A manual of diseases of eucalyptus in South-East Asia - Center for ...

Mycosphaerella leaf diseases
Diseases
Leaf spot, leaf blotch or leaf crinkle, depending on symptomology
Causal organisms
Worldwide more than thirty distinct species of Mycosphaerella are recognised on Eucalyptus
(Park et al. 2000), causing a great variety of symptoms. The genus Mycosphaerella as found
on Eucalyptus has not been clearly defined and may actually represent several distinct
genera. This possibility is supported by the association, with different Mycosphaerella
species, of a wide range of anamorphic states. Anamorphs include Colletogloeum,
Colletogloeopsis, Coniothyrium, Phaeophleospora, Pseudocercospora, Sonderhenia,
Stagonospora, Stenella and Uwebraunia. Several of these anamorphs are discussed in the
sections on Phaeophleospora and Pseudocercospora spp.
Significant changes in name combinations and association of named anamorphs with
Mycosphaerella have often been often made. This provides considerable difficulty for the
non-taxonomist in assessing which species are present in plantations and how their
observations relate to published information. Names used in older literature might not
accurately represent the fungus in question and these should be used with some
circumspection. Descriptions of 10 Mycosphaerella spp. found on Eucalyptus, their synonyms,
anamorphs and hosts are provided in Set 124, IMI Descriptions of Fungi and Bacteria (Crous
et al. 1995), the most recent taxonomic treatment being provided by Crous (1998). Useful
characteristics for identification are lesion morphology and their position on the leaf (Figs
18, 19, 21), fruiting body morphology (Figs 20, 23), ascospore and conidial size and shape
and the mode of germination of ascospores (Figs 22, 23). Molecular methods are increasingly
being used, to support more traditional approaches, in the identification of species of
Mycosphaerella (Carnegie et al. 2001, Crous et al. 2001)
Collections of several Mycosphaerella species, associated with Eucalyptus, have been made
in East Timor (Old unpublished), Indonesia (Crous and Alfenas 1995, Crous and Wingfield
1997), Thailand (Pongpanich unpublished) and Vietnam (Yuan unpublished). No systematic
attempt has been made, however, to determine which are the most common and damaging
Mycosphaerella species in South-East Asia. For this reason the main biological, morphological
and pathological characteristics of the fungi will be summarised at the generic level, drawing
largely on information derived from temperate species.
Host range
It is likely that all Eucalyptus spp. can be infected by one or more species of Mycosphaerella.
For example, Crous et al. (1995) listed more than 50 hosts for M. cryptica (Cooke) Hansf.
across all Eucalyptus subgenera. Juvenile, intermediate and adult foliage are susceptible to
infection by this pathogen. In their check-list of fungi recorded on Eucalyptus, Sankaran et
al. (1995) provided host lists for many Mycosphaerella spp. and their anamorphs. Host
19