Strategies for integrated deployment of host resistance and fungicides to sustain effective crop protection.

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An epidemiological model will be developed that integrates the action of fungicides and cultivar resistance against a plant disease, when the pathogen is concurrently evolving insensitivity to the fungicide and virulence to overcome cultivar resistance.

We have previously gathered experimental data sets to validate/test our models for fungicide resistance evolution. Such testing had not been reported previously. The proposed project will allow us to gather data to validate our cultivar resistance/virulence model. This will be the first test of such a model in the scientific literature. The collection of a sufficiently large and detailed data set is enabled by expertise at the James Hutton Institute on the molecular biology of effector genes. This enables the quantification of selection for virulence in pathogen samples from field experiments, using PCR type techniques to track inoculated virulent and avirulent strains.

A set of experiments, on the pathogen Phytophthora infestans (causal organism of potato late blight) will test the hypothesis that cultivar resistance reduces selection for fungicide resistance. A second set of experiments will test the hypothesis that fungicide treatment slows evolution of virulence against cultivar resistance. The tested model will then be used to explore the dynamics of the effect of fungicides on the evolution of virulence, and the effect of the use of cultivar resistance on the evolution of fungicide insensitivity. Epidemiological phenotypes for host resistance and fungicide action, which are effective at constraining evolution, will be identified. Finally we will explore the combined deployment of the two crop protection methods to develop disease control strategies that are durable. These strategies for the durable control of potato blight should help to inform industry, via knowledge transfer pathways described in the impact plan.

The research will develop strategies for the durable control of potato blight through integrated use of fungicides and cultivar resistance. New insights arising from the project will generate messages for industry and revised guidance. Messages are likely to include, for example: (i) the extent to which the current balance between genetic and chemical control is appropriate to maximise durability of control, (ii) the epidemiological phenotypes of host resistance (e.g. whether the resistance predominantly reduces foliar infection, sporulation or tuber infection) which are most effective at slowing selection for insensitivity, (iii) the effects of deploying cultivars each with different resistance genes, compared against pyramiding genes, and (iv) the evolutionary effect of altering fungicide dose, according to the host resistance of cultivars. These messages will be exploited through existing mechanisms of communication by the Potato Council, the industry partners, and the Fungicide Resistance Action Group (FRAG). Messages will be presented to the wider stakeholder group through roadshows and demonstrations/posters at grower events, and at a European scale through the EuroBlight network (www.euroblight.net). These approaches to ensure impact have been used successfully by the project group in previous and on-going work.

Identification of outputs: The work in Objective 4 will lead to the outputs relevant to potato growers, agronomists, the crop protection industry and plant breeders. Starting in year 2 we will organise meetings of the investigators and project partners aimed at forming practical messages. At least three such meetings will be organised during the project. During these meetings we will also initiate the various activities for the 'application and exploitation' of outputs as described below.

Application and exploitation of the outputs: Established routes to impact which have proved to be effective will be exploited in the project.

- The proposers will present their work at roadshows and grower events such as Potatoes in Practice, the East of England Potato Day, the Potato Council Winter Fora, the ADAS/Syngenta Potato Conference, the Bayer CropScience Potato Meeting and the SAC Blight Event. These events, together with wider horticultural events, will be used to present findings to all relevant sectors of industry.
- Key messages can be conveyed to growers and the industry in the Scottish Agricultural College's (SAC) Crop Protection Report.

- The Potato Council (PC) will help interpret research findings into messages and guidance which is appropriate for crop consultants and individual growers. PC will also disseminate project findings through their KT initiatives; for example by Growers Advice Sheets.

- FRAG representatives will be invited to the meetings aimed at developing advice on durable control of potato blight. The PC/FRAG publication "Potato late blight: Guidelines for managing fungicide resistance" should be updated.

- EuroBlight : The proposers contribute to the EuroBlight Network to disseminate findings from their research on potato blight. EuroBlight organises a pan-European 3-day workshop every 18 months. Results will be presented and discussed at the workshops in October 2014 and May 2016. Workshop presentations are written up for the proceedings and made freely available via the EuroBlight website.

- The industry partners will use their existing routes to disseminate information from the project to their stakeholders. The project team will offer to disseminate findings at demonstration sites of the industry partners. The project will offer new approaches to disease management that aim to extend the life of fungicide active ingredients and the durability of cultivar resistance.

The combination of these routes to application and exploitation guarantees an efficient route to direct impact of project findings into farming, crop protection and plant breeding industries.