|
Blackberry plant infected with the rust, Phragmidium violaceum.
|
Background
History of biological control of blackberry in Australia
A search for biological control agents of European blackberry
started in the late 1970s in Europe and led to the identification
of Phragmidium violaceum, the blackberry leaf-rust
fungus, as a promising candidate for biological control. While
strains of this fungus were being assessed for specificity,
the same rust was discovered in 1984 in Victoria and assumed
to be an illegal introduction.
The rust spread quickly following the incursion, but did
not appear to be as damaging as strains selected during the
European work. Subsequently a selected and fully-tested strain
(F15) was approved for release in Australia in 1991.
Since then, the blackberry leaf-rust fungus has provided
useful control of blackberry in some situations. For example,
in some areas of Victoria where climatic conditions for disease
development are optimal, vegetative spread of dense blackberry
thickets has been significantly reduced by repeated defoliation
by the rust over five to ten years. However, the existing
populations of the rust in Australia have not been effective
at controlling all biotypes and taxa of blackberry, even in
areas where the climatic conditions are recognised to be most
favourable for disease development.
Work in the 1990s by the Cooperative Research Centre for
Australian
Weed Management (Weed CRC) led to a much better understanding
of the genetic variation within the European blackberry complex,
and improved prospects of enhancing biological
control of this weed. At least 14 different taxa and 40
different genotypes of European blackberry have now been identified,
some of which reported not to be susceptible to the strains
of the rust fungus that currently occur in Australia.
For more information see the publications
list and general information on the Victorian
Department of Primary Industries web site.
|
