Current: Integrated disease control in sugar beet

Timescale: 2021 - 2025
Project Lead: Angharad Hughes: PhD study (supervisors: Prof Debbie Sparkes and Prof Mark Stevens)
Project Sponsor: University of Nottingham, BBRO, BASF and Felix Cobbold Trust

Project Summary

The most important fungal foliar diseases affecting sugar beet in the UK have historically been rust (Uromyces betae) and powdery mildew (Erysiphe betae), both of which have been well controlled by a combination of azoles and strobilurin fungicides. However, in recent years, other diseases, such as cercospora leaf spot (Cercospora beticola) have become more prevalent, possibly due to the warmer summers associated with climate change. For example, in 2020, cercospora led to canopy destruction of many crops that had also been affected by drought and virus yellows leading to combined yield losses of up to 80% being reported by growers.

Main Objectives

This project will use a combination of field and controlled environment experiments to evaluate the efficacy of a range of active ingredients, both alone and in combination with other chemicals, in terms of disease control in sugar beet.

Three years of field experiments will be planned to capture a range of environmental conditions. It is proposed that field experiments will be carried out at Sutton Bonington and at a site in East Anglia, to further extend the range of environments and disease pressures. Controlled environments are useful to ensure disease incidence when not occurring naturally in the field. For example, powdery mildew thrives in hot, dry conditions and hence high disease pressure can more reliably be created in the glasshouse than in the field. Similarly, cercospora leaf spot infection in the UK is currently sporadic but ideal conditions can be created in controlled environments and plants inoculated artificially. The experiments will include varieties which contrast in their disease susceptibility to further stretch the experimental test-bed and explore whether recommendations should be tailored according to varietal resistance.

Foliar disease levels will be monitored regularly, recording infection levels of rust, powdery mildew, cercospora leaf spot, ramularia and any other diseases separately. Canopy expansion and persistence will be monitored closely throughout the season using the BBRO drone or the University’s tractor-mounted camera and Crop Circle. These instruments measure a range of spectral indices including NDVI, NDRE and mndBlue, canopy temperature and canopy cover and hence will allow us to test a) whether pre-symptomatic disease infection can be detected by spectral changes and b) whether spectral indices can be used to assess foliar symptoms, thereby replacing the very time-consuming process of visual assessments.

The final element of the project will be evaluation of the carbon balance of fungicide use in sugar beet. This will build on existing BBRO work on the carbon footprint of UK beet to quantify in what circumstances (i.e. disease pressure, varietal tolerance) the carbon used to produce and apply fungicides is offset by the extra carbon fixed by the crop.


Latest Report

Outcomes / Key Message For Growers And Industry

Year one conclusions

Last year’s trials aimed to reveal how treatment with different fungicide groups affected plant physiology and resulting yields, with weekly physiological readings followed by final harvest data. There was a focus on stress tolerance in the polytunnel trial, while the field trial focused on a larger range of fungicide treatments and a comparison between two varieties of differing disease susceptibility. The smaller trial gave some interesting indications of treatment interactions with plant physiology, but most of the highly significant data came from the larger field trial. These first year experiments (2021) are summarised in the first section of attached report, with a focus on this year’s experiments (2022) later in the report.

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