BACTERIAL DISEASES OF EUCALYPTUS

Transcription

1 BACTERIAL DISEASES OF EUCALYPTUS T.A. Coutinho, S.N. Venter, J. Roux, X.D. Zhou and M.J. Wingfield ACPP APPS, Darwin 2011

2 INTRODUCTION Estimated 18m ha of Eucalyptus planted in 80 countries Numerous fungal diseases are known and cause considerable economic losses to the industry Bacterial diseases are less common, sporadic and can result in significant losses particularly of young trees in nurseries, at establishment and during the first two years of growth Many are considered to be caused by emerging pathogens

3 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)

4 Bacterial Wilt Strains belong to the R. solanacearum species complex (traditional Race 1 Biovar 1 (Brazil), Race 1 Biovar 3 (China, RSA, Congo, Uganda, Australia) Hosts include E. grandis, C. citriodora, E. saligna, E. trabutii, E. urophylla, E. pellita, GChybrid Tropical regions Transplanting problem Young trees are particularly susceptible

5 UGA ext plant pathology

6 There is variation in tolerance among Eucalyptus species, hybrids and clones e.g. E. deglupta Chemical control unsuccessful Avoid injury to plants during transport and transplanting

7 Crown Gall Been reported from South America, Europe, Africa and 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

8 Bacterial Die-back 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 artificial inoculation 3 7m high trees Blackened 5-10cm of distal area of twigs led to death of terminal buds Epicormic shoots produced

9 Bacterial Blight and Dieback Causal agents Endophytes Pantoea 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 nurseries and newly established plantations

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11 Pantoea ananatis First reported to cause blight and die-back of Eucalyptus in SA in 2002 Subsequently isolated from diseased material collected in Uganda, Rwanda, South America and Thailand 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

12 Pantoea ananatis

13 Pantoea ananatis JOURNAL OF BACTERIOLOGY, June 2010, p Vol. 192, No /10/$12.00 doi: /jb Copyright 2010, American Society for Microbiology. All Rights Reserved. GENOME ANNOUNCEMENTS Genome Sequence of Pantoea ananatis LMG20103, the Causative Agent 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,1,4,5 Fourie 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

14 Pseudomonas cichorii First reported to cause blight and die-back of Eucalyptus grandis seedlings in Brazil in 1995, Argentina, Paraguay and Uruguay in 2001 Problematic in nurseries and in young plantations Has been isolated together with Xanthomonas axonopodis in Brazil

15 Xanthomonas spp. Xanthomonas vasicola and Xanthomonas axonopodis isolated and found to be pathogenic to 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

16 Blister bark disease Disease first observed in Argentina and Uruguay 10 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

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18 Conclusions Increase in emerging bacterial diseases of Eucalyptus in the last decade There has been either an increase in host and/or geographical 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 carefully monitored.

19 Acknowledgements University of Pretoria National Research Foundation Tree Protection Co-operative Programme THRIP initiative