Chocolate spot of faba beans in South Australia

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The University of Adelaide

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RA(Y

Faculty of Agricultural ^and Natural Resource Sciences

CHOCOLATE SPOT OF FABA BEANS IN ^{SOUTH AUSTRALIA}

Jeremy Ian Dennis

B.Ag.Sc., UniversitY of ^Adelaide

Thesis submitted for the degree of Master of Agricultural ^Science

Departrnents of Plant Science (formerly Agronony) ^and Crop Protection (formerly Plant ^Pathology)

!'Iaite Agricultural ^Research Institute Glen Osmond, South Australia

May, ^L99L

TABLE OF CONTENTS

CONTENTS Summary

Signed statement Acknowledgements

CITAPTER 1 INTRODUCTION 1. 1 T,TTERAIIUFE REVrElf

L.1.1 Host

Description Distribution Production

Uses

1.L.2 Disease slrnPtoms

Effect on Yie1d

1. l-. 3 Causa1 Organism

Description Host Range

Survival Dispersal

1. 1.4 Host-pathogen Interaction Infection Conditions

Physiology of Infection Variation in the ^Host Variation in the ^Pathogen

l-. 1. 5 Disease Control Cultural ^Methods

Fungicides

Disease Resistance

PAGE

i

Ll-L

iv

1 L L 3

4 6 7 7 8 9 9 t-1 11

l_3

L4 L4 L7 L9 2L 23 23 24 25

L.2 PROJECT OBiIECTIVES

L.2.L Background

L.2.2 Objectives

CHAPTER 2 EXPERIMENTAI,

2.1 ORIGIN AND UAINTENANCE OF FUNGAIJ CUI.,TURES

2.L. L Collection of Isolates 2.L.2 Reference Isolate

2.2 SUMMER SURVIVAI. AIID SOURCE OF INOCULUU

2.2.1 Alternate ^Hosts

2.2.2 Survival on Stubble ^{and Crop Residue} 2.3 CONDITIONS FOR INFECTTON

2.4 ^ACCESSION BY ISOLATE INTERÀCTIONS

2.4.1 Detached Leaf Screening Technique

2.4.2 Comparison Vüith lrÏhole Pl-ant Inoculation 2.4.3 Screening the ^VüARI y. laba Collection 2.4.4 Screening ^AgainsE Botrytís Isolates 2.4.5 Disease Development in the Field

CHAPTER 3 DISCUSSION AI{D CONCI,USIONS

3.1 ^DTSCUSSTON

3.1.1 ^Summer Survival and Source of ^Inoculum 3.1.2 Conditions for Infection

3.1.3 Accession by Isolate rnteractions 3.2 CONCT,USTONS

Appendices References

27 27 28

30 30 31 33 33 37 42 50 50 51 54 56 62

65 65 66 68 70 73 81

l_

8Uu!{ARY

Mycelia1 infections on crop residues of faba ^{beans are} the most important mechanism for sunmer survival of Bottytís

spp which cause chocolate spot in southern Australia, and are

the main source of prirnary inoculum. ^Up to 41 active colonies/

2oog of residue, and survival for ^more than 12 months in the field were recorded.

Host range studies ^showed that Vicia natbonensis Acc. ^SA

22648 and V. sativa cvs. Languedoc and Blanchfleur hlere as

susceptible to B. fabae as V. faba cv. Fiord. other grain

Iegume species tested , including V. viTTosa ssp. dasycatpa cv.

Namoi and V. benghaJ.ensis cv.Popany, ^srere resistant.

A model describing the relationship ^between

infection å (I), temperature (T) and wet period ^(W) for 8.

fabae infection of V. taba cv.Fiord leaves in a controlled

environment was determined as f = ^34.85T + 89.91-(LnVü)

0.85T2 -2.69 ^(Lnw) .T -4o4.96 (Rt = ^{0.93 )} . This showed

significant correlation hrith field observations ^and predicted that the best conditions for infection ^would occur in ^wet spring weather.

A detached leaf inoculation technique was developed which was as effective as whole plant inoculations in screening for disease resistance. ^The technique bras used to identify

partialty resistant V. faba accessions held in the ^Waite

Agricultural ^Research Institute collection ^and to screen these

against B. fabae and B. cinerea isolates collected from field

surveys.

These tests and exposure of plants to natural infection in the field provided no evidence for races within B. ^tabae

1L

and

B.

cínerea. They

identified

accessions derived from the

ICARDA

lines

^{BPL 710 and BPL 26L as}

^the

^{best sources of}

resistance

to

chocolate spot

in Australia. B.

fabae was

identified

as the nain disease causing ^organism while ^B.

cinerea can cause t'he same syrnptoms

but is

usually ^ress

aggressive.

It

was concluded

that

^optimum disease control

will

require an integrated ^approach using disease resistance

supplemented by fungicides as appropriate.

LLt

STATEUENT OF ORIGINAI,ITY AND CONSENT TO PHOTOCOPY OR I,OAI¡

This thesis contains ^no material which has been accepted

for the ^award of any other degree or diploma in any

university. ^To the best of ^my knowledge and belief, this

thesis contains ^no material previously published or written ^by another person, except where due reference is ^made in the

text.

I give ^consent for this thesis being ^made available for photocopying and loan.

Jeremy I Dennis

lv

ACKNOWLEDGE}ÍENTS

I especially thank ^my supervisors, Dr Eileen ^Scott

(Department of Plant Pathology), Dr ^Ron Knight (Departnent of

Agronorny) and Dr AIan Dubé (South Australian Department of Agriculture) for their ^{support and} advice throughout this proj ect.

I also thank staff of the waite Agricultural ^Research Institute and S A Department of Agriculture for their

assistance, particularÌy:

Alison Soden ^(SADA) for help in all ^aspects of the project, and invaluable assistance with ^glasshouse

experiments.

Kevin James (WARI), John Paterson ^{(SADA) and llayne} Hawthorne (SADA) for help in field experiments.

Terry Fechner (WARI) for help in supply and maintenance

of equipment and materials.

Hugh vtallwork ^(SADA) for extensive ^use of the word processor.

Financial support ^!,¡as provided by the Grain ^Legurnes Research Council and the South Australian Barley ^Research

Committee. Laboratory facilities ^{were made} available ^through the ^South Australian Department of Agriculture FieÌd ^Crop Pathology Unit.