Review of bacterial pathogens of economic importance to UK crops

Summary

Summary:

Bacterial diseases affect a wide range of UK crops, especially horticultural crops and potatoes, and could potentially affect cereals and oil seed rape.
By their nature bacterial diseases tend to be sporadic but, when they do occur, often cause significant losses (up to 100%) in individual crops.
Most of the most important diseases of large scale cereal crops in the developed world are caused by fungi. It is therefore inevitable that investment has focussed on development and registration of pesticides targeting fungal crop diseases.
Most plant pathologists and crop protection specialists are primarily trained in mycology (fungi) and some of the common concepts and principles that apply to fungal diseases (such as latent periods, environmental conditions needed for infection) do not apply to those caused by bacteria. This can lead to misconceptions about the philosophy and appropriate approaches that are needed for effective management of bacterial diseases.
Growers tend to focus on control measures that they can apply themselves or implement directly, and would ideally like to have an armoury of products and other protective measures that they can apply to growing crops when disease is observed.
Copper-based products are amongst the few with bactericidal activity that have been shown to be effective in some crop/pathogen situations. However, with withdrawal, or increasing restriction of use, effective, practical and cost-effective disease control options become increasingly difficult for growers to design and implement.
On the other hand there are a number of bacterial diseases that have been effectively controlled through careful application of seed (or propagation material) testing and treatment policies, that are based on sound knowledge of the biology and epidemiology of the pathogen.

This review will aim to list currently recommended/approved control measures for a range of bacterial plant pathogens prioritised as the most economically important to horticulture, cereals & oilseeds and potato sectors. Bacterial pathogens of seed, propagation, glasshouse, field and storage components of the crop production system for each crop will be considered. Bacterial pathogens to be considered will include as well as additional pathogens currently causing concern within the different industry sectors or posing a potential future risk to UK plant health. These will include pathogens indicated in the recent AHDB Horticulture GAP analysis (CP132). We have already begun to devise a preliminary list of bacterial pathogens that affect or could potentially affect UK crops (See Appendix 1)

In addition, by identifying the most effective control measures for particular diseases, thereby maximising production efficiency, this project will also contribute to minimising environmental impacts by avoiding the use of ineffective chemical treatments.

Benefits to Industry:

The total cost to UK industry resulting from bacterial plant diseases is difficult to estimate and will vary greatly for different crops and production systems and according to climatic conditions both within and between years. This review aims to compile current industry data on economic losses due to specific bacterial diseases of key importance to each sector so that they can be ranked in order of priority. Information on efficacy and availability of different control methods will be complied in an easily accessible format to facilitate knowledge exchange across the various industry sectors. This will help to promote common practices and treatments which decrease risk and impact of bacterial diseases as well as to prioritise future research where effective controls are missing or support is needed for continued or extended approval of effective treatments across different crops, or for the validation and introduction of new control methods.

Increased shared knowledge on the occurrence and control of bacterial pathogens should ultimately result in reduced losses to disease and sustained production of high quality crops. Targeting the priority diseases in each industry sector will aim to maximise potential savings. Critical expert evaluation of the range of control methods available, coupled with practical experience of affected growers in each sector will ensure that the best control options are selected and integrated and that money is not wasted on ineffective biosecurity or treatment options.

Some examples of previous estimates of losses in different crops/sectors:

Bacterial canker in HNS: £125,000 to £200,000 pa
Bacterial canker in stone fruit: £500,000 pa
Leaf spots, blights in herbaceous perennials: £15,000 in a single batch of 10,000 plants
Xanthomonas black rot: up to £10 million in some years (could potentially affect OSR)
Spear rot of calabrese: £15 million pa.
Bacterial (most likely Burkholderia) rots in stored onions: 40% loss in individual crops
Pectobacterium in bedding plants £800,000 pa
Crown gall in HNS: 10-30% loss of nursery stock in fruit trees
Root mat in protected edibles: £75,000 pa in one large tomato nursery; 15% overall.
Blackleg in seed potatoes: 2-14% of stocks downgraded pa during classification.
Common scab in ware potato: £6m pa

Sector:

Horticulture

Project code:

CP 174

Date:

01 April 2017 - 31 July 2017

Funders:

AHDB Horticulture

AHDB sector cost:

£15,098

Project leader:

STEVE ROBERTS, PLANT HEALTH SOLUTIONS

Review of bacterial pathogens of economic importance to UK crops

Summary

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