Coniothyrium zuluense, a new canker disease of eucalyptus: addition to the EPPO Alert List
A new canker disease of eucalyptus was first observed in South Africa in 1989, and the causal agent was later characterized as Coniothyrium zuluense. The disease was first noticed in an isolated location in Kwazulu Natal (Zululand), and is now common in sub-tropical regions of South Africa. It is considered as one of the most serious problems affecting commercial forestry in Kwazulu Natal. C. zuluense causes measle-like necrotic spots on stems and branches. These develop into large girdling cankers that reduce wood quality and may lead to the death of trees. In 1996, a similar disease was observed on Eucalyptus camaldulensis in Thailand. Molecular studies showed that although the fungi from South Africa and Thailand presented some differences, they belonged to the same species C. zuluense. More recently, during a survey carried out in Tabasco state, Mexico, canker symptoms were observed on E. grandis trees. The causal agent was identified as C. zuluense. Comparison studies showed that the Mexican isolates are closer to those from South Africa than to isolates from Thailand. As C. zuluense is apparently emerging and reported to be very damaging, the EPPO Secretariat decided to add it to the EPPO Alert List, bearing in mind that other canker diseases such as Cryphonectria cubensis could also be considered later.
Coniothyrium zuluense (canker of Eucalyptus)
Why: Coniothyrium zuluense came to our attention as a ‘new’ and severe disease reported in several countries in very different parts of the world.
Where: C. zuluense was first described in South Africa (most severe in Kwazulu Natal, less severe in Mpumalanga (formerly Eastern Transvaal)), and later found in Thailand and Mexico.
On which plants: Eucalyptus species (at least E. camaldulensis, E. grandis, E. urophylla, E. tereticornis, E. nitens, more data needed on host range).
Damage: Infection initially causes measle-like necrotic spots on stems and branches. These develop into large girdling cankers that reduce wood quality and may lead to tree death. Copious amounts of red/brown kino (gum) exude from the lesions.
Dissemination: Data is lacking on the biology and epidemiology of the fungus. It has been observed that small, single-celled spores infect stems directly through the epidermis of the young tissues.
Pathway: Plants for planting, cut branches, wood of eucalyptus from countries where C. zuluense occurs.
Possible risks: Eucalyptus are grown in the EPPO region for forestry and ornamental purposes. So far, C. zuluense occurs mainly in sub-tropical areas, but more data is needed on its biology. In South Africa, C. zuluense is considered as a severe disease of eucalyptus forests and a limiting factor to tree propagation, but data is lacking on its impact in Thailand or Mexico. The present geographical distribution is very scattered and could perhaps reflect different introductions which would mean that the pathogen has possibilities to move over long distances (but this has not been demonstrated). In the literature, C. zuluense is considered as a serious threat to eucalyptus production.
Sources
Ciesla, W.M.; Diekmann, M.; Putter, C.A.J. (eds) (1996) FAO/IPGRI Technical Guidelines for the Safe Movement of Germplasm no. 17. Eucalyptus, 66 pp. FAO, Rome.
Roux, J.; Wingfield, M.J.; Cibrián, D. (2002) First report of Coniothyrium canker on Eucalyptus in Mexico. Plant Pathology, 51(3), p 382. (also on New Disease Reports http://www.bspp.org.uk/ndr/jan2002/2001-38.htm)
Wingfield, M.J.; Crous, P.W.; Coutinho, T.A. (1997) A serious canker disease of Eucalyptus in South Africa caused by a new species of Coniothyrium. Mycopathologia, 136(3), 139-145.
INTERNET
Web site of the University of Pretoria (ZA)
Van Zyl, L.M.; Wingfield, M.J.; Coutinho, T.A.; Wingfield, B.D.; Pongpanich, K. (1999) Molecular relatedness of geographically diverse isolates of Coniothyrum zuluense from South Africa and Thailand. http://www.up.ac.za/acadmic/fabi/tpcp/newsletters/may99/1999-4.htm
Van Zyl, L.M.; Coutinho, T.A.; Wingfield, M.J. (1999) Morphological, cultural and pathogenic characteristics of Coniothyrium zuluense isolates from different plantation regions in South Africa. http:// www.up.ac.za/acadmic/fabi/tpcp/newsletters/nov99/page15.html