclalionis srrpposcdlr "lcll knoun" (169).bul has been little studiedin conrparrsonlo bl;rck\\tllnut Molisch(197) Ibund that volatilcs fiortr Pcrsirrrr ualnut shoolsucrc slighth inhrbitorr. Holevcr.tttost infortttittiort lcgarding thc Pcrsrlnualnul sccmsarrccdollrl During thc eitrlrlcltrs ol tltc black ualnul conlrovcrs\-Califorrria uirlurr{ gro\\'crs rrolccl poor gro\\lhof plantsrrndcr./. regio but lourtdthat this could bc rcncdicd tlrrotrghnrtrog,cn applicalion(175).Gcncrallr.itisacccdcdbvAnrcricrngro\\crstrgrecdtltlt./. rrgrais lessloxic than../.llgra. allhoughresults (222) illuslratethat thc rcllrtrvcdcgrcc ol' itthibilionof tlte tuo spccicsin bioassal'dcpends on lhc tcst specles.It lrasbcen rrotcd thalpotatocs. bcaus and alfall'ado not gro\\'ucll bcncathlalnul (l(r2). ln uorlhcrn ittdia.,/.regio is coutrnonlvgro\\'r.l along bundsand tcrraccrisers of cultrvatcdliclds andthcre is lotr specicsrichncss undcrneath llre canopr ln colllpansorrlo control arcas (2+.25) Furlltcrtttorc.of eight trccsstudrcd, ,J. re?ro uas forrrrdto lurrc lhc nrost pronottrtccdcffcct in reducinguintcl crop biornirss(br' (r9'l',,)irrrrl trrr c\ cn lllorc pronottttccdcffcct on sulluncrcrops. Lcal'lcachatcsol',1. rcgto $crc lorrndto inhrbrt gerrttinatiortof scvcralagricultural spccrcs (l9l) and lcaf cxtracrso1.../. r-rrr:ra lcrc inhibitonto sccdlinggrostlt of ulteal aud corn and to gcrrrriuutionof corn"brrt not ltcat t29-1.1.Walnul hasalso becn irnplicatcd in "soil sickncss"problcurs. lhat is. thc rc-establishrttcntor lllallltcrlrlncc of a uulnul pianlalionlnav pro\c clrlficrrllfor no tl IL'ill i.s

obviousrcASon (92) While organiccourpounds havc bcen idcntified in contribulingto "'soil sickncss"probleurs of fmil spccicssuch as applc and pcach.thcrc arc no snclr data aborrtu'alnut. as .vet.and il rnar,bc thal tcrnporiln dcplctionof soil nilrogcn br tuudcrston'r'cgclalion is the major causc.

Griiurutcr(ll-t). in his irnportantmonograph on allclopalln-reurarkcd that irr its trativcltabitat in Asia Minor. r'alnut u'oodlandhas a ratherpoor uudcrstorcvuhicli tttavbe linkcd itt someu'al lojuglone. but he offeredno evidence. hr reccntlirncs. this vicn ltasbccn coufirured b1' I{ussain et ol. ( 13{) u'ho furthcr rcportcdthal. in Pakislan crops suclt as corn. turuip. potato anclbcans rvere cornmonlv unthriftv uhcn groun ttcar nalnut lrccs. The aulhors subsequentlvfound that e\tracts of r',alnutleaves^ stctns.hrrlls and bark. liltcr leach:lleand rain leachalcinhibited thc gcrnrinationand sccdling grorrlh of corn. trrrnip aud bean. Shool ertracls of ,,/.rcvia rrcrc forrncltcr cctttrpletelrittltibit tlte gcrttttnalionof uinlet'lvceds sltch as .llopacuru.srrr.r'rtsurrtitlt',t. Lor:luctt,rallla attd Ilophonrr,srophoni.strutn. lhilc thc grassIttliunr rrrtrltillttrtrrttttas not sigrrificantlr aflbcted (30I ). With surnmcrhcrbs" - llraranlhrt.:ratroflexu.t. Digitario .sttnguittoli,t,Pctrlulaca oleraceo \\,erc signiflcantlv inhibited. uirile Pnt.rttpi.s .\t('phoniattoitnd.Yonlhium .slrumario \\'crc nol. In'ricrr of thc potential cffectso[ luglouc.Bauckurann {22)slrrilcd four cliflcrenturixlrrrcs of grasscsundcr ualnrrt trccs. and found no effcctsof supprcssion.

Kolcsnicltcnko( l-5tt) notcd thal oak uas inhibitcdbv ualnut l-caflcachatcs. rool c\tracts and soil c\lracts of ./. re,qiohave all becn shourr lo dcnronstrittcsonrc dcgrccof inhibition rn bioassar'(23. 1.59.2-19). bul liltlc clse is gircn T'tt.ltt't al. (299) grcu 'rlltlt.tutsccdlings in excar,atedu'alnu( soil und found no injurious efl-ccts. rtlticlt is not sulprising in r,ieu of thc labiliw of luglone in soil as rcportcduilh .,/. ni.qra.

J.2.2.Eliects on phltoplanl

I1 has been suggcstcdthat ualnuts nravallccl fresllvatcrbiotu throrrghrtrnoff lnd/or tltc lcachirtgol'rvalnut littcr in rvatcr:lhis uun'bca particrrhrltroblcnr in arcas sullportlllg,llalntrt proccssinguhcrc uashiugsarc fcaredto lurrrufish (232). \\thilc thc cflcctsol.iuglorte on aquaticaniruals are uell knoln. its cffcctson phrtopllnkton arc conrparalivclr'littlc knowu. Juglonervas lound to affect,\irlroguraand ('hilontrtna.salconccntratiotrsaslol'asl0?M(102)"andsludiclilh F,'u.qletto slrouccl that pholos\tttltcticforins ur'rc lar rrrorescnstive than colourlcssfornrs (26 l) Kr:rlci itndLvnch (160)sunocd lhc inhibiton effcctsof u'ahrnthull c\lreclsand.juglone on a ttntnbcr of tnicroorganismsiucluding the cl,anobaclcria('alothrix. .lrrahaeno and .lnac.r'.tli.tand thc green algae Ilractcacctccrr.sand ('ot,lu.strttttr. Ho.ucrcr. conccntrationsof juglonc u'crc irt c\cessof 30 pprn. Randalland Rragg (2i-t) lorrncl tltlt tltc cvanobactcriurtt.\o.rroc conunune and lhc dcslrid Scenetlasnttr.r'ucrcinhibitccl .Iuglon.r .s:pp.,jtrglonc antl allehtpalh.t tl

br I pprtt.jugloucand tlre cvauobacterit,lnohaena.flo.s-oquaa tr 0 5 pprn.iuglonc^ rrhc-rcas('ltktrella p.r'r't,rtoidtt.rarlas unlflcctcd elcu br lt) pput -frrglonc. Al tcr.r lcnr conccnlrations(10 ppb. 10t)ppb). juglonc had a slight stnnulator\ cffcct on Vo,r/oc. .lnuhaetta and ,\'cenedesntu.t.Kcssler ( 150. l5l ) found lhat lhc grccn algac (-lostcritrrrr.,\licras'terias, Pantlorina, I:utlorina and SpintEyr.?\\'cre cr,en lcss scnsililc lo.iugloncas thcscspecics rvere eilhcr unaffcctedor slroucdslighl slirnulationat 1.7-l ppnl (l()'jN,I)juglone. Hc. thus. concludcdthat thc nrost likell cffccl of ualurrt lcrtcltateon lreshu atcr algaclas increascdbionrass because of inlribitionof ltcrbirores lulorcscuslt i\ c to juglone.

3.3. Other n alnuftispp.

l, J.cineruria: J.r:inereo.another natir,c of castenlNorth Anrcnca. is kno\\'n as tllc buttcrttut^or lesscorunronll as thc ntite ualnul. lt is of litlle cornurcrcialvalue ancl is scldontplanted. hcncc. it has not attraclcdattentioll sinrilar lo,/. nigra and./ r'cgla. Jonesartd Morsc (l-l-5) rcported carlr obscnations uraclebt A H. Gilbert'tlurt cinqrrcfoil(Potettlilla.fruticttsa)" a coliurou rvccdrvas gcncrallv lound dcad u'ithin a circtrlttrarca oftcn grea(crthan tltc canopl of butternut(,/trgltrtr.; cincrea) trccs arrd llrat ittlurrsccnt relatcd to inlcrmiuglingof cinqucfoilroots \\'ilh buitcnrul roots. Thc crtctttof the cflbct gcncrallr incrcascdrrith (hc agc of'thc trcc. lt lrasulso bccrr obscncdlltal J. r'inereouas associatcduith thc dcathof Pinu.srrrtr.rrt (272). Thc oulr crpcrirttcnlaluork uith J. c,insrg61shorred no significantcffccts on (oulirtoplants (7{. 75).altlrough thc plantsof J. citrerea\\'crc onl,v a lcar old. ll..I.mu"ior.' Thc Arizon:rualnut. ./. tttttjor^is also regardcdas an allcloputhic candidateand.J. mandshuric'a has bcen found to bc inhibiton in bioassaltl92).

The lack of convircing resultsdcmonstraling rllclopathr uith ,/. nigro or ./ t'cgirtitt a naturitlsctting is rtot surprisiugaud is sinrilarlo thc si(trationfound rrith I'.ucalvptu.s.auolhcr gcnus n'ith a good chcmical anuoun (327" i2ti). Thc rcsLrlts surtttnarisccl.aborc. couforurllith the theoriesof Rabotnor,(230.2.1 l). uho suggcsted thlt allelopallrvis unlikely lo be obviousin naturalenvironurents u'hcrc sclectionovcr tttillionsof rears has alreadr'filteredthosc specics intolcrant of thc torins conccrued. Conversclr-allclopathv is likelv to bc most dramalicin enr,ironnrcnts.cspcciallr thosc artificiallrcreatcd srtclt as in agriculturc.trircrc spccicsrrith littlc cocvolutionar\ histonarc brought together.

{. JUGLONE

Tltc allelopathiceffects of the rvalnutshavc bccu rrsuallrascnbcd to thc conrpouudknonn as juglone. allhough this approachis likclv ovcrlr srnrplrstic Indccd.tlrcre is a varictl' of othcr secondarymetabolites in,lug,lans. uhich havebccn irnplicatcdin allclochetnicalinteractions. including phenolicacids (.1L l17. 131). t6 ll'illis

flavortoids(181.27'/)- arnines (l(r8)" alkaloids (30). terpcncs (19. 169)and of coursc. naphthalcnvlderir,atires. Juglone (-5-hyd1ea1-1.-l-naphthoquinonc or 5-hvdrosr -l.l- naphthalenedione)is oue of the naphthoquinones.uhich occrlr inftcqrrcnll\ ilnd usuallvin srnall aulountsiu plants. houcver.-juglone is an oddilr in that occurs irr relatir''cabundance. It is of great interest(o ecologistsas it has beclriruplictrlcd lll ir rride arral'of allelocltcrnicalinlerections. including allclopathr. lts gcucrllh rcuch at'ailabilitr'.its rclativeease of isolationor prcparationand its predictablcpcrforurancc in bioassaYhave rnade it a cornmon subjectin allelopathic trork. for csaurplc. irr classroolllexperitnents (l{-3. 198, 271. 285. 322)" theorcticalaud ntcthodological studicsin allelopath\(82. 269.315. 317) and bioassar,sludicsofthc corn;tarativc to.ricit.lof various organic cornpounds(2;12). Juglonc has also been tlrc srrb-iqctof nurnerouspostgraduate disserta(ions in the plant sciences(3i. f-i. 7J.'76.81i. l5(). 166.2.18.239.268.314). Juglone rvas first isolaledin l8-i6.bul nanrcdjuglonc in 1877 and becaureprirnarih' of intercstas a dl'estuff(32()). Jrrgloncis an orangcish cornpoundu'hiclr sublirneslt l-5,5oC.It can be noticcd rvhcn fresh bark is stripped frour s'alnut rootsor fresh fmit hulls are cut. as lhe tissuclums Icllouislr due to thc formalion of juglone. There is sornedispute over lhe natural occurrcnccof "1uglonc. Dauglrertvct al. ((t8) mainlain that juglone is restrictedto the Juglandaccae.ahhough they onlv testedthe Juglandaceaeand closelyrelaled families. Jugloncoccurred in all se\Ierrspecies of ,Iuglons crarnined and in some speciesof relatcd geuera such as Car.y'a,Plo(1'corva, Pterocar.v,o-C.vclocar.va. However. therc arc also rcporls of juglone occurring in genera of unrelatedfarnilics. Lomatio (Proteaccac)(11)6). (laesolpinio(Caesalpiniaceae) (203) and-4strogala,s (Fabaccae) ( 179) It lxrs:rlso bccn reportedas a tnetaboliteol'r'arious fing|. Petticilliun tliyersuntyar. ortrcunt196). lt rnutant form of lbrticilliun dolrliae (283) and \'I1,c11tn1ro"rolla./ijien,ris (282\.

Researchby Dorv Chernical Co. has. apparentll'.suggestcd thal UV radiation is required for the biosYnthesisof juglone. u'hich mav explain rvhv sontc csperirrrcnrs tvitlt -/. nigro in glasshouses.rvltere most of the UV radiationuas losl. r iclded ncgillivc results(17-l). Horvever,in direct conflict rvith this is a stalentcnlbv Clinc and Neclr' (57). nlto maintainedthat juglone concentrationsare higher irr glasshouscsecdlings than in field grou,n specilnens.Recent lork bt'Renessc(238) indicatcslcnf c\tracts of J. nigro ttnd ,). regia become tnuch more inhibiton aflcr exposurc to 02 arrd firll ligltt. shich suggeststlrat pltotocatalvsisis involved. Juglonecan bc biosrnthcsiscd througlr an apparentne\us of pathrval'sritich originatenith o-succirllbenzoicucicl (199). derived front thc shikimic acid paths'at'(seeFigure l). Juglonc is u'rost abundantin the plant as a gll'cosideof cr-hydro-iuglone(1.-1.,5-trihyclrosvnaphlhalcnc) rtltich. follon'ing enzl'matic hydrolysis to releasethe sugar. is rcadilv oridiscd to jttglotte undcr aerobicconditions. Jugloneor its prccursorsutt\. participatc ilt lhc fonnation of more cornplex colnpounds including mcthvlatcd forms (27). sclcral luglone oligonters"including dirners.lrirners and possiblr'.lctranrcrs lrarc bccrr identificd irt lissucsfron Jtrglan.r'spp.. but their fhnclion is unkuoun ( 122. ll I . I l2 ) t1 ,Iuglans.spp., juglone ond allelopath.t tl

Thc lactthat freshll,cut tvalnutlulls qill lunr firsth rcllou rtillt jugloricand thert turn black" after further oxidation. indicates that other corr.rpoundscatr bc easill fomrcdfrorn.juglone (ll3). The fate of juglone in tlte cnr,iroutncnlhas rcccntlvbeen elucidated(sec Figure l) and degradationproceeds enzltttaticallv via the actiottofthe bacteriaPseutlotrtona.s puticlo Jl or J2 trtich. ultimatelr'. forrus 2-ltldroxvlnuconatc scmialdehrdc and pvnn,ate(202. 2-10.21I ).

At one pointluglonc itself l,as thoughtnot to occuruaturalll in plant tissuebu1 was thought to bc present onll in tlte fortn of a glrcosidc of l.l.-5- trihrdroxrnaphlhalene(s-hvdrojuglonc). It is no'waccepted that -juglone. in addition to lts prccursorsand b1'-products.can be found in plant tissucs.altltough nlosl oflcn ill snrallquantities. Hol'ever" in somestructurcs. such as in fruits of ,/. regia. therc can bc a distinct gradicnt of juglone and its concentratiouis greatcstiu tlte cpiculicular rrar. n'lrcrc its concentrationhas been recordedas constitnting up lo 29.8ohof the u'as (228). Similarh. Binder et ol. (27) found that juglonc and -5-hldroxl'--l-oxo-u- lclraloneor 2.3-dilrldro--5-lty'droxy'-1".1-naphthalenedionc(p-hvdrojuglonc) comprised l8 6% (18.2pprn) and 3.3'2tr(3.2 ppm) of thc naphthoquinonccompouuds o[pcelings of unripeblack I'alnul (J. nigra) fmits u'hereas.for the uhole hull. thesequanlitics changcdlo 26Vnand 567n"re spcctiYell'. It is no1kno$'n $,hethcr.juglone concctttration changcsrvith the agc of thc tree:cxpcrirncnts rvith l'alnul sccdlingshale oftcn sho'n'u littlc allelopathicactir.in' (e.g. 30.1). Horr'cvcr.eveu cotl'ledons of genninatedualuut sccdscontain the p-glucosidaserequired to convert hydrojuglone-p-glucopvranosideto the agh'conco-h1'drojugone rvhich. under aerobic conditions. rapidlv oxidises 1o the nore stablejuglone (83).

Pedersen(21.1) has shou'nthat elcctronspin resonancespcctroscopv is a rapid andsiniple technique for assafing juglonc/hvdrojuglonefrour srnallplant samples:hc foundlhat. in eight speciesof Juglan,sscrcened. the leaf conccnlrations\\'ere 1.1-2.9 tttg/gDW basis.although the techniquewhich detectsorlho- lntd poro-qniuols.lhus. 'total nleasrrres .;uglone'" Rccentll'. Girzu et a/. ( l t)5) havc providcd a melhod for thc specificdetermination of juglone from frcsh samples.using high-pcrformance liquid chrouratographr'.Girdling esperinrentssuggest that juglone is prodLrcedin the lcalcs or othcr green tissncsand lhcn translocatedvia thc phloern.(37). Pralavieracr a/. (229)found that the xrlan sap of ,/. regia coulaincd.jLrgloneand could causcgrafting failLrrc. Thc juglonc concentrationin lhc rllern sap of .l. regict has bccn found suffrcicntto inhibi{ secdlinggrouth in bioassar'(229,291).

{.l.Pcsts managcmcnt Tlte raison d'ctre for juglone. like rnost sirnilar secondaryurelabolitcs. rs linkcd primartlr'1o dclcnce against a rangeof enerniesincludiug insects.neuralodcs. bactcria and fungi. Jugloncis rvell establishedas a deterrentto insects(10-1. 108. ll6. I+1. 2()8.13-). 295. 318) and inseclsl.hich feedon meurbersof the Juglandaccaccomuronlr' l8 Ililli.s

arc lessaffected br.juglone (295). As is often the casein the courscof coevolrrtion.a fcrvitrsects lltich feedselectivell' on.Iuglans have cxploited the toxicitvof.juglonc. lbr cxanrpfc. tlte lan,ae of the chn'somelid beetle Gctstrolittoctcpre ,r,ro sccrele juglonc lo detcrant predators( 189). The rcadl'ar,ailability ofjuglone has attractedsorne intcrcst in exploitingits propertiesas an insecticidc(3 l. 250).

Juglonehas beenshorvu 1o plal :r role in discaseresistaucc irr scabc:rrrscd br ('lad(),\poriuttrcor.\:igenum (31 . 80. 329). ualnut blight causcdbr .\rlrtlrr)nt()ito.\ conpe.ttris (-52)and antlrracnosecaused by (intnnonio leptost.t:lo(-57,1. gails causcd b1 Ph.y'llox'eraspp. (12-l) and lTusiclatliume.ffitsunr (123). Juglone has bcen emplolcd as a successfultreatrnent against some fungal plant pathogcns(275). It aplrcarsto ollbr the firsl linc of dcfenccagainst invasior.l as it is, for exanrple.an cffcctile inhibilor of conidia gennination in C. can'igenumbul has no effecton subsequcntcolotrt, groulh or spontlation(329). This accordsrvith lhe unusualh'highconcentration of,jr-rglonc irr tltc cuticle. There is considerableseasonal variation in.juglonc quantitics in diffcring tissucsand juglone is usualh nrostabuudant during the voungcr slitBcsof thc plant stnrcturc.For esample.66lsz,janiet al. (37) reponedthat juglonc ailititrsits hig,hcsl lelcl irt leavcsin Junc and in nuts in Septcnlber. Jugloncalso appcarsto acl ils a plt'r.toalexinand is cotrttnortlvfound to bc nrore abundanl in dlurage'dor inlcctcd -totrrl tissttcs(80" ll5" l2-l)" althoughHedin et al. (l22) found lhat thc en.lounlof -iuglotre'.including ils precursors.docs not increascin danragcdlissrrcs of pcc;rrr Juglonchas also been found to increascthe activity of polr,pholoxidascirr t'itro (2,)) and. tlttts.tnav also plav an ancillarvrolc in dcfcnse. The prcscncco[.jrrglorre lll rool lissnetttav be linked to its nelnatodicidaleffccts (9 l. l7U). An cnigutlrticfcarrrrc of .Iuglan: spp. is that. dcspitcthe presenccof .juglone.rlosl spccicsappci)r lo bc cu;lrtrlc of lbrming nr,corrhizac.bolh endotrophicand cctotrophic(c.g i9" 2(r6).uhrclr sttggcststhat the fungal associateshar,e urechanisnrs capablc of dctorifrrng or scqucsteringjuglonc.' Marked intraspccificr,arialion to r.asiculur-arbrrscrrllrr cofonisirtionrvithin sccdlingsof.1. nigra (81) supportthis rierr.

{.2.Germination and secdinggrorvth As iuglone is a naphthoquinottcit is ven reactir.ein biologicalsrstcrris. rthrclr probablvexplains ultv it gencrallris nol recordediu larl;,canlollllts tn hcalllr ltllnr tissue.Tlterc arc ntllllcroussludies u'hich havc dcnloustrtlccl thal .jrrglorrc cln rnlrrttrt gcrtnttralionand sccdlingor plalltgroulh (tttt.l3:1. 267.3211or itccclcnrlc scucsccncc (-53).ittcluding one n'ltich ltas attculptcdto asscsslhc eflect of substrtrrtiontrltc ancl positionuithin lhc naphtlroquinones(276). Anrong thc fcu corrrrrronlroccurnllr.l napltthoquinoncs.pluntbagin (2-nrclhoxr-,5-hldrosr-naphthoquinonc). folloucd br .iuglonc.are the most inhibilon. Generalh.juglone can acl rcadilr ru o.uclirtroni rcduclionreactiot-ts and. as a reductant.ma\, couconritantll'crcalc polcntialh harntfLrl frcc radicals such as superoxideald hrdroside (267). Juglonc can bc uscclils an artificialclectron acccptor in thc Hill rcaction(2J9" 2tt9):it is a rrscfirltool in ccll Jttglan.s.spp., juglone and allelopotht t9 biologvgeneralh' as an electron acceptorand as an inhibitor of numerouscell proccsses.especiallv those lhich rell on thc nrovemeutof cationssuch as K+ or Ca++ acrossmcrnbrancs (90. 207. 3()8) Juglonehas bceu for,rnd1o dismpl the actiritics ol rnitochoudriaand chloroplasts.These cffects and othcr uravbe duc to its rcactioll\\itli tlriolgroups (127. 128. l-s7"170.209.216" 211.219). Jugloneappcars to havethc abilin to inlerfereuith the slnthesis(S) phaseof the cell division qcle lhich mal be due"agrin. to its reactivih.nith thiol groupsand ma1 hare potentialas al auti-cancer drug 1l{8). Juglonecau affect basic plant proccssessuch as cell divrsiou. cell clongationand root formation(60. l-56).and it behavcsas a trpical plant grolth substanceiu bioassar.in haring a grcrttereffcct on radiclegroulh than on hvpocol11 gronllt (29-i). Its sirnilaritr to svntireticplant horurones-such as uaplithaleneacetic acid.suggests that it rnar-actas a plauthornrouc undcr certaiu circuurstances ( l.12. 6().) Nlorcrecentlr..juglone has bcen shonn to pror)lotcrool forrtlrtiouirr nalurrl seedlutgs(11(1. l+l)

5. VARIABILITY IN THE EFFECT OF W.A,LNUT

Probabh'tlteurost rcring issucregarding allelopathv in ualnut is lhe rariabilitr of thc effcct. This occursfor severalrcasons. (a) markcddi{Tererrccs rr.r the abundancc of jugloneand associatednaphtltoquinones alnollg and riithrrr the diffcrcnl rvalrrut spccies.(b) distinct seasonaldiffcrenccs in thc occurrcnccof nirphlhoqurnoncsin iialttutspccies. 1c) distinct differeuccs iu tlic susceplrbrlrtrof plirntspcclcs to llalnrrt alielopathl'and(d) gcographicaldiffcrenccs rn allclopathiccflcct of rralnul drrclargch to liglrt conditions.soil conditronsand soil uricrobiologr. 5.1. Intcrspccificand intrasllccil'icvirriltion

Jugloneis regardedas a constituentof nrost.if not lll. of the knoun u,uluut specics.artd has been cotrfinucd (cither as.juglonc or ln'do.prglorrc)irr./ir.g/rlrt rttst'tr, ./ regia,.l. cinereo,.l. tnantl.shut'ico../. trrctyttr.,/. ttiittrrti/oltrr.,/. \ tntt't'tttt'rltttt Jr. vilntttreono..1. ,\tenocerpo. .I.y11pp.1yy1s, ./. r'utlta.ttir.sl.r as ucll tts sonrcsltccics ol tlrc rclatedJuglaudaceac gencra (-or'\'ct. l)t(t1t((u'td. ctc (6|i. l{).1.2111 Anrouq./rt,Jlutr.t spp.tt is gencrall-rconsidcrccl tlltt tltc highcst.lrrgloncconccrltriltions tilc lorrrrclin,/ nlqraand that this spccicsltas becn obscrrcd 10 cinlsc lhc luostdarrlrgc to othcrpliult species.Hon'cver. Matlce\'(192) in bioassarsuith,./. itrarttl.slturtcu,,Jntgra and./ regrafoturd tltat aqueousfoliar of c\tracts ol J. tttant[.sh1/r/.]1/ \\erc llrostiulubilon. lt is rlortlt noting that lc|els ofjuglonc harc bccn found in l)rentttt.r11spl) colnpalltblc to thoscin,luglon.: spp (2 l-l). Thus.lliis gcutrsalso uarrants slud\ lls un allelopatliic crndidate.

\Vhilcthcrc hits bccn cousrdcrablc nork on tlrcscasonrrl ruriabilitr of.jugloncrn ualntrl(see belou). but.little uork has bccu donc on intraspccificrariulion Il hls bccnrealiscd that in the uut-grouiug industn lhrs ftrccthus grc:rtlnlportancL- ul 2t\ ll illi.s

brceding progranrsas iuglone lcr,els.particularli in pccan. havc bccn linked to rcsistanccagainst larious pathogens. Although it is cr idcnt that thc eflcct of u'aluut ou olher vcgetationcan bc quile variable (.12.2++) the causcscan bc uranifold. Atnong the fcu date on iutraspecificvariatronrn juglonc in ualuut. Lcc and Carnpbell (167) found that the ./. ntgra culiivar'Ohio'had significantlrllrcatcr conccntratibn of 'Thomas' -irrglonein the hulls than did thc cullivar and an unuaurcdseedling. but thc sitmecultirar had the lou,cstjuglone lcrels ir-rits foliagc. Cline :rnd Neclr 1-s71 rcportcdunusualh' higlr.juglone ler,els (11.2 rng/g leaf DW) in onc parliculartrce iunorrgsttltcir sanrples.De Sciscioloat al" (11) fouud up to lcn-fold rlriatiou o1' juglonc cottccutrationsin soil under sevcraldiffcrcnt rvalnrrttrccs: hou'ever.nhilc lltescoccurred on differentsoils. therc appearedno corrclalionuith an1'soil paranrcter. Rencsse(238) found that three diffcrent vancties of ,/ t'agia diffcred nrarkedll in their perforrnancein various bioassal's. Thcrc nral or rnal not bc vai'ialionin juglolrc conccntrationu'ithin a singletrce: Lce and Curnplicll(l(r7) lbund no diffcrerrcein iugone coucentrationsfrom sarnplescollccted fronr lhc rrplrcruud lo\\'crparls of a trce. uhcrcls Coder(58) recordedsignificantlr highcr.jrrglonclcrcls in thc lorvcrparts ofthe lcafcro\\'n.possiblv due to differcnccsilr pholosrnthcsrsor li ght-induceddecav of mctabolites.

Anotlter littlc studiedaspect of juglone variatronin ualnul rclatcsto thc agc of the tree. 11is courmotrlyreported that toxicrtvproblems. for eranrplc"sitir nursecrop specics.are not apparelltfor scveral1'ears and then thercis a relatilcll rapid dcclinc of llte nurse trees This situalion ura]'be relatedto a genuincphrsiological diffcrencc '71" betrvectr voung aud adult u'alnuttrces (32" 75. 221)"or is rnorclikclr an esprcssion o[;t .iugloncthreshold in soil bcing reachedduc to an incrcasingroot slstcllr al)d -;ugloneload. Iu onc stud)'(167).a t\\'o-\'carold black n'alnut scccllinguus fcrrrnclto il,,,%, jugloneconcentralion of 7.73pprn (DW basis)in lts rootsin Sclrtenrber. uhrclr uas sir times thc conccntratiorrfound in lhe foliaec.

5,2, Seasonall'ariation

Most inr,esligatorshave found that the abundanceof .jugloncrn thc spccics ktrorvnto contain ltigh levels of juglonc. such as .1. nigra. confornr1o tlic plulir Itpparcllcvtlteorl'. that. is allelochernicalsoccur in tissucsduring thc perrodsnhcrr lltn arc most vtrlncrablcto hcrbir,orcsand/or palhogcrrs Tliis occrrrs.trpiclrllr. during lcaf opcningand dunng fnrit forurationand is reflcctcclirt rcportcdhigh lercls of juglone in leitvesin'June/Juh and high levcls in fnrils in Aug,ust-Scptcrnbcr Houevcr.lhe mcnthsslrosing rnarinurcan van'aurougcultirars (l(r7) The ovcnrll situationis further cornplicatcd.as differentiuvcsligalors huvc nrcasureclthc abundanceof differcnt compoundsundcr lhc nrbric of "iuglouc'". As jrrgloncis toric. it is usuallv storcd as tlte more benign rx-hvdro.jugloncglrcosidc Tlrus. sonrc irrr.cstigatorssccking purc.juglonc in rralnLrttissuc uun obtairrlou vrlucs(c.g. 32.6(r) Juglans spp.,juglone and allelopath.t, 2l

'potcntial' 'total l'hile other investigatorshave chosento measurejuglone or juglone' throughsuccessive qxtraction in an oxidising environment. u'hich mealls that juglone precursors.such as g-hl'droquinone. form juglone during tlte ertractiolt process: For eranrple.Borazjani et al. (36) found thatjuglone levels in,L nigra leavcs averaged about 1.3 nglg (fresh tveight) during the grorving seasonand peaked in Jture.u'hich accordswith the data of otherw'orkers (109. 122. 123). Whilst Coder (58) used thc samemethodology as the preceding rvorkers, his data appear to be in error" as he reportedleaf concentrationsof potentialjuglone of about 0.1 mg/g (dr-l rreight). uhiclr ruasabout a hundred-fold difference. The link betweenjuglone concentration and developmentof the structureis emphasisedby resultsfrom Hedin et al. (123) tt'ho found that immature J. nigra leaves forrned in the late groulng season(September) had l.15 mg/g (FW) comparedto 0.0{,5 mg/g in the rnore conllrlorl older senescing leaves.Data from -/. regla shootsshou, also a build-up of juglone during lhe grou ing seasonu'ith a peak. firstll', in May and then again in July (292, 331).

As discussedpreviously', juglone is convertible u'ith the h1'drojuglonesand capableof fonning glycosidcs. Thus, part of the problem in assessingthe abundancc of juglone in rvalnut tissue is in determining rvhat exact rnethodshave been used for juglone extraction and measurement. A comparison of tu'o reports frotn the satne gronpillustrates thc discrepunciesin the literature: Carnal et al. (50) extracled dricd lear,csof ,./.regia and found no juglone. rvhile Girzu et al. (105) c\tracted fresh (Mat ) leavesof ,./.regio and rccordedspecificalll' juglonc. rrsing spectrometn'.levels of about 0.5%(fresh rveight basis). rvhich n'ould convert to about5% (dn'l'eight basis).

5.3. Variation in the effcct of Juglans nigra on othcr plants

At first" concernabout black walnut centredon its effectson apple. grapes.tolnatoes" potato€sand alftlfa but. once the problernbecarne linkcd to the chernicalsubstancc juglone. llterebecarne fqrr in sornequarters that black r,r'alnutwas a "'poisontree" aud tnar.have to be eradicatedfrorn the landscape.In 19-51.Brooks (32) finallv tackledthe problcm of ultich plants\\'ere and lere not a-ffectedb1'black l'alnut as. o\,cr the courseof 12 1'cars.hc lud sun'eledthe effectsof solne 300 rnature trces on neighbouringvegetation in fir'e diferent States.His data are sorner.rluldiffrcult to interpret as he providesonll' sirnplc lrcquenciesof sone60 lrcc species.35 slrubs and vines and 123hertaceous species rvithin and u'ithout the root sprcadof black ualnut but Brooks does describethose speciesutich hc iudges to be tolerantor intolerantofblack rvalnut.

There have been nurnerousreporls of the effcctsof black l'alnut ancl/orjLrglonc on indir,idualspecies but there have been no seriousattculpts to document the effcct of blacku'ahut on vegetationpattcrning. Eflectssomtimes defl comuronsense: tosrcil-r mavbe luorc apparentseverirl lneters from the trunk. even outsidethe canopl. becausc theroots nearest the trce arc too deepto rnakeconlact u'itl.r othcr roots(221). Clearh. 2) LIiIIi:, therc is n ide variation in the respouscof plant spccicstLr u alttLttbtrl thcre catr also be rltr.asltcltficr.ariatiol ilt tolerallceof salnut courportucisstLclt ls.jLrgltllle (2Ji ). in rcccnt vcats.tl cgnsiderablevolume of intbtnrationhasbecot-ne atailable lhrc,trglt agcllclL's stich lts ihe Amclican Holticultirral Socret1,.unir,ersitv e\tension ser-r'icesaud Itttrserics:it'iticlt ol-this has bcen drssen.rirratcdin leafle( for.nrand or iu electrouic form via thc Itrtetnet. \.\'irilcrlrost of' tl'risiplblmatirtn is r-u.rsubstantiated.n.u.rch o1- it has bcctr gcuetated bl erpelrettcecltlt plotessionalsro\\ers. The ialious listsof plantsrecordecl tu tltiscetrtut'r'as be ing lfflctecl or. unlfl'ecte-dbl,black l alnLrtare ccillatedin'fable 2. Reltoltssoutetintes conttaclict ollc allotl)cf. for exarnple.as in the caseof persinunon andholll'. trlerhapsbecattse of intraspecillcvariattotl i1 thc q'al6ut trees obsr.ned. clilier-entcultivals used ot. mole likely. soil ditfelences.

Fulthclmole. assessntentof sensitirrf.v- may varv becaust'of dit'feriug rllethodology: a plant sr-rchas I.ontc'c't'ttnrtucl;riis vel sensitiveto juglorte in bioassal'or hvdloponrc cultLrre(244 ) but may glor., satisfactolilr.uncler lleld conclitions.Thele are some groups strchas tlre conifer.s

(Pirropliyta).Betulaceac. Hlicaceae. Olcaceae. Rosaceae and Solanaceae.n'hcre there is li high percentagecrf plants r.eprl.teclas al'fected by black s alnut. Itr tttost o('thesegr'otips llrcrt' ls at leastoue ntentbel uhich appcarsto be resistantand. conttrrottly.it is a spt'ctesu'hosc rratrrr-allarrgccoinciclessithtb.aIol.|ttq!trtr.rsitp.artdot'C,rnrrspp. Folcrartlplc.thecotlflets

JttittpL't'!tslri.qllrrilrlr.r Pittttsyir{ittt,i //.t anrl /l\lg.r LLItt(t(ltlt.\i.\.Rltotlotlatrth'rttt pt't't(!\'tiIL'ttot(l('.\

rn ihe Ericaceac. Fc,t'.sitltrLtspp. ul tite Oleaccae:Crtttttt',.u.s spp.. ("r'r/arrrrt,.,hltttt.ttt,\lttltr's

:ttrt)rtttt'itt.Prtttttr: :,r'tolittt'ltld Rlrl;rr.s r,'tt;rlctttttit: irl thc Rosacr-ae:autj Pltvsttlisjpp lll inc

Sqlalaceae. lulilrcl ien.is sr-rppor-tto ihe argunrentsot Rabotttor (230. :3 i ) lttct-itiottuti '-tlr,.tsiililir pt'criorrsir'. At thc spccific lcr ei. lt sL'cl1tsillso tirat ihcre are cltitii tti.slllat lrc

rL'slstauiio tirecil'ects ot'bilck N lltlttt. Juglans spp.,juglone and allelopath"v z-)

Table2. Speciesrvlticlt are rcportedas affcctedor unaffectedb1' Juglans ttigra

Division/Fanilr'/Sp Comuronname Affected Unaffectcd

EQLISETOPII\'l"t Ecpu.settunttrvense Horsetarl i6

PTEROPIIYT.\ A:; pl en i un p Ia I yn ew' on Eborrt' spleenrvort 16 Arn),nufilspp. 8+.22 1 .4thyn rr n as p lento rcl e.s Lorvlandladl'6t'tt l6 .1th1'nunlhe l)' pte ro ides Silvery spleenrvort l6 Bottyc ltitLtil dt s se ctutt Dissectiongrape lent 16 B. tlts:ecttunt,ar. obltcluunt Conlrton gr:rpelent l6 Ij ulb i no p.v t s bul ho.s ct 221 De n n.t tt t:tlt i tt I lI t1 c ttI o bLt Hiry-nceutedf'ent l(r Dr|optert.\ct ls|0ta Crc'stedrvoocl t-em l.+.15.251 Dryoplerl s t nterntecl i tr Intcmrediateshicld l-enr 16 Dryoptens nttn'grnalt s Itlarginalshield 1-em 16.95 Dr10ptensspinuloscr 77 AIotteuc ci a struthtopter i s Oslrich lim 15.8.1.221 Anocleasenstbilis Senstivefem 14.16.84 ()snnndacinnanomea Cimrarnon l'em 14.15. l(r.95 Pol),stichumspp. I i ))l Po 11,stich u m ocro sti c hotd es Christrnasfenr 15.8.1.95 fibodsiaobntsa Obtuse \Vootlsiii l6

LYCOPODOPIIY'TA L; copodiuntc antpIa n atum v at- .flabellt.fbrnte l6

PINOPHYT.\ Juniperu.schinensr.s l1 ,luntperusrirgrnidna Red cedar 16" 17.3.1.67. 84.176.221.270 Lunx kuentp.fin Japaneselarch l6 I\cett ubie,t Nonvay spruce 16.67 17 I'inu.sden.st.flora Japirneseled pine 261. Pinu.;1e.fteryt .Teliiel'pinc l(r. I 7 Putrtstnttgo Srrissnrourtrrn prne 16 Ptnu.;ntgra Austrian pine 261 Ptntt.vrestnostt Red pine 5. I 6. 3.1.67. ll9. 176.221. 270 Ptnusrigidct Pitch pin"' l6 PintLssh'obu.; White pine 16.67.89.218. 221.211 Prnrrs,rlites/l r.' Scotchprne 16. 6"/. 244 PintLstueda t oblollv piuc 16.67 Pintrslhundhergt .Iapaneseblack ptne 261 Ptnttsrtrgtntuna Scrubpine l(, '[hu1tt occrdentalts Arborvltac l6 16.17 21 II1lli s

I)sugocanuclensr.s Canadianhernlock l.l. 16. 17.67. 8.1.2_i I

}T,\GNOI,IOPHYTA LILOPSIDA ANIARYLI,IDACEAE Galanthusnival.is Glory-o1'-the-snow 14. 15.84.95,z,sl ,Vdrclr.rt r spp. Daffbdil (t^7 ^'.1rcl,rjilJ' Jolln F,velyt'. 'l itsurpassable'.'KingAllied'. Ice Follies' et a/. Datrodil 16 Na rci s su.g'Cheerlitlness', ' \tllolv Cheerfulness. 'Geraniurn'.'fe1e-a-tete'. 'Sundial'. FebruaryGold' Narcissus 216. 176.221

ARACEAE .{lrsaema tripht,lluil Jack-in-the-pulpit 15, 16. (r7. 81.95.221

.lsarum europueunt Wild ginger 1-{.15. 16.8-1. 251

(]()TI\IELINA(]F],^\E L'ontnelrno coflnunis Virgina dar'llorver 1(, T'r'udescantiartrgtntanu Spidc'r$od 1-+.15. 8.1.251

CYPER.\CEAE C'are.rspp. Sedges l6

DIOSCORET\(-'EAE Dir.sscoreavillosa \\rild vanr l6

IRID.\CEAE Crocu.sspp. Croctrs 1{. 15.l(;. ti.l.95.251

1l.r spp. Iris 16.221 Irt.sstbericct 1.1.15. 8.1. 95

I,II,IAC'EAE Alliunt cepa ()nion t6. 67. 176.221.283

Asparogu.solficuralts Asparaeus 16.270.283 (lhtonttdoxcrltrcilliae (ilorv-oi--the-snorv 15^8.1.251 ('olchrcttnt sp. r\utuulll crocus 67. 176.221 ('onvalltna ntutalr.s l-ilv

Ilenerocalli.s litlva Davlilv l.+ 1/o.rttr spp. Plantarnlilr 223 LS.8.1. 9-i. 221 []osto fbrtuttet Plantarnlih 1,1.251 llo.slu lanctlblia Plantarnlrh 1.1.251 llo.;tu nttngtnulct Plantarnhlr t.l Ilosta ttndttlal

fIyuanthoides spp. Spanishbluebell 25i I l;nctn thor d es hi spa nicus Spanishbluebell 14.I 5. 84 Hyounthttsx Hyacirrth lrl Ht'ttanthus'Citv of Ilaarlem' Ilyacinth 84 HtcrcinthusonentaIis Hyacinth 15.251 lllrrolr cvs Lily 221 liiirll' Enchantrnent'. .\sianhvblids Lilv tb Itnope spp. t6.67 :\lttsc ari botrt'oides Grape hl,acinth 14.15. 16.8.1.95.25r

( )phtopogon spp lr,Iorrdograss 84.221 Pollgonatwnspp. Solomon'sseal 84 Polygo nalt un coilt iliutahon Solomon'sseal 14.15.221.251 Sctllusiberica Siberiansquill '[t'tq'r71t 15.16.84.251 11716t lbad lily 15.8.+.221 Trilliunt spp. Ti'illium 15. 16.67 . 221 Trilltuu cerntuut Nodding trilliurn 1.1.84.25t Tt'iIlitLn grand ifl orunt \\'hite wake-robin 14.8.+.251 'lulip Tititpasp. 283 'lit 'Iulip ltpt g ergi i' Toronto' 8.r,95 firlrpr s Danrrn '\\rhi'te \blcano'.Cum Latrde' Tulip 14.8.+. 95. 2,51 'i\lcrry Titlrpas Widorv'. '\\'est Point Tulip 16 'Blue Zrrlipas Parrot" Parrottulip 8.1 L-\,uldri0spp. 221 LituItnu grandiflora Big merrl,bells l.l. 15.ti.I.9,5.251 (;ttt|ana per.fbIiata Bellrvorl l6

ORC]IIIDAC][,AE Hdbenuyldl06sr., t6 Sptranthesgrucrlis Slenderladies lresses l6

POAt]EAE )grostrsolbct Redtop 16.3.+. 67. 171.221 .4ndropogonrtrgnicus 34.273 .4rrhen crt herwn eI a li tr.s Titll o:rtgrass 16.3:l .Jlenasp. C)at Bronts sp. Brome grass 16.34 Docttlisgionerutur Orchardgrass 16"3.1.67. l'74.221 Ddnihontdsptcut.r Povenv grass 34.176.221 Fe.;tucaelunor Fescue 3.1^67 f'esttLcLt Titll fescrre 270 llolcu lunattrs 3.1 Holcts nollt s \:un egottt,t' Velvetgrass 16 Lolitnt sp. Rl'c .)+ .\lu h I e n h erg u.t r hreh er t Nimbleuill 16.34 j' t ntcrrtn c la nde stt n unt I)eer tongrregrass 16.l:l r)hietnil pruten.\it Tinrothvgrass 16.31.6i.116 ftoa conpressct Clnada irluegrass l6 f)oe l14ten\ts herttrrckYbluegrass 16.14.67.211.221.:70 26 Il'ill i.s

[i tItctLtnue\tt\:]uu \\'heat 16.3-1. (i7 ,:(au1)1Lt\'.\ Conr 258 1(t..1.1. 176. 221. l7(). :t1

stIil-.\(rE.{!t Snnlacrnu rucenoso False spikenard l6 a,),/1.^spp. (irccnbriar 16 \1.\(;\oLIoPSlD.\ .\( r!tR\cti..\Fl )cer spp. lrlaple 221 .4cerg tnnulu (iiruralamaple 24t ..)cer trt:gtuttlo Bos elder l(r.l7 . )ccr ntgrtun Black rrraplc 16.t7 .lc{r polnt.tlttnt Japaneserlrplc l-1.I (r.I'1. l+8" 2-i1 .tctt p1ll111r1111rr,clt.s.yecntm .lapanesentltplc 16.2.18 icat' nt l)t uil| Iletl uaple I6 .'tCef SatCChdt!un Sttgarmaple 77 )cer suacl1(tIIt1IlDl Silvr'r nraple 16.67

.\\.\(rARt)t,\CE.\E llhtr.;

^\\NO\.\Cts,..\E ).strnutu tnlobu Pirparv 16.t7

.\PI.\CE.\l,l l)uttctt; cttrottt \\'ild canrt 16.14.270.2ri1 ,\|yrrht.s uIpe.:tttt Srleetciclcv l5 Pt r.\t11r1cu.\ttlt \:a Parsnip 1(r.17-1. 221. 283

.\P(XrYN.-\CU.\E I incLtnttnot Pcrix'inkle 15.221

.\QI'I t.',()t-I.\CE.\F, '16. llex opuca Americanhollr' 251 l7 llex verttctllalcr IUichiganholh. l6

.\R.\ I,I.\(]E:\8, .4l Ct|1it \pt11().\tt IlerculesclLrb I 6

ARIS'r'OLO('Ht.\Cn.\l:, .-lrt.stitlr.ttht

\s'l'tiR.\cit..\I ichtlleuntllelblitun Conrrnotrvamon 16..l.+.27() -ltlth j.()\tLt.pp Rag*eed 16. .l-l iill(:iltlLtttd spp. Prrsst's tocs I 6 ./us/an.s,tpp., 1ug/one ancl allelopath.t 27

.-lsterspp. ,dslcr 16.3.1. 8;1. 270 llrrlenr spp. IJeggar-ticks 16.-r+ C u I e n clu I ct o.ffi c t n al t s Pol rnarigokl l.+.8.1.251 (-htconwu inh hus Chicory 16 (- h rt s ut't t I rc nn rn t spp. Shastadaisl l6 (.-hrrsunthennun spp. Clrrysanthentun 270.283 1-+.15. 2;18 (' 'l ht t :ttntltenrt n Ieucunlhe nutn Ox-evedaisv 6 (' I ry su n t h em tu n nt o r t.foI i u nt Chrysanlhenrum l6 L'/r.ul//, spp Thistle 16.3..1 D c't1d t tt t1t h et n (1 sp. 251 Dorotlctun spp. Lcopord's-bane 1.+.15.84.251 Elephantopus spp. [,lephant'slirot l6 firtgeron onntttt.* Daisl,fleabale 16.3J gero Iirt n pfu lu tlel p h u s Philadelphiafleabane t6 Ertpu lrntu m cOe I d sti nuil1 NIist-florver l6 Ett ltuto r t tLtn pr t pureunt .loe-Pyerveed I6 !lt:ltntrnt spp. Sncezerveed 16 lltitc:tnrluts spp. Strrflog cr l6 y H eI t ttnr htL Iub ero sun Jenrsalelnarlichoke t.+.15. 251 ilt{u.1il:il splt. I Iau,kn'ced l(r f{ t er uc nn auro /)ticunt Orangehaukrveed 14.15.251 LuLtucu s?p. \\'ild lettucc l6 gtiltt Lt na sp.'Desderlona' 251 I'rLnttnthes spp. Riltllcsnak!--root l6 ]lutl[,echq hrrta Brorvn-eyed susan l6 Senecto,luretrs Goldenragrvort l(r.3{ Solrcirrgo spp. Golderrod 16.3.1 TLra-r'crcrittt sp1t. Dandelion 11.16.31.270 ['ernonra spp. Irotrrveed 16.3J Zrnntt spp. Zrnnir, 81.:70.:s.r

I}.\LSI\TIN,TCElIE Inpttrcns spp. Jervelrveed I6

BE(;()NI,{CI]-\E lJrqonid\pp. Regonia I-1.3-1.:70 Begontar senpervrens 13cgonia :.i l

BERBERII)..\(]I'.IE iJatherts cundjen,\ts .\nrrilcall barlrerr1 l(i llptnerlnrn snp ipinredirrnr ,r.1.1):. ll l i'ocioLt ht l ltLn e ntotlt \lavapple 221 i) oclc;p h rl I run ne I ro tt tn t \lavapple I:. l{).8,1.tl BIaTt'L.\t'l:,,\ta, -i,ulopean )ltiu,\.glturnos0 aldcr 57" 211 .'ilnttt,11"s.v61 litrroolh aJdcr lb Eetutu tll)

Be lttI a n tgr a' Hcrilage Riler birch I (l (0rptnus curoltntana AmericanIronrbearrr l6 Cory'17rtlmencana IIazelnul l6

BIGNONIACE.{E C a ta I7t a b igno n rc ide sColnnton catalpa t+.16.8.1.21t(.2it

BORAGINACEAE l[y'otor,t Forget-me-not 223 "r. AI)'o.sotisalpestrts Forget-rne-not 15.l2r '\'[.)'o sa ti s s\'lY d tI ca Forget-mertot 8+ ['rrlnonaria spp. Lungworl t4.16.8.1.251

BRASSICAC]E;\E Brctssica spp. Nlustard l6 Br0.r.sica oleraceu var.irotrltrs Cauliflorver 2t{3 Brcts stca oler.lcea \af cdpitata Cabbage 16.67. ri.l.270 :R3 Denlarra spp. IIe:peris ntolronalts Toothwort l(' 2)I I]T]XACEAE Pctchysandra spyt. t6

C'AES.\I,PINI,\CEI\E Ctssia narilan&cu \\'ild senna l6 Cu s.sto ntcitans \\'ild sensitiveplant 16 CANTPANTILACEAE CantpanuIa arnet icana T.rll bellllorler I t' (-unTtanula latifolia Bellflorver lJ. 15.8.+. 251

C],\PRIFOLI.{CEA[:, Lontcera spp. Honeysuckles 221 Lontcera sp. Red-budhoneysuckle 2li.l Lontcero canaden.st.t .\nerican tl\.hotr.r'rr',.0'. t6 Lontceru ntauckiu Aniur honevsuckle 214 16.17. (t7 Lontcero tdtlt tc(l Tularianhonevsuckle 1.+.16. 17. 2.18.25 1. }i.r

Lontcera tylosletnt liulopean tlv lronevsuckle l('_I 7 Srrnrblcrus c(tn lden st s Connron c'ld.r$errv l6 Iihttrntrnt spp. Vibunrtun 221 81.22 r I'i hto nt rt n a c er i l r,'I rt tnt \Irrple-leaveclr,ibuntunr l6 I i hurnurn dentInun .{rrou.wootl l6 lihrtnllnt Tr,rruru \\hvfaring tre.' r'iburrrtrnr t6_l7 Iil,rlnttnt opultt.s Eruopealr cranbcrry bush l6 vibunlunr I i hrtnttnt plicLrtrun DoLrhle-filcvibunrunr l6 I i hu rnttnt prunr lb Ittun Black harv I6 tihurnttDl stebcrldir Sicboldvilrumunr 16"176 C-\R\'OPH\'LLACE.\II Cera.;tttnt scandens N'lousc-elrchickuccd 16 Dientht!s aflnr'n0 Depllbrd pirrk l6 :;iellund ilte.lt.t Chicksccd t"+ .Juglan-sspp., juglone and allelopath.v ?()

CEl,;\STR{UllAE Celastrus.tcandens Clinrbingbittersuect 16 Ernrrlrrui.sspp. 221 EuorytrnrsalattLs lluming bush lT6- 221 Etonynusatilcrlcanus Slrarvben'1bush 16 Etrontnntsettropea Ertropeauspirtdletrce l(t- 17 EtLonynttLsltcnmltontant:r \ltldo.'ttouulus 16. 17

('II[,NOI'ODL\CE.{E Betuvrlgan; Sugartrcct 16.283 l(,.3'1. I 76.221.270.283 CLL'SI-\CEAE lI1'pencun spp. St. Johr's sofl 16 Ilypertcunprolificun Slurbbl'St. Jolm'su'ofl l6

CO\\'OI,\'[TLACEAE Can'olttltt.sctr\Jensts Fieldbiud*eed 16 Iponoetttncolor l\,lomingglorl' ?51 Iponoeatricolor Nloming glorl 14. 8{ 'lleavenlvBlue'

coRN.{cE.{tt Cornr:ulternt.foltd AltematcJeaveddogwood l6 Corrutsanonunt Silkr,dogrvood l(r ('orntts.flondtt Florvelingdogrvood 16.l7

CR.{SST'L.\C]EAE Seduuucre Golden-carpct 1.1.15.8.{.251 SedrLnspectohi le Showy stonc'crop l.+.8.{.251 Sechtntternatrun Slonecrop I6

Ct'S(lti I.\(llr.\E (-r.rcrl.rspp. Dodder l6

EB[,r-.\('D.\8, Dto:ptro: \\rgnldnd Pcrsirnmou 16 107

EL.{E^{GN.\CU,.\E, Elueognustngtrstr./blra Rr.rssianolive 16. 244 f:lLtei]guL!tunbellata .{utunurolive 211 16

ERI(].\(]E.{E .l--crleaspp. Aztlea 16.84. l7(r. 221.27() ( inVrrsrrcirspp. Huckleberrv 16. 3,1 Kttlntttlattfblta l\lountainlaurel 16. 34" 84. l'76.221. 223' 270 11Elr.r\pp Pieris Rhotlodenclronspp. Rhododcnclron 16. tt.l. 176. ZZl.27o Rhotlorlenclroncatavhtense 221 Rhotloclentlronnornnlun Rhododendron 221 30 fiilis

Rhododendron pertclwnenotdes Pinrterbloonr Rhoclodendron ri Exburv t4. 84. 248 hybrid 'Balzac' Rlrododentlron 84.95.24ti.251 Rhododendron x Knap Hill hybrid'cibralrar; Rhododendron I,hccinrun 84.95.248.251 spp. Blueberry 16.34. 176.221. 270 I hcci n tr nt corytnb osutrt Highbushbluebern 16 FABAC]EAE IJ1ptist.t australis Blue falsc ('aragana indigo t6 arborescens Siberianpeashnrb, (-ercts 744 canaden,sts Rcdbud Corontlla t6, 17.81.270 variq IIairy velch Detmodium 244 spp. Tick trefiril G le d i t,stct l(> tr ia cant hos Honey locusl G Ied i Is i a tr 'l'hotnless 16 iac an tho s.f, inennis lroney (il-t,ctne locust t7 nux Sol,bean Lespedeza t6. l8.l spp. L:spedeza LespedeLt cuneatct 16.56 SericeaIespcdeza 244 Lespede:a sttpt{laceu Koreanlcspedeza 244 tl.ledicttgo spp. I fediccrgo 34 satrvtt Allalth ,\lelrlonr.s t6.67. t76 zlt. 221 spp. Srveelclove.r Phu:eolu.s l(r lrtnutus Linra bc'an Phuseolus vtlg.tris 16.67.176.22) \\hx bcan:snap bcan t6.(;7. 176.221. 2l{.t Pisrtn satittunt rct Ro bi ni a pseutloacac 270 283 '[r itt Black locust i b It tu n h1, l6 I bn d i.fbI t unt Alsike clovcr 7i'r/b|iun h1,bridunt l(; 34 Trifoliun incarn0lunt Crirtrsonc-lover Trilbltttmpratense t6. 67.211 '/t'rfoiiun R.:d clover repens 16.14 \\'hi1eclover 7i i./blrrrtn I6.3.1.221 sp. FIopclovc'r l.?crtt./itba l(, Broad bean I tCt(t 31.270 \.tllosLt [lairy vetch 225 F,\GAf]EAI' (.'a.\taneu dentotLr Chdstnut Custanea I6 nollts.stna Chinesechestnrrt Fugtt.; 119 grun

GENTI.\N.\CE.{E Gennunaspp. Gentian 84 GenttLtnaasclepiadea Gerrtian 221 (ientitna septenfda Gerrtian 15.221

GEruNIAC!)AE (ieran t tuttro b ( rUanwil Herb roberl l.l. Li. 1ri.l{.1. 95. 251

Geranmn .\anguneun Cranesbill l.l. t5. r6. 8.1.251

IIA]\INIANIELIDACEAE HdililnLtnells|ilginidna \\'itch-hazel l6 Lttytdanbtr s\'raci1Iua Srveetgum 16.l7

HIPPO(]ASTANEACEAE Aesculttsglabra Ohio btrr'kc1'e l6 ..letculttsocttndrct Srveetbuckeve l6

H\'DROPIIYLLACEAE Hydroph 1'l Ir m t'i rgt ni an wtl Virginia rvaterteaf t.+.8+"251

JUGL.{NDA( E.,\8, Cttryo sp. Hir:kort' 16.221 Jttglantctnerea \\'hite rvalnut l6 Jugktnsnrgra Black wahrut 95

L.{NII.\CEAE .4itqa reptan.s Bugleu'eed 223 14.15.8.1.9,i.251 Colersspp. Coleus 270 Col I t n ton n cana ele n s i s Rich-rveed t6 Curul(1orryatnOt(les Dittany 303 Glechomahederuceu (hound ivy lr+ Hedeonaltulegtoides Perrnl'ro1al l6 Leonwttscdrdioca I\{otherworl t6 \lenthoppenta Peppermint 16^270 t\lonardaspp. Becbalm 8:l ,l lanardadidrrtitt Beeblanr l5 -\lonctrda .listtt lo.sct \\'ild bergamot l.+.16.251 itIontrda punctalct Holsernirrt l6 \epetLl hederdceo Gi Il-over-the-grorurd t6 Prunellavtlgarr,s Heal-all 16.3-t Prnurthennrnspp. Nlorurtainnrint 16 5aA,raspp. Salvia 91. 173.221 Stttcht: b.t:

LITTRA(]E.{E Lindetr hrn:o1n Sprcebush 16.l7 s{7rr"l/rzti|unrioIium Sirssaltas l6 )L II'illi.s

I,OBEI,I.TCE"\E Loheharnllata Incliantobacco 16.34 Lohelias07,1,r"r, Grcat lobelia l6 Lobehet.sprcatct Spikedlobelia 16

II'THR..\(]EAI.], ('upheu peliolct Clamml,cuphea 16.34

NI.{(,lNOLI:\CEAE bnorlendron tulrpi.fera Tulip tree 244 l6 .\lagnolto spp. lr{agnolia 2Zl .\lagnolra acwntnata Cucumbertree 16 1fagnolta .soulungiana Saucermngnolia 16, 67. 1'76

NI-{L\:\CEAF:, .llcea roseo Hollyhock 1'1,15. 84. 251 Ilrbr.rcrrsspp. Hibiscus 251 Ilibtsctt.;escttlentus Okra 270 Hihrsctt,sst rtacus Rose-ot'-Shlron 14" 8-+ \lttlt,u rotuncltfblra Commonmallow i6

\IENISPERTI.{CEAE \lent:1tt:t'nntntconadense Moonseed l6

]\IOR\CE.\F], ,\lont: ulhu \\'hite mulberrv I7 .\fonrs rul:rn Retl rnulberry l6

\\'ss.\cFt,.\tt .\ i .r.yir.rriyzrrcl Blackgum lb

ol,E-\CE.\8, ('hronanthrts t'trgtntcat Fringe-tree t6 f:'or*rhru spp Forsvthiir 16.8.+.176.221.251 Forl1thia .\uspensa \\'eepingforsllhia l.l Fruxtlnrl untenclna White ash 16.211 Fruttttu.; ntgro Blackash tb Ltgtt,strtLntsp. Prir,et 16,67 Si rrrrgrr spp. Lilac 16.84.2'70.283 221 St rtngu \ per.\tc0 Persianlilac t76.221 Srrtngo \:ul4ut t.\ Corrnrronlilac 116.221

ON.\(;Ii..\CE.\E ( tri tirir ,ltt,ttltrtttlcultt aj ()enetheru spp. llr-cningprinrrose 16 O<:ttctheru.frutico:tt Evcningprinrrose 1.1.15. 251

O\:\I-lD.\(-'11,.\ll ()rrr/r.rspp. \\irod sorcl 16. .l- Juglans spp.,juglone antl allelopatlt.t,

( hctltscorntcttlalt Creepingladv's sorel l.+

PAEONIACEAE Paeona spp. Peony 16, 67. 84, 1'76. 22r.2'10

PAPAVERACEAE Sangttinu'ncanudensis Bloodroot t.l. 1,5.8{. 2: I

PL.\NTAGIN,\CE.4.E Pluntctgonulor Colmnonplautail 16 Illunlu-?olonceolalunt Englishplantain I (r

PL:\TINACIDA[, Pldtdnusoccitlentalis Svcarrrore 16.t7

PLU}IBAGINACEAE .lnnenutulgans t,at lLluclleOna Thrifl 223

POLEIIONIACEAE ['hlo.rpanraiata Surnmerphlor 14. 15. 16.8{. 25l. 28i Polenontlu]ireplans. Jacob'sladder 223 l.+.84.95.2-il

POITGALA(]EAE Polygalasongutnea lvlilkrvort l6

POLYCONACEAE Fugoprrun sp. Buckrvheal 34 Rtrlte.r'spp. Dock l6

PORI't'LACi\CE.\,8 ('/.n,orrd spp. Springbeauty l 6 t.-latlontu\lrgrmco Springbeaulv' I 5

PRIIIT'I,AC[,,\Ii C)clctnenspp. Cvclatnen 15.l2l PrmtLluspp. Prilnula 221 l'nwilu x poltuntha Polyanlhuspriurrose l.l. 15. ll-1.2-i i

R\NI'\(:t'L.\('E.\[, 'fhrntblsvecd .lnenonespp. 16 .)nentoneapennia Z2l lnentoneqrunrluelolia .\neri!'an u'ood irnertronc I 5 .-icyult:,grttct:t,r ttleo Colorldo coluntbine 16 .i,qttltgt ciutLtclen.\t; \\'tld colunrbin.- 16 l ldr.rrirsl)p. Clcnratrs l.l- 8"1.:51 I'lcntotttternlloru S\\eetautruDDclcmatis l(r. 17 (-lemttts\'trqlntilnL1 \'irgirr'stron"'r Ir, L.runthrh.tenuli,; \\'intel irconitc l-t- 15-ti-1.251 lltrilehortr.tspp. Ilellctror.' 8-1.:21 llirnttncttltL.;spp. Crol lbot 16 -tl II'i ll t,s

i I u nt I n (:rt I tI s .lt c Lt t't tr Pilc*on l:l [<0ntLn ctt ltL.\repe n -t Br.rttercup 223 7'ltitlrctrrtntsp. I\leadorvrue Ii. l2l

RIIA]\INA(JEAIJ C ettltd htts dtttt,t tt ltntIs Ne$ Jd'se\'leil l6

ItoS.\('FlAt,l .'int el a t rc ht er c u n a de n.st.s Serviceberrl l6 .4 r on t u at' b rt tr.ftt I ra Red chokc-bern l6 (.'otone.tsler sp. Coloneaslcr 84.95 ('t {ttdegu.\ spp. Hanthonr t6 C.l clonra oblongtt QLtince 16.).70 (-ierll spp. .\'ens l(i Len't.t luponr(.Lt Kerria 16.17 Ke rr t0 lupon rc.L' Pleniflola Douhle-florrerken'rn l6 .1./1iiru r spp. Applr's t(t.34. r<"1. 176. 210. 211.221. 270 191 'Sta]'n)an' ,1lafu.r sp. c\'. 17(r^191 .l /a/rus spp. Crabapple 67. 221 16.67 f,lttltt.c corondrict American crab 16 I Iolls hcrpa Hopa crabapple 67.r'76 16.(;7 I' h;,s oc trprts oprtI ilb I iI t.\ Nine-trark l6 f' o tenlr I I <1c anaclen s t s Corrlnon cinquefoil T6 Pote nt t I I d fi ltt t co.t.t Shnrbbt'cinqueloil 16.t76.221 L'rttnu,t cunertcana \\rild plunr 16 f't trntt.t ctt'tttnt SNeet clrerrv 283 Prttntt: cera.su.g Sorrrcherry 210 P r tt n tt : pe n n st l\:dn i c u,tt Irire clrr'rrv l6 ['rttnti, /terstcu Pcach ?l I ))l l9l Prttntt: :erott nct Black cherrv 16.I7 l' t I u1| t.\' .\'rt b h i t't e | | Lr \\'eepingHigan cherI1 16 ['t ttr]|ts tontentos0 Nanliing chern l6 Prrtntr.s virgtniana Choke chern' 16 Prtacanlha sp. Firetlronr t6 1'\l lts coil1ltlIIt1|s Pcar 84.221 I'rrus calleryontl Callery pear l6 Rll>as

I?tLbttt oclottrt tL.y Purplell orveringrasptrerry 16 Rt t l,tt s Pro",rr,,,o tt t Dewbern, 251 Rt tll.\cE.\Ij ( i0lrtun spp. Bedstrau' 16.l.+ (laIirun odorcrltun Srveetu oodmff 1'1.15.251

Rt r'.\('t,1.\E .Iuglans.spp., juglone and allelopoth1 l5

l.dnthot\'lrnianurcannn Pricklvaslr l6

S.\I,I("\CEAE Petptltttsp. Poplar I7 Saltxntgrtr Black uillou 16

S.\\IBT]T'ACEAB, SonhtrcrLsconudensts Colnnon elderbern, 16

S,\PIND.\(]L,AE Koelrenena panicu.lata Goldenrain-tree 16.1"7 SA\IIRd(;ACEAE ..lsti1bespp. Falsespiraea 14,15.84.95.251 Heucherospp. Coral bells l6 t5. t6. 221 Heuchertx bu:oides 'Pluie deleu' Coral bells 14.84 Ilrdrangeo sp- Hydrangea t6,283 Ht,lrungeuorborescens \\'ildhydrangea 16. 84. 95 Phtlutlt:lphu.tspp It.fock orange 95.zzl

SCROPHIII,.{RIACEAE I'erhLtscanhlattona N4othmullein 16 lbrbosctrntthap.sus Conrmonmullein 16 Ibronrcu.filr.formrs Cr!-epingveronica 1.1 I'erorucaolfictnahs Common speedrretl 16

SNIAROTTBACEAE .lilunthusglandulosaTree ofheaven 16 sot,.\\.\uE.\8, ( LtpslctLluunmttutt Pcpper t6.84.t'76.221 Ltcoperstconescttlentum Tornato 16,34,84. 176.221. 2t0.211,2't0.283 lliicoliuno tabaccuttt Tobacco IJI Ph,r'.ra/r.rspp. Grourrdcherry 16 Solununat'tutlarz Nighlshade 221 Solununtnelongena Eggplant 16 Salunnil tttberotilnt Potato 16.3'1. 8'1. 116.210. 2rr.270

ST.\PTIYLE..I,CEAE -\taphlled trr.lollu Bladdernut 16 s]'\'R.\(:.\C}t.{E Ilaleuu curoltntt Carolina sih erbell 16.l7

I'II\'\IEI,EA(]E.\E i.)Lrp h t tL t nt:-e re t t ;tt Daphne l.l.1l-l.2,il 36 Ili ||i.s

T'II,IA(:DAE Tt ltu tunertcancr Bassrvood TtI ra httteroph.t.i t6.67 ltr \['hite basswood Tilia plutyphl'ltos l6 Bigleaf linden 16.t7 t]Li\I.\CDAE Celtr.r occidentalrs Ha!-kberry [,ilnntsantertcttntt ot 16.17 Atnericane|n I ll nnLtliilvct l6 Slipperl'elrl l6 TiRTI(]AC]EAE Prlea prtntltt Cleanveed t6 vI()L.{CE.\E I i olct spp. \icrlet Iiola canadensrs 16.31.270 Canadaviolel l,iola cornuta 14.15. 84. 2,51 Homed violet Iioltt.;orornt 14.15. 8.+. 251 \lbody blue violet I iola i'1.t14.2-s1 x vittrockiana Pansv I'1.ri4.251.283 VITAC]EAE Pat he n oct.s st rs c1tu nquefolia \rirgina creeper l:1.16. -14.91. 176.221 I irrr spp. 251.270 \\'ild grape litr.yt'inikrtt 16_31. 176. Grape 221.270

5.4.Soit effects

A centralissue in assessingthe importance of.juglone in lo^ger''it1'a'd mo'ement allelopatln.lras bebn its in the til J"!ro"e can persistiu -\'earfollo\\ing the sorl for moretha' a treeremovar. particularrv irirr. sturnp (89) investigated hasuol becnkrlrecl (22 r ). Fisrrer three 22-2i lear-old;rr;; plantations Irtrd of ..t.nigrrt andI)inu.s. .\.rrol)u.\ P' re'\'in.^raitt south*eslei' ontarlo. C*uau. I' cachptarriition. rrrrec rt'ithdifferent drainage were represented. pincs soirt'pes gro*.i'g near\villullt drainedBrant soil trcesou rlrc rrcll shon'edno;ffects: itror" o,r the imperfectlv gro*rhonJ,i,or. drarnedTuscola soil ;ti,T'.:.l'Tffllr#j:*o ontrre pooirv draireJ coruood so' \\crc a,r.e\peri,ne"r b"odd;il; :'fllT ',"",,i either"uet" ;:"::',T:,i'.i,:,1:,:'f:''Jffi': or'.dn," andnronitor.a itr.o*ntration #,:,:'i,1j'j:i for 90 dals ustngbioassu.r. at, its.plir.rotoxicilv after Thc 1.: ^t111, :0 dars rrndiuglorre \\,as nor duccrabtc da\s.\\'hcreils trre \\'et soir contirrucd afrcr6() ta inhibitscedring gro$1rr a,rd rrirrbour.jugronc throrrghlltc entire90 dn1'5.n"t".ri,",iions orlugto,rern lhc ficlctbr po'dcr ancl an uprandsire in southe.,riiiinoir'rr'r,cd 'lllglolle]:i:::^(iiilarcouccntratioll thartl,.r.'r,u, a gradic'r or a\va-\'frottla *'alnut trec a.d do*'n*ard i' rhc soil. '.itlr a .I tLg Ia ns,sp1t., .j ugl one and a I Ie I ctput h.t' 37

maximalmean value of 3.9-5frg/g (about2 x l0-' M) soil in topsoil(0-8 cm). A

comparisonof mixed plantingsof black walnut and auturnn-olivelEleagnus untbelluta)

with rvalnutand Europeanblack alder (Alnus glulitzo,:ct)on similar soils revealeda

significantlydifferent juglone regirne,likely causedby diff'eringmicroenvironmental and

microbiologicalconditions (226, 227). Fligherjuglone levels in black alcler nrixed

plantingsrvere consistent with the earlierdecline of this speciescompared to autuntn-

olive. It r'vasalso found that nodulationin Eleugnusungustiliilia co-plantedwith J. nigra

didnot occur rvhen planted on bottolnlandsoils, rvhereas there rvas good nodulationin

uplandsoil: whether this differenceis relatedto differing.juglone regimes in the soil was

notstudiecl (332). De Scisciolocl al. (77) investigatedthe seasonalvariation of.juglone in

soil,finding that the pattemconlbrmed with jrrglonelevels generally reported in the plant

parts,rvith peaks in springand autumn.

An often forgotten f-actis that the effect of walnut trees seemsto develop with

nraturationof the treesand, thus, may not be a problernin youngplantings. According to

Rietveld(244), there is a build-upperiod of l2-2-5years before the et-fectsofjuglone may be noticeable.lt is frequentlyobserved that walnut may be grown successfirllyin the cornpanyof a nursespecies such as Alnulsglutirutsu, Eleagnu.r unthellatu or even pine for severalyears befbre any darnageis apparent(244).

Another little studiedaspect is the effbctof juglone on soil arthropodsand soil formationin general:the soil unclerrvalrrut is likell'to be differentfrom neighbouringsoils becauseofjuglone or otherfactors. Brooks (32), in his surveyofblack rvalnutsites, fbundthat soil underu'alnut rvas uniibrnrly rrore alkaline,with differencesin pH of upto 0.7. Wood and balk particlcsfl'orr trees containing juglone, Curj'u illinoiensi,s 38 II'.illi,t and,/uglan.rnigra. are reporled 1odccompose rnuch rnoreslo't\ll than those liont olltcr hardu'ood species(.1) and earth\\'onns havc been recordedas bcing scarceirl ualurtt areas(176). Summersand Lussclrhop(286) found that coresof walnul soil. uhen rcnrovedbe1'ond the influence of the u'alnut canopv.increascd in both arlhropod t.uturberand dir,ersity.Moreover. the authorsconcludcd lhat the grcaleraurounl o[ soil orgatricnratter associatcd l'ith l'alnul could bc ascribcdto thc gcneralrctardation of dccomposerorganisms.

The latcof juglonein soil hasbcen surprisinglr'littlc studicd uulil rcccntlr. It Itasbccn suggeslcdthat juglonc lcr,clsin soil nurl dcclinc as.lrrglorrcbccourcs iltcorl;oralcdin(o soil orglrnicrna(ter (lltlt. 253). ils.jugloncllts bccrrrcltortccl irr dcgntdaliorrproducts o[ humicacids frorrr undcr ualurrt ({7). or sorbcdonto colloiclll parliclcs(89) Thc suggeslionhas bccn srrpportedin parl b1 thc [rndingsslrouing tlrc lou rccovc4'ofjuglonc aflcr il had bccnaddcd to stcrilcsoil (77). This sould also crphin short-tcrrninlribition as found"for cxurnplc.b.r Conrad(-i9). Il has also bccrr strggcslcdlh:tl thc sccruiugvariirbilitl' of ./uglunsallcloplr(hv nra,r. in plrl. bc drrc lo variittionin tltc abilitr of ncighborrringplarrls to titkcup anddctosifr'.juglonc fronr (hc soil( 296 )

Rcl(crtmrticrct ol. (2-Ill).in Cerurant.first drscovcrcdilr black urrlnut soil all acrobic.lllolilc Gritnt-ncgatir,crod-bactcriuur. idcn(ificd ;rs 1).icur1()nt()no5ltutitlo Jl. capablcofttrctabolisingluglonc:fut'llrcru'orkshorlcdasccorrdstlarn/l prrtitla J2uls itblc lo clcgradclugortc (202). Givcn u glrrcoscsorlrcc- tlro corrldcon\crt -jrrglorrc slcprvrse1o 2-ltvdroxrmrrconicacid Schrrridt(2-5-5) irr lhc tj.S. dcntollstril(cdtllitt il bitctcrirttrt.idcntificd also:ts l).st'rrtltttttonttr. collcclcd lrorn uulrlrt soil.ulrs call;rblcof rlrpidll rrrctltbolising.lrrglonc. l-lis rcscarclr suggcstcd that. rrudcr acrobic corrdilions. jrrglortcults unlikclv to pcl'sislin soilsirl sigrrificuntcorrccrrtnrlions us tlrc bactcrirrrrr Ittd tr higlt affirritr for.jrrelonc. This poinl is no(euortlrlus it indicutcsthut lllcastlrclllclltsof soil juglone rttrrstbc cloncnrorc or Icssrrrrrnccliulclr to havc lnr tttcittlittg"as cxtrac(ablc.luglonclcrcis clurdccliuc uitlrirr ir rcllrtivclrshort pcnod rll' tirtrc(< -t h) and calt be rcduccdIo

pg) addedto 100 g soil demonstratcdthat rapid subsequentaqueous c\lraclion l0 urin lalerrielded less lhan l% otthe addedjuglone (77). Weidcnharncret al. (31(r)*statc thatthc solubilitl'of juglone is 52 pprn or about3.5 mM" uhich is ccrtainlr adequatc 10causc sclere grorvth inhibition. but it uoultl seem that.juglone becoutcs prcfcrcntialhadsorbed b1' soil particlesor organicnlaucr.

6. DISCUSSION

Whilc thc genus,Iuglan-sprovides l'hat arc probablrthe urostuidcll acccptcd cxautplesof allelopathicplants it nrust be concludcdthat therc still rs no urtatnbiguousdernonstratiouof its cffcct. In a pro'ious papcr(326). I haveargued that thcrcare sir critcria requircd to dcuronstrateallclopathr. (A) a paltcrn of inhibilron (orassociatiou)of onc speciesu'ith anothcr.(B) lhc putatirc donor plant nrr-rstlrroduce btologicallractive substanccs"(C) the putativcdonor nursthale a nrodcof relcascof allclochcnricalsinto lhc cuvironnlcnt.(D) lhcrc tnusl bc u nrodcof allclochcnrical lransportand/or accumulalion in thc en'r'ironlncnt.(E) the rcceiler plant nrust har.c sonlenrcans of allclochcrnicaluptakc and (F) the obsen'edsvurplours and patlcrn of grouthcallnot be erplaincd solely'br pllsical or othcr bicllic factors.strch as conlpetrllonor hcrbir on.

Whatis clcarin lltec:tsc o[lalnut is thatlhcrc is uell krroun(allhough uot lhat ucll docrrnrcntcd)intcraction uith sclcral planl spccics Thc spccicsof ualnul irrc kttounto conlainsubstanlial quantities of naphthoquinoncs.particrrlltrlv actllc iu thc forrtrof juglonc.as lell as olhcr phcnoliccourporrnds. ll is lcss clcar hou cractlr .iugloncis rcleasedinto thc cnlironnrcnt.although utosl uccountsag,rcc thut it is rclcascdas a \\'atcr-solubleglvcosrdc of lldro-juglone.u'hich is then hrdrollscd and orrdiscdto form lhe actirc.jugloneHouo'cr.juglonc is not particularhrnobilc in thc soiland it appearsthat it is rcadih'adscrbedbr. soil organic matter.nearbr roots. or bactcria.It has also bccn argucdthat" as juglonc is rapidll mctabolisedbv soil bactcrir.it is unlikclr'10cvcr rcachconccnlriitions in soil"aud conscqncntllin roo1s. sufllcicntlo causeanv apprcciablccffccl. Dcspitcattculpts (c.g. 2(rft.y.uo one has as rc[ dctttottslrlttcdthal lugloncrs actualll lakcn up br plant roots.although lhcrc arc Iltltllcrotlsglassltotrsc cxpcrirncnts uhich pror.idcdatil orr tlrc cllcctsoI luglonc on planlgrorth. particularlr,iu aqucousculturc.

Thcrc ts certainh'loo rnuch q,idcnce to coucludethat u'alnut has no cheurical cffccton ncighbouringplanls. Hou'er,gr.it ccrtainlr rcnrainsfor morc and bcltcr uork to bc done. Manr qucstionsnced to bc ans'ucrcdlhrough nrorc crilical uork.. For cratttplc.tvltat is thc cffcct of ualnut in rls naturll cnvironmcnt'l Hou grcal is 'r'ariatior.r ttttraspccific in lrglortc production'l Hotv docs.juglouc cntcr a rcccptor .10 I{i llis

plant'l ls thcrc an,vcorrelatron betrveen juglone concenlratiouiu uitluttt tissueand in soil and rcccplorplant respollse?Will iuvestrnentin juglone rcscrrrcltlcacl 1o leacl1o tangiblcbcncfits in agriculture.forestry'. pltarutacl or othcrareas'J

ACKNOWLEDGEMENTS

I n'ish to thank the follou'ing indir,idualsll'ho gcncroush'assistedin acccsstrtg resourccs. Mr. Abdul Chafoor Abdul Rahccrn.Mclborrrne Iuslitutc of Asian Lrtrtguagesand Socictics.Univcrsitr of Mclbournc.Prof. Toufic Fahd. Slrasbourg.Fntnce. Ms Dianc Forrcst.Universitl ol-Califol'niaat Davis,Mr JanresCornelius. Illinois StatcHistorical Suno. Uurr,crsit'r'oftllinois - Urbana-Chanrpaign"Mr. Bob Sicklcs.lorva Strttc Unircrsitr" Arncs.Dr. Jerry Vrn Saurbeek.USDA ForcstScnicc. North Ccnlral Forcst ExpcrinrentStation. Nlissouri. Mr. Gan Austin. MoreheadSiate Uui\ersit1. Kcttluckr. Prof Marsha Fanning. Lenoir-RhvneCollcge. North Carolina.Nlr. Paul Holtncr. SorrthemConnecticut Stale Univcrsitl

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-{. .\llrs,x- F.L. and \lurph1- R.IL ( 1962). C()l)rparrti!e rates ol'dL'conrposilioll in soil rrt rr,\rtl anti lrrrk particles ofseveral ltarduootl species..'iol1 Science Sot:jetvof ,'lntertttr J)ttctttiut!;26: -163--i(rt 5'-\|tlren.F.\\''r.orr(l968)'Inconrplrtlbi1itr,lrl.ll1ackir.alIlrttant1rctlpine''tlllllt|itlrl ,tnd Fr;re,sln llitnonrhly lleseurch l-i:tt'.,21 . i9. 'it'n-reor 'l ir. -\1tlr.'rt.ir \\' r'on (1<)i6j. Rgrtr//..;,'i itrnntri! itti

9 .\rirnrrriorrs ( 1926). ls the $'alnut poison? LLhth rngton li tar 1926(:\ugusr i): 8. l{). .\n,rttrnieittst !929a). Elack rvir!nuttrc-e eifcet uoon plarrt iife. .llralr.',r,r \.lir../r-'rrrr,r;-11: -8. i 1. .\111--111111u,,.i 1929h\. \\'ulnrrt p,'isttn isoialetl ,'.arr':,;rk Tinte.:1() l cir : h- i i. l2 \-nottvittotLs(19:9c).\\iruidhitic'criticrsrrtol'biacirlvainuttree. i,,r(,r/..1? .\tit.lo!1t )t!t -lM. .i3.'u\trotrr.tuotts(l995i'\Virinrrtl|l(.ibrltlen}tlttcsicitl..':lutl i-i.' \itortrrnotts(i99(r). iiitiittttTottctti. \lichigrrr Statcl'nrlcrsitr i:ilanslrn.

,1.*.\.tttrrtrttttrtts(1998a).(lcttlentn?1,-;tleiunrt.s.!,',:,"jirthell.titltr'!i.'() ljilkPrr;scirrrinii,:rcrrnial: '.{).* 1.n()n\nr()us(19(.)8b). Bixck ttiinut l(r,\';.iIr. tircet 7ri;. l)!'l)rrtr;tEt)trrt tlrrrljerrltrrr.'. \licltir:,rn Si.itr r trir.ersitvGT-1025. '1.1 J ugl a n.sspp., .i ug It :, n e o n d o I I eI o1t 11 t +t

17.* .\ronvrlous (1998c). Black vulnut lo.vc/$'. I)a\\'es -.\rborelurn.

i8.E \ror:rrrrous (l 998d;. IIAlnlft toflcit),. Geocitic's.

19..\rer. .1..\\'ilrrer. .\.\f. .-\tkinsolt.R. Aschlrrarr.S.irl. I-ong, \\i.D.. \lorrison. C'.1..rntl 0l.zrk" l).\1. t 19911. 'l'crpenes crnittecllrout agricultural species lirund rn Ciililbrnia's Ccntrrl \alicr .lotrtrrul ot G e op hy si c a I Re.sett rc h l.,i t m o sp h e re ) 9 6 : 9329 -9 33 6. 2Cr..\u\ong.T.K.. \\'cstflll. B...\. antl Russell. R.l-. (1963). Pharnracologicrl aspccls ot.juLlott.'lottc,tn 7 23 5-239.

21..\rreltcltt.\'.. Deltpoor..{.R.and \[ahnrodian.\t. (i973). Jtrglone:thr cchtioto\rcprirrciplc tt!'['ttti'cutt'r ! r ctxt n tI it i r u. l:)i1 \'l oc h enti st r r,'1 2 : 300 1-3 00 2. 22. Rruckrrranrr.\1. (1974). (irrsnrrschungen fiirl\ialnusslnltgen. .\littethtngen |lebe tLnd Uetn, Ob.:tbutt ttntl ,\i'rLchtevertrert ilng 24 : 3 79-38.1.

2-1.IJtrtstctskji. O..\. (1971)..lixicosis dl'(ndhard soils in depetrdcrrctt>n ecoloqiell errtdili(nls and hio,itrqir-al ( pceLtfiarittcstrl' llttit-bcrrrrng plants IRussirnl. In. l:t:tologo-l'toklttntttltt'.;Lt? )\n/)]1 I:dDtlodei.\t|i|it lla.ytentt v Fttctt.seno-akh.(F.d.. .\.\1. (irrrrlzinskii). pp 47-50 Kicr : \rrtrLor r Dunrka.

l.l. llhrll, Il.l)..Kalcthr. \1.S. and'lod;rria. N.P (1997). \llclopalhic erclusiorr ol rrntlerslr.rercr,'ps br r{!'olbreslrvtre!-solC;arh\\'al}linrriuirs..lllelop(tthr',/otunrii J:.121-.121(

25. I)lntl. Fl.l).irnd'forlarir. N.P (ii.,92). Stuclieson lllclopatlrrc rxclrrsrrrr oi undcrstorc\ br srrnc aqrolrrlcstrr trcc crops ol' (iarltwal Ilintalr ava. In. .iiieiopathl tn ,'1gto<,r:osl sterirr (Lris.. I). l rruro iuld S.S. Nanval). p. 129. Flisar : tlan,ana .{gricultural L.Tlrir,ctsrtr'.

36. BhLtran.K.C.. iJhLrvan.D.K. ancl Podos. S.l\1. (1991). l-ree ratlical crrltanccrrenohiolie is an ill(hr!-!-r()i calirract irr rabbil. Free Rudtcol Researi:h (:oDDnmi(:ittlo/!t 12-73. 6{)9-620.

27. Binder. il.(i.. Bertson. \1.E. and Flath. R.--\. ( 19ti9). iiight I .J-naphlhorlLrin('n!'s1l'()lrl Itt...tf ttu\ Fh) tocherrtt.vrr) 28 . 2itr9-280]l

l3.Rirbt.\\'.(i.(1929).Lllack*ahlr(1rr'cscllc'ctscrplairr.'d.,'uner;cttn.\tu.ittt;tttti !929(.\rrqrrst):51.

l9 lSlrrgcrrrr:rrora-l,\. rr:d Shchcrirartorskir-L.R. i l'.)15) l.ll!11,rt'1.-.lrt;tflltirrrlLriltrrt.;rndsrpolriri:,'n iitr Jclr\ itv of prrlvphcuolorttlase i'rn ritr.ri Iitrrssianl. In: [:t:toiog,t i,r'i;hiruichesL:1. ( ),,t1t'\\ I':/rtlnoLiet\t\'tIctRAsrcnti r'!rtolseno:akh. (lld...\.\1. (irorlztnskii).6:.17-lt Kicr : \rlrrl,irIr Dtrnrka.

30. Iliainr.K. (1962). Ihe presencer)fnicoline in piants.i'lora 152: 1i1-172.

.ll. IJlrrszrk.i:. \l\\'rol. .1..ilrrinatha. .i. I)rordz. fl lrrd Chnrielerricz..,'. 1lD()()). I.]llicti\cnvss ol'rrrlilcr'rl;rrr1s oi iJilult orie,in rl Drotcelion,ri packag!ng rrratcri;rlslgrtirrst st6r'agr'tllsccts. ..r/,/trilrrl,li'.:,opitt,,i ",ntonrciogt I I {}: 95- i 00. ]2.Botlc.it'It'il1)58).i.]ell|:iqe.',rttKetttttlris'rilc'i.''uttltiscltcr 5l : J.l0--180. j.\. -ll. firrt.. lj)i<,i\ .,'it!..tittte \lujt.\ n',;t;tiDnt)i ,ugi()t;€;t1 n(:lttl!,!ttt:).\...iLlr,,rj. ,,i ,r,).\r7|t /r,,, ,/(e.r;rt!ni -L,'.;rri.,. l l. Sc. lliesrs.Killsar -\lrte i'ni,. ct.itr. ]{'l]ocs.1,.i{'li9t6)'.\]l.'ioniiti1\':llirlllliliijiltcrl].1||]i|i).i..\.ei1pilllris,''1ne|i(i:1i'.\''|L].,{']')i]1|!i]

.15.B(\rii;'l;tli;. \. i 19Sl t. ,.;cci.r7'eice ,t1 ,j11E1y:714"4nto1g :ittlnttt tnt; |!:ci:ttr;e{ .\crjr/.)/r.jl !Lt2ttlit)i.\ 'i:"t?11:r: '111:;t;'i ;1i.rrtie.s :'t11SiCCitiloil. tt,tCtihe lntitre:itrt ttl iittt,rth 17.€2tLl.it(,r.,,).1 ' t)r..e:1!ii!ttt)t:.. . lh D. titesis .,fissrssiopiStilte I iit\ e:\rr\.

36. ilorrzltni. .".. Gra',g.. C.l{. rind fledin. ;'.-\. li:)!il). .\:rLiner' ,-riiriglonc i.'rcls .r;ror:g rrillnuls ,lrti rickirrrcs. !r::ctin i)ttarter!t' 17( I ) : 9-l -l i". ilorr;:1;rrti-\.- {irare.:.i-'.}1. :,:rd [ierrirr. P.\. I l9)]ij). ()ccLrrrelec,)r:uitror)!'1n rll.rr)lrs lrssric:,'1 1r.6.s;1,111.t '5 jrrlLd sl)!'Ji,is., !:t tq)utit/,\r(,X,\' i + i(l-l -+2L + -!, I{'iI I i,s

.lli. lilrtlrrrr- (;i. (197.1). the l?ol,: l .itt,qlutt.s t1t:Jtu tLl old itt'ltl vr(csrrtztl \l Se thesrs.Irrrponir- Karrsas'l:atrsrs Stalc Collcgc.

.19. Ilrirrksorlh. lt..l. and Fairlie. l).11 {190-s1. 11.4rn,Funoncs:lrc e(rnrneli{i\c r}'\r-n.pt)dL'inhibitols ol'lll\'-l pr()(einirse. Btocltinrca er Riopht itc.t ,-lcla l25J: 5-8

.1().IJlssenroret.\.and\{ichaud..l (1917).Srrrtur.'nouvellcclasscdctrtedicanrctrttlchlr.-rtt l(s(lttitl,\ttu\ p!'ro\\'d.s. Btilcttn (]etu'rul de Therupetttttlrrc lleclicctiu et (-htrttriqtcale l(t9:75<)-766.

.ll. lhrla. Ij.. .hrontcrrski. \\' and Suiirtck, L. {1960). ()ccur-r'cucco1'c:rlleic lcirl in strnc rnctlieittrrlphnts. . jC I d j ){ ) I t, t11 Lt t: i) h.t rDtd. ettl t. d I 7 -l() t -30(r.

"12 Brooks \1.(i. (1951). l,.llicts o1'bl:rck lralnut trces antl therr pr()duct( on other'\'cqctrtr()n. ll.ttr I'iruttt;Lt .igrtctLltut tti F)ty:erntwnt Stutrtt iJrtllettn JJ? 1-.17

J1 Jlrilrtr. li.l. (lr)42). IrrjLlrioLrsrnfirrence ol'halk ol black \\illnut or) scc(llinqs ()l l{)r)rnlorrrrti altilllt. \,,,r4 \jir (}arlar.' .4 t:ot tutton,.innuiri l?cltotl J.] : 97-l(i2. .1J'l]t.tlrrtr.()-Il'lrntl(ireelr..I-'.I'(l9fi7)'()\idants1ress:aglssilllcap1trt'rcltlorrlitllri;tcltctrtrrt|lera1lr Sctt'nceReseorcA 15: 9-12.

-15. LJrLrner.\t.ll. ( I 969). \\rrlnLrt and pinc don'1 uri\. /.b/'e.r/ I:urtner 2ll : l5

!(r. Canrpbell. (i.ll. and l)a*son. ,f.O. (I989). (irorrlh. r'reld. anrl r,rlue proicctiol)s for black \\nhurt intelp)atllina,s nrth black altler and autunut olrve. I'orthern Jotrnal ol .4,p1tltedFttresln 6 . 179-t32.

-17. Crrbrllas. I.. .\ndreus. 1".lnd Nletche. lU. (1972). Corrtrolling cllict ol'srxnc liltcr conrp()nenls 11)1l)c fbnnation rnd propcrtics ofthc organic ntatter ofa calilcarcrtus btoutt soil. ljrLllet;tt t.iit ! 1.c,;1, .\'ttltttnale Su1ret1s711gcl','lgrononile. et le.\ lnalil\trre.\'.lltDt(nt.ilte'\l{: 2-15-lt'l

{11.C'rrrlarr,r. (}. (l55fl). l)( Srrhlrltt.trc.N()nnrbero l. [)c(rcrrrrrr.

4!1. Clrrncuu. \\r.ll.- Clark. llB. \\'illianrs. R.D.. Ilarurah. PIi. (1976). Il:rrrhroods pirurtcd in olti tlclds 1hr,rcd b1'priortreecolcr. l;'Si).l liort:stServcelle.teLuch[)epur N('-13{: l-16.

50. Canlat. -.\..Petit.fcan-lrre\1et. C.. Nluller. D. and [,lnrirrson. .f.-L.(1993). Pcrccntaseof plincipiri corupor'r!'l]ls in the Ieaves ofnalntrt.,/rrqlcrnt s regta L,. ['luntes iletltctnales et i'ht tetrhertrpte 2(>: --1I 2- ].19.

51. Cirse. P.I rrnd Furrk. i).1'. (1973). Tlrt cc.mplcx ctlicts of jtrglorre()n thc gro\\lll ol pinc. spnlec. ,rnil lrreh s!'cdlrngs.ln:Prr.tceedrngtof thetrilih,\u'otth.lnEtlcaDI:ot,tttBtttlo,ttll,li':'ltol. il.ds..('.\. Ilollis iuld --\.L. Sclurllace).p. ..122

5l.Chirtlo(-Grndllirtlir.ll(199.1).llactc-r'iosedunovcr.(f()!ln()sispllcnoljrlucsctr.srsliule.. i41,'ti'11tt.t\)1: 3 1-.12. j.l Clrarr. \-.S.\. arrd Rrro. S.S l{. (199+). l-he cll'cct ol'ccnrilr l)lrcnolics(rn \cnc\rcllec (\l lrdisll lil,l'it,t,:t,, r?tr)ru.tL.) leal cLscs.Jourwtl ol l'hyolo.qicctiile.seurch 7: .ll-4.1

54. Clten- R. and l'igrratello-.1..1.t1997). liole oi([llnor]e inlerrl.'tlirlcs ls clcclron sllultlcs ur licr)t()n irnrl photoassisted lrcnton oridalioils ()farolrlatic cornportnds.I:n|ilo)lDte]1lttl S

55. ClarL..\.\1..,Itrrgcrts. T.\1. and liuflbrd. C.D. (1990). Antrnricrobral aclivitv r)l yuqlurc. I'lr,r'/o/lrr'r'ri1rr' 1?ei.

5(r. Clrtrk. I'.U. and \\'illianrs. R.D. ( 1979). Black *alnrn qr()\\1hinc.!'irs!'d bv i'r1!'llliultrrg \\ rtll nilr()gL!l-li\ing slrrtrbs anci trccs. Proceedtngs lndtun.lturlent ol St:ente tlu: ti8-91

-i7 Clrnc. S and Ncclr. D. (1981). Re)ationshipbct\\ccn jurenilc-lcaf'rcsrstrnce 1ri .rrrlhrruroserurcl lltc prcscncc of jrrgltue antl hvdro.ltrglonc s.hlcoside in bllck u irInu(. ['h.rtotl,tt ht>lr':<.t 7-l : ) fi-i- I St

58. Codc'r'-K.D. (1983). Selsonal changes ol'-lttglone polcntial in icevcs ot biack \\ithlut (,./i(.q/.11\ntlqr,.t |..\ .Jottrnttl ol ('henttcctl Ecologl 9 . l2O3-1712.

i9 C

60. Compton.Nl.E. and Preece,J.E. (1988). Etrect ofpheuolic courpoundson totraccocallLrs and blaclbern shootcultures. Journal o1'the,4ntertcanSocietl,.for Horticttltural Scrence173: 160-l(r3. 61.Cook. Ll.T. (1921). \\rilting causedlrv u'alnul lrces.Ph)topathologl 77 :31('. 62.Crescenzi. P-di (1171).De.4gncullura Iitlgare. \'enczia: .lohannes Rub.-us. 63.Crosbrr .\.L. (1976). \\/alnutlrees: lhcsc tree's nrav bc hazarclorls10 thc h.-rlth ol'thcir nciqhLrouringplrnls. (]reenScene 1976 (Nor.) : 12-13. 6.1.Crozier. A.A. (1891).I'opulor Errors .4l1outPlents. Ann Attor : RegtstclPutrlislring Co. 65 Daglislr,C. (1950a).The isolationand identilicationofa hvcil'ojugloncglucosid.. occurlirrg in the rrlrtrt. BiochemistryJotrnal 4J : 452-457 66. Daglish.C. (1950b). The determinationand occrirrenceofa hl,drolrgloneglu,:oside ir 1hc uirlnul. Brochentistt'rJournal 47 : 459-462. 67.Dana. Irl.N. and l-errrer.B.R. (1986). Black rvalntrttosicitv. Hone lard & (iurclt:nIIO-11)3. (*) 68.Drughertl \\'.. Snrith.S.. \\'igal^C.. \:erhoek.S. and \\'illianrs.S. (1995).Distribrrlion ol--i-hrdroxr-1.-l- naphlhoquinonearrd other nirphlhotluinonederivalrres in thc Juglautlrrccae(\\illnut lirnrrlr) and relatedlanrilics. Cttrrent Toprcsrn I'lant I'hystolog-r'15: 3-15-3J7. 69.Drvidson, .l. (1939). Sonte.urtituswcredquestions. Norlhern,\:rr1 (irr)rler',s ,;.\soctLtttotl ,4t1ntLtl Repot t 3(t 58-66. 70.Daris, E.F. (1928). .The toxic principle of Juglan.snigra as identifiedl'i1h srrrthelicjugl,rne" ancl its eft-ects ontourato and allallb plitnls.Anerican Jotu nal ol'Botanr 15: 620. ' 11.Darmon. J.O., Knorvlton, S. anclSun. S.II. (1981).The efcct ofjuglone conccntriltlonon the gro$lh ol Frailkia in il!,'o. Foreslrr ResearchReporl. Departnrenl of Foreslrr,.Iinrlcrsil) of lllinois 8l-2. | 72 Darvson,J.C).and Se1'rlour.PE. (1983). Ell-ec1sol'.fuglonc concentrntiolr on gtxrth in vilro ol Frtnhcr fu13 .rndRfti--obitun.iapontclunStrain 71. .Iournul o.l'('hentcal [)colog,1'9 ll75-l184. 7.1.Dtrvson. J.O. and VirnSanrbeek. .'I.W. (1993). Intcrlhntinq soodv nursecrops ploln()t.s clillircrrlial grxrth of bhck rlalnut saplings.In: Prcceechttg.to.f tle Qth(-('ntrul lldnl\v)c,d l;ort,.;t(lon.fbrt:nce (.I:.rls.. A.l{.Gillespie. G.R. Parker.P}-,. Popc;rnd Ci. Itink). pp.455-46.1.(;S[).i Iiore.stS.,tnit:e (ienerul 'lbchn tcaL Report N(l-161. 71.DcPairnr. N.K. (1982)..4llektpalhl' tn theJuglundacsde. l\I.Sc. thesis, Southern ConnecticLrt State Collcgc. 75.DePairla. N.K. (1983). Allelopathice{licts of butlernut and black ualnut seecllingson tolllxto!'s. ,\'orthern \-ut (iroy,ers,4ssociatton Annual Report 71 : 123-129. ?6.De Sciscicrlo. B. (1988). The Se:asonalPattern of Juglone in Soil Beneath.luglan; nrgru (black trerlntLtt und the [nfluence of J . n gra on I]nderstorv lbgetatrcn. tr[. Sc. thesis. S\ racuse:Sttle I :ni\ crslt\' ,)f \er,lbrk.

77 De Scisciolo.B.. Leopold.D.J. anti \Valtou.D.C. (1990), Seaserltalfaltr.rns of juqlorreirr soil herrtrllr Jugiansntgra iblack rvalnut)and intltrenceofJ. ntgra on untlerslorv\eqelation. iotlntti ol C'henicalEcology I6 : I I I l-i 130. 78 Didn'.N..Dubreuil.L.andPinkas.\1.(1994)..\ctiviryofantlroquilronicandnaphthrrquinoliccrrrrrpt'unds onoral bacteria. Pharmozie {9: 6E1-683. i 19 Didrv,N.. l'irtkas.lvl. and Dubreuil. L. (1986). Artimicrobial aclivity of sorncnaplrthotltriuones found ur plants..4,nnales tie Pharnaae Fruncd!s 11 : i3-18. 80.Diehl. S.\1. Ciraves. C.l{. anclHedin. PA. (1992). Crlochertrie-irlrc.sponses ol'p.-can to (-laLle:l)ontill co^,igenum'.tn .situ loctlization and clrrantificalionof lirngitosic pherrols.f'h1'toputltologl Il2 . 0.r7_l0JI 1lL. Diron. R.K. ( 1992). Secdsourcc and lesicLrlar-lrbuscularrnr coririzal sy,rnbiontallicts grrrrlh o[ ./rrqlclrr zrgruseedlings. ,lev Fotests2 203-211 -+.l tl"ill is

82. Dornbos.D.1.. and Spcncet.(;.F. (1990) NirtLrlulprtrclucts pll\1oto\ici1r: r bioassrr sLritirblcfir'.rtrlll tptiurtiticsofslightlr'\\'11!-r-s()lubl!. c,rrttptrtrrttls. .l3. 91. Foltcrcr.R. and Irlenriug.II.\\'. (1991). 1'heetliuts ofplrrnrbagin on devclop:rentol'the parrsitic nertrittodcs llaenoncht,s contortus antl ,.lscrrlls.\t{!in. (-onpdrcttive Broth.'ilt!:lt r LLttill)[1.1 tlpla'qt ('. (.-ahtpLtttlive Phurntt:tiagi und Tortc,.ilo!:.)l00: 519-5J2. 92. Fregoni-NI. (1962). La srrccessiapples. Ttan.sct,rtontol tht' llltnot.:Stutt: llrir rrcttltrtralSocrel_r: \erv Series{: 78-86. 102. (iitrrtrirnrt.L. atcl von Arx. A: ( l9-17)..{nlibiotics as pliult plrrsrrrirp,>isons. ll. BattchrL tl,:r rchtret:erischenbotant.tchen Gesellschalt 57 : l7.l-183. 103. Gibbs. R.D. (1974). (llternoluxononl ct./Flovertng l''iunt.s.t \rolunrcs.\lorrtrcirl : trlc(iill-Qrrr'cn's I rtrrcrsilr Itrcss.. 10.1.(liltrer1. l].1... llaker. .1.E. and Norris, D.irl. (1967). Juglone(5-hldro.rr-1..1'nrphlhrrr;uirrone) lionr Crrvr o|ata a dctcrrilntto fcedrngbv Scolytusrnultistrialus. Jottrnal o;fln:ect l'h;..stologtl3r 1453- Juglans .spp.,juglone and ollel

105.Girzu, Nl., Fraisse,D., Cantat, A.P, Carnat. A. and Larrraison,J.-L. (199S). High-perfbrnranccliquicl chrornatographicrnethod forlhe determirratiorrofjuglone in fresh walnul lettes. Jottrnal of Chromatographl'l t05: 3 I 5-3I 8. 106Gordon.A.NI. and \\rillianrs.PA. (1988). Intercloppingvaluable hirrrlrvood tree speciesand agricultural ctops.Agrologi.\t l7(3 ) : l2- I 4. t07 Gordon.J.lL (1981).Persintrnorrs under black walnlts. Pontona ll(4) :220. 108Govr'rlor.H.L.. Schultz.J.C. and Appel. H.N{. (1997). Impact ofdielary allelochcrnicalson g\ps\ nrorlr (L;nantru dspdt) caterpillars:inrportauce of nridgutalkalinitv. Journal ol In.:ectPh1'siologl J3: n 69-11 75.

109Grales,C,H.. Hedin. PA. and Langhans,\ilr. (1979). A sunev ofiuglone levels among pecan.hickorr, and rvalttut.hl Pn>ceedtngs,4nnual Conventton of Southea,stPecun (irotrers ,.lssocrttrtc,n.pp. 103-lI L Hilton Ilcad. SouthCarolina : South!.astenrPecan (irorvss ;\ssociarion. Il0 (ireene.K.\\1(I929).Thetoxic?eflbctoftheblackualnut. Nltt(]rower(Do\tntneroLt.f,u.)7(3):l-3. (ileene. ll I. K.\\'. ( 1930).The loxic (?) e1lbctof the black walmrt..\'orl,4el n .\'ut ( irotrers ,'1.s,soc:tution.-jnt.uLul Re1xtrt20:152-157. (iries. ll2 G..\.(19'l3ca). Jtrqlonc (5Jndrosr-1.4-naphthotluinone) - a pron)isinglirrrqicitlc. I'h.trop,trlt,tirtgt 33: ll12. ll3 Grics.Ci.A. (1943b)..lLrgloue - the activeagent in rvalnuttoricitr'. .\'orthern ,\;tt (irotrers.,lssoctttttol .4nnualReport3{ : 52-55. ll4. Grtirnrncr.(i (1955).l)te'(legen.setttgt Beetn.flusxrng Hoherer Pfltn:en -,,illelo1>athte..Iena:(irrstar. Fischer

ll5. Gueldner.R.C.. \htes. I.E,., Reilll', C.c., \!bod. B.\\'. and snrilh.\1.T. (199.1).Lcvr'ls ola hydro.guglore gltrcosideiIr dcvelopingpecau leavcs in relationto scabsusceptibilirr..Iotrrrutl ol the ..itlertcaz Ho rnar ltura I Soct e4, ll9. 498-504. (iLrjrr.(i.f.. ll6 Rao-R.\'.S. arttl Slukrrrirrtr..\.\:ll. (199.1). Rioactiritr ol'rrrrLrmlh,)Lelrn'1rg plLrrrrbrqlrr,,irls agarnstrnsecrs. Phstophaga ltrluclra.s) 6: l l 7-l l9 ll7. GLrpta,S.R.. Ravindranath. R. anclSeshadri,'f R. (1972).polvphenols olJ1tgl.ln.\ trrgrtr. I'htrochentt.;rrt. | 2631-2636.

ll8 Haasis.FW (1930).Foresl pltnlations al Biltmore,N.C. tlSD:l IltscellitneotL\l)trblr(:tttron 6l : l -10. ll9. Hartnrann.H. (1981).\\ralnut roots in a chestnutgardcn. Zlre,\irr:helt3l(J)..6. l20 llatrser.C.E. (1982). .1!lelopathic EJlect.sof'Festuca trnLndtnttce.ton the (jrotrtlt r,>l'.lugl(rlt.tntgt..! Seedlngs.l\[.Sc. thesis. Soulh*'est N{issouri Stale l_tnivcrsit\,. l2l Heclnlirn.J R. andt'luchinskj. D. (1995). Sorteannodtrlation and ritroqclr liralirrr orrsoil anrencledrith plantresitluc.s. BtoIogy anclFetttIttl oi SotI 20: 2.ql-288. l22 lledin.PA.. Colltrnr. D.H.. Lrttghaus.\lE. and Graves.C.H. (1980) I)istriburiorrol juglrrrrelnrl relaterl contpottl'tdsin pecanand their ellect on [--tt.sic]cdruntelltr.stun. Jotu nttl of ..igrta:ttlhrtLtlttntl l:itril Chenusuy28:3.10-342. 123.llcdirr. P \.. Langhans.\'.E. antl Ciraves.C.ll. ( 1979). Itlcrrtificiltior)ol .iugloncin pccln as possiblgfirgtor of resistancelo l:ustcladium ellit.stttrt. Jotu.ttt.l of ,lgncultura! unclIaocl Cltcttt!.\tr\.27..92-9J 124.Iledin. P.\', Necl.\\'.\\i, Burks,N{.L. and Grirnlel E. (19li5).Flvalualion o1'plant constiluents associirted uith pecanPh,ry'/o"rercr gall fb''alio,. -rou nal of-Chenticctllicolog,t, ll : 473-4g,1. 125.Hedrick. t'P. (1905).The relationshipof plarrlsin the orclrard ['roceedtn.q.'ol tlte Soctertlor I iorttcttIntrLtISc:ience l9Q3 : 7 2-82. l26 lleinrirrrrr.\1.F. rrnd Stcrertsrrn. \\'.R. (1982). \\lalrrrrtantl bultcrnuttosicilr'. I rtt.t:t:tIt ol Ilrt<.ttn.;rrt ('ooperattve ErtenstonServce [)oaunent.\3182 : l-2. I6 It'illi.s

127. He.il..\.N{.. Eirrhellig.F.A. and Raslt'russr'rr..1.A. (1993). Iilllcls of juglonc on qroltlr. plrutosrllltesis..rntl respiration.Jorrrnal ofChentrcol Ecologr l9 : 559-i68. 128. Il"-ll. LN(.^ Einlrellig.F.A.. Ilasrrrussen..l.A.and Qrrah.S. 1199-j).lrll'.'cts o1'sor'::olcorrc and.iuql()ne {nl liutclions oi rsolaledchloroplasts and nriloc-hondrin.I:n: Plunt Srqnol.srn ltltttru(:tto11.\tttll ()thrl Organisn.s.(urrent 7'olncsrn PlantPh;,siolog-r'rrrl. ll (Eds..J.C. Schultz and L Raskru).pp. 2.15- 236. Rockville. i\Iarvland : Allclican SocretvolPlarrt Phvsiologlists. 129.Il.-rrera. (; .\. (l5l I ). Ohra cle.4gucrtlhtra..{lcala de llcnares: .-\lrras(iuilL.rt tlc Ilroear. l.l(1.Ilcrshcr'. .f.\\'. (1929). Some intcresting tl;tta on tltc toxic cll,\ctol uirlrrulspdcics ()n thcrrrsclres rurrl crclr rrtlrcr..\lrt ( )rotrer rDotrnulNtovn.Po. ) 711t: 3 l3l. Ilirakarra-K.. Ogirr.-E.- j\[olrrroslriru..l. anti Yeiinra-Nl ( l9li6). \rf hthrxlurr](\nrslitrn .lrrrilrrrrtlacrau I'hytoc hem i stn' 25: I 494-1495. 132. IIo. C.\1.. \\\r. S.ll. ancl\\'u. C.C. (1990).!.raluation ol thc corllrol()l'n)()s(prit()cs urtlr irrs.'clsrorrllt regttlators.Kuo ll.strrng I Hxrch Ko H:ueh I'sa(-hrh 6.366-174. 13.1.llradilik. J.- Henntarrrtova.L. and Fiserova.H. (1986). l',llcc1of sonrr phcrxrliccorly()urld\ (\n !',r(r\\tll corrr-lations in llax (1,rnrrll tr,\tlati.\'.\tiltutilL,.). ,-1ctul. n!\,(t\tlutts.ltrrcttltttrrrt I.ut.itlro. .Jgrononticu |lrno 31(1) : 39-76.

13.-1.Iltrssain. 1.. Ihsart.L and Kil. Il.-.S.(1991). .\)lelopathie.ellicls ,rt \\itltlul pllnts (..ltglttut/(,.g/{7 1..) ()rl f')ril el()p sprct!'s..{Ofrr.i/?JottrnaIol }Joltrtt.lf-l : r3-I0(1. -.\\\\all) l.3,s.11t" irf (1802l. Libro de .'lgrrcultttra (lransl. .I..A.Banrprcri). \[aclrid: lnrpr'.fltrt .\lsr>Pulrlislrcd rn Scvill.' ( I 878) and \{adrid ( I 988). ll(.. Iltn irl-\rulnt (186-1-7) Le Ltvre cle l'.lgncttlttLre d lbn-ul-.,jvutn (trilnsi. Clcnldnl-\lullct). l':rrrs: \ 'lirnis l:ranck. .\lso published in ( 1977). 'fraductton l-17. Ibn \\hhshrrla. (1995) l- .'lgrtcttlttoe .\tuh.rtaeile. cn droh(,uttnhtc( it .lhrt lJttl:r.iiuntLl h ',11r ul-Kusdanr connu .tot!.tIe nc;nrd lbn Ilhhstt'.yct1ll'-\'

1"14..loltttsotr. K.S. antl I cltorr. (i.\\'. (1996). Ithrsiological rrndtlielarr irrtlucnecsr)n lni(igut tr(i()\ ron(lili()ltsJrl gcrrclrrlrstLepidoptcrlr.r la,nae..Journttl oi lnsect Ph)..\tologr 12. I9l-l9tii. l.l5..lortc's.L.R. arrtl \lorse. \\..1. (l,X,.l). The shrtrhhr clrqueliril as a rrced. Iirntont.i,qrt,.ttIrruLrl 1..t1:t'runt,tr Stttttort.lnnuol Report 16 : 173-l'79 l-16..lrrse- S. (1997). Intt:rspect.ltc lnterucltol.\ tn.-llleycropping. the ['h,r.:tttlo.g,rtrnl I)tct.t,eoLI]cntt\tr.l l'\ltlrtenl I'ttltng. ,llleloputh1, Jttglun.s tltSro. Ouerctt.\ rubrtt /eu iltu,t\. (.ortpstrtront. Plt.f) thc.is. PrrldrrcL nivcrsitr. Iuglan.s spp , juglone ond ollelopatlt.t t1

l-lf .Lrse.S.. Benjnmrr. T.. Stlll. l.. Ciillcsprr'..\.R.. lloorcr. \\'.1,..\lenscl. D.lJ.. Scilcrt. .l.lt. arrd Ilichlc. l)..1. tl91)7). Riologr arrd ec,lrornics ofa bleck rralnut-eorrr allev cropprng srslerrr ht. l,'itotrit,tlgt litr tht : rLtrre ,tt lJluc:k IIllnnt. ['roceetltn:4s r'i the fitth Riotl; llitlnttr Sirlplrrrrlr l.SD.i ] ore.,:r Serrtce (ienerol Techntcnl Repot / \C- I 9 l. pp. 203-208.

148.Klmer. H.. Koide. T.. Ko.tinra.T.. Hashirnoto. \'. arrrl Haseqaue. \1. (1998). Inhihition ol'eell grou'(h in cttlttrrt br'(lulllones.(-unt:er Btotheretpy und lludtoph.tnildcetutcol.\ 13: 185-l8ll.

1.19.Krsttnrolrt. \1.\l (1971). Ftrngicidal actiritr ofphrloncitles lionr qre.'n lerrres arrtl unripe perielrTrsol rtrfrttttsIRrrssian]. l'chenle Zaptrl;r.i:erhutd:htntkit.\/edrt:rn.sl,ogo in.;tutrtcr33 : 7-l-85 l5ti. Kcsslcr.C.1'. ( 1985) The .illeloputhlc ]lll.'ct.\ ol ./rtslone t5-h.r'Llroxtl.-l-t1uD11th,)qtrrn()ttt't .)11 ltri.shttt:tt.t.ilgai t itottl:. \l.Sc. t)resrs.lll()ontsbrtrq I'nir crsrtt. ('htntttul 15f Kesslcr.C l. (1989). Hlt'ectol .juglone on liesllrater rlgal grorrth. -lortrnul ct/ Lcolo,q-r li l52 Kcssfer.K..1. (1985). Cornpanitrt plantirrg o1-bllck ualntrt *ilh aLrlurrurolive lo control .\1tco.;1rht,.trellu lerl spot of rralrltl. ln. ['rcceecltngs oi tht, jth ( entrul Htt,^ood [:ore\t t-ot1i(,rci\c(.

l5-l Kcssl!'r.K..I. (l9lll'i). Corrrplrrrionplltnting ot hlack urlnut rrith autuu)u olivc to corllrol \\al11u1 irnllrrrcnosc.Phrtrtputhr.tlogt T8: 1606

lil Kiut.S.-11.. l.ec. K.-S.. Son. J.-K...1c.G.ll.. l^-e. J.-S..Lee. C.IL and Cheorre.C.J. (1998). C\1()lo\ic .onrpoullcls tiour tire roots ot.-/Lgl(rrJ rnand;hurtca. Jottrnal ol .\'cthrrul Protlrrclr 6l: 6-l--l-(r{5.

l]5 Ktpfeclr.li.C. (1195). The j:iiect.s oi Stqar,\laple Ll.cer :uccltortun .\lar.tlt.) an

l5t'. lrltrrrl. lL (1()76).Chrnqes ofe,rorrlh .'longation in rrteal and barlcr coleoptileserus('d b\ sonr!'phenolii sul)slilnccs.lltologtu (Bralisln a.l3l : 281-286.

157. Kocppc I).1r.(1972). Sorne reactions ofisolatcd conr nritocholtdria inllrrenccd br jLrglorre.l'h.tsrolr,'girt Plutltit,'t(ttt21 . 87 -91.

158.Krrfcsnicherfio. \1.\. (1968). Riokhtntchesbe I':atntovlt)'anr)u Dret,e.sn)klt lltsrentt. \loskva: L!'snil\r Pl onl\ shl!'lulost'

159.Krzhr'r'nikor: LG. (1978). Allelopathic potenlial ofonlamental loodv and slrrulrbr plants ll{ussiaul. In: I'rt,i.lt:nt).illelol)(rrr1 (Ed.. .\.\1. (hodzinskii). pp. 95-96. Ki.'r' : \aLrkorrr I)urnki.

l('0. Nr.rlil. \\ \1. lnLl I-ureh- D.l, (1978). I'he inhibition of \rnous n)lcro-orqrnislns br errrclcualnrrt lrtrll e\trrcts andiuglone. lhcrohrcs Lelter.r { : 175-181.

l6l. |'rirtts.P. (1942). .labir lbn ll;rvvanr. Contrrbutiorr a 1'histoile cL's idees scierrlrlitluc'stlans i'Islanr. .\lentotre.tl)[e:ente.\ a l']n.stttrucl Eglpte 15: l-.106.

l62. Kroeb.'r.1.. (19.1(i). Pllarze'tilieurrdschaliert - PllirnzenJjendschalicn. Dte l)hLtrDtu:tel.275.

l63.LrEangc'.I:.(1951). L'actionbactericidedel'ertrartdesfer.rillcscleJttglctnslagicrl.[irerrch].('r;rrrTrte.t Ik:ncltt.ytlr., setnct; de iu Soctete c)eBtologe 1Jt : 2097-2098

l6'1. I.rgrange. Ir. (1956). L'tcti()r1 irntibiotiqric de Juglctns rega 1.. (-c.lnpfe.sJlentllt\.le\ sennt'cs tlc lit Sctcrtlte,le BLologte 150: 6l-l-61j.

Itr5Irrtqhrus.\.E..lledin.P.\.arrdCiralc.s.('.1{.(1978).1:unqilo\rceherrricrrlsinpccrnlissue./)/.1/?t/rle,rrr.. l?epatrer62 : 39.1-898

166.Lcc. K.-C. (1967). .\,'Litttrcotld ()ccltltnce ol Jtrplone in./tt.qirrntntq,t i. \l.Sc. thesis.K,rnsrs S1;tle litrr crsrtv

167.lte. K.C. and Carnpbell. R.\\' (1969). \irtLrre arrtloccurrclrce ril .juglonc in /rrgltrn, nt.qrt. |1rtrt.;crt'nceI :297-298. lo8. Lenrbeck.li. lnd Skolltsch. G. (1981). Distribrrtron ol'scrotonrrrrrJltclLrn\ /.cqrr/sL'.ds drlnrlq ontoqenclre devrfoprlent rurtl qc'rrnrnrticrn./ettsthrtit iiir Pllun-enpht \talDgie lll:.l:19-.1,5.1 +u Il'iI I i.:

169. Lenrbcrko\'ics. E.. ilo1hcl!i. F.. and IIctesi. [i. (1987). Sorilr phvtochcnrieal cl)aftlctrnstics ()1..1]r!/,/,r\ regLt L. Acta Ph

l'70. I,i. Ij.lI.. Nishirnura. ll.. IJasegaua. K. and Nlizutani. J. (1993). Sonrc phvsiologieal cll.'ct' errd tltr possible rrtechattisrn ol'action ol'juglone in plants. Zosso Kenkttt 3a:714-222.

l7f .i\lacDaniels.l..II.(1977).Rlackrvalnutlo\icit\.\:€ry, Ibrk'l'ines Septll:43.

I 72. \lacl)anicls. L.11. ( I 9tl0). Further observationson thc loricitr of black rr alrrut on t(\nrirlocsittttl s,rrrc ollrcr pfarrts. -\brrfterr Nrtl Grnsers.{s\ocrc,lnn .tlnntrctl}k,llrvt 7l: 112-126

l7J. \lacDaniels. L.H. (1981). Eiglrtt re:rrsrritlt tlrchlack urrlnrrt..\ror'lfigln l\'ttt (irttttt'r;.lr.so

175. itlacl)anicls. l,.ll. and \lucrrscher. \\'.C. ( 1941). Illack rvalrrut toxicitr'. ,\:rtrthctn Nrr/ (irlir lr ' .issoi:tul,on ,lnntol Re1:ort3l : 17).-179.

176. \lacl)irrrir'ls.L.ll. arrtl[)innorv. D.1,. (197{r). \\'alntrlloxicitv- antrrrrolvcd ploblcrrr. \'otrht'trt \/rt(i/1,r,'7. . 1.\r( )(.t u t t o il ..ln nrt u l I?.cy;'rt 67 : l l l- 122.

177. \lacl)anicls. L.ll. rrntl I'rall. \.1. (l9li2). ('ontprrrirlirrccllccls,rl bl:rck rrrtlrtttlloticitr \)l) lr)rlrirlrif\. potalocs ilnd pcppcrs. Nt'tlhe:nt.\)r/ (irow,r'.r .lsvt<:tultotl.lnrtttrtl llt'1,r,rl7J 57-(':

l7lt. \lahu.jart.Il.. |.aur. I). and lla.lal. ['.1.. (1992). Ncnrirtacidalaclivitr ol'phcn,rlie c,rruP,rurrdsrrqrin't .\ l el otdogtnt: t1togn ll il. .\'entdrologt.t,\ l ?Lltl( t o neu 211 217 -).lr).

179. Ntarichkovlt- L. and Ktrrrrrnore. I]. (l9l{l). Isolation ol llarrrnoitls iln(l sonrc lccrtrrrp:rrrrirrgsubstlnec. lirrtt thc abor,e-grourttl l)arl ol'sonre ,.l.rtrugultrs ct:ntrrrlltrntL.:.lirnrilv LcgLrntinositc flittssrtnl I'yrthkntv lirrnuct

lSl. \lrrrkrrrq.L.1.. (19?l) \l.'thod,rl'lisb cullrrrr'.[1.S l);llcnl.l-602-]r-1.

182. \larston..\.. Nlsorrtlri..l.l).arrtl lloslL'11nlann. K. (l9l{.1).NrrJrh(ho,1trin,n.'s ()11.)roJl)\/,)r,r\ir/,rr1,r/i/r\i.r' tftcir nrollrrscjcitlalrnd lirngicitlal activili..s.l)lantu ,\l<,Jtcu 5ll:27')-281). lt.i.].\lanin.II'(l957)'L-hcnltt:u],)spec|lo|.I.'t:ol ot' . \gricu lture.

It{..l.\lasci;rn!.it)li..l'.N1.. \\'allacc..l \\1. rrntl llacorr..l.R. (1991). Cotrtributi()nsl(r rrrrdcrslantiinc,thc ehcrrrrr'rrl alrsr'l)rlof JltglLtn.\n/8fiI: th!' isolittiottarrrl idcttlillcrttiott ol'llitrtlttrlttl c()nstilll.llls. .ltt,, ti,,ttt .lolrnul of'llotun1 8{) (6 Suppl.): It)(r. f 3,i. \lasscr'. .-\.1].(1925). .\rtlaqonisttt ol llrc rralnut (.JrLgldn,\ntgru L. it:n(|.J. (:nt()!u L.) in ccrtrrin l)lrrl rtssoerltions. l>h;'toltntholo,qt l5 : 771-7ttl. l,\6.\lasscr..\.1:].(1928).-\rcrnlttrccspoisonoust()olhcrtr!'csal)dplrnts'.)ltlotrt't(irr;rrlrl5 -l l87.\lrlltcus. lt.S.(1995)..itl!t]tt(r .rrTlrnrrasrtcstorgiu)isnllirrrrr.'lsrrrirrqsLrpcrrrriilc-rrc

138. \l:rthrrr. S.ll (1972). Spcctroscrrpicancl chcnricirl critlcrrcc.rl tlriuon..s irr s,'il lrtrrrrrrs.],,1/ ).trrr.. ll.] r36- r39. lS9. \lrttstrdir. K. arrtl Suglru,lr,r. I;. 1l9li()). I)clenstr., sccrcti()n ,rl'clrrvsornclrd lrrrrrrc ( ltrt.:otrt.i,t |tgultipttnctiltu co.slellu (Nlarserrl). (.-. pttprtlt L. arrd (irr.rltrrltnd tl.,l.)t(ss.t llah (Cr,lcitflerr Chrr solrtelida.'.1.,lp pl retl E nto nto lopy u ntl Zut i r:g1' 15 : 3 l (r--120.

191).\l:rtstutrtrlo. \1.. \lisali. S. and Chibrr. S. (1998). -\rorn:rlic hrtlrosv conlpour).lsas inhibit,rrs lirr prr;tt.rs.l ol'hcrpr-ssirnplcr virus trpe l. arrdlheir Lrseas antillcrpc\aqcnts lpltentl t. /t,tni

l,)l \lrttotrr. H.(i. (l9.l.l). ..\ conrrrrerciil black {llnul vcnlure. .\b/.t/tern .\t!l (irrtxt.t.)t:acrttltttll ''ttttltLul fiepttrr35 .79-82

192.\latvcer. \.NI. (199.1).,.lllelopati)Lr kak l'uktor Lkologrchc.sLot Srg/t. Srnrrra : SitttrarskoeKrtizltttoc lzdiltel'stlo.

193. \lc\\'horter- Douglirs. 13rSantand Schroedcr (1874). I)iscLrssj\\tr.liutt\ttcttort: rtl rht' llltrtrtts Stitt'' llorriuilhtrLtl Social-r'.Nerv.Series 8 : 66-67.

191.\lcllirnia. N.ll (198.1).Influcrrce ofleal'lcachirlcs ofcerlain rlooclv spcciesirt usricttllLtralcrops. /;rcr'trtir ,lotirnul oi Ecolog,r'll : E2-86.

195.\lillcr. .\.G. (1926). \\ralnutsartd apples.Farnt.lownal 1926(.Ju\') . 17. 'lhLrnrson. lr)t,\lirir.\l.antl lt.H.(1973).NaplrthotlLrinon.'sinLontLrlrusPccics..l'lt_ttrrclrt:ttttsrtt 12:1.151-l.l5l l9l \lirjirch. ll. (i917). lter 5,nrr,,.t.,etiler J)il.tn:r (tt!l dte--lnderc -,)ilektl,uthtt..lctta. (iu.t:tr lirsclter l91'(\[oscler.\II.]antll\rrrcs.\\''F''(l97d)'[JatL1t1.\'|l11|14|'a1lulra|ol')''Slttrtlllllbarll

199 \liilfcr. \\'.-tl. rrnd J-.'istncr.lt,. (197(t). l..l-traphlh.rtltrinoltc-nn irtlertttctliatcitt.jrrgl,rttc (,i-hvdr,xr-1.'1- nirplrthoquinone.;biosvnthesis. l' h) t oc h cn ts t t t, l5: .107-"l l 0.

2()t) \liilleL.\\'.-L'. arrtl Lcistncr. i:. (i97tia). I\lctatrolic rclation bctue.l naplrth.rlerr.'Ll.'rirltircs iu../rrt-/.inr I)h1toc ltt:nt :t ry 17 : I 7,-15-l738,

201 \ltillrr. \\'.-L'. antl l-eistner. E. (l97llb). r\gl1c-onesand gllctrsrdcs ol'()\\genal.d lrilplrtltalL'tlcsrtitd a gftrc

202. \tiillcr. ll. and Linqcns. F. (1988). l)cgladation of l-4-rraphthot;Lrinorrcsbv l'.i.'rrr1orl,;nd\ pttrtlu Btoi rt.qi c u I (' hc nti.tt^' I I oDpe- Se1I er 369 : I 03 I - I (1,13.

2()3.\aqcsh*rr. (i.. Radhakrishnuialr.Il. irrrdN;rralirlu. 1..1,.(19,\-{). (lrcurolarrrrorrr ol I crrrzrrlrrri.r. (-rttrentScrence 53: tal3-81,1. 'lhe 20{. \rr'lor. C.\\'. (1930). Secrt,t o.f the Stngng //ecrrt. \\'anrer I\'c-ss.

2()5.\crrc. I..\. tnd Dlssrrn. J.0. (1989a). Jrrglon.-reduces grruth. nilrogr'nasc rrctiritr. antl rrrol r!'spirirli()l of actinorhizalblack aldel seedlings..Jr.turnttl o/'Clte'nucul l';co log-r' l5 182-l-181('

2()().\ea\d. L'\. rnd l)auson..l.O. (1989b)..luglone:.'tiicls on black alder phlsiologv rntl its detorilicllioit irr soil. Irr: 7fic Co)ttullttnX QtLestlbr QtLalttl . Proc"'etlirrgsol the I;ourlh l)1rrcl \\'rrlrrut Srrrrposirtur. (Fd.. J.t.. Phelps).pp. 182-192. Walnut Council.

107 \.rrhauscarlislc.K.. \ icrlirrg. \\'. and \\hgrer. Il. (1997). Scrccning ofplanl ertrac-lsrnd plarrl constilucrlts lirr c.rlciurn-clrlrrnel lrlocking irilivit\'. Ph.l tolr edrc tne l' 6'7-7 1.

208.\orlis. l).\1. (11)77).Rrrle ol'r'epcllirtrls airtl d.'tcrlarrtsrn llcdirrg ol'.(,'colitrirttiLlt!.\tt tuit,: ltr'.lt,,:r i'iitni l?e.ritrcncdarl'estr. (Ed.. l'..\. llcdin). pp. 2l 5-23{). \\'ushingtelr.l).C.: .\nrtricrur C'hcnriertlSoeietr.

209 Ohtir. \. Siralingrnt, P.lr{.. l,in. S. autl lkel,rla. N. ( 197:l). lsolati,>n r'i' nap}rt}ra,,lrin lionr ualrtLtt 'Oniqurunri'alld i1s ilrhibitorv action on o\idatrve phosphorvlation rn nritr-clrorr

210.oflon. C.R. (19;13).tp;rtle 10 thc t-ann. Il'izrt lirgtnto )gtctdturol l-..tpenneni Sttiltott Ilrllettn 3111:1-5(t.

2ll. Ortorr.C.ll. rnd .Tennr:fi. ( 1948). Researcltp.rrvers of thc lafnl. IIt.\t l']rgnta ..lgncttitttrol I',xpannttnr Stttton Bulletin f,3{: -1-.15. ll2. [)rrtlhlsuradhi.\1.;rntl I]ahu. \1.]{. (1973;..1 rrc$ bisjriql,rnc li()nl il,g/rt?r.!/cg/./ r()()[ bilrl l)h\I().het, t \tr\' 71 : 2012-201f.

2ll. Prschlc.\1.\['.. Dalson. J.O. and Dalitl. Lt.B. ( 1989). Soil lritrosenurineralizrtion in plantaliurtsol.ltigitttt, /1r8/uil{erplallled rrith E/,rcngrils lt,ttbellLtlLlitntl.llntts glutino;tt. f'lunt untl S'>tl I18: -13--12.

214.Pcdersen. J.,\. (1978). \alurallr occrlrring qtrinols and (lllinoltesslrrdir'tl rrs !qni(luin(nlcs br clectr',rnsPin rcs(\ranee.Pht tt.tchentr.:trt'17 : 775-778. 50 Il'i I I i.s

215. I)c.'plcs.Ir..\.(19tl13). Illackualrrut-bothcrsonrelteaulr'. ('()t(ntt\'.lrtrtttt,tl t\1t..\1,)rtt\.li.il5: .'l('--l{ ()\ 2l(r. I,.'rtu..lirs..1.. Ribascarbo ancl Giles. I.. ( 1996). l:,lltcts ol'all.'locltcttticals ott plitltt t'csprtitti()llitll(l rsotopcti'actionrtion b1'the altcrnativc-oriclusc. Jottrncrl ctl (-herttrctrlL'<'ttltttt'22' 80 l-l(05.

217. I,erlingr'r'..1..\...\ngst. \\'. iruclSchu'azenbach. Il.P. (1996). Kinctics o1'lltc lccltrctiotlol'llcrirclrlo.'lltirtt 'lt:cltnttlr'r':r'30: trncl 2"1()l(-.lll .iuu.lr)ncil solrrtiirnscttnlaitring ltvclrog.'tt. i:ut'ttttt'tttrertlul Scrent;": 218. I)erlr.G.S.(1932).Sonre tr-eeantrrgouisrns.f'roceetltng,;of'lhel'<'rttts.\'lvurtru.ictrL.lerrtt'()lSt:t€t1c€ 6:136-l

219. l)cr1r'.S.l:. (1967). Inhibitign of resprr:rtionbv juglonc in Phust:oitt.! alld -1.irr.)p()t\tL()ttlJttll,:f ttt t't 'litt't'ey ' lJorunrcul (. lul, 91 26-30.

2).tJI)lrillrps.ll (182()t. l'orrtctt'trLy "l (irsui ]Jrttutir.[,onclort . . &.1. .Uttttatt 221 prcclrnlrila.(). (198.1). Illack rvalnul to\lc11\'.j''ttctsheel. \lirttsllr of'.\g,rictrlttrrc rttttl l:o,rcl-()rltarl() (i 050): 1-2.

222. l,irrterrre.K.ll. aucl 1'erpo. .\. (1977). Thc ph.'norncnorruf qertttirtalittttlllclr>pltlrv itt Irltttt'ill rt 'l e\perilltellt:tl ertvirttttttlt'rtr/'/<'t.r iri' l..lrttttlutrtr u(? 2t53-217| 'l'lre 223. Pironc. P.P.(1938). dctrintental etlbct

22.-t Plinr thc Fllcler.(19,50. l9-r6; \'urtu'al f{r.stor'1'('ll'ansl. FI. Racklrartr"\\'ll S. .Lltcs) \irltttrtcs \ rrrrd\-l Lorrclorr: \\'iII iarn FIeirrenrannI-tci..

125. l)ouclg. Ii ( 1987). .\llclopathic irrterlcr..rrccof'black ualutrt lrccs rrtllt ttttrogctt-lirtttr-t,lllirttts lrl ll)l\c' plantings. In:.4llelocltetnicqls; Role rn.lgrtc'rtllrre unt.ll:ltt'e'.ttt'.1'. \ClS SvtttptrsttttttSeries.ll(i (l.tl. G.lt. \\'allcr). pp. 195-2()4 \\rasbirrgton.I) Cl .\CS.

22ri. l'ondel'. F..'l'at1ros.i\1.G. and l-aclros.S.ll. (l9fi7;. l-.tlicts ol'.jrtgkrncur qr()\\1ltand tttrclttlrttiottol'ltrttrl vetch. -\'olllret'n ,\ut (]trtvet':; ,ls.socrttltou.lnnttul Reltt,t'tt* , -11,--r()

227. Poncler'.Ir. and Trtclros.S.fl. (l')85)..hrglonc c()llcclllralion rn s,ll bcuclrllt blltck nrrlrrtrt ttttetnlarttetlrrrlh nitrogerr-fisillg spr'cies..Jottrnal a.f(-hernrcul llcoiog.t'll ; !.37-9{2

22[l.l)r.asac1.R.I]N.:trld(itilz.P.-(i.1|990l.Strrtirccrr'ascsll.tltrt|u'il\cSn|ltllitrits.ll.rralttttl.|,t.tt'|tlt.ltt'tlttt'.l' 29' 2097-2099.

229. l)r-atar,iera.;\.G..Knninrki. A.H. ancl Rurgo. K. (1981). (iro*th irtltibitors tu rr'lctrt erutlales ol l'crsttrt rr';rlnuts (Jrtglans rerqia L.) and thcir possitrl.' role in grali lirilure. .i,tto ntti 6l tht' .)tttet'tL'ot1So,'ts1t lot t iorfictilttrctl Sctence 108 ; I ()-l:l-l 0-t-5 230. Rabottror'. T.,\. (197'7). 1-he signific-anceof th.. coerolutron ol'olgtrrtrsrrrslix'thc lbrrttitlio'l ()l pll\1()ecll()\cs ()ltsltc:lte.sh,(t IRtrssian].Bltdleren'!,!osl:ot,,skogo l.\;l))'lttt(l(.t[)r'trot]t. r )Lltcl l]tttlrtgrc:hetti;rrtl2:9l-l0l -f..\. 231. Itabotrror'" (l9t(2). Inrportanc.' o1'thc c'r'olutiorrarvapproach ttl llrc sltrclvol'allclrrpittltt. .\'lr ic i .lottrnol o/ f..c:ology 12 127-130

232. Radis. I'}..Sc'igle-\lurancli. F. llcnoit-Ciuvot. J.1..rrrrd Kriubok. S. (199-l). lirricitr of'nalttttl ltttsk-sitslrirtg \\ilters llitter Re,secrrch26. l5t)3-1506

23.].Rltrradc.S,attclI)lrlid.S.B'(l98.5).QttitttltrcslrspllIl1t.gf0\r.tlrrcgtrlatrlt.s.l'lttrtt(itl,lrtll]||gttt|tttrit.l'J:.1-1

2.]4.Ranc1aIl.\-.I).andI}rirgg..I.D.(i9Il6)'l:f.l..'ctstlf'itrqltlrre(5'.hrtir'osr.1..l.rrir1llrtlrrl(ltlill()ll!')()l.|t|leitlil! .lnohdetl(t llot-rtrlttuer..\'o.r/rrc coDtt)ntt1( attd .Sc'srre

236. Il.'inking. O..\. (19-l-3).Possrble trlack rvalnut tosicitv on lourrrto and cabbaqc. \,'itrlhertt \rl ( ir',ir ,'r' ,-issot:talrr.xr,lntrtnl I?e1:ort 3{ : 56-58.

217 Ileinkirrg.()..\ (19-17) I]lack rvalnut is cleacllr,totonlirtoes. 1-'lrnret (|rotrer J-l : -1.15-

2.18.Itcnesse. D. r'orr (1997).. Erpc'rinrentelle L.lntersuchungerrund konceptionc-llc l'lrcrlcqurtgen llit ettt screcning-\'ertahren des allelopatlrischen Potentials ausgeu'iihltcr Ilauutitt'tclr (./u,q1(/rt.!spp. Eucull'pttt.sc:ttrnaldttlensrs). Bethe/ie:tt cler Tropenlancit'n't. Deut,\che.; lnstrlrtl Irtt' li'ostt.:tltt' rtitcl Srth!ntprschel.Ltnclvirt.schali, I init,er.;itir (ie.sqmlhoch.scrrleArr,i,rc,1, II'il:t:nhttrL.tt'ir 5ll: l -2(tt,

2.19.Rcllerrrrrarer. I{. (1985). (lnter,srtchrulgen:ur En1'rnutik dc,s huklertellett..1rtglontrhhtttte: Ittitttg,urtl Dissertatiorr.I irrrversitiil I Iohenlreint l{(). Ilr'tlcrrnritir'r'.II.. Ktrpas" [:. arrrl [,irrgens. F. (l9fl3). Degraclirtion r>f"juglone bt ['.:erttlr>rttotti.t.slttrlrclu .11 l:1...\lS.\lrct'ctbtologv Lelrcr.s l9 : 193-195. lll.llr'ttenrnlicr. II. attclLirtgors. I'. (l9tl5). l)urillcation and sonrc propertics of trro rsolitnetiorritl.lttltl,rrtc Itvths las.'s liotu /'.yerrr1ot)rot'ta.\ prtticlu J1. Brologtcal ('heni.stt'1' I{op1te-,\a.t'ltr 3(t(t. 6.17-t,-1t,. ].l]'l{ertrolt|s.'I..(l987).Contpara1tr'c-e|ltctso|.lrlicrcliccotllptlttltt1sltttt1t1ttillrlttcsorl.irrhillitl. gennrllation..1nnuI s ol lIntun)' 6ll 2| 5-223. ll3 Ilict\eld \\'..T.(1979\. l,.coloeical iurplicalions o1'allc'lopirthr irr tbrestrr. ln: llt:.gcnertrtrrtg ( )uLt lt [,'plandLlurtlv'or,tdl.'orest.s.Pr<>ceedings]9-9,lolutS.IIi'tghtF-ore.sn'.t'(-onlirentt'(l.cls II..\. IIoll andB.C. I;ischer).pp.9{)-112. \\'estl,allrettc : PurclucIinivclsitr. 'l'hc' 211. Rietveld.\\'..1. (1981). significauce of all,.'lopathr,in black rvalnul cultural s\stcnrs. .\'ttt'tht'r'n.\,,ttl (it'overt.-lssoctttlton.-lnntul |leportT2: ll7-13-1. :\lso ptrblish"-clin 1982: l'$1.t.1 7:r,,'".r'/SeltLr.r' 'l'ec'hnrcul (]enerul Repot t N(l 7{ : 73-t16.

215 I|clrcld. \\'.J.(19113)..\llc'lopathic cllbets ol'juglolte

2{6. I{ictreld.\\',.1.. Schlesinger. It.C. and Kesslcr. K.J (l9tl3). .\ll.-lopathre u'llcctsol'l.rllck rrulntrt tin lrttt'opcartblacknldc'rcoplanledas.lnurs!'specics.Jottrnalol(-henttcul Iit'oiog.r'9:lll9-ll.l.l

217.Rink. (i. and \:iur Sanilrt--ck..l \\'. (1985). \ariation alnong black rralnut s.'ctllirtgliurrilics l) r!'sistlncc to contpetitrr.lnancl allelopatht. Plttnt and Soiltlfl: 3-10. * 2-18 llrrlrinsort.Il (1998). Plant friencl.sof'the blucl" valnttt..,\ncrican Ilorlicullulirl Soeictr. 2.{9.Iloshchin,r" \.D. (I97-l). Rcducing po\\'c'r'ol'*ooclr,pl:rnt leaf inlirsion and irrhibrtiorrol'Iiill rcaelion rrrtlr 2.tr-diclrlorophcnolbv thelrr. In: l-'r:tctlogct-Ihokhrrntche.tkre( ).snor')" l':,ru)tot!t:rlt\:t.\'u l?u.\tentt \ l'rtotseno:akr. (1.d..A.\1. Grodziuskri). {: l0-15. Kier' : Nirrrkovrrl)rrrnka

25().Roslrclrina. \-.\. itnil Roshchina.\:l). (l<)93).'the E.rcretctt'.t'['lrnctrouof ltrght:r l'itrrttr. l]crl in: Sprinqc'r |er.laq. l5 r Iltrss.\1. (199(t). \\alnuts: a nrired [rlcssine,.I:lotrer uncl (ittrcien {l}({trg Scpl) 5.]-l-1.

252I{rprna.R.l}. (1989). .\'c lrlack rvahrut trces poisonous to hollr'.' Holly Soctett ,JorttntrlT(3) : -l-l-l

253Sarz-Jirnenez.C.. Haider. K. irrrd\lartin. J.P (197,5). Arthroclrrinonc-rllld ph.'nols as iutr'l'nlcdirrtcsiu llrc ttrnnatit.rltof dark-colrtr',,'dlturrric acicl-like pignrents l'tr,'[ittrttttrttn echrnttluttttrr. Sr.ttlSctt,l('s Sr.,c.'relt' oi ^i rrrcrtca,i ottt'na I 39: 6.19-653.

25'1.Schlesrnger. Il.C. ancl \\'illianrs. R.l). (198.1). Nrrrse crops inrprove black ualnrrt groullr i-rtre.\l I-.'t'oltig.t (rnLl.\ldltlpernent 9 235-243.

2rS.Sclrrrridt.SK.(19f(8).l)egrad:rtrortol'jrrglonebvsoil bacterur..lutt'nul t>/ ('hertrtcul [:.'t:,;,log.t tJ l5til-l-i7l

25r, Schrrridls.K t 1990) [:c,rlorlicrriirrrplicltiorrs ol' thc cleslrrrctrou ol'.juc,lorrc (5-lrr rlrorr - l.-1- ttaplrlhoqutnone) bv soil bactcria..icntrnul ol (.'herrtrctriF.colog,.l'16 : 35-17-35-19 257 Schnticlt.S.K. ancl R I'.. l.er ( 1999,;. \licrobral colltpctitioli arrd soil structurc linrir 1hc c\prcssrorr ol itll.'ltrcltcttticrrlsiu rtatur,-'. In. [trtnct1tle..\LulLl i't'crcltce:.ytn 1)lont l:.'celog.\'..illt'l,tr'h,'rnir',.ti lnreroclron;(l'.d.. Irttlerjit. K.\1.\1. I)akshiul atrtlC.1,. |or ). Ikrca Ilaton : CI{C' l)rcss(irr prcss). 52 II'illi,s

2-58 Sclrrreiclerhan.F.J. (1926). Apple diseasestudics iu northcnt Virgrrria. Iir,qtrttct.1,!rtutlfrn'trlI:.tpt t'ittttnr StqtrctuRullenn 2{5: I-3,5"

259. Sellr"iclc.r'han.F..T. (1921a).'Ihc black u,irllrut (lrtglans ntgt'tt 1,.) as a carrscol'lhc clcalh o1'applc lrccs Phrtoltuthol ogy t7 : 529-540.

2(r0. Sclrrr.'idc'rlrau.F..1. (l927tr). Rect-rrtdeveloprrtcnts ru tlte cortrol ol'lrtrrl (lis!'ascs. l'ri,,tt'tlttt,!,t ,tt tltt lirgtntu Sfute llctrticttltttrul S

2{rl . Sclroplcr. \\'.11.atrcl K.'llcr. \i ( 1951). .\ctiotr ol vitirrrrinK3 anclnrc()lilric ilci(l olr lhc !',r'ccttitrrcl e olourlcs: lirrrrrsol-[rr,glenu gracrlis.lJulletrn cle la Socitili cle(-ltitnta Btolo,girlttr: J3: l25l-12(r0. ().J-9(, 262. Selrr.'iner.1,..1. (1949) Ciur bltck u'irhrut poisorrpiues'l trlorrr.s.'lrhot'ettttttIJttiit'ttit -l :

2(r.l Sclrrerrrc'r.l',..1. ( l9-i0). Carr trlack u'alnut poisttn prnes'?-\hqde'li'ee'23(l | 2 2(r4. Sclrrerrtcr.(). :urd Rced. II.S. (1907a).'l'hc'proclucliou o1'dcl,.'tcriousc\ercllr)lrs l)\'f()()ls. iJnlletttl ()t ritl 'forret' lJc,ttu n t cu I (' ln h 3l . 2'79-303.

2(.5 5.1tr.,trcr.0. irnclIteed" Il.S. t 1907b). Sonrc lirctors int)u..nctngsoi llirtilitr. l ,\ I)(l)at'tntt'nl ..let'ttrLltttt',. Bttrc;crttql Sorl,sfltrllenn -10 : l--{0.

2(rti. Schtrltz. It.C. arrd Konnanik. P.P (1982). \'esicular-arbrrscularul'corrlriza arrd srril lirrrlitr irrllrrcnec lnirtelal concL'r)trationsin secdlings of cight hardrvortd spc'cic's,('trnut.littn .lrtttttiui nl l'vt'q'tl |le.:cttrc h I 2 : 829-834.

2tr7. Sc'gur:r-.{guilar.-1.. I{akrrrau. I. ancl Rvdstrotn. J. (1992). l'hc ellict of'5OII-1.-l-rraplrtlrotlrnn()lrc()n Norrvitv spruce secds tluriug gL'nnination. Planl Phystolog1' 100 : I9-i,5-l96 I

268. Slrclrttiur.R.R. (1971). .1tt llt:ologrcul Evultttttron o/'tht: ,4lleloltutltr<-lnflttt:nc't: oi ,/tt,qlttrt t'tt(

2()9. Shillir)g. l) G. ancl \bshikan,a. F. (l9ti7). .\ rapicl sc.ecllirrghioussav lirl thc strrrlvol';rllcloplthr ln ilielochentr<:als:Role tn ^-lgnctLltttrauttcl Frsre.stry(l';d.. (; Il. \\rrllcr). pp .j1-l-1-12 \\'asltittsltrn. I).C'. \C'S

27() Siclhtr.(i S.. I'}ardhitsitradhi.i\1. irnd Bahu. \t.ll (l9Z-i.1 Jsoletionof'trrs-.1ug,iorrc liorrr ,ltttlitit.\ r'e',!rirl'rrrlk iu<.lrttn,iottrnul o.f(-ltentt.strt' 13: 7-19 l7l.* Silrir. }l.\1. (1997\. I)llrrl aquirrslplarrt.'lhe ['u.gtntu(;(tt'Llenrt\eru.r'lericllJr -l). 272'Srrlitlr..I'It'(l941).()rtcpliltt1"slttea1isittttrt|tc-rplarlt'.spoistlrt.'\'ol.|htlt.lt ilt:ltttri 32 : 2ll-.1I ..

273 Srrrith.i{.\1. (19-12). Sortrc ell'ectsol'black Ioctrstsand blrtck rrulrrtttsoll s()r.llllcitstcrrr()lrio Duslurr.'s.\lol,' Sc'rence53 : 385-398.

27'i Sriclcrtttrist.C..1. ( 1973). .luglortc,,r't,1 nllglcrpirthr. ,lotrt nul r>1(-ht:ttttcttl [:,'drtc'trtr;tt1 5tl 7li2-7|i.].

27-s.Sokolor'. I.N.- Clt.'khova...\.F...Fllseci. \'.1'." Nilor" (i.1. arrclShchcrburrr>r'skir. I It l1')72) SlLrrlrol atttirtricrttbialactilitr ol' certiritr llaphlho(luin()nes lltussiarrl. l'r'rkltt

277. Spregf. I'. artclChirikcljian. J.J. (1g72). Flavortoid disrributrou in,.ltt.glun.sregrti i'lttrt'nlLt:t(21.7ti()-7,\l

27fi. Stcllitt. K. artcl l)r--scltel.ll. (1975). Chcnrisr-he Koltsitutrou rrrrd antilirne,rrlc\\'rrkrrnq rorr l.-l- Itltplttltttchittottcn.dcrert biosvnlhr'lisch.'r Zuist''lrcl)pro(hlktc trnd chcrrrisehrclricrrclt.'r'stollc l'luitt,r \letlrca 27 : 201-212.

27'). Stcirrbcls,..1. ( I9594). ltas.trche Lehr- ttnd I:-or.ychrrng.scut,ttttltit'ir IIt'ttt-. ( )i>:t- untl (-ittnt'trhtrrr (ietse'nheint tllheutgctu).lJet'tchte/i'ir cla,rRec'hnrtng:;1uhr l9-:- 5,\. Juglans spp.,juglone ontl allelopotlt.r' 5:l

280.Steinberg.J.(1959b), Hassiche Lehr- und For,ychrtngan,stalt.fiirII''ein-. Ob,st- ttnd (iqrtenburt Gei,senheim(Rhinegau). Rerichte.fiir Rechnrtngs.Tahr I 958, 5 9. 281.Stic-kner'. J.S. and tloy, P.R.(1881). Discussion.Transactions o.f the I[i.scon.srnSrate f]orticttlttral Societyl1 : 166-167. 282.Sti.'rle. a..q.. trpadhlall R.. I{ershenhorn.J.. Slrotrel.G.A. and lrlolin. A.G. (1991).'I'he phltoloxins of A[l,cosphaerella.fi-tt"en.v.r.the causative agent of Black Sigatokadisease.of t'ranirtrrrs and pliuttains. Experienticr(Basel) {7: 853-859. 28-1.Stipanovic.R.D. and Bell. A.A. (1977). Phenakctidemetabolites of Ibrtrcillirtnrclahlioe. 2. "\cc'tuttttlalion of naphtholderivatives b\ at'rerrant-rnelaninnrutant bnrr-2. Al1'cologra 69: 161-172.

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307. \ian Satntreek. J.\\'.. Schlesinger. R.C.. Pondc-r.F. aud Rietveltl" \\r.J. (198-5). .{ctinolhrzal spccl!"s as n\rrsc crops 1br black rvalrrul. ln: Proceecltng:; o./'the 5th (-entrql Ilarcltood [:-ore.s((,'onlettnt;t: (lr(t .r () Darvson arrrJK...\. Nla.ierus).pp.257-263. SAF Publicalion 85-05.

308. \arga.2.. Ilc-ttc'.L.. l)antjauovic. S. attd Gaspar. R. (199(r).'l'he cf1icl ol'.iuglorrc ou tlrc rtrcnrblrtrrc polential attd rvhole-cell K+ curreuts of hurnirn lvlrrphocltes. Iltochentrcirl nntl Rrop)y,;1a'r,1 Re.se a rc h (- o n nrr t n ic ctI r on.s 2l8'. tl2 8- 83 2.

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313. \\'alker'. t, C, ( 199()). l--ttre.sts:tt nultu'uli.yI'.s.grttcle to tree.\ tttttl litre.st et:ttlog.t. \cu York : .Lllru \\'ilcr & Sotrs.

31.1. \\ang. K -L (191 l). I)hy'srolctgrcal I'.//ect.sr,ti Jttglone ctit IIrgh<:r Plctnr.:. Ph.l). th"sis. Kurrsas Stirlc [-rriversi1l,.

315. \Veidetrhattrer.J.D.. Ilartnelt. D.C. and Romeo. J.T'. (1989). Derrsitv dr-pencleulphr'totosicit'.: clistingrrisltil)gl'L'sourcr' contpetitiort aud allelopirthic irrtcricrcrrcc in plarrts. .Jortrnul ol' .lpltltt'tl Lcologl'26 : rcl3-621.

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319 \\.estlall. t).A.. Rtrssell.R.L. anclAuvoug. T.K. tl96l). I)t-plr'ssalllilgeltt tiorn uahirrt hrrlls. Sc'ierrce'13J 1617.

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321.Wiarrt.H.\iandRarrrirez.\{.A.(197.1).Dolr'tplantrvhitepllenearrvalirrrti.frceI'lttnler.r".Vols,r25(-l):3()

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324.\\'illianrs. R.D" and l{oagland. lt.E. (1982). The ell-ectsof uaturallv occun'irrg pheuolic courpctuuclson seecl genrrinntion.Il'eed Scrence 30 : 206-212.

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126.\\'illis. R.J. (198-5).fhe historical basesof the c'onceptof alleloplth\'. Jor./'/?ulol the I{t.stot'1'olRrolc,g.t 18:71-102.

327.\\Iillis. R.J. (1996). Allcloprrthv in L'ttcct/l'ptu.s:.\ustralian studics. ln:.'lllelopcrtht': /'relcl ol).\et'\:(ttt()n.\ uncl'\lethctdolo.q-t'. (l,ds.. S.S.Narn,al and P.I'auro). pp.4l-6-1. .lodhpur: ScrcrrtilieI)u[.rlisltcrs

328.\\'illis. R..1.(1999). .\ustraliart slrrdies on Ettcalyptlr.r-:a revieu. ln: Prrnctple:.sand l>t crc:ttcesrn l'l,tnt Ecologl': Allelochemicql [ntertction.s (Ed.: Inclerlil. K.NI.N{. Dakshirri urcl C.L,. l-or'). Bocu Ralou: CRC Press(in press).

329.\\bod. B.\\r..Gottu'ald. T.R. and Reillr'. C.L. (1988). Pecan plrrllospherc clrcnricalsirrllrrcncc'gennirrirtiorr of pecanscab coniclia. Jottrno! of'the.,lmencLtn Soctet)'lor'[[orticrLllttrql Sctencr tl3. 616-(l 19. 'i'. 330.\\rorlidge. I. (1677). Systena IIortt-cttltttree. or the.,lrt ctl (iurdentns. Lt-rnclorr: llurrcl lnd \\'. Hertsrttirtt.

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332.I.ttzer. S l. and Dau'solt,.l.O. (1989) Scitsonulcltirngcs in uocltrl.'nitlorlcrtirscactivitr til'.1/irir.sglrttitl,,.rtt itnrlEleagnu.t ctngrt.stifblia, Tree i'h1 ::tolagv 5 : I 8-s-19.1.

* EnlriesfolLrned rvith an asterisk lrave l'r..crrsorlrL-ed fi'onr the Irrlcrrrct.