Australia
July 4, 2016

The Russian wheat aphid. Symptoms of damage include leaf streaks and rolling of leaves. Photo courtesy of Michael Nash, South Australian Research and Development Institute (SARDI), a division of Primary Industries and Regions SA (PIRSA).

The Grains Research and Development Corporation (GRDC) is encouraging northern grain growers to adopt a simple four-point plan in dealing with Russian wheat aphid (RWA).

As the GRDC implements a multi-faceted research, development and extension approach to better inform future control of the pest – detected in Australia for the first time in May – growers are being encouraged to continue to scout fields, report any concerns and where necessary implement a considered management strategy.

Any suspected sightings of RWA in New South Wales should be reported to the Exotic Plant Pest Hotline (1800 084 881) while any suspected sightings in Queensland should be reported to Biosecurity Queensland on 13 25 23.

GRDC grower services manager north Sharon O’Keeffe says with RWA now established in South Australia and Victoria, the focus in the southern region is on surveillance and management focussed on a four-point plan known as the “FITE” strategy.

The “FITE” strategy revolves around four basic principles:

• Find (look for characteristic leaf streaking or rolling symptoms on cereal crops and grasses)
• Identify (positively identify RWA in consultation with an industry specialist)
• Threshold approach (consider international thresholds for control, factoring crop growth stage and potential yield losses)
• Enact an appropriate management strategy that where possible encourages beneficial insects.

Ms O’Keeffe encouraged northern growers and agronomists, and particularly those in southern New South Wales, to be on alert for signs of the pest but to consult State-based authorities before undertaking any control measures to avoid unnecessary spray applications.

“Because this pest is new to Australia, there are still lots of unknowns around basic population dynamics, developmental and reproductive processes and what the triggers are for long distance movement under local conditions,” Ms O’Keeffe said.

“The GRDC, its research partners and other agencies are working tirelessly to improving our understanding about how this pest behaves, its impact and suitable approaches to management under our environment and cropping systems.

“One of the leading priorities is to generate a better understanding of the relative effectiveness of the insecticides currently registered for control of other aphid species in Australian cereals.

“While an Australian Pesticides and Veterinary Medicines Authority (APVMA) permit currently exists for the use of chlorpyrifos and pirimicarb (APVMA 82792), we need to compare these active ingredients with other chemistry including neonicotinoid and synthetic pyrethroid insecticides.”

Ms O’Keeffe said in addition, the economic thresholds for control have not yet been validated locally which is critical to provide increased confidence in grower decision making around when to spray.

“Whilst we do have indicative thresholds to guide growers based on international experience, it’s important to understand that the economic threshold for control will vary with different situations,” she said.

“Potential yield loss in our environment, crop yield potential and cost of the chosen control measure must be considered when weighing up spray decisions.”  

The GRDC has previously invested in pre-emptive pre-breeding activities associated with varietal resistance to this pest in a partnership led by Murdoch University and involving national and international collaborators.

While no resistance to RWA was identified in a screen of major Australian wheat and barley cultivars several years ago, encouragingly the project did develop some material where resistance genes were introgressed into Australian cereal backgrounds.

The GRDC continues to work with research partners and plant breeding companies in Australia to make germplasm available for commercial breeding. 

Ms O’Keeffe said that in the meantime, it was important that growers and their advisers scouted crops, report suspected sightings to the relevant authorities and speak with their local district agronomist in relation to an appropriate control strategy, if necessary. 

“It’s a similar situation to that of any other insect pest in crops; assess what the level of infestation is and determine if/what treatment is necessary,” she said.

“The FITE strategy is a simple way to assist growers in the decision-making process: Firstly, scout cereal crops and grasses and if you Find typical symptoms of damage (such as leaf streaks and rolling of leaves) then the second step is to positively Identify the aphid species present – consult your local adviser if unsure. 

“The third step is to consider economic Thresholds for control before getting the sprayer filled and ready to go. International advice supports an economic threshold of 20% of plants infested up to the start of tillering and 10% of plants infested thereafter. It is important, however, to understand that these thresholds have yet to be validated under Australian conditions. The main point here is to avoid prophylactic sprays where the pest is either not present or is present in very low numbers within a field.

“The fourth step is Enacting an appropriate management strategy; one that factors in the importance of encouraging beneficial insects which may act as natural predators, as well as the potential impact on honeybees.”

The GRDC has just released a comprehensive Paddock Practices article on RWA, available from the GRDC website http://www.grdc.com.au or https://grdc.com.au/Media-Centre/GRDC-E-Newsletters/Paddock-Practices/Monitor-RWA-numbers-closely-over-winter. 


More information:

NSW Department of Primary Industries website - http://www.dpi.nsw.gov.au/content/biosecurity/plant/russian-wheat-aphid.

Queensland Department of Agriculture and Fisheries (DAF) Beatsheet Blog - http://www.thebeatsheet.com.au. 

Plant Health Australia website - http://www.planthealthaustralia.com.au/ or http://www.planthealthaustralia.com.au/russian-wheat-aphid-management/ for more information on Russian wheat aphid management.

GRDC website - http://www.grdc.com.au 

Call the Exotic Plant Pest Hotline (1800 084 881).
 

Website: http://www.grdc.com.au

Published: July 4, 2016