Detection and management of bacterial diseases in Australian allium crops (VN13005)
Status: Completed project
Key research provider: The Queensland Department of Agriculture and Fisheries
What was it all about? Beginning in mid-2014, this three-year project was tasked with studying bacterial diseases of onion crops in order to improve understanding of their introduction, spread and survival – and in turn help build the industry’s capacity to manage them. There was a particular focus on bacterial blight of leek, which affects onions and shallots and is caused by the bacteria Pseudomonas syringae pv. Porri, or ‘Psp’.
In its course, the project found…
- There is a strong link between temperature and disease symptoms caused by Psp – with warm, dry conditions not conducive to Psp infection and disease development, while cool, wet conditions are favourable to the disease.
- Thrips feedings and other mechanical wounding can increase the risk of infection where bacteria is present. Here, there was a relationship seen with free water – with cool wet weather or overhead irrigation shown to disseminate bacteria over the surface of plants, increasing the likelihood of bacterial presence at wound sites from thrips feeding. The researchers noted that thrips feeding damage in the absence of free water is unlikely to exacerbate disease, but appropriate control of thrips within onion crops, and consideration of irrigation regimes to minimise leaf wetness, is something to consider.
- The amount of Psp bacteria that infects plants affects the level of disease severity, but not necessarily disease incidence. In particular, higher bacterial concentrations were found to enhance the development of the yellow leaf symptom seen in Psp infection.
- Good news for growers – there can be consistent recovery of plants from infection and disease symptoms. The researchers found that when warming temperatures and/or a decrease in humidity and free water led to outer infected leaves senescing, pathogen infection of newer leaves was less likely, allowing plants to recover.
- No commercial red, brown or white onion varieties show resistance to Psp species, and all varieties showed similar susceptibility.
- The Psp populations studied were sensitive to copper. The researchers noted that while there are currently no products registered with the Australian Pesticides and Veterinary Medicines Authority specifically for the control of bacteria in onion crops, there are more than 40 copper-containing products registered for other uses in onions – with potential to expand the registered use of some of these products for the control of bacterial diseases. Further work is needed, however, to look at appropriate application methods, regimens and formulations for field control to be successful.
- Essential oils may also hold promise in regard to control, with clove oil showing good bactericidal activity in the lab. Again, further investigation would be needed in this area, with this research still in its infancy.
Disease surveys throughout the project didn’t actually detect Psp in Australian crops, and no diagnostic samples were submitted from any growing region during the project period either. The researchers did, however, look at samples of Psp collected in the early 2000s during outbreaks in leek crops in southern Australia, and from the 2011-12 outbreak in onion and shallot crops in the Lockyer Valley in Queensland. There were key differences observed, including aggressiveness on onion – indicating multiple introductions of Psp into Australia (and that spread from the leek outbreak in the early 2000s was very unlikely). Given Psp is spread in seed, the researchers noted a continued risk of further introductions of the pathogen into onion growing districts.
Full details can be found in the project’s final report, which will soon be available to order through Hort Innovation’s final report order form. Final reports are free to Australian horticulture levy payers, registered Hort Innovation members and industry representative bodies. Not registered with Hort Innovation? Become a member now.
This project was also tasked with enhancing preparedness for potential incursions of exotic diseases, such as Xanthomonas leaf blight of onion, caused by Xanthomonas axonopodis pv. allii. To this end, the project team worked with Plant Health Australia to produce information on the disease. Download the Bacterial blight of onion fact sheet here.
An IPM extension program for the potato and onion industries (MT16009)
Status: Ongoing project
Key research provider: IPM Technologies
What’s it all about? This project for and funded by the onion and potato growing and processing industries has a focus on integrated pest management (IPM). Its core activities are to support growers in adopting IPM on farm – improving pest management with minimal pesticide use and a reduction in associated costs – and include workshops, the use of demonstration sites with commercial crops, and the production of materials such as articles, guides and case studies distributed in industry channels.
The project is also responsible for training advisors from Australia’s major onion and potato growing regions in IPM.
What’s the latest update? With the project’s first year drawing to a close, the concept of IPM in onion and potato crops has been brought to both growers and advisors in South Australia, Victoria, Tasmania and New South Wales. In areas across these states, initial workshops have been run to outline IPM principles, with feedback collected at these events feeding into the development of on-farm demonstrations.
Subsequently, on-farm demonstration trials have commenced in onion and potato crops at 25 sites in South Australia, amounting to 395 hectares of onions and 940 hectares of potatoes being produced using an IPM approach with support from this project so far. Yet more demonstration sites for the 2017/18 season are due to be established as crops emerge in the south east of South Australia and in Victoria.
Visits by IPM Technologies entomologists to demonstration trials have shown participating growers and advisors the range of beneficial insects and mites of importance and highlighted the value of cultural control options. Regular contact with project participants (both face-to-face during field visits, and via phone and email) is allowing the project team to demonstrate how decisions can be made on insecticide selection and use (or the decision to not use an insecticide).
The first growers involved in the project have now grown onion and potato crops using IPM for the first time, and for some this has meant growing their crops without any insecticides at all. The project team reports that these growers have seen the theory put into practice on their own farms, and are adopting IPM on all their potato or onion crops going forward.
The IPM Technologies team also report that participating advisors have seen the value in using IPM and there has been a significant change in the type of advice being given by these advisors, who have ceased recommending routine, broad-spectrum insecticides and are now promoting IPM. They suggest that the project is having a noticeable influence in facilitating widespread adoption of IPM in the regions where extension activities have been targeted to date, and work is continuing towards making IPM a standard method of dealing with pests of onions and potatoes.
Interested in trialling IPM? Through this project, telephone and email support is offered to growers wanting to use the approach, and can include advice on pest management decisions week-by-week. Learn more here, email the project team at firstname.lastname@example.org, or call Dr Paul Horne on 0419 891 575. Also look for upcoming workshop details in industry channels.
To note: with the threat of tomato potato psyllid, the project has received additional funding from the potato growing and processing industries specifically for activities related to the pest, which you may see pop up from time to time.
Development of an onion white rot forecast model for Tasmania (VN14001)
Status: Ongoing project
Key research provider: Tasmanian Institute of Agriculture
What’s it all about? Onion white rot is a serious fungal disease. Beginning in 2016, this project is developing a forecasting model for the disease’s infection periods in Tasmania. It will identify conditions that precede high-risk infection periods, and help in understanding optimum timings of fungicide applications for control of white rot.
What’s the latest update? The project is continuing to collect data through both field and planter-bag trials, in order to model onion growth and white rot infection. There are commercial field-trial sites in north west and northern Tasmania, where root growth is being monitored along with factors that may precede infection, such as soil moisture and temperature. The planter-bag trials are being conducted at the Tasmanian Institute of Agriculture Vegetable Research Facility, where the timing of infection and the influence of inoculum depth on infection are being studied.
When data collection is completed, there will be three versions of the forecast model created for growers, to account for three key onion planting periods: May, July and September. The data will be presented as a fact sheet detailing for each planting window the combinations of soil temperature, soil moisture and crop growth stage that signal the start of infection periods.
Australian onion industry communications (VN15002)
Status: Ongoing project
Key research provider: Cox Inall Communications
What’s it all about? This project delivers effective and timely communications to ensure Australian onion growers and other industry stakeholders are kept up-to-date with the latest R&D outcomes, marketing activities, and other industry news and information. In communicating R&D in particular, the ultimate goal is to lead to practice change for growers, boosting productivity and profitability.
The project is also supported by Communication support on VN15002 – Australian onion industry (VN15003) which provides funding to Onions Australia to facilitate work with the communication program’s external service provider, and to deliver event management for the industry (including for grower walks and conferences).
What’s the latest update? A number of regular communication channels continue to be produced and maintained by the two projects, including but not limited to:
As well as accessing the above resources, if you haven’t already, subscribe to the industry e-newsletter here.
industry minor use program (VN16000)
Status: Ongoing project
Key research provider: Hort Innovation
What’s it all about? Through this project, levy funds and Australian Government contributions are used to renew and apply for new minor use permits for the onion industry. These submissions are prepared and submitted to the Australian Pesticides and Veterinary Medicines Authority (APVMA).
What’s the latest update? All current minor use permits for the industry are searchable at portal.apvma.gov.au/permits. Permit updates are also circulated in Hort Innovation’s Growing Innovation e-newsletter, which levy-paying members receive monthly. Not a member? Sign up to our membership program for free here.
Other R&D projects of note…
- Review of the national biosecurity plan for the onion industry and development of a biosecurity manual for onion producers (VN15001), an ongoing project that is responsible for reviewing and updating the onion industry’s biosecurity plan. In identifying, prioritising and looking at the management and surveillance of key biosecurity risks, the biosecurity plan provides a framework for risk mitigation and for managing the impact of potential pest and disease incursions. While the plan itself is a high-level decision-making document, for growers the project will also produce a biosecurity manual detailing key exotic and endemic pests, weeds and diseases, and how to minimise the risk of them.
- Enhanced National Bee Pest Surveillance Program (MT16005), which is delivering a nationally coordinated bee-pest surveillance program to help safeguard honey-bee and pollinator-dependent industries in Australia. It builds upon the previous National Bee Pest Surveillance Program (MT12011), and includes upgrading sentinel hive arrays, strengthening relationships with surveillance operators, the introduction of new elements such as Asian hornet screening and more. The surveillance is designed to enable the early detection of high-priority pest incursions that can impact on honey bees, providing the best opportunity for successful pest eradication. The onion industry is one of several contributors to the project’s work.