Onion white rot, caused by Sclerotium cepivorum, is prevalent in spring onion production regions of southestern Australia, causing crop losses ranging from 5 to 50% if crops are not protected with fungicides.
Alternative treatments to fungicides are needed to ensure the efficacy of the limited number of fungicides available to control this disease is not lost through overuse and for integrated management of white rot.
In onion trials in New Zealand, good early season control of white rot has been reported using the biological control agent Trichoderma atroviride isolate C52.
Consequently, this biocontrol agent could be a suitable treatment for white rot control on short-season onion crops such as spring onions and shallots.
This poster describes the evaluation of the capacity of T. atroviride C52, applied alone or in combination with fungicide applications, to protect the roots of spring onion plants against white rot infection.
| Kirsten McLean
- The fungicide boscalid provided effective long-season disease control and yields increases at the two high disease sites.
- Trichoderma C52 levels in sandy soils were probably less than optimal for more effective early-season biocontrol.
- Dispute that, in a low disease site Trichoderma C52 (2 applications) was capable of providing a level of protection equal to that of procymidone.
- In a high disease site, the biocontrol applied at sowing gave a reduction in disease of 50%, indicating that Trichoderma C52 was also able to protect the roots of plants against early season infection when its levels were highest in the root zone.
- At the two high disease sites, fungicide sprays added to biocontrol plots prevented further spread of disease. Trichoderma C52 showed potential for the control of white rot on bunching onions, therefore it warrants further development.
There were many people and organisations that provided assistance to make this research possible. They include:
- DPI personal Craig Murdoch and Slobovan Vujovic for assistance with technology transfer activities.
- Peta Easton for technical assistance and Dr. Liz Minchinton for collection of survey data in NSW and SA.
- John Hunt of Agrimm Technologies Ltd for his valuable advice on biocontrol trial preparation and Rob Stanic for arranging supply of Trichopel Ali52 and other products for field trials.
- Doug Wilson and Paul Geister (NuFarm) for advice with fungicides and Elliott Chemical and Serve- Ag Research for supplying DADS for field trials.
- Peter DalSanto (AgAware Consulting) for advice with fungicides and processing minor use permits for fungicide treatments.
- Soheir Salib, Department of Primary Industries, Knoxfield for assistance in establishing and harvesting field trials and reviewing this manuscript.
- The spring onion growers in Victoria who graciously allowed trials on their farms and provided assistance in their establishment, maintenance and harvest.
- Agrochemical companies for providing samples of fungicides and other companies for supplying biological products for laboratory, glasshouse and field work.
The authors thank the members of the Steering Committe, Rocky Lamattina, Tony Lamattina, Craig Arnott, Karl Riedel and others for their valuable advice to this project.
This project was commissioned by Horticulture Australia Limited with funds frrom the Vegetable R&D levy..
The Australian Government provides matched funding for all HAL's R&D activities.