Western Australia
September 8, 2008
Western Australian lupin growers
can better predict their risk of bean yellow mosaic virus and
prevent yield losses using a new forecasting model developed by
the Department of
Agriculture and Food.
Department research associate Tim Maling will promote the model
to some of the world’s leading lupin researchers at the 12th
International Lupin conference in Perth next week (14-18
September).
Mr Maling said bean yellow mosaic virus (BYMV) was an
aphid-borne virus which caused significant yield losses in lupin
crops.
He said in south western Australia, yield losses of more than 60
per cent could occur in years when aphids infested young lupin
crops. But in years when aphids arrived later in the season, the
risk of disease was generally low and infection caused little
yield loss.
“BYMV is spread by aphids to lupin crops from adjacent infected
pasture,” he said.
“When aphids build up in the pasture before lupins are sown, the
risk of BYMV in the pasture is greater and there is a higher
likelihood that aphids will transfer the virus to the lupin crop
early, generating a substantial epidemic.
“Other risk factors include the proximity of infected pasture to
lupin crops; length of growing season; climatic factors
including rainfall, temperature and wind which influence aphid
numbers, and cultural factors determining plant density, time of
canopy closure and extent of groundcover.”
Mr Maling said by understanding the factors that drive BYMV
epidemics in lupin crops, the department had built a detailed
model describing pasture biomass, aphid population dynamics, and
the spread of infection within lupin crops.
He said the forecast model was validated with data collected
over two years from four varied trial sites at Badgingarra,
Avondale, Mount Barker and Merredin.
“The framework developed allows for automatic modelling of 465
localities throughout the grainbelt and has greatly improved the
speed and scope of the forecast we can deliver,” he said.
“The model uses daily temperature, rainfall and evaporation data
to calculate daily biomass or ‘greenness’ levels, which in turn
are used to predict aphid population levels throughout the year.
“The movement of aphids into the lupin crop, and the subsequent
spread of infection are then simulated.
“This ability to provide timely local disease risk forecasts
enables lupin growers to weigh up the economic and environmental
cost of applying control measures against the potential loss in
crop productivity.”
The control measures to help minimise the virus spreading
include isolation from clover pastures, rotation with non-host
crops, sowing a perimeter non-host barrier of cereal, sowing
lupin at high seeding rates, promoting rapid canopy closure,
maximising groundcover and minimising tillage.
Depending on the level of risk, growers can decide whether they
need to implement some of the control measures or deploy the
full package.
“Effective targeting of this integrated disease management
strategy based on the model’s risk forecasts will decrease the
financial loss from BYMV infection and encourage increased
planting of lupins in regions of high disease risk,” Mr Maling
said.
The results are presented as best, average and worst case risk
maps to be published annually as part of a suite of disease
forecasts on the web at
www.agric.wa.gov.au/cropdiseases.
Financial support was provided by the Australian Research
Council (ARC) and the Department of Agriculture and Food for
Western Australia (DAFWA) through an ARC Linkage Project. |
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