Latest Projects

Summaries of the current and most recent projects undertaken by Plant Health Solutions

Onion neck rot: seed infection, pathogens and treatments


HDC is funding Plant Health Solutions to investigate seed-borne neck rot in onions. Neck rot can cause significant losses in stored onions. It is caused by three species of Botrytis: B. aclada, B. allii, B. bysoidea. B. bysoidea is thought to be less important; B. allii and aclada were previously lumped together as one species (B. allii). The disease is seed-borne but symptoms are not apparent in the field and only develop in store. It is likely that most seed is tested by seed companies, and is treated with fungicides. Nevertheless major losses still occur in some years. The absence of field symptoms means the link between seed-borne infection and storage losses is obscure; it is further affected by weather conditions and inoculum load, therefore there remains some controversy about the importance of seed infection. This project will provide an independent assessment of the prevalence and incidence of the disease in commercially available onion seed in the UK. We will also provide some insight into the relative importance of the two main species that cause it, both in seed in store, and examine the ability of seed treatment fungicides to control the disease. Finally we will also begin studies to determine if it matters which pathogen(s) is/are present on seed.

Funded by: AHDB - Horticulture

Development of Novel Biological Seed Treatment Technologies

2010 - 2014

This project will develop novel seed treatment technologies to deliver biological control agents (BCAs) for the control of seed-borne diseases of vegetables. The project will primarily target two important diseases (onion neck rot, parsnip canker) which have a high impact on crop production in the UK and where growers are faced with recent withdrawal or absence of fungicidal seed treatments for the pathogens. The project therefore addresses an urgent requirement for alternative seed treatments which directly aligns with the overall TSB initiative to address the potential loss of pesticides as a result of changes to EC directive 91/414. The current seed processing techniques used for the target crops present several opportunities for interventions, enhancements and treatment applications. We will aim to exploit these opportunities to apply BCAs and develop novel formulations to enhance/maximise their activities. Successful BCA seed treatments will have a lower environmental impact compared with chemical fungicides while increasing productivity and farm income through reduction in waste caused by the rejection of diseased crops, and reducing the need for imports. It is envisaged that there will be economic benefits not only for the UK growers but also for other stakeholders such as seed production and BCA manufacturers, and the UK economy as a whole.

Funded by: Technology Strategy Board

Bacterial diseases of herbaceous perennials

2010 - 2013

Bacterial diseases have caused sporadic but significant (e.g. 100% crop loss) problems in a number of HNS herbaceous subjects for a number of years. There is a general lack of knowledge amongst growers about how to identify diseases caused by bacteria; and except for well known diseases with clear symptoms, the only reliable way of diagnosis is by laboratory examination and culturing, thus accurate information is difficult to obtain.

During the first year nurseries will be surveyed for bacterial diseases. The results will be used to inform and direct the work in subsequent years which will comprise trials work and detailed epidemiological investigations in years 2 and 3. The project aims to benefit herbaceous HNS growers by providing information which will assist in the identification of bacterial diseases and identify practical management strategies for their effective control. This is expected to lead to a reduction in the use of ineffective spray treatments, and reduction in losses and ultimately increased profitability.

Funded by: AHDB - Horticulture

Management of Bacterial Canker in Prunus spp.

2010 - 2013

Bacterial canker has been an on-going problem for HNS growers for many years and also causes losses to stone fruit growers. Bacterial canker may be caused by two distinct pathovars of Pseudomonas syringae: pv. morsprunorum (Psm)and pv. syringae (Pss). Psm is host specific to Prunus spp., whereas pv. syringae has a much wider host range, with the potential for cross infection between a number of different species and genera. Although the stem canker phase is the most economically important, these pathogens may also cause leaf spots/shot-holes, shoot die-back and flower blights. The overall aim of the project will be to identify management options which will be of benefit in the control of bacterial canker of Prunus spp. To achieve this the project will: aim to identify the main sources of primary inoculum on propagation nurseries; examine the potential of targeted treatments to reduce/eliminate inoculum; examine the relative merit of different practical approaches for cleaning/disinfection of pruning knives/secateurs; and critically review relevant scientific and advisory literature and draw together with the new experimental work to produce a factsheet with clear practical recommendations.

Funded by: AHDB - Horticulture

Relationship between disease incidence in stored bulb onions and first year sets

2011 - 2012

There is a perception that the risk of certain onion diseases may be increased when crops are grown from sets. The major diseases of concern to the industry are: bacterial rots thought to be caused mainly by Burkholderia gladioli pv. alliicola (Bga; particularly in heat-treated red Rijnsburger type onions), neck rot caused primarily by Botrytis aclada/allii and Fusarium basal rot caused by Fusarium oxysporum fsp. cepae. One possibility is that the necessary heat treatment of some cultivars may lead to increased risk of disease. This project represents a first step to address these issues by determining the incidence of the major bacterial and fungal onion pathogens thought to be associated with sets of different types and establish if there is a relationship between disease incidence in sets and subsequent problems in the harvested bulb onion crop. It is anticipated that, based on these initial results, a follow-on project will investigate way of reducing the impact of any disease problems associated with sets.

Funded by: AHDB - Horticulture

Disease management in organic brassica seed and transplants

2009 - 2011

The project aims to evaluate a range of organically acceptable brassica seed and transplant treatments for their efficacy and cost effectiveness in controlling a range of common soil, seed and air-borne diseases. The treatments tested will include microbial inoculants and suppressive composts that are currently available for use in the EU. The work will benefit both organic and conventional plant raisers and growers by exploring alternative options for disease management that reduce disease levels and improve the quality of brassica transplants. The project will be a collaboration between Warwick HRI, Plant Health Solutions and Garden Organic (HDRA).

Funded by: AHDB - Horticulture

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