Abstract:
The genus Quambalaria includes several
important pathogens of species of Eucalyptus and
Corymbia, mainly causing leaf and shoot blight. Recently,
extensive shoot and leaf dieback and stem cankers
suspected to be Quambalaria diseases have been found
on young Eucalyptus urophylla E. grandis trees in
Guangdong and Hainan Provinces. The occurrence of
Quambalaria species and their association with eucalypt
hosts within China needs to be investigated for tree
diseases management. The isolates from the diseased
samples were identified based on their morphological
structures and phylogenetic analyses with DNA sequence
data for the internal transcribed spacer region and large
ribosome subunit RNA of the nuclear rDNA. This
work revealed that three species of Quambalaria were
present: Quambalaria pitereka from Corymbia citriodora,
Q. eucalypti from E. urophylla E. grandis, both isolated
from young eucalypt leaves and shoots in Guangdong
Province, and Quambalaria simpsonii, which was isolated
from stem cankers of E. urophylla E. grandis at four
different sites across Guangdong and Hainan Provinces.
These results confirmed that Quambalaria agents were
associated with the diseases occurring on eucalypt hosts in
South China. This is the first report of Q. eucalypti in Asia
and the first report of Q. simpsonii in China on Eucalyptus
trees.
