Russian wheat aphid. Photo: Michael Nash, South Australian Research and Development Institute (SARDI), a division of Primary Industries and Regions SA (PIRSA).
Photo: M. Nash
GRDC continues strong offensive against aphid The Grains Research and Development Corporation (GRDC) continues to respond to the Russian wheat aphid, Diuraphis noxia, incursion by further investing in a broad range of research, development and extension activities that will help better inform future management of the pest.
First identified in Australia in May this year, Russian wheat aphid (RWA) is now relatively widespread across Victorian and South Australian cereal-growing areas and has recently been detected in southern New South Wales.
“In an immediate response to the incursion and in yet another example of grower levies being put into action, the GRDC has been working behind the scenes to instigate and invest in a range of activities that will guide the long-term management of this new pest of Australian cereal crops,” says GRDC General Manager Crop Protection, Dr Ken Young.
“As part of an integrated approach to future management of RWA, investments are being made in many areas including: determination of aphid biotype; chemical control options (seed treatment and foliar); plant resistance activities (screening, germplasm access); importance of natural enemies; biology and population dynamics; yield loss and thresholds for control and; and various communication and extension activities, including the Find, Identify, Threshold Approach, Enact (FITE) strategy.”
Dr Young says efficacy trials conducted by the South Australian Research and Development Institute (SARDI*) shortly after the pest was identified have provided initial information relating to the management of the pest using foliar-applied insecticides, where aphid numbers have warranted control.
These trials support the use of either chlorpyrifos or pirimcarb under Emergency Use Permit (APVMA 82792) and have demonstrated effective control with 300 grams of active ingredient per hectare (g ai/ha) chlorpyrifos or 125g ai/ha pirimicarb.
GRDC Southern Manager Grower Services, Craig Ruchs, says “whilst this work has been both timely and critical in guiding the short-term management where aphids have been present in high numbers during winter, the GRDC has recently initiated a broader research program to gain greater insight into the control of RWA using a range of commercially available insecticides”.
Mr Ruchs says a total of 19 GRDC-funded trials will be undertaken by Peracto across a range of environments in Victoria and SA this spring to:
- Provide a direct comparison of the relative effectiveness of commonly available insecticides including organophosphate, synthetic pyrethroid, carbamate, and sulfoximine chemistry (Group 1A, 1B, 3A and 4C modes of action);
- Evaluate insecticide dose response;
- Better understand the interaction of temperature on pirimicarb and chlorpyrifos activity, including dose response;
- Provide guidance on the impact of spray volume and spray quality on the efficacy of chlorpyrifos and pirimicarb;
- Investigate the effect of spray adjuvant on insecticide efficacy and crop safety;
- Determine the yield response to RWA control using insecticides and provide data to inform future economic thresholds for control.
Further trials may be initiated over a broader geography including NSW, should pest pressure enable such undertakings later this season.
Dr Young says that whilst insecticide control will be an important tactic for control in some cases, information from other countries where the pest is endemic indicates that natural enemies will play a critical role in the long-term management of RWA through a more integrated approach to control.
In addition to a more extensive evaluation of foliar and seed treatment applied insecticides, work has been initiated to specifically address questions relating to the importance of natural enemies for control as well as basic population dynamics and economic thresholds under Australian conditions.
Dr Young says that a GRDC-funded project currently underway in partnership with SARDI and the Victorian Department of Economic Development, Jobs, Transport and Resources (DEDJTR) will closely monitor RWA populations at 16 locations across SA and Victoria to provide data that will support development of preliminary Australian thresholds and quantify the relationships between crop stage, crop symptoms, RWA numbers, parasitoids and predator populations and yield impact under Australian conditions.
“The project will help to better understand RWA population development rates and develop flight predictive capacity under southern Australian cereal crop conditions, including key factors influencing pest development,” Dr Young says.
With respect to the longer term objective for growers to have access to cereal varieties exhibiting resistance to this pest, GRDC Manager Disease Traits, Dr Lauren Du Fall, says a range of activities are being undertaken this spring and summer. Grower-funded GRDC investments in varietal resistance to RWA will include:
- Testing a differential set of material to determine which aphid biotype is in Australia and therefore establish the resistance sources that will be effective;
- Screening of major Australian wheat and barley varieties to evaluate if any exhibit resistance to RWA. Previous screening in 2008, showed that no elite Australian material had resistance to this pest;
- Screening of a range of diverse wheat and barley material from international sources with putative resistance to RWA as well as material from Murdoch University with resistance to three aphid biotypes.
Since the declaration that the pest could not be feasibly eradicated in June this year, the GRDC continues to actively promote the need for industry to implement a considered approach to the control of RWA.
A further communication and extension project that has been recently undertaken is an extensive review of global literature relating to the biology and management of RWA. This GRDC funded project will deliver a publication targeted for use by growers and advisors entitled ‘Russian Wheat Aphid: Tactics for Future Control in Australian Cropping Systems’. This publication will provide an invaluable resource to the Australian grains industry based on an extensive review of existing global research papers and journal articles.
*SARDI is a division of Primary Industries and Regions SA (PIRSA).
Overall GRDC investments:
Dr Ken Young, GRDC General Manager Crop Protection
02 6166 4500
RWA plant resistance and screening of germplasm:
Dr Lauren Du Fall, GRDC Manager Disease Traits
02 6166 4500
Activities in the southern region:
Craig Ruchs, Manager Grower Services, GRDC Southern Region
Sharon Watt, Porter Novelli