STUDIES ON THE INTERACTION OF NEMATODES

AND FUNGI

THE DISSERTATJON SUBMITlED IN THE PARTIAL FULFILMENT FOR THE DEGREE OF

M. PHIL. IN BOTANY

BY

R.P. Srivastava

DEPARTMENT OF BOTANY ALIGARH MUSLIM UNIVERSITY

ALIGARH X97&

35 S .\\8. .

'^^^>'.«u..:cH.'''

DS118

Th« «uthor gra tefu l ly acknowledges his profound debt

to Prof, Abrer M, Khen, Botany Deptt . , Muslim Universi ty,

Aligarh, for many valuable suggestions and great help he has

received from him throughout the preparation of t H s work.

He I s equally indebted to Dr. S.K. Saxena, Reader, Botany

Department, Muslim University, under whose experienced and

scholar ly guidance this work has been done. He i s no l ess

grateful to Dr. M.M.R.K. Afridi , Professor and I-fead of the

Department of Botany, Muslim Universi ty, for giving him a l l

necessary f a c i l i t i e s of l i b r a ry e t c . Ills thanks are a lso due

to Dr. Dhirendra Prakash, Muslim University, Dr. S.K.Mathur

& Mrs. Ant la Mathur, DBptt. of Botany, Agra College, Agra, who

have helped him from time to time i n one way or another. And

f ina l ly , he i s glad to place on record his great obligation to

Dr. R.P.Verma, P r inc ipa l , and or M.N. Qjpta, Head of the Botany

Deptt . , Agra College, Agra for providing him with a l l the

f a c i l i t i e s he needed in connection with this work.

Author.

C O N T E N T S

CHAPTER PAGE^

i . Introduction and review of l i t e r a t u r e 1-23

2. Materials and methods 24-29

3, References 30-41

Plant o parasitic nenatodes constitute ona of tha

nost inportant non.insact pasts which Unit tha agricultural

production and at timas tha losses are trenendous (Hjtchinson

m l » » 1961; Taylor, 1967; Van Berkum fiJi. £ 1 . , 1970).

Ihe plant nematodes, by interacting with other

components of soi l biota, specially the soi l microflora,

affect the disease situaUons forming the so called "disease

complexes". Ihus th6 pathogenecity of plant-nematodes under

moneysthogenic conditions may not be very important in the

etiology of plant diseases than interactions between nematode

and soil microflora. Ihe subject has been crit ically reviewed

by i»ltcher (1965), Fbwell (1963, 1971).

TfnB association between plant-parasitic microflora

and plant-parasitic nematodes i s directly related to the mode

of parasitism of plant nematodes being less developed in

ectoparasitic nematodes than endo-iparasitic nematodes. In tha

former i t appears to be more of **additive* and in the latter

"synergistic*. Ihe subject matter has thus bean reviewed

nematode wise.

WGRATDHY ECTOPAMSinC EMA DDES :

Heplolainus t —

Hoplolaiawja vlniformls has been found associated with

FUtariya oxyapor»ii f.pial in early yellowing of peas (Labruyere,

H Jil*f 1959). Xn»etilation of nematode alone caused a slight

: 2 t

g£«y difcolouration of portions of tho root and cracks in

tht eortox «dthin which nematoda eccurrad. Inoculation with

tha fungus alena producad a suparficial discolouration of tha

cortax whan tha inoculun was placad in diract contact with

the root and no visibla dasnaga whan tha inoculum waa placad

at a short diatanca from the root. Inoculation with both tha

organisns rasultad in axtensive dark brown discolouration along

the roots and coupleta decay at the point of inoculation.

In the absence of nematode, the fungus colonized only outer

layers of the cortex, whereas in the presence of nematode, the

fungus penetrated into the vascular bundle.

Brodie and Cooper (1964) reported that cotton

seedlings grown in soi l infested with H, tylenchiformis became

predisposed to the attack of Rhizoctonia solani.

\i9bhunt and Weauer (1972) observed the strongly

combined effect of nematode and Fusarium oxysporum on the

growth of peach seedlings. Ihey further reported that seedlings

grown in soil infested «d.th Hbplolaimus and Fusarium ware

smaller as compared to th»se grown in so i l infested with

either of the pathogens alone. Further, using H,galeatus,

Tylenchorhynchus claytoni and Criconemoides xenoplax in

combination with Fusarium oxvsporum. tha combination of jj.

galeatys and F.oxyporum gave the highest reduction in the

growth.

Thi rol« of H»indicut on tht stverity of ««©dling

blight of £lc« has boon obtorved by Rainana ±^ a l . , (1974}

wh»z«in H.lndicu* Incroastd the severity of seedling blight

of r ice when present together with Helminthosporiun oryzse,

H.galea tus alone has no effect on the development

of wdlt of cotton caused by Fusarium oxysporum f.vasinfectuw

but when present together with other nematodes such as

Bslonolaimus longicaudatus and Meloidogyne incognita,

considerably increased the wi l t (Yang Ffenry ejfe j j^. , 1976).

Helicotylenchus :

There i s only one report about the association

of HBlicotvlenchus^wilt diseases. Stover (1966) reported

that Hhizoctonia solani was more commonly found in shallow

lesions on Banana roots caused by Helicotylenchus spp.

Tylenchorhynchus;

Tylenchorhynchus claytonit caused a s l ight to moderate

increase in the incidence of blackshank of tobacco on the

resistant variety DiMle Bright lOi, in association with

Phytophthora parasitica yar. nicotianae (Graham, 1958),

Holdeman (1956) observed that T.claytoni increased the incidence

of wi l t caused by Pusariun oxysporum f. nicotianae in a

susceptible variety of tobacco. Similar synergist ic ef fect of

nomatode-fungus has boon observed by Haglund & King ( l96l) in

s 4 s

th« xooUrot of p«ct btt^tn 4phano«yct» •ntelchet and T,

BKirtlnii* B«odi« and Coopar (1964) pointed out that T.claytonl

incroasod tho Incidonco of root-rot caused by Rhlzoctonia

sQlani in cotton but did not langthon tht poriod of suscoptl-

bi l i ty. Hindri x JJL l i . , (1965) obsorvod tha t Tylenchorhynchu>

•pp., in addition to other nematodes, was responsible for

increasing the peach decline. Khan JLi i l* t (l97l) observed

the interaction of Rhizoc tenia ftolani and T. bras si cap in pre-

emergence damping off of cauliflower seedlings, T.brass!cae

alone did not affect the percentage of emergence of cauliflower

seedling« however, the nematode considerably increased the

pre-emergence damping off cause by Rhizoctonia solani.

Paratylenchus t

The pin nematode ^aratylenchus ha ma tus has been

associated with a species of Rhizoctonia in root-rot of celery

(Lownsbery and Lownsbery, 1952) and witti Rhizoctonia. Pythium,

and Fusariua in root-rot of mint (Hbrner and Jensen, 1954)

but these have not been studied critically.

Belonolajaus :

Holdeman and Graham (1952) reported that Belonolaiwus

gracilis greatly faeiUtated the development of Fusariuiii wilt

in susceptible and resistant varieties of cotton. Minton

and Minton (l966) have reported that B.longieaudatus did not

affect cotton seedling enesgence, however Fysariuai «dlt

developed as plants beceae older i f they were simultaneously

•iqposed to neaatodt and the fungus.

: 5 :

SEDBNTARy BCHO^PMkSLnc HEMATDDES :

Tyl»nchculu> s

Fildnets«r, £ i l l * • (1962) observed that rough

lenen feeder roots end crowns infected vdth Tylenchulus

seml-penettrens for • long time had the highest incidence of

infection with Risarium solani and F.oxyspormn* Roots from

the areas newly invaded or not yet invaded by the nematode

had much lower percentages of Fusarium infect ion. There was

no apparent relation between this nematode and infection by

Pythium, I^ytophthora or Thielaviqpsis. O'Bannon gji « i . ,(1967)

observed that lemon root decay by Rjsarium solani increased

considerably when T*semi^perwtrans was present but this was

not true when Fusarium oxysporum was present with the nematode,

MIGRAlDRy ENDOPARASmC NEMATODES :

U. tylenchut :

A very interesting relation between Ditylenchus

dipsaci and Botrytis a l l i i in collar rot of onion has been

reported by Myuge (1959). When water into which the nematode

had excreted enzyme was injected into onion plants in the

presence of Botrytis a l l i i , lOOJIt plants became infected with

collar rot in contrast to disease incidence of 30 percent when

pure water was used under similar circumstances.

Radopholus :

RadopholMt s i a i l i s i s commonly associated ,vi Ih citrus

decline but tpeciee of RiaagitiM may be associated vdth the

i 6 :

rMOHitodt in •tloLogy. FUsarium together vdth Sclcrotluin and

Thielaviqptis apptaced to bt inportant in the "decay phase"

of the disease (Du Charme and NMiks 1957). The incidence of

infection of citrus crown pieces by Futarium was increased

four fold in the presence of R s i m i l i s (Bider and Feldmesser

196l). There may be somewhat conplex interactions between

these two organisms in citrus because variet ies that were

tolerent to the nematode apoeared also to be tolerent to the

fungus (Feder and Ford, 196l).

Although R. si mi l i s was not a prerequisite to Panama

wilt in the Qcos Michel variety of banana caused by Fusarium

oxysporum f. cubense, the disease expression was aggrevated

and the period between inoculation and appearance of symptoms

was considerably shortened when t)^ nematode was also present

(Loos, 1959).

The root rot disease of banana var i e t i e s . Dwarf

Cavendish and Williams in Australia appeared to be ent ire ly

due to FUslmillis and the fungi, Fusarium oxysporum and

Rhizoctonia solani acted only as secondary invaders (Blake,

196li Stover, 1966).

Pratylenchus :

R»ot lesion nematodes have been associated with

Pkisatiua wi l t of cotton (Snith, 1940; Holdeman, 1954), but

the relation hat never been examined c r i t i c a l l y . Rhizoctonia

solani and Pjf tylenchwt ntqlectus were very c lose ly associated

• 7 •

in x**t-r*t •€ «dnttr whtat (Btnsdict and Mountain, 1956).

7h« conbintd •ff«et •£ tha fungus and tha naaiatoda in raducing

tha grawth af whaat was approxlnataly tvdca that producad by

aither vf tha pathogans alona. Tha incidanca af fungal infactien

of tha roots nay ba corxalatad with nanatodo papulatian but tha

affact af the two parasitas appeared to be additive rather than

synergistic.

Ihe classical studies on the interrelation of P. pane trans

and Cylindrocarpon radicicala (Hastings and Boshar, 1938) shewed

that the fungus alone reduced the growth of a number of plants

including potato, carrot, red clover and violet by 6 to 11 per

cent vAiere as the fungus and the nematode reduced the growth

by 50 to 75 per cant. More recently, SLootweg (1956) reported

that Cylindrocarpon radicicola alone produced no lesions on the

root of narcissus, whereas the fungus and P.penetrans produced

extensive lesions.

True synergiSB between \AarticiIlium dehliae and P.pane trans

has baan damanstratad in the etiology of egg-plant wilt (Mc Keen

and Mountain, I960) and to a lesser extent in tomato wilt

(Mountain and Me Keen, 1962). the incidence of wilt was striking.

ly increased by the nematode i f the level of the fungus in the

soil was low. Symptoms of wilt in tha egg-plant appeatad 20 days

earlier and tha incidanca of wilt at tha end of 8 weeks was 65

par cant highar in plants growing in soi l containing both the

: 8 :

ergmitnt than in to i l conttining only the fungus. Th« exact

nochanisn of inttractlon hat net boon known but tho noinatodo

eauset oxttntivo cortical nocrotis within 24 hourt on tht roott

of ogg-^lant and tht fungus may utilizo the necrotic pathway to

the vatcular titsuet. The root population of the nematode wat

usually much higher when the fungus was alto pretent and there

were indications that complex interrelations existed between the

host plant, the fungus and the nematode (Mountain and Mc Keen,1962),

The presence of P.penetrans resulted in earlier and more

severe syofjtoms of Wrticillium wilt in a susceptible variety of

strawberry. However, varieties of strawberry resistant to wilt

were not affected by verticiIlium albo-atrum when the nematode

was also pretent, although the latter reproduced readily and

caused many root lesions (Abu-Gharbieh, j i ai,., 1962).

In the etiology of charcoal rot of sorghum, the nematode

P.hexincisus and the fungus, Macrophomina phaseoli caused a

significantly higher rating under dry to i l conditiont than did

the fungut »loiie (Norton, 1958).

The pretence of P.penetrawt retulted in earlier and more

tevere tynptOMS of Vtrticilliuii wilt in a tutceptible variety of

ttrawberry retittant to wilt were not affected by Wrticilliuw

alhoatrua when the neaetode wat alto pretent, although the latter

voprodueed readily and eauted itany root letiont (Abu-Ghtrbieh,

&ijl*» 1962).

: 9 :

I^pptxmifil i t subjected to P.ninyyt - VtrtlcllIliwB wilt

inUraction. Iho (^Unun ttnporatuxo for wilt development w«s

influenced by P.ainyue. It shifted fren 24°C when fungus wet

present alone to 27^C when both orgenisms were present (Bergeson,

1963). Faulkner and Bolander (1969) reported that optirnuin

temperature for nematode reproduction was also changed in complex

situations. These authors have also reported (1970) that nematodes

positively influenced the incubation period as well as the

incidence and severity of the wilt.

I>)»inell and anclair (i967) have concluded that P. pane trans

might interact with VerticiIlium dahliae on elm and maple.

Nematode incre-ssed invasiveness bv V.dahliae in tte f irst year

elm seedlings treated with ftratylenchus. This effect was

nullified by the addition of potassium.

Root lesion nematode was also involved in certain root->

rotting complexes. Mountain (1954); Banedict and Mountain (1956)

reported that P.minyus interacted with Rhiioctonia selani resul­

ting of wieatc growth from root-rot. Edmunds and Mai (1966) have

shovfi ^at P.panetrens combined with Trichoderma viridife caused

mere reduction in root and shoot growth in alfalfa and celery than

either ef the organisms alone. The fresh weight of corn was

reduced mere when P.sribneiil and Fuseriurn meniliforme were present

together khan when either ef the organisms was present alone

(Palmer U l I . , 1967).

: 10 I

Ittlfc ©f p*«t ill vir. •Itendo* cauMd by Fuf rjuw oxytporuBi

f .g is i rac« 2 wtt •nhanesd by F.p»n»tynt (ftinhorst and Kuniyatu,

1971).

MLchell and Powtll (1972) hava raportad tha Influanea of

P»brachyurus on tha inddonca of FusariMin wiU in cotton. A

graat parcantaga of plants wiltad when tha nematode and tha fungua

ware applied simultaneously than when nematode was added two weeks

prior to the fungus or when fungus alone was used. Colonization

of roots was most extensive in plants simultaneously treated with

nematode fungus combination.

Burpee and Bloom (1974) have observed th«s interaction

of VerticiIlium albo~atrum and P^penetrans on potatoes. Initial

symptom development in the fungus and the nematode plus fungus

treatments appeared one week and two weeks respectively prior to

the development of natural senescence. The nematode reduced tiie

inoculition period for the development of wilt.

Maximum population of P.penetrans occurred at about

12 par cant soil moisture, 20^C temperature 4.5 p . Damage

to the potato crop was minimal due to low nematode population

densities (Gould, 1974). A glass house experiment suggested an

additive pathogenic effect of P.penetrans and wrtici l l ium albo..

atrum en aolanum tuberosum (Gould, 1974).

i 11 :

Cbottnans (1977) has ttudiad the interaction of P.penetrans

and VtrUcllUMB app. on flax. Aecording to hin P. pane trans and

\%rtieiUiuti> app. acted synergist ical ly under certain circumstan-

eee, bui a mifdmm population of both nematode and the fungus

was required, when the i n i t i a l population was higher either the

fungus or the nematode induced minimum growth and maximum wi l t

and thus masked the e f f ec t of the other pathogen.

There was posit ive correlation between the presence of

P. thomei on potato and the severity of VerticiIlium dahliae wi l t

where there was fa ir ly high population. Even re la t ive ly

Verticillium tolerant variet ies sustained losses of 30-40 per cent

in presence of P. thomei (Krikun and D'orlon, 1977). Mullar(i977)

observed the interaction betwsen different species of Pratylenchus

*"^ Vsj^ticillium albo-atrum. Out of five species used P.penetrans

and P.vulnus enhanced the wil t .

SEOENTABY ENDOLPARASETIC NEMATODES t

Ross (1965) reported that Hiterodera glycines was more

• f faet iv* in predisposing soyabeana to Risariuw wilt than

^ * Msloidogyne incognita. Soyabeans, however, ware somewhat more

tolerant to root»knot nematodes than cyst nematodes and this

could explain tha difference in the coaplex. In sugarbeet

Jorgenaon (1970) noted that neaaticides controlled the disease

eaystd by H»tchichtii and Fusarium oxyaporuw. The fungus

: 12 :

«pp«xtntly inhlbiUd nmiatod* invasion and devalopiRent resulting

in the decrease In the nenatode population.

Cyst nenatodes are also capable of Interacting vdth certain

fungi to promote root decay, Polychron^oulos f l jJL* t (1969)

reported that roots and seedlings of sugarbeet v«ere greatly

damaged by a cooplex of H.schachtii and Rhizoctonia solani.

Wounds and root proliferations induced by nematodes, appeared to

facil itate subsequent penetration and colonization by the fungus.

Ssedling symptons developed rapidly after infection by both the

pathogens. These authors concluded that giant cells resulting

frora H.schachtii as well as adjacent areas provided a hiahly

suitable sul»strate for fungal growtti.

Dunn (1968) reported interesting interaction involving

H.rostochiensis with Rhizoctonia solani and Colletotricuffi

atramentariua on tomato. James (1968) failed to observe any

influence of H.rostochiensis on disease caused by Catramentarium.

Ray (1968) studied sites in tomato roots jointly infected with

H.rostochiensis and grey steri le fungus. When both the pathogens

wore present, giant colls were either not formed or deformed.

Nematode larvae failed to develop into adults. Plants inoculated

with nematodes only produced t^ica l giant ce l l s .

The adverse effect of Pythium ultimum and P.aphanidormatum

was far greater when the nematode infestation occurred along with

fungal infection, the effect with the fomer was synergistic

: 13 :

whlU with la lUr tddltiv* (Whitney, I97i). Whifcn«y (1974)

obttxvtd the synergistic effect of P.ephenidermttum with

He tegedege eaeh^chti on su^arbeet. The increased danping off

of sugerbeet ^peered to be associated with the increased growth

of the fungus around the infected centres because the nutnber of

centres remained constmt whether or not the nematode was present.

The susceptiMIity of the fungus was not lengthened by nematode

infection. The effect of Pythium apharii derma turn and the nematode

in ccKBbination was additive for damping off and root-rot of

sugerbeet (\l«>itney, 1974).

Aieniji s J t i i . , (1975) observed interrelationship between

H.glycines and Phytophthora megasperaa var. Spjae in soyabeans.

According to the authors soyabean seedlings (2, 5 and lO days old)

of 3 cultivars varying in susceptibility to race 1 of Phytophthora

aegasperaa ysr. Sbjae were inoculated with «ach of the organisms

alone and in coorigination. Seedling disease was more severe in

susceptible cultivars when both the organisms were present than

fungus alone. P.aegasperaa infection significantly reduced the

population of H.glycines en roots but did not break resistance.

The developmeiit 9f VarticiIlium wilt was mere severe

in tomatoes growing in soil to which lOO cysts of H. t aba cum

had been added than in se i l without the nematodes, whereas

Ruarium wilt development was less severe (mi l t r , 1975).

i 14 :

imloidogyiit s

Thtr* are l«rg« numbtr of •vldences whBZ«in interaction

between this genus and the soil ?aicroorganittns occurred. The

most coiMNOn bf these appears to be with genus Fusariuw especially

with varieties of plants that are resistant to the fungus.

The association of root-knot nematode with cotton wilt

has been observed in the fields for the last several years.

Atkinson (l892) was anong tha f irst to notice this association

when he observed that infecticm by root-knot neinatodo increased

the severity of Fuserjurn wilt in cotton. Since then the inter­

action between these two pathogens has received much attention

on a variety of host plants. As early as 1928 Bosen postulated

that the action of root-knot nematodes on roots was largely

that of producing localised h^erplastic overgrowths consisting

mostly of soft parenchyma and a reduced amount of cork and wood;

this type of tissue offered excellent oppottunity for growth of

cotton wilt fungus. Martin, SJt£L>*(l956) reported that the

incidence of wilt in both susceptible and resistant varieties

of cotton by Fusariuw oxysperun f>vasin fee turn w*s significantly

increased in the presence ef M.incognita and M.incognita acrita»

Critical work has been carried out on the interaction

between root*knet nenatede and Fusariua wilt of tonato.

Jinkins and Ooursen (1957) found that F.^xysporua f« lycopersici

•lone er with reot woundling, did net c«Mse wilt in tamato

variety ehtsaptake. But when M.hapla was also present 60% ef

: 15 i

tht plants vdlttd; and whtn M.incogniU acrlta was prassnt

100 psr esnt 9t tha plants wLltad. mndlar studies by Cbhayi

and Minz (i960) shovnad eonclusivtly that root-knot nematode

interacted ^ t h Risariti» increasing the incidence in tomato ««ilt.

Interaction between Maloidoovne and Fusarium have also been

denonstratad on alfalfa (Mc GUire, £ i iL* i 1958), black beans

(Thonason, 1958), Cbwpea (Ihomason, et a l . , 1959), mimosa (Qlll,

1958) and carnations (Sehindler, &! £!• , 196i). m»m certain

species of Miloidogyne are frequently mCMee effective than others

in causing interaction, shotMS it*s not sinple wounding by

nematodes responsible for diseace complex but something else .

The root-knot * fusarium vdlt interaction in tobacco

has been more interesting* Melendez and Powell (1967) reported

that giant cel ls and adjacent xylem elements in both Fusarium

susceptible and resistant plants were extensively colonized.

C ant ce l l s , however, ware sensitive to fungus invasion and

became devoid of protoplasm soon after invasion. Fungal hyphae

present in such cel ls gradually became debilitated. Occasionally

the female nematodes and gelationous matrix of eggmasses were

invaded, ^rter and Powell (1967) observed that in some hosts,

the nematodes apparently ware capabla of maximum predisposition

only after 3»4 weeks. This time interval would be sufficient

to permit the formation of galls along with accompanying

morphological and physiological changes. The appaarence of

Fusariun vAlt symptoms was more clo^ly related to the time of

: 16 :

nematode inoculation. Ihis fact does not hold true of other

crops (Johnson and U t t r e l l , 1969). Goode and Mc CSbire (1967)

pointed Out that root-knot neesatode infection enabled certain

races of F.oxysporum f. lycopersici to attack tomato variet ies

ordinarily resistant to those races and suggested that fungus

mutated in the host in the presence of the nematode.

The interrelation between.M.incognita and Phytophthora

parasistica var. nicotinae in black shank of tobacco i s 4 so very

interest ing. Sasser, e^ al . t (l955) observed that the resistant

variety Dixie Bright 101 was much more susceptible to the fungus

in the presence of the nematode. The fungus had a dis t inct

aff inity for hyperplastic and hypertrophied areas of galled root

t issue. In such regions, the mycelium was more extensive and

vigorous then in the non-galled areas. The hyphae progressed

rapidly and directly into the hyperplastic tissues and syncyt5='.

After invasion, a compatible relation was formed between the

fungus and the host c e l l s undergoing hyperplasia. Fbwell and

Nusbaum (i960) concluded that nematode provided a highly suitable

substrate for the development of the fungus.

Interactions between Meloidogyne and Rhizoctonja have

been reported on cotton (Rtynolds and Hanson, 1957), soyabeans

(Taylor and Wyllie, 1959) and peas (Sayed, I96i ) , M.hapla has

• much greater e f fect than M.3avanica on incidence of damping -

off of soyabeans (TayUr and Wyllie, 1959).

: l7 :

Kushncx and Critt«nd«n (l967) obt«rv«d that decay in

affalfa root* by aittiar Fuiarlum roaaua or F.oxyporum f.batatas

increasad whan M«Incognita acrlta was pxesant with tha fungus.

Root-knot nematode also interacted with other rhizosphare fungi.

The frequency of occurrence of Mparqillus flavus from peanut

shells increased manyfold i f M.arenerea was present (Mlnton and

Jackson, 1967).

Very often thft status of noroially unimportant fungal

pathogens i»d been elevated to major significance by nematode

infection. I^well and Batten, (1967) and Melendez and Pbwell

(1969) reported that both Rhizoctonia solani and Pythium spp.

caused dancing o f of tobacco seedlings, but usually w*s insigni­

ficant. The Rhizoctonia also caused root and stalk disease known

as "Soreshin", but the occuriince of this condition in the fields

was sporadic* However, tobacco plants previously inoccuKted

w4th M.incognita by 3-4 waeks ware infected with either of these

fungi, tha disease intensity was aggravated. On the other hand,

Ut t la danage resulted i f the fungus and the nematode were

applied simultaneously.

Jbwell (l97l) observed some effect with fung«a which,

although pathogenic on other crops, have not been reported on

tebacco. 4>ecies of Curvalarja. Botrytis. Asperoillus and

UmidlliiM invaded and caused decay of tobacco roots i f roots

Wife predisposed by prior root-knot neaatode infection. KLthout

the pzediapetition, these f^g i appeared to be incapable of

s 18 :

tsUbUshlng • p a n s i l i e rtlationship of tobacco. SLmllarly

MtUndtz and ^woll (1969) raportod that Trlchodoma tp.

although poor pathogenic, btcant pathoganie and induced decay

of tobacco roots i f roots were infected with M.incognita and

these losses due to the disease syndrone were comparable to

that caused by the interaction of Pythium sp. and M.incognita.

Several cases have been reported where the susceptibility

period of the plants has been increased in the presence of plant

parasitic nematodes (Brodie and Cooper, 1964). Cotton plants

were susceptible for longer duration to Pythiua debaryanum only

when either M. incognita or M. hap la was present. Mi n ton and

Mlnton (1963) observed that on cotton roots jointly infected

^^^ ^ incognita acrita end Fusarium oxysporum f.vasin fee turn,

there was abundant fungal growth in nenatode induced giant

cells as well as the xylen. The fungus also grew well on

decaying cortical end epidermal tissue but poorly in apperently

healthy tissues. Mglncognita predisposed cotton seedlings to

Altemarla tenuis, Fusarium oxysporum f.vasin fee turn, Fftii roc tenia

solani and domerella qossypel (Hifner, 1967).

Overman and Jones (1970) reported that in tomatoes both

the stunt nematode. Tyleneherhynchus capltalis and root-knot

nematode M.incognita increased the Incidence of Vtrticilllum wilt.

: 19 s

Btxgtson, ftl £iL>» (l970) reperttd that populations of

actinonyeelas was low in tht rhizosphare soil of cotton roots,

infacted with M.incognita, whare as population of Fusariuiw was

tnoro in the rhizosphaz* of galled roots. According to Powell,

al£L»» (l97l) the cotton roots shoved symptoms of necrosis

when inoculation with M.incognita in combination with some of

the non - patho^nic fungi like Ourvularia, Botrytis, Aspergillus,

PeniciIlium and Trichoderma. Necrosis was more especially

severe in treatments in which nematodes preceded the fungi by

several weeks* None of th» fungi induced the disease unless

M»incognita was present. Agrawal and Goswami (1973) have

reported greatest reduction in seedlings, root and shoot weight

and highest mortality ra te was observed in plants inoculated

with nematodes followed 3 weeks l a t t e r by the fungus. More

severe symptoms and an elevated mortality rate were observed in

plants inoculated with two pathogens simultaneously, as compared

with when the nematode followed the fungus by 3 weeks of when

plants were inoculated with ei ther pathooens alone.

Similarly simultaneous inoculation With root-knot

nematode and any of the fungi such as Rhizocotonia solani,

Pythiun sp or C3lletotriu8i atramentariun resulted in more ^t,^igi,a,g,ggig,0agiu00 II I m \iummmmmmmmmHmimmmmmm mmmmmmmmmmmmmmmmmmmmmmmm

damage to the egg plants (Azam, 1975).

: 20 :

Sumner and Johnson (1973) have observed that more p lan ts

wilted In so i l when M.Incognita was present even in the

v a r i e t i e s of water melon r e s i s t a n t to wi l t . The sever i ty of

wi l t symptom was proport ional to the i n i t i a l populations of

the root-knot larvae .

Effect of the fungus and nematode i n t e r ac t i on on nematode

reproduction and host root development was studied by Conroy

and Green J r . (1974). In the presence of Trichodorus ^ r i s t e i

the incidence of VerticiI l ium wi l t on tomato increased a t a l l

the inoculum dens i t i e s of the fungus. Such r e l a t i o n was

observed with M.incognita.

Palmer and Mac Donald (i974) have observed the In te rac t ion

of Fuseriurn spp. and nematodes on maize, Average dry weight

of seedlings inoculated with both M.incognita and Fusarium

monilifomie was l e s s than those of seedlings inoculated with

e i t h e r of the organisms alone. Further F.moniliforme alone

decreased root and shoot weight of maize seedlings more than

when fungus was combined with e i t he r Pratylenchus scr ibner i or

P.penetrans. Golden and Van Gundy (1975) while working with

okra and tomato reported th->t okra and tomato roots Infected

^^^ M.incognita in the f ie ld and in the green house were

highly suscept ible to infect ion by Rhizoctonia so lani . Root

decay by fungua occurred 4*5 weeks a f te r nematode infec t ion .

G^acla and Mitchell (197S) reported that in peanut, pod rot

was nose aevtxe when pods were exposed to s o i l containing

: 21 :

combination of Pythiuw tnyriotyluni and Fusarium tolani or M,

aronania than when pods were exposed to P.mvriotvlutn alone.

\lbbstor (1975) observed that formation of the giant

c e l l s in response to M. javanica in tomato made the plants

susceptible to wilt caused by Fusaiiua oxysporum f . lycopersic«i .

Ferraz and Lear (1976) reported Criconemoides curvatum

Paratylenchus di an thus and M.hapla showed a synergistic

interaction with Fusarium oxy^orum f. di an tht in causing carna­

tion wilt . The plants wilted ear l ier and more severe symptoms

were observed with the nematode*fungus combination than with

the fungus alone.

Ndubizm (1977) reported that although M,hapla, firatylenchua

penetrans resulted in a greater growth reduction in cherry

seedlings but presence of these nematodes with WrticilUum

dahliae caused more severe growth reduction than either nematode

or the fungus alone.

Fields of gram in and around Agra have been found

heavily infected with gram wilt caused by Fusarium oxysporum

f. c icari . At many places the damage to the crop has been

tremendous and the growth of the plants has been scanty and

In patches. The soi l type and other agronomic practices ditf

not appear to be very much different from the remaining part

of the f ield and also with the adjacent re la t ive ly good crop.

: 22 :

A clos* examination 9f such roots rovoaUd the prostnce of root*

knot gal l s in adition to the nodules and Pusariuw les ions .

This situation has arisen as a result of the presence of the

two pathogens together forming 'HJisease complex" syndrome in

gram. Hsnce, with this aim in view the following aspects wil l

be studied.

1. Effect of Fusariuffi oxysporum f. ciceri on the emergence of

seedlings of different variet ies of grem.

2. Effect of Meloidogyne incognita on the emergence of

seedlings of different var iet ies of gram.

3. Effect of inoculating the seeds with F.oxysporum f . c icer i

^^^ ' "'iDjESSSLH. simultaneously and 5, 10, 15 days

prior to one amther on emergence of tho seedlings of

different variet ies of gram.

4. Effect of inoculating gram var ie t i es resistant and

susceptible to gram wi l t , different Inoculation densit ies

of root-knot nematode M.incognita, and the fungus

F.oxysporum f . c i c e r i , simultaneously and 5, 10 and 15

days prior to each other on tha development of wi l t

s ymp tons •

5. ttstopathology of roots infected with F.oxysporuw f . c i cer i

and M.incognita alcme, and when infected with two

pathogofis together.

: 23 :

6. Efftet of diff«r*nt doses of various oll-cakss,

noiRStleidot, fungicidts and htrbieidos on tho dovolopmsnt

of gram wilt with both undor tnonopathogonic and bi-patho-

gonic conditions.

7. Scroening of different varieties of gram against M,incogniti

*'* P»oxysporutii f>ciceri under ruonopathogenic and bi-patho­

genic conditions.

i 24 :

2.1 Raiting ef Stedllngs :

9i»dUng« of different varieties of gram, Ca.cer arietinuw

vdll be raised in steam sterilized soil-sand mixture (3:i) and

will be inoculated vdth the fungus F.oxysporum f. ciceri and

Wiloidogync incognita both singly and together.

2.2 Maintenance ef cultures ef the nematode and the fungus :

A single egg^^ass of M.incognita obtained from infected

roots of tomato/gram will be surface steiilized with 1:500

solution of Chlorax for 5 minutes and washed thrice in s ter i l i z ­

ed dist i l led water. Ihe egg-mass will then be transferred to

steril ized dist i l led water for larval hatching. The seeds of

gran will be inoculated with larvae hatched from egg-mass. The

culture of nematodes thus raised will futther be multiplied on

gram/tone to for subsequent studies.

culture of F.oxysporiwi f .ciceri originally isolated

fron infected seedlings of gram will be maintained on P.D«A*

The inoculum of the fungus for inoculation purposes will be

raised in 250 ml Erlen meyer flasks containing Czapek's Dox

Agar mediun (QLstilled water-1000 ml; Agar-20 g; Skicrose-30 g;

NiNO -a g; Mg90 -500 mg; Ka-500 mg; KH^I^-l g; F»SD4-T^aees).

i 29 :

Ihrt* tNt«ks old nycttlium mat Mill bt mae«r«t»d in

wiring blandtx and pUntt will b« inoculated by pouring lOO ml

of suspension containing lO gms df mycaliun around the roots

of the plants.

2.3 Inoculstion of plants wltt> fungus and nematodo t

For studying the effect of the two organisms on

emergence of seedlings, steril ized soil contained in steril ized

pots will be infested with the fungus by mixing lO gms of

mycelium with 100 gms of soi l or 1000 larvao of M.incognita

per 250 gms of so i l . Sterilized soil will also be infested

with the two organisms together in the following manner :

1. Nematode and fungus simultaneously.

2. Nematode 5, 10,15 days prior to infestation with fungus.

3. Fungus 5, lO, 15 days prior to infestation with nematode.

Known number of seeds of different varieties of gram

will be surface steril ized with 1:1000 mercuric chloride

solution and will be sown in the soil infested with the fungus

and nematodes separately and together in the manner given above.

After 5, 10, i5 and 30 days of sowing the number of seedlings

emerged will be counted and post-emergence losses would be

determined.

In order to study the effect of M.incognita on the

development of wilt syaipto«t the aeedlings raised in the manner

: 26 :

givtn «bov«, will be inoculated with 100 ml of suspension

eonfcdining either 10 gm% of fungus mycelium or 1000 larvae of

root-knot nematode. In mixed inoculation a 200 ml suspension

would be pfp»X9di by nixing the two inocula. The suspension

will be poured aroi«nd the seedlings by making 4 holes at

equidistance. Uhinoculated plants would serve as the control.

2.4 Effect of oi l cakes, fungicides, nematicides and herbicides

on the development of disease syndrome.

Oil cakes of neem, castor* ground nut and mustard at

the rate of X gm of oil cake per 100 gms of soil» and certain

systemic nematicides (Tenic and Dasanit) and fungicides (Bevistin,

Calyxine,Aureofungin) at the required doses will be incorporated

in the soil both before and after infestation with the two

organisms separately and together (2.3). The seeds will be

sown in both infested and uninfested soil treated with oil cakes/

and nematicides/and fungicides. Hsrbicides (2,4-0; MCPA; 2,4,5-T)

will be sprayed on the seedlings after their emergence.

2.5 His tops tho logical studies :

Btxinq and staining of materials :

Killing and fixing of infected roots will be done after

1,2,4,6 and 8 weeks ef inoculation. The root pieces will be

fixed in F.A< 4s 1, heated i|>to 95^0. After cooling the material

will be transferred in Bouin's fluid (Picric acid saturated

•quous solution 75 ail, formalin 25 ml and glacial acetic acid

25 ml), lb tnaure the full and rapid penetration ef the fixativei

t 27 :

fdu&tdi pxetsur* in vaccuun desiccators will be used to get

rid of «ir in diseased tissues* Ihe root pieces will be

left in 70 per cent ethanol until used for sectioning.

The material will be dehydrated by v«ashing i t in

ascending ethanol series and ultimately will be stored in

absolute alcohol. The dehydrated material will be brought to

solution of methyl benzoate and will be kept there for about

10>l6 minutes or until they sink to the bottom. This would

make the material transparent. Ihe materia? vwill be stored in

a 2 per cent celloidin solution for about 3-6 days. The

material will then be transferred to benzene with three changes

of 3 minutes each. Thus the material will be ready for embedding

in paraffin.

To ensure the complete penetration of wax, the material

will be passed twice to warm paraffin. The embedding dish after

being cleaned with xylene, will be covered with glycerine and

will be half f i l led with warm melted paraffin of melting point

56®C The material would be placed in the dish and the dish

would then be f i l led with melted paraffin upto the brim. Tht

blocks will be cooled and stored for sectioning.

Sactions will be cut at about l5yu - 20/u thickness.

The paraffin ribbons containing sections will be mounted on a

slide by using albumin-glycerine, as adhesive.

Tht sl ide se px*P*'*^ ^^^ be kept in an incubator

running ati 60^C f»r an hour. I t will then be passed through

t 28 :

xyUnt • •r l e s in ordtr to ensure completo removal of paraffin.

The s l ides vdll be passed through descending series of alcohol

and wil l be brought to 50 per cent alcohol and vdll be stained

with Cor8on*s staining fluid for 5 minutes. After staining,

the s l ides would again be passed through ascending series of

ethanol. The section wi l l then be mounted in Canada Balsam.

Finally the s l ides wil l be examined under the microscope.

The detai ls of the histological changes brought about by the

presence of nematode alone, nematode-fungus together and fungus

alone, as compared to uninoculated control wi l l be studied.

Necessary diagrams would be drawn, and microphotographs would

also be taken.

2.6 Recording of observations :

After 60 days of inoculation plants wil l be uprooted

and would thoroughly be washed in runninc water. The length,

fresh and dry weight of root and shoot wil l be determined.

Roots will be examined carefully and root-knot index vdl l be

determined as follows :-

0 - No gall ing

1 - B*w ga l l s without eggmasses

2. - B»w gal ls with eggmasses

3. * Moderate galling with eggmasses

4. - Haavy galling with eggmasses

5. - Severe gall ing with eggmasses

The fiodulatien of the roots wil l also be rated by

weighing nodultt per gm of roots and wi l l be expressed in terms

• f n«d»toot f«tlt«

: 29 :

Root-knot inftctftd roots vdll be naceratod in waring

blender and number of larvae present per gtn of root will be

determined. Nenatodes vdll also be isolated from the soi l by

Gobb*s sieving and dec ntation technique. The number of plants

exhibiting typical wilt symptoms will be counted and percentage

of wilted plants will be determined. While making observation

the severity of wilt symptoms will also be taken into considera­

tion. Throughout the studies proper controls and proper repl i .

cates would be maintained. All the data will be subjected to

stat ist ical analysis.

: 30 :

B I B L I O G R A P H Y

1. Abu-Gharbl*h, W. »E.H.Vtrn»y, and W.R. Jenkins, 1962 Rslationship •£ mftidtw namatedes U vdlt of strawberries. Phytepathelegy,«52!92l(Ab8ti;!

2. Adeniji, M.O., D.I. Edwards, J.B. Sinclair and R.B.Malek.l975. Interrelationship of Heterodera glycinea and Phytophthera megaspenna var. Sojae in soyabeans.

Phytopathology ^ : 122-725.

3. Agarwal, O.K. and B.K.GoswaAd, 1973. Interrelationships between a fungus Macrophomina phaseoli and root-knot nematode, Mtloidogyne incognita in soyabean - Glycine max. Proc. Indian National Science Acad. 39:701-704

4. Atkinson, G.F., 1892. Same diseases of cotton. Ala. Polytech. Inste. Agr. Exp. Sta. Bull. 41:61-65.

5. Azam, M. Farooq, 1975. Response of egg-plant seedlings to root-knot nematode, Meloidogyne incognita alone and in combination with Riizoctonia Splani, Pythium sp, and Qalletotrichum atramentarium. Ph.D. Thesis Aligarh Muslim University, Aligarh.

6. Benedict, W.G., W.B. Mountain, 1956. Studies on the etiology of root-rot of winter wheat in South Western Ontario. Can. J. But. M^ 159-174.

7. Bergeson, G.B., 1963, Influence ef Pratvlenchus penetrans alone and in conbination with V a r t i e i l l i t i alba-jJjUBL M growth ef peppermint.Phytopathology 53;ll64-6g

8. Bergeson, G.B., S.D.. Van G^ndy, I.J.Thonason, 1970. Effect of |^l«i<i*ovft» 1*Vnitff •" the rhlzotph»re microflora and F^taidiia wi l t •£ twnate. Phytopathology ^:l245-49i

: 31 :

9. BUk«, C D . , 1961. fteot-rot of bananas cau«ed by Radopholua &inili« and i t s control in N»w South Walas. Nomatoloqlca Ji: 295-310.

10. Brodia, B.B., W.E. Cooper, 1964. Halation of parasit ic ntmatod-«s to post-emergenca damping off of cotton. Phytopatho-loty 54; 1023-27,

11. Cobb, N.A., 1918. Estimating the nema populations of s o i l . U«S. Deptt. Agric. , Bur. Plant Ind., Agx, Tech. Car. l J l -48 .

12* Cb)^n, E., and G.Minz, 1960. Nematodes and resistance to Rjsarium wilt in tomatoes. Hassadeh 4Q, : 1347-49.

13. Conroy, J.J* and R.J, Green J r . , 1974. Interictionsof root-knot nematode, Meloidogyne incognita and stubly root-nematode, Trichodorus chr is t ie i and >ABrticiIlium albo-atruro on tomato at controlled inoculum densi t ies . Phyto­pathology §4 I 1118-21.

14. ODOsemans, J, 1977. Interaction and population dynamics of Pratylenchus penetrans and Verfcicillium spp. on flox,

f^rasitica 32 * 53-58.

15. DuCharme, E.P., and R.W. Hanks, 1957. Pathogenic complex of citrus spreading decline. Florida Agr. Expt. Sta. Ann. Hipt. 1956-57J 190-91.

16. Dunn, E., 1968. The interaction of Hiterodera rostochiensis and certain so i l fungi on the growth of tomato plants.

Int, 9yap, Nona to I , , 8th Antibes Sspt, fi : l l 5 .

17. Dvdnell, L.D., W.A. Sinclair, 1967. Effect of N,P.K, and inoculin dontity of VtrticilllMii dahliae on populations of Pift»Unc>iy» ponetrano in roots of Aaieriean elm and sugar napplo. Phytopathology £ 1 : tlO.

J 32 :

18. Edmunds, J.E., and W.F. Mai, 1966. Population Increasa of l^afcyUnchus panatrana in alfalfa and celery root* infacfead vdth Trlchodamia virida. Phytopathology ^ : 1320-21.

19. Edmunds, J.E., and vV.F.Mai, 1966. Effect of TirichoderiBa vlride, Fusarium oxysporum, and fungal enzyines upon the penetration of alfalfa roots by Pratylendius penetrans. Phytopathology gg, : 1132-35.

20. Faulkner, L.R., and W.J. Bolander, 1969. Interaction of Vgrticllliuni dahliae and Pra tylenchus minyus in Verticillium wilt of peppermint : Efect of soi l temperature. Phytopathology 52. • 868.

21. Feder, W.A., and H.W.ford, l96l. Effect of Fusarium upon the growth of seedlings of several burrowing nematode tolerant citrus root-stock. Proc. Floride State Hbrt. Soc, 21 • 43-45.

22. Fftder, W.A., «nd J. Ifeldmesser, 196i. The sperjiading decline coRplax : the separate and combined eff(>cts of Fusarium spp and Ridopholus similis on the growth of

Duncan grape fruit seedlings in the greenhouse. Phyto­pathology fii : 724*26.

23. Fsldmasser, J . , W.A*Fader, and R.V.Rabois, 1962. Movement of Tylenchulut semi-pane trans into rough lemwi roots and

in soi l and i t s relation to Fusarium in tfie roots. Phytopathology S2 :9.

24. pBrraz, S., and B.Lear, 1976. Interaction of four plant-parasitic nenstodes and Fusarium oxysporms f.sp. disnithi on eaznaiion. Ej^arientiae 2Z • 272-77.

s$S:

25. Gi l l , D.L., 1958. Effect of root-knot nvnatod^s on F^sarluffi vdlt of nimos«. Plmt Dis. Ri#tr . i2: 587-90.

26. Goldtn, J.K. and ^D. Van Qjndy, 1975. A disease cotnplex of okra and tomato involving the nematode Meloidogvne lOCOgPlfcf and stdl inhabiting fungus Rlzoctonla lOlan^ Phytopathology §^i 265-73.

27. Goode, ff.J., and J.M. Me Guire, 1967. Relationship root-knot nematodes to pathogenic var iabi l i ty of Fusarium oxvsoDrum f.lvcopersoci. Phytopathology SHi 812.

28. Gould, M.D., 1974, The root lesion nematod<-Vertici 1 lium wilt disease complex of potatoes and pathogenlcuty studies of the lesion nematodes on selected ornamental and cover crops. Dissertation Abstracts International. 2£B: 783,

29. Qracia, R. and D.Y. Mitchell, 1975, Synergistic interactions of Fythium mvEiotvlum and Risarium solan! vd th Weloido-qvne arenaria in pod rot of peanut. Phytopathology ^ : 832-33.

30. Graham, T.W., 1958. Root-knot end other nematodes in relation to the development of tobacco black-shank. Phytopathology,^ : 343.

31. Haglund, w,.A., and T. li King, 1961. Effect of parasitic nematodes on the severity of common root-rot of canning peas. Neoiatologica j& s 311-14.

32. Hastings, R.J., and J.E. Bosher, 1938, A study of the pathogenecity of the meadow nematode and the associated fungus CylindrioearDon radieieol^>. Can.J. Research J^i 225-29.

33. Hefner, J . J , , 1967, Effects of combinations of fungi, bacteria and nematodes on cotton seedlings as influenced by so i l teoiperature and ssed quality. Diss. Abstr, 22$ 3369-70,

: 34 :

34. Hendrix, F .F . , W.M. Ibwtll, Md J .H .C^n , and W.A. Cimpb«ll, 1965. P«theg«ns associated with diseased peach roo t s . Phytopathology 55. : 106l.

35. Holdeman, q*L., 1954. Nematodes as poss ible menbers of disease complexes involving other p lant pathogens. Plant Disease Heptr. SUpol, 227 : 77-79.

36. Holdeman, Q.L., 1956. The e f fec t of tobacco stunt nematode on the incidence of Risarium vdl t in flue-cured tobacco. Phytopathology 4^ : 129.

37. Holdeman, Q.L., and T.W.Qraham, 1952. The associat ion of the s t ing nematode with some p e r s i s t a n t cotton wi l t spots in North Estem South Carolina, Phytopathology 42, : 283—84.

38. Horner, C*E. and H.J. Jenson, 1954. Nematodes associated with mints in Oregon. Plant Disease Ffeptr. 3§, : 39-41,

39. Hu*;chinson, M.T., J . P . Heed, H.T.Strew, A.A.Adward and P. Schroeder., 1961. Plant parasi t ic nematodes of New Jursey. New Jursey Agric Hxptal Sta. Bull.796.

40. James, G.L., 1968. The i n t e r r e l a t i onsh ips of the causal fungus of brown roo t - ro t of tomatoes and potato root ee l worw, Hgterodera ros tochiens is . Ann.Appl. B i o l . j ^ : 503-10.

41 . Jenkins, W.R., and B.W. Cbursen, 1957. The effect of root-knot nematodes, Meloidogyne incognita a c r i t a «id M.hapla

° " R<*»yim» vd11 of toma to. Plan t DLs. Reptr. £]L ^ 182-86.

42. Jo)yison, A.W., and i U H . U t t r e l l , 1969. Effect of Meleldegyne ificdqiiif acrita and M.hapla, en Fysariuw wil t of

ehrytanthtnuB* i .Mmatel , l s 122*25.

: 35 3

43. Jor9«nson, E.C., 1970. ^ta^onis t i c i n f r a c t i o n of HitTodTa sehiieh^i and FnftfAuffi QxYfpgFtfffl on sugarbeets. J. Namatol 2 *• 393-98.

44. Khan, Abxar M., S.K. Saxana and M.W. Khan, 1971. Interaction of ly^igoetonia tgtiaOi. and Tvlanchorhvnehus terttSlCit m prt-wnergence damping off of caul i -flowtr seedlings. Indian Jr. Nematol. j ,* 95-98.

45. Krikun. J . , D. Orion, 1977. Studies of the interaction of Verticilliuifl MillM. and Ftatvlgnghus thornei on potato, Phytoparasi tica 5 i 67.

46. Kushner* V.D., and H.W, Crittenden, 1967. Influence of potassium chloride on the intesrelationshio of fungi and nematode in alfalfa roots, i^ytopathology 52 : 464.

47. Labruyere, H.H. , H.Den Ouden and J.Vi). Seinhorst, 1969. Ejqjeritnents on the interaction of Hoplolaimus un^fprmls. and fijStfAMni QMMJSHiiSLJ' QXSL race 3 and i t s inqjortance in "early yellovdng" of peas. Nem a to logic a £ : 336-43.

48. Loos, CaA., 1959. Sytnpotom expression of Rjsarium wdlt disease of Gros Michal banana in the presence of Radooho-lUS. Siml^i § ^ d MtlQJ,d9gYp^ jpcoqn^ta acri t^. Proc. Helminth. 3>c, Wash. 2^ : 1^3.11.

49. Lovmsbery, B.F. , and J.W. Lownsbery, 1952. Paratvlenchus hamatus associated with celery disease in Connec­t icut . Phytopathology ^ s 13.

50. Martin, W. J . , L.D. Newsom, and J. E. Jones, 1956. Ralationship of nematodes to the development of Fusarium ««ilt in cotton. Phytopathology 4§. : 285-89.

: 36 I

51. Mc. Gbixe, J*M., H. J.Walters, and D.A.Slack, 1958. Iha r«la> tionship of root-knot nanatodes to tha davalopment of aiaarluiB wilt in a l fa l fa . Phytopathology 4 2 ''^^^'

52. Mc.Keen, CD. , and W.B.Mountain, i960. Synergisen between Pratylenchus penetrans and Vertici Ilium albo-atrurn in eggplant wi l t . Can. J. Bot., ^ : 789.

53. Melendez, P.L., and N.T.flowell, 1967. Histological aspects of Fusariian wilt-root-knot complex in flue cured tobacco. Phytopathology 51:286-92.

54. Melendez, P.L. and N.T. Powell, 1969. The influence of Meloidoqyne on root decay in tobacco caused by Pythiuiii and Trichoderma. Phytopathology ^9:1348.

55. J/dchell, R.E. and W.M.flowell, 1972. Influence of Pratylenchus brachyurus on the incidence of Rjsarium vdlt in cotton. Phytopathology ^ : 336-38.

56. Miller, P.M., 1975. Effect of tobacco cyst nematode, Haterodara tabacum on severity of \%rticillium and lUsariuHi wilt of tomato, ^ytopathology j ^ : 81-82.

57. Minton, N.A., and E.B.Minton^ 1963. Infection relationship between Meloidogyne incognita acrita and Fusarium oxysporum f.vaslnfactum in cotton. Phytopathology S^ i 624.

58. Minton, N . A « , and E.B.Minton, 1966. Effect of root-knot and string nematodes on expression of Risariua vd.lt of cotton in three s o i l s . Biytopathology S^:319-22.

59. Minton, N .A . and CR. Jackson, 1967. Effect of Meloidoqyne agenerje on the incidence of Aspergillus flavus in pta nuts. Namatologie* J2. • X^*

: 37 :

60. Mountain, W.B., 1954. Studies of nematodes in relation to brown root-rot in Ontario. Cin.J.Bot.22 '* 737-59.

6 i . Mountain, W«B., and C.D.Mc. Kef»d962. Effect of Vertici l limn dahliae on the population of F»retvlejichus penetrana. Nematologica 2 • 261-66.

62. Muller, J. 1977. (Interactions between fine Pratylenchus spp and Verticillium albo-atrum) Vitechselwirkungen zwischen fung Pratylenchus - Arten und WrticiIlium albo-atrum, Zeits. fur Pfl anzen Krankheicen und Pflanzenschutz £4 i 215-20.

63. Myuge, S.G., 1959. The reciprocal action between nematodes and lower fungi in plants. Rev. Aaol.Mvco 1.38:350.

64. Ndubizm, T.O.C., 1977. Effects of earth worms, nematodes, cultivations and host plants on Verticillium wilt of peach and Cherry. Annals of Appld. Biology. SSl, : 153-61.

65. Norton, D.C., 1958. The association of Paratylenchus hejdncisus with charcoal rot of sorghum. Phytopatho­logy ^ : 355-58.

66. Oc Bannon, J. H,, C.R. Leathers and H.w. Reynolds, 1967, Inter­action of Tylenchulus semi-penetrana and Fusarium sp. on Rough lemon. Phytopathology 52. : 414-17.

67. Overman, A.J., and J.P.Jones, 1970. Effect of stunt and root-knot nematodes on VTtici l l luM wAlt of tomato. Phytopathology §SL • 1^06.

^&%l'a9|J^r, L.T.,D.Mac Donald, and T.Kbmirtdahl, 1967. The ecolo­gical ralationship of Riaariui weniUfenit to Pgatylenchua tcribner in teodling blight of com, FKytepathology ^ : 825.

: 38 :

69. PMIWX, L . T . «nd D.aMac Donald, 1974. Interaction of FusTlum spp and certain plant-parasit ic nematodts on maize. Phytopathology §i± i 14-17.

70. Pitcher, R.S., 1965, Interrelationship of nerratodes and other pathogens of plants. Hslminth. Abstr. 2£ • 1-17.

71. Polychronopoulos, A.G., B.R. Houston, and B.F. Lounsburry, 1969. Penetration of development of Rhizoctenia solani in sugarbeet seedlings Infected with Hsterodera schac^^tii Phytopathology 52. * 482-85.

72. fbrter, D.M. and N.T. Powell, 1967. Influence of certain I' leloidoQvne species on Fusarium vdlt development in flue-cured tobacco. Phytopathology SI : 282-85.

73. Powell, N.T., 1963. The role of plant parasit ic nematodes in fungus diseases. Phytopathology St2, • 28-35.

74. Powell, N.T., 1971. Interaction betvseen nematodes and fungi in disease complexes. Annu. Rev,Phytopathol. 2.!253-74.

75. Powell, N.r. and CJ.Nusbaum, I960. The black-shank-root-knot complex in flue-cured tobacco, ^ytopathology 50; 899-06.

76. fbwell, N.T., and O.K. Batten, 1967. Cbmplexes in tobacco involving Meloidogyne incognita,Fusariurn oxysporum f.r^^eotianae and Alternaria tenius. Phytopathology a i : 1044.

77. JV)well, N.T., P.L.Melendez and C.K.Batten, 1971. Disease complexes in tobacco involving Meloidogyne incogni ta and certain s o i l borne fungi. Phytopathology jgJL : 1332> 37.

7 a Banana, K.U* S.C. Mathur and Y. S. Rao, 1974. ItoU of Hoplolalaua Indlcut ot\ the ••varity of toedling blight of jrico. Current Scienc* ^ : 687*88.

79. Ray, A.K., 1968. Tha formation of giant ce l l s in tomato infected by the potato cyst nematode, Hgterodera rostochien-» i s and the grey s t er i l e fungus. G.S.F. Nsmatologica.

80. Heynolds, H.W., and R.G. Hanson, 1957. f8iizoctonia disease of cotton root-knot nematode in Arizona, Phytopatho­logy £1 J 256-61.

81. Rosen, H.R., 1928. A consideration of the pathogenicity of the cotton-vdlt fungus FUsarium vasinfectum. f'hytopa-thology i ^ J 419-38.

82. ft>8s, J .Pt , 1965, Predisposition of soyabeans to Fusarium vdlt by Heterodera glycines and Meloidoqyne incognita. Phytopathology 25L : 361-64.

83. Sasser, J*N.. G.B.,Lucas and H.H. Fbwus, J* 1955% Ralationship of root-knot nematodes to black-shank resistance in tobacco* Phytopattology 42, : 459-61.

84. Siyed, M.Q., 1961. The effect of nutrition, pH, and nematodes on damping off disease of pea, tomato, and cucumber, Dissertation Abstr. 2iU'701-02.

•5. Schindler, A«F., R.N. Stewart, and P.Sameniuk, 1961. A synergistic FUsarium-nematode interaction in carnations, Phyto-patholoty JUL * 143-46,

86. 3Binhorst, J-w. and K.Kuniyasu, 1971. Interaction of Pratylenchus pene t.rans aad Ritariua oxysporum f .p j s i race 2 and Fbtylenchu* Aniforailt and F.oxytporua f , p l s i race 1 en peat. KkiBatalogica XI : 444-52,

: 40 :

87. SLootwtg, A.F.F., 1956. Root.zot of bulbs caus«d by Pratylen. chus «pp. and Hoplolalmus spp, Nematologica j , ; 192-01.

88. Sndth, A*L., 1940. Distribution and relation of meadow nereatod• Pr<tylenchus pratensjs, to Fusarium wdlt of cotton in Q»or^a. Phytopathology 22 * 710.

89. Stovert R«H., 1966. Fungi associated with nematode and nematode lesions on banana roots. Can.JrBot. 22, : 1703-10.

90. Sumner, D.R. and A. i '. John son, 1973. Effect of root-knot nemato­de on Fysarium wilt of watermelon. Phytopathology ^ : 857-61.

91. Taylor, A.L., 1967. Introduction to research on plant nematology. F.A.O. Bull.

92. Taylor, D.P., and T.D. Wyllic, 1959. Inteirolationship of root-knot nematode and Rhizoctonia solani on soyabean emergence. Phytopathology 42. ' 552.

93. Thomason, I . J . , 1958. The ef fect of the root-knot nematode, Meloidogyne javanica on blackeye bean wi l t . Phyto­pathology ^ : 398.

94. Thomason, I . J . , D.C. Erwin, and M.J. Garber, 1959. Tht relat ion­ship of the root-knot nematode, Meloidogyne javanic* to FUsarium wi l t of cowpea. Phytopathology ^ s 602-06,

95. van Berkum, J.A. and A.R.Sishadri, 1970. Some important nematogical problems in India. lOth Int. Synp. of the European Soc. of Nematology, Pascara ( I ta ly ) .

5 41 i

96, Webster, J.M., 1975. Nematode induced g t l l s and giant ce l l s : their e f fect on host and pathogen, .'roc. Can. Phytopath. Soc. 4 l s t 9BSS. No. 42 : 25-26.

97. Wehtifftt, E*J. and D.J. Weaver, 1972* Effect of nematodes and Ftosirium oxysporum on the growth of peach seedlings in the green house, J. Netnatol. ± ; 236.

98, Whitney, E.D., 1971. Synergistic e f fect between Hate rode ra Schachtai and Pythium ul tlmum on damping off of sugarbeet vs . additive e f fect of ^^££h«chtii_ and P. iphanidertTjatum. Phytopathology §X • 917.

99. Whitney, E.D., 1974. Synergistic e f fect of Pythi um ultimum and additive effect of P.aohanidermaturn with RschachHl on sugarbeet. Phytopathology ^ : 380-83.

100. Yang Ffenry, N,T. Fbwell and K.R. Barker, 1976. Interactions of concomitant species of nematodes and Fusarium oxysporum f. sp. vasin fee turn on cotton. J.Nematol £ : J4~ 80.