September 25, 2013
The Grains Research and Development Corporation has developed a new fact sheet to help growers identify, manage and prepare for Barley Yellow Dwarf Virus (BYDV), a disease which can affect all cereal crops.
Research scientist Trent Potter says that growers should be proactive and develop a Barley Yellow Dwarf Virus management plan which includes crop monitoring, green bridge management, pre-sowing seed treatment and foliar pesticide sprays.
Mr Potter says BYDV is transmitted from plant to plant by aphids, which spread easily throughout regions, specifically when they take flight in autumn, coinciding with critical crop development, and again in spring.
“When aphids colonise an area, they multiply rapidly and feed on surrounding plants. As they feed they may contract the virus and then transmit it to an uninfected plant,” he said.
“The virus then damages plant growth, grain fill and yield potential. Aphids, either infected with BYDV or not, also can have a direct feeding effect on the plant causing stunting and developmental problems.
“Growers should be aware that the earlier aphids attack, the more severe is the damage caused by BYDV.”
In high risk areas, such as the long season areas of South Australia and Victoria which can receive high summer and autumn rainfall, growers should always consider:
– Using seed dressings with imidacloprid which have been shown to reduce aphids in cereal crops at the early stage of growth when plants are most susceptible.
– Applying insecticides (synthetic pyrethroids) before aphids and/or BYDV symptoms are evident. This risk-based application will help kill and repel aphids.
– Select resistant varieties where possible.
– Ensure ongoing management of the green bridge (volunteer cereals and grass weeds) through appropriate herbicides. Spraying out perennial grasses near and around cereal paddocks at least three weeks before sowing may reduce aphid numbers.
Mr Potter says research suggests that it is critical to plan the control strategy and have it in place before sowing starts.
“Do not wait until aphids are found because infection or damage will have already occurred,” he said.
“Further, symptoms of BYDV infection may take at least three weeks to appear, so often once you see the symptoms the plant is already severely damaged.”
Mr Potter says if growers’ notice sporadic patches of plants that have turned a yellow, red or purple colour, which is most defined at the tip of the leaf, extending to the base, then the plant is likely to have BYDV and aphid management is required.
“Growers in high risk areas should treat each year as a ‘BYDV year’ unless there has been low rainfall over summer and autumn. Waiting until aphids or BYDV symptoms are found is too late,” he said.