Western Australia
June 27, 2007
After a two year hiatus, downy
mildew has returned to Western Australia’s southern cropping
areas, infecting canola crops at Williams, Katanning and
Pingrup.
GRDC supported
Department of Agriculture
and Food Western Australia canola pathologist, Dr Ravjit
Khangura said downy mildew in canola had been scarce in the past
two years due to drought.
“However, this year’s good opening rains in southern areas
favoured infection and spread,” she said.
Downy mildew mostly occurs under cool, moist winter conditions
in the early stages of canola growth and pre-disposes canola
plants to white leaf spot disease.
Currently no fungicides are registered for downy mildew or white
leaf spot control on canola in WA and little is understood of
the disease’s impact on yield.
“Despite some early seedling mortality, with subsequent yield
loss, most of the canola paddocks under question are likely to
outgrow the disease,” Dr Khangura said.
“This is because plants become resistant to downy mildew once
they have passed the seedling stage.” |
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