Studies on a seed-borne Septoria disease of Phlox drummondii Hook : a thesis presented at Massey University in partial fulfilment of the requirements for the degree of Doctor of Philosophy

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1

STUD� ON A SEED-BORNE SEPTORIA DISEASE OF

PHLOX DRUMMONDII HOOK.

by

B:ugh Trevo.r Yenham

A THESIS

Presented at Massey University

in partial fulfilment of the requirements tor the degree of

DOCTOR 01' PHILOSOPHY

November 1966

A.CKIO YLE DG ME)J'l S

.... _---

I 811

Webted

^{to Prof ••• or i..G. Thomas, Hr J .D. Sargent} aDd Dr J .S. Yeate.

tor aotiDg .s supervisors.

I al80 _nah to tbuka

Hr .l.M. Bryant for u8istan4t. with the statistical analyses.

Mi •• D. Sco.tt .n� Mis. C ^.• Hitchell to.r preparation of the illus'b'ationa.

Hr8 _M. Wood for preparing Pigure 3 ..

Pro.feno.r E.E. But.ler,. Depsrlment o.t Plant Patholo.gy, University of Cal1fo.rnis to.r II8ll\1 helpf'ul disoussio.n. o.n the subject o.f taxo.nomy.

DJ' i.r.J. ·Clark. to.r helpful criticism of the manuscript.

CONtBNTS

... _---

!!&.t

PREPACB ^{••• •} •• ^{• •• • •• •• •} 1

I TAXONOMY OJ 'lIB P.lTHOGEM ^{• •• •• •} ..

..

^{• • • ..}

A. Introc1uction ••• • •• _{••• •} •• •

B. Consideration ot HerbaZ'iUDl Material ••• ^{• ••} n

1 . type Collections ^{••• •••} • •• 11

(a) Septoria pblogis ^{• • • •••} ••• 1 1

(b)

^Septoria divaricat& • • • • •• ••• 12

(e) Septoria drummondii ^{•• • ••• •••} 12

(d) Discussion ^{••• • • • •• •} t6

2. other

Herbarium Material

^{••• ••• • •• 20}

<a) _Material Studied ••• •• • • • • 20

Cb) a.aul

^{ta and Discussion • •• •• • 20}

c. Study' of Pield CollectiollS ^{••• •••} • •• U

1 . Materials and MethoclJJ ••• ••• • • • 24

2. Results ••• ••• ••• ••• 26

(a)

-

P. drummond.ii ^{•• • ••• • •• 26}

(1) Symptoms _••• · .•. ••• 26

(11) Pathogen Morphology ^{••• • • • 31}

(b)

^{l.. pa.nieulata •• • ••• •• • 37}

(1) Symptoms ••• ^••• ••• 37

(il) Pathogen Morphology ••• ••• 44

l. Discussion •• • • •• • ^{•• •••} 59

D. Cul tura.l Studies •• • •• • ••• • •• 61

1. Materials and Methods ^{• •• • •• • ••} 61

It

•^•

2.

Results

^{• • • • • • •••}

(i) Colo� Characters of the Wild tYPe

(ii) CuI tural Variants ^{• • • • • •} (iii) Morphology: of the Vild type ^{• • •} (a)

Mycelium

^{• • • • • •} (b) Pyenidia ••• • • •

(c) PycDidioB-pores

"

^{, •• •}

(d)

Secondary conidia

^{•• •} Ce)

Spore

germiDation • • •

(iT) G:rovth in Relation � ,Temperature 3. Discussion ^{••• • • • • • •}

�thog-enici ty Studies ^{• ••} .. ..

Ma:teri&ls

and Methods ^••• ^{• ••}

Results • •• . ... ^{• • •}

1.

hoof of Pathogenicity:

^{• ••}

2. Clr08S Inoculations ^••• • ••

(a) Suaoeptibil i ty of _{, . --}P. clruIImoDdii to

fr_!.

paniculata

. .' .

• • •

• • •

• ••

• • •

• • •

• • •

• • •

• • •

••^•

• ••

'

...

• ••

• ••

• • •

• • •

Isolate.

,(b) Su.ceptibili� ^of·�. panieulata

to Isolates

from _-P. drummondii

DiscussioD

^{• • • •}•^{• • • • • • •}

SEBD TlWlSMISSIOH S'NDIJiS ••• ••• • • •

.1. Introduction • • • ••• • •• • ••

B.

Ini tial Bridence ot !ransmissioD in

Connvciai

Seed Lines

C. Studies Relating to Seed Contamination ^{• • •} • ••

1 . Detection of Surface Borne Inoculum ^{• •• • ••}

!!:.u

63 64 64

68 68 72

15 15

78 86 86

92 92 93 93

93 93

100

t01

104

104 1 05 1 06 1 06

Page

2. 'fiabili ty of Inoculum Contaminating Seed ^{• ••} 107 ta) "iabili ty of _spores in _cirrhi .. '. .. ' . 109

(b) Viability of spores in pycnidia ••• 110 3. S •• cUing Infection trom Contaminated seea • •• 111

4. Discussion ••• . ' .

.

^{••• • •• 114}

D. Studi •• aelating to Seed Infection ••• • •• 115 1. n.tection of Infected S.ed ••• • •• 1"

2. Seedling Infection from Infected _SHd • •• 1'11

3. Pathogen Surrl'l'al in Naturally Iutectec1 Seed • •• 119

4. Method. of Seecl Infection •• • • •• 121

5. Artificial Int.etioD of S._ ^{••• •} •^•• t29

6 •. DiseNa.lon ^{• •• • •• •}•^{• •••}

130

E.

^{Extent of Disease} !ransmiaBion in Commercial Seed Lines 131

III EPIDEMIOLOGY • •• ••• ••• • •• 139

.A.. Humid! ty and Establishment of Infection ^{••• • ••} 139

B. Inoculum Potential ••• ••• • •• t41

c. Boat Penetration .' .. ••• • • • 143

D. _Spread of _Infection ••• •• • • •• 145

E. Pield Survi "f"al Between Seasons • •• • •• 147

<a> Survival as Seed-borne Inoclllum ••• .' .. 147

(b) Survival aa Pree-living. Mycelium in Soil • •• 149 (c) Survival in Plant Debris in Soil •• • • •• 150 (d) leleaae ot Spo_res trom Pycnidia Winwred in _Soil 151

IT DISCUSSION AND CONCLUSIONS ••• ^••• ••• 154

!!!&!.

SUMM.ARY • • • • • • • • • • •• 1 62

BIBLIOGRAPBt •••

....

^{• •• • •• 165}

.APPFm>I� ••• ••• •• • ••• 170

Plate Ho.

1 2 3

5

6

7

8

9

.!!!!! �!.

... ---^{PL ATES}

Type material ot Senteri&.

phl

^ogis S&Cc. & Speg.

!;ype material ot Septoria c1iTaricata. Bll . & BY.

Type material of Se_ptoria. drummondii _BIl .• , & EY�

•••

•• •

•• •

Photomierograph (phue contrast) ot pycnid:iospores fl"OIIl herbarium collections of P. drummondii^. • • •

_.

Box ot commerciallY raised !. drummondil seedlings .showing severe infect.ion·. ^{..,.� ••• .. ...}

Sever. intection in pricked-out.. 4^01111lerciaJ.ly raised l.. drummondii s:eed1ings.. ^... '. • • • • •

lnfected leaves from l. ^drummoDdii. se.edlinga, &bowing Datur. of lesions _and pretus-e production of pycnidia,.

Infected leaves collectec1 in late 8UIIIIIler bom naturallY'

infected: P'. _- drummondii _{plants.. ...} ^. ...^.

AaeXoal re_produc^ti^ve structures of Septoria sp. OD!.

clrummondii MeCllings aeve-lopec1. from infec"ted Uni tec1

Kingdom seed. ^{. ... '. ... .•.•• .... '.}

10 As^exual reproductive structures of 8eptoria Bp. on!.

12.

tJ

14 t5 16

17

drummondii seedlings developed from infected Dutch seed.

Irdectecl _{shoot ot}

.!

^...

:y

ieulata .bowing field symptoms (Mana.1nl.tu collec1i1on ^{.• ... '..' . ..' ...}

Early and late stages _in the development ot symptoma on l;. paniculata (Ha.na.watu collection).. ... .^{. ..}

Asexual reproductive structures _of Septoria sp.. on l. ..

panic:ula:t& (Manavatu coll.cUon).. . ^....

Asexual reproductive structures ofSeptoria sp. on.f..

pa,nicula.ta (received from Holland as !. .. pblogis) ...

. ...,.

.� .^.

Asexual reproductive structures of Septorio. ape on.f..

paniculata (received ^trom Quebec, Ca.nacla as

!. phlogis)

Asexual reproductive structures of Septoria ap ^.• on

E..

P,8Jli.culata (received from Br! tish Columbia..., Ca.n.a.do. as

1. divaricata).. ^{... ..,.... .... • ••}

PDA plates streaked vi th spore suspensio.ns prepared from na.turally infected l. .. drummondii andl..paniculata plants, and incuba.ted ^'_for six da.ys at 240C. ^{..... • ...}

l!&!.

13 14 17

23

28

30 32

11

42 41 45

46

47

48

65

flaw No.

18

19

20

21 22

23

24 25

26

21

. 28

29

30

31

� 32

33

Vild type lIlOD08porOUS isolate. from naturally inteetec1 l.. th"uIEoDdii a.nd 1_ peiculata plants. ^{• ..}

Surface topography o� aged l. druanondii ^{iaolate. •• •} CUl tural degn.dat.ion in monosporous wild type isolates

derived from infected

1:. drunIIlondii �eedlinga.

^{• ••}

CuI tU'1'1J;l varian^ts subcu1 tund :from IIIOD.OsP01'OUS wild type

i solat&a c1erivec1hom interied!.. drwmnondii seedlings.

CuI tural _variant^s subcul turec1 hOlD aonosporoue wild type

isola.tes

deri

^{vec1 from} infected!.. paniculata plant..

(Manavatu eollectiou). • _ • • • • ••

stages iD the to:rmationof wcnidia by a!. drwmnondii

isolate on PDA ^slide cuI turea., ... • • •

Further stages

in

^{the to:rmation of} pycnidia by a l.

.drummoDdii isolate on ^{PD.l81ide oultuna.}

Seeonc1ary ccmic1i.a ^producti^on 011 PDA ^8lide cultures ^by

P., drummondii isolates. .'.'. ^{• ••}

-

Secondary

^conidia produrlion on P».l ^slide cultures by

Z. :eani

^{cula. ta} isolate... • .^{.. • ••}

....

• • •

• ••

,Stages in the germiD8.tion ot pyenidiospores on PDA slide cui turea-I, inoculum from an infee" l; ^{• .}

c1rummondil

seedling. ••• .... ^{.' • • •••}

1fm.1;her ^stages ^{in the} germinati^on of pycmidiospores on PnA slide cui turesl inoculum from an in1ected P.

clruIIInondii

^{seedling. ••• . ••• - •••}

Vegetative mycelium of a monosporous P .. drummondii isolate on a PDA slide cul ture. ... .. ..^.. , ....

Stages in the germination ot pycnidiosporeson PDA 8lide

cul

^tures; inocul\llt from a tield ildected l.. panic:ulata

plant (ManaVo.

^tu collection). • • • .. ...

Purther stages in the

germination

of pycnidi08pores on FD.l.

slide cultures; inoculum trom a field infected P ..

panicu1ata plant (Mans.vatu collection). - ...

Effect of temperature on growth rat.. of Septoria isolates from!. drummondii and!. p,aniculaia plants. • ••

The 1ntluenee of temperature on macroscopic features ^of

mono.sporous wild type isola.tes from E.. drummondii &Dd

!. pe.niculata plants. ... ^{••• ...}

61 69

10

11

73

14 19

80

81

82 83

84

85

87

89

Plate Ho.

35

Proot ot pathogenicity: artificia.lly inoculated !,.

drummondii plant. • • • • • • • ••

Proof of patbogenicitYl paniculata plant.

artiticially inoculated!_

••• • •• • ••

94

95 36 lDfected ^{leaves from}

L.

drummondii plants artiticial� in-

oculated using a Manavatu!.. paniculata isolat^{e, and} an

isolate from a P. paniculata collection received ^from

Holland. ^{•• • • •• ••• • ••} 98

31 Infected leaves from X. drwnmondii p^lants artificially inoculated using isolates from!. paniCulAta collections

received from Quebec, and British Columbia. ^••• 99 38 Excised!.. ;eaniculata ^shoot a.rtiticially inoculated with an

isolate trom a!. drumrnondii seedling. ^••• t03 39 Lesions vi th ^pycnidia on stems ^and leaves in the 'ricin! ^ty

ot maturing ovaries ot _-P. drummondii. ^{••• •••} 105a

40 Mature ovaries ^ot

E..

drwmnondii ·with sepals bearing pyenidia

o� the ^causal organism.. ^..^{.. • • • • • •} 116 41 Colony ot the pathogen arising from

infected..f.

^drurtJOODdii

seed plated

to

^{YDA.. ••• ••• ••• 118}

42 Infected seedling showing cotyle^donary lesion and pycniclia.. 120 43 Sepals bearing pyenidia _adher^ing to the eu:rfa.ce of maturecl

45

46 41

ovaries from ^adult 1. drummo�dii plants. u. 123 Continuous ^prodUc^tion ot pycnidia on sepals

and

^pedicels

from !. drUDlllondii infloreseences. ^{••• • ••} 124

Placentas from two matured ovaries showing p7es.&nce of

pyenidia of the pathogen..- ••• • •• • • •

Colonies of the pathogen developing from the ^placenta and one of the three seeds from a. matured. ovary. ^{• • •} Stomatal penetration of a�. drummondii ^{leaf �} hyphae

f'rom ge.rmina till, pycnidiospores. ^{• • • • • •}

126 127 144

1'igur8 No.

1

2

L I ST 0 1' flGUBE S

-.---- ... - --- ... ---

Bange and mean ot the length of pycni.diospore1l trom

!. drummondii and !.. pa.nicula;ta collections grouped according ^to species of pathogen and compared with

data in the original descriptions of type ^material.

Bange and IHHUl ot the diameter 0:1 WCnidia trom

1_ drummoDdiⁱ a.nd l. pariiculata collections grouped , according to species ot pathogen &Dd eomparec1 with

data in the original descriptions ot t,ype material.

3 Diagrams of a mature ovary of 1_ drummondii allowing

location ot the seed in rela.tion to the inter­

locular septa.

57

58

128

'table No.

L IST 0 1' t ABLBS ... --- -- ---

1 Distinguishing characters in the orig1nal description

o.f tour species _ot Septoria on _Phlox app. ••• 10 2 Dimensions of pycnidia and pycmi.dicspores ^from type mate-ri&l

of !. divaricata Ell. a Ev. ^{••• • •• •• •} 15 3 Dimensions of pycnic1ia and pycnidiospores from type material

of S. - drummondii Ell. 8: Ev.. ^{••• • •• •••} 18 4 Comparison ot spore d^imensi^ons end pycnidia diameter ot

herbaria specimens on p. drumrnondii and labe

l

^{led as}

!.

drUlIJ'llOndii,

!.

divarlcata, and

!,_ phloRa. ...

²¹

5 Dimensions _of pyenidiospores and pycnidia trom 12 Manavatu

collections of �. drummondii; seed of unk:n&vn origin. 36 Cempar^ison of spore length ^from

j!. drummondii

^{plants raised}

from

impor-ted inteated Dutch and Englis^{h seed.} ... 38

7 Comparison ot pycnidial diameter

from!..

drwJInondii plants

ra.ised from imported Dutch and Uni ted Kingdom seed. 39

8

Septation of' spores from E.. drummondii plants raised from

infected Dutch ^and United Kingdom seed. ... 40 9 Pycnidiospore

length

^{and pycnidia diameter floom Sep1ioria}

infections of !. ,&umm0ndU c'Ollections; collected

data. from Tables 5.6 and 7.

.

^{... •• • ••• 41}

10 Dimensions ot pycnidiospores and pycnidia from 14 collectiODS ot P. pa.ni cul a. ta in the Ha.nawa tu. ^{.. • •} • • • 50 1 1 Septation of spores trom _tive colleot.ions of 1. pniculata,

in the Manawa.tu. ^{••• .'.. •• •} "

12 Dimensions o,f pycnidiospores ^and p,ycnidia trom two

13

14

15

collections of E.. paniculata trom Holland; specimens

racei ved as,!", phlogi,s. ^• .. ^{• • •• •• •} 52 Dimensions ot pycnidiospores and pycnidia ^trom tive

collections of E.. ^paniculata _bom Quebec, Canac1a;

specimens received as

1. phlogis.

^{• u ...}

DimenSions of pycnidiospores and pycnidia trOl!l three

specimens _of E,. paniculata from British Columbia, Ce.na.da;

specimens received 8.S !. divarica.t&. ^{••• • ••}

P,ycnidiospore length

^and pyonidia diameter trom Septoria infections of !. paniculata; .collected data from

Tables 10,12,13 and 14. ^{••• • • • •••}

53

55

Table

No.

1 6 MeBll8 and standard errors of means ot seven _group

collections trom

E,.

drummondii and!. paniculata 56 17 Length ot pyenidiospore. produced by monosporous wild type

isolates trom

E,.

drummondii field collee1iions. • • • 76 1 8 Length ot pycnidiospores produced by monosporous wild type

isolates tNm 14

E,.

paniculata field collections. _TT 19 Effect ot tBDlperature on colony diameter of IDOnosporous

wild type isolates trom !. drwIInondii and !. paniculata

collections. • •• • •• • • • • • • 88 20 Infection of

1. drwDnoDdii

^with

Septoria

isolates trom

�.

pudculat&. ••• • •• • • • ••• 97 21 Seedling infection HSul taut on use ot cODllllercial seed. 1 06 22 Viabili ty ot inoculum in tree association vi th cOlIIDftCial

.eeI. .^.. .. . ... . . . .. . 1 09 23 Seedling iDteetion from box SO¥D" a:rtiticially con-tam1na'ted

.eed. • • • • •• •• • • • • • • • 1 1 2 2<4 Percentage of infected .eed from matured ovaries vith the

u.ociated sepals and pecticels inteotecl. ••• 1 1 7 25 See41iq infenion resulting hom soving seed from ovarie.

vi th the as.ociated sepals and pedicels infectecl. 1 19 26 SurriTal of the pathogen in naturally infected seed. 1 21 27 Extent of .eed transmission in commercial seed lines. 1 36 28

29

30 31

Sualllari.ed data from 'fable 27. ^{••• •• • • • •}

Effect ot humidity following inoculation on infection and disease s..writy. •• • •• • ••• • ••

Influence of spore concentration on infection. •••

Eftect of vatering method on spread of infection amol18 seedlings in se.eel box.s. • • • •• • • ••

Seedling infection resulting from infected seed held in

1 37

1 40 1 42

1 47

soil. • •• • •• • • • ••• • •• 1 49