Onions: Investigation into the control of White Rot in bulb and salad onion crops


FV 449 - Onions: Investigation into the control of White Rot in bulb and salad onion crops

Start Date: 
Completion Date: 
Project Leader: 
John Clarkson
FV 449

Industry Representative: Phil Langley

AHDB Horticulture cost: £12,296

SummaryAllium white rot, caused by Sclerotium cepivorum, can cause severe crop losses in UK bulb and salad onion crops.  S. cepivorum resting bodies (sclerotia), which can survive 20 years, have built-up in fields due to intensive repeat cropping, particularly in many of the fen and silt soils most suitable for Allium crops. 

Considerable research effort has been expended worldwide to increase understanding of Allium white rot disease and its control, particularly by soil treatments, and this will be critically reviewed including the epidemiology of S. cepivorum, the efficacy of physical, chemical or biological pre and post-planting treatments, plus the practicality and cost of different disease management options. Options developed for other soilborne plant pathogens will also be examined. Review results will be discussed with BOPA and AHDB to identify the most promising, practical and economic treatments appropriate to UK onion growers.
Control treatments will then be evaluated through glasshouse pot experiments and field trials as appropriate over two cropping years. Integrated strategies for communication to growers will be identified and developed to facilitate the sustainable production of onion crops, aiming to work towards effective and long-term management of the disease.

Aims and Objectives

To develop an integrated crop management strategy for sustainable control of Allium white rot in bulb and salad onions.
1. To critically review recent worldwide research on Allium white rot and its control;
2. To identify from the review the most feasible and promising control treatments for management of Allium white rot in the UK and their cost of application;
3. To determine the efficacy of selected disease management treatments in controlling Allium white rot in pot trials and in the field, alone and in combination;
4. To propose an integrated crop management strategy for Allium white rot based on the literature review and project results;
5. To communicate results to growers through reports, a factsheet, articles in AHDB Grower and growers meetings.
The work will cover both conventionally and organically grown bulb and salad onion crops as appropriate.