September 17, 2003
From:
Australian
Broadcasting Corp., ABC News 26 Sep 2003 [edited] <http://www.abc.net.au/news/newsitems/s954293.htm>
New strains
of wheat disease found in South Australia
It is feared an early
outbreak of a highly infectious wheat disease could dramatically
reduce South Australia's wheat yields. Stripe rust disease has
been detected in crops at Loxton and parts of the Yorke
Peninsula.
Richard Saunders of the South
Australian Research and Development Institute says the
earlier-than-usual outbreak is a concern because crops have not
yet reached a stage of resistance. He suggests it may be a new
strain of the fungus that is causing the disease.
Saunders said that there are
2 new strains of stripe rust in Australia, one in western
Australia and another in eastern Australia. The western strain
was very prolific in 2002 and is expected to eventually occur in
South Australia.
[Wheat stripe rust is caused
by the fungus _Puccinia striiformis_ f.sp. _tritici_ (Ps). The
fungus, also known as yellow rust or glume rust, is a problem
for grain farmers in cooler climates and at higher elevations in
Australia. The first outbreak of Ps in Western Australia in 2002
caused crop losses ranging from 30-50 percent with greater
losses (65 percent) in some areas.
Disease control measures (chemical control) applied at early
stages of growth reduced crop damage considerably. A major
concern is that the western pathotype/strain could spread to
eastern Australia where the disease has been present since 1979.
Partial and major resistance genes are present in the eastern
wheat cultivars, which should provide some degree of disease
protection. A popular cultivar, H45, which is susceptible to Ps
and blotch caused by _Septoria tritici_, is likely to be
withdrawn in favor of more resistant cultivars such as Bowerbird
and Drysdale. - Mod.DH]
