BACTERIAL DISEASES OF EUCALYPTUS

T.A. Coutinho, S.N. Venter, J. Roux, X.D. Zhou and M.J. Wingfield

ACPP APPS, Darwin 2011

INTRODUCTION

Estimated 18m ha of Eucalyptus planted in 80countries

Numerous fungal diseases are known and causeconsiderable economic losses to the industry

Bacterial diseases are less common, sporadic andcan result in significant losses particularly of youngtrees in nurseries, at establishment and during thefirst two years of growth

Many are considered to be caused by emergingpathogens

1928 – crown gall (Brazil)

1974 – bacterial dieback (Australia)

1988 – bacterial wilt (China)

1990 – bacterial wilt (Brazil)

1994 – bacterial wilt (Australia)

1995 – bacterial blight and die-back (Brazil)

2000 – bacterial wilt (RSA and Congo)

2001 – bacterial wilt (Uganda)

2002 – bacterial blight and dieback (RSA)

2004 – bacterial blight and dieback (Rwanda, Uganda and South America)

2007 – blister bark disease (South America)

Strains belong to the R. solanacearum speciescomplex (traditional Race 1 Biovar 1 (Brazil), Race 1Biovar 3 (China, RSA, Congo, Uganda, Australia)

Hosts include E. grandis, C. citriodora, E. saligna, E.trabutii, E. urophylla, E. pellita, GC hybrid

Tropical regions

Transplanting problem

Young trees are particularly susceptible

Bacterial Wilt

UGA – ext plant pathology

There is variation in tolerance among Eucalyptusspecies, hybrids and clones e.g. E. deglupta

Chemical control unsuccessful

Avoid injury to plants during transport andtransplanting

Been reported from South America, Europe, Africaand Asia

Hosts include E. robusta, C. citriodora, C. maculata,E. terricornis, E. camaldulensis, E. occidentalis

E. saligna considered to be immune

Problematic on seedlings in nurseries

Crown Gall

Been reported only from Australia

C. citriodora and C. maculata susceptible

E. grandis, E. haemastoma, E. saligna and E.laevopinea considered to be immune after artificialinoculation

3 – 7m high trees

Blackened 5-10cm of distal area of twigs – led todeath of terminal buds

Epicormic shoots produced

Bacterial Die-back

Causal agents EndophytesPantoea ananatis Pantoea vagans?Xanthomonas vasicola Pantoea eucalypti?Xanthomonas axonopodis Pantoea deleyi?Pseudomonas cichorii Pantoea wallisii?

Pantoea rwandensis?Pantoea rodasii?

Capable of causing substantial losses in nurseriesand newly established plantations

Bacterial Blight and Die-back

First reported to cause blight and die-back ofEucalyptus in SA in 2002

Subsequently isolated from diseased materialcollected in Uganda, Rwanda, South America andThailand

Disease of young trees, seedlings and cuttings GNs (in SA) particularly susceptible Problematic in nurseries Select tolerant genotypes Has been isolated together with Xanthomonas

vasicola in South Africa

Pantoea ananatis

Pantoea ananatis

Pantoea ananatis

JOURNAL OF BACTERIOLOGY, June 2010, p. 2936–2937 Vol. 192, No. 110021-9193/10/$12.00 doi:10.1128/JB.00060-10Copyright © 2010, American Society for Microbiology. All Rights Reserved.

GENOME ANNOUNCEMENTS

Genome Sequence of Pantoea ananatis LMG20103, the CausativeAgent of Eucalyptus Blight and Dieback

Pieter De Maayer,1,2* Wai Yin Chan,1,2 Stephanus N. Venter,1,2 Ian K. Toth,1,4 Paul R. J. Birch,1,4,5Fourie Joubert,3 and Teresa A. Coutinho1,2

Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa1; Department of Microbiology andPlant Pathology, University of Pretoria, Pretoria 0002, South Africa2; Bioinformatics and Computational

Biology Unit,Department of Biochemistry, University of Pretoria, Pretoria 0002, South Africa3; Plant Pathology Programme,Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom4; and Division of Plant Science,

University of Dundee (At SCRI), Invergowrie, Dundee DD2 5DA, United Kingdom5

First reported to cause blight and die-back ofEucalyptus grandis seedlings in Brazil in 1995,Argentina, Paraguay and Uruguay in 2001

Problematic in nurseries and in young plantations

Has been isolated together with Xanthomonasaxonopodis in Brazil

Pseudomonas cichorii

Xanthomonas vasicola and Xanthomonasaxonopodis isolated and found to be pathogenicto Eucalyptus in South Africa and South America,respectively.

E. grandis clones susceptible in SA

Host shift of X. vasicola

GU and UM hybrids susceptible in South America

Xanthomonas spp.

Disease first observed in Argentina and Uruguay10 years ago

Causal agent identified as Erwinia psidii Infects E. grandis, E. dunnii, E. globulus and E.

maidenii trees E. psidii originally reported to infect guava trees in

Brazil Suggestion that it has undergone a host shift Restricted to trees in the first two years of growth Trees do appear to recover rapidly

Blister bark disease

Increase in emerging bacterial diseases ofEucalyptus in the last decade

There has been either an increase in host and/orgeographical range

Species and strains isolated lack specificity Outbreaks are sporadic Host shifts appear to be occurring Although they do not appear to be a serious threat

to Eucalyptus spp., they should be carefullymonitored.

Conclusions

University of Pretoria

National Research Foundation

Tree Protection Co-operative Programme

THRIP initiative

Acknowledgements