Disease Warning - Puccinia
The Eucalyptus rust
pathogen: Australia in 2010; South Africa next?
Foresters in South Africa
have been made conscious about Eucalyptus rust since the 1990's, and the
pathogen Puccinia psidii has been feared in Australia ever since it
first started causing disease on Eucalyptus in South America in the 1970's.
This concern for Australia became a reality early in 2010 when P. psidii
was detected in the state of New South Wales. The appearance of the pathogen in
that country has been described, amongst other things as an "ecological
holocaust". Recently, despite quarantine efforts, the disease had been reported
from north Brisbane, rapidly spreading along the east coast of Australia.
Native Australian Melaleuca species are especially susceptible and it is
already predicted that this genus maybe wiped out completely.
The appearance of P.
psidii in Australia should be of significant concern to forestry companies
in South Africa. However, it is not just Eucalyptus species that are
threatened. During collaborative studies between the TPCP programme of FABI,
Australia and Brazil, tests of native Heteropyxis natalensis in Brazil
showed that this South African endemic is one of the most susceptible species
tested with P. psidii (Image). Recent studies in Australia showed that
Australian species of Eugenia, Metrosideros and Syzygium are also
susceptible. In fact, more than 11- plant species in the family Myrtaceae has
already been shown to be susceptible to this pathogen.
The rust pathogen, P.
psidii, can be spread in wind currents, infected plant material and even on
humans (on their clothes etc.). Foresters, botanists and anyone visiting forest
areas/parks in Australia, Brazil, Hawaii or other countries where this pathogen
occurs are encouraged not to bring any plant material back with them. Upon
returning to South Africa it is strongly advised that you wash your clothes and
shoes before entering gardens, forests, farms and plantations in South Africa.
Forestry companies and conservation agencies should also, as a matter of
urgency, implement management strategies and prepare for the imminent arrival
of this pathogen in South Africa.