Re: Onion White rot

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Re: Onion White rot
« Reply #15 on: May 30, 2010, 19:25 »
Knew I had read it somewhere:

A new "biological" control for onion white rot, developed through HDC-funded research, will be described to growers at the ADAS/Syngenta UK Vegetable Industry Conference & Exhibition on 28 January.

Project leader Ralph Noble, a senior research scientist at Warwick HRI, said the treatment involves incorporation of composted green waste and the soil-dwelling fungus Trichoderma viride into soil before planting or sowing.

"In two field trials there was very high disease pressure throughout the growing season but we recorded no white rot with this treatment and yields were comparable with or higher than yields from sets treated with the fungicide Folicur," he said.

White rot, caused by the fungus Sclerotium cepivorum, is the major soil-borne disease affecting onion crops. HDC estimates that 15 per cent of the UK crop is affected by this disease, causing losses worth 7m each year.

The project was based on the discovery that incorporating onion waste from processing, controlled white rot in subsequent crops because sulphur compounds in the compost stimulated white rot spores in the soil to germinate, but the fungus then died in the absence of the host crop.

With onion waste in short supply, the HDC project looked at other materials and found that brassica waste, green waste and poultry manure are also effective.

T. viride suppresses many disease-causing fungi, including the white rot pathogen. The project has also been looking at ways of applying T. viride to onion sets as part of an integrated control strategy.

The conference, held at the East of England Showground, Peterborough, will also include presentations on the state of the industry, food security, carbon footprinting and crop protection in the wake of EU legislation changes.

- For more details, contact Michelle Patching at ADAS on 01954 268214.


The conference was Jan 2009, not sure what ADAS is.

If it is Sulphur compounds that stimulate the white rot spores to become active then die from lack of a host it makes me wonder if adding straight Sulphur would do the same?

I am presuming from reading the above that composted onion waste is added in the years or time that onions (alliums) were not grown. Seems implauseable to stimulate it and have onions in the ground at the same time.

Interesting about poultry manure.

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