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Ongoing project

Optimising chemical and cultural control of onion white rot (VN20007)

Key research provider: Arvensis

What’s it all about?

This investment is developing a more effective integrated disease management strategy for control of onion white rot. Onion white rot is a highly destructive fungal disease of commercial onion crops. This project seeks to improve current control methods for the disease, as well as identify new methods that can be used to combat onion white rot.

The research will incorporate:

  • Development of a pre-plant soil DNA test to identify disease risk prior to planting
  • Identification and development of natural germination stimulants to reduce disease inoculum levels prior to planting
  • Optimisation of spray timing and dose rates of current fungicides
  • Identification of new fungicides and biological controls for onion white rot.

The project team will work closely with the onion industry to extend any new findings to onion growers. Regular updates will be provided to industry, as well as trial sites visits later on in the project to demonstrate the integrated onion white rot management program developed.

The method for the soil DNA test has been developed and validated and the focus now is on field testing to determine sampling procedures and pathogen thresholds.  The test has been added to SARDI list of PREDICTA Research tests.

Two pot trials are being conducted in 2022/23 to evaluate a range of products, for activity on OWR as germination stimulants. 

Two new fungicides have recently been registered in onions for management of OWR, Luna Experience (Fluopyram, group 7 + Tebuconazole, group 3) and Intuity (mandestrobin, group 11) which will offer growers 2 new fungicide groups (group 7 and 11) for management of OWR.  Trials conducted as part of this project have demonstrated both Intuity and Luna Experience provide effective control of OWR.  Trials in the current season are focusing on evaluating Intuity and Luna Experience in various programs with other registered fungicides.  These trials will be harvested and assessments completed in February 2023 and results will be communicated soon after. 

Extension activities conducted since the last update include a project update provided to Onions Australia at their annual meeting in October 2022.  Further extension activities will be conducted once results from the current season trials are available.

This project is being conducted to develop an integrated disease management strategy for onion white rot (OWR, sclerotium cepivorum) in onions. It focuses on the development of a pre-plant soil DNA test (in collaboration with SARDI) to achieve the following:

  • Identify disease risk prior to planting.
  • Evaluate sclerotia germination stimulants to reduce disease inoculum levels prior to planting.
  • Improve understanding and efficacy of current fungicides (tebuconazole and triadimenol) in relation to disease epidemiology and fungicide behaviour in soil.
  • Identify new fungicides and biologicals for disease control during the crop.

The soil DNA test methodology, based on extracting PCR quality DNA from soil samples for testing by PCR for specific detection of sclerotium cepivorum, has been developed by SARDI. The project is now focused on validating the test to determine sampling procedures and disease thresholds.

A detailed study protocol for two fungicide efficacy and crop safety trials has been prepared by Arvensis Research, with input from Hort Innovation and the product manufacturers to evaluate new products for disease efficacy and crop safety.

The two trials from the first season have been completed and a report has been submitted to Hort Innovation. The trials have identified a range of new fungicides with new modes of action for control of OWR. 

The data is being used to develop the protocols for the second season of fungicide trials.  Two of the new fungicides included in the trials are currently being assessed by the Australian Pesticides and Veterinary Medicines Authority for potential registration for control of OWR in Australia. 

Another field trial was also completed to look at the factors effecting the efficacy of triadimenol, which is currently used for post-crop emergence for control of OWR. This trial has been completed and a final report has been provided to Hort Innovation.

Sclerotia have been produced in the laboratory and a methodology has been developed to evaluate sclerotia germination stimulants, which will commence this year.

Related levy funds

This project is a strategic levy investment in the Hort Innovation Onion Fund.