Current: Cercospora SporeNet & isolate monitoring

Timescale: 2023 One year pilot extended to 2025.
Project Lead: Dr Alistair Wright
Project Sponsor: BBRO

Project Summary

Cercospora Leaf Spot (CLS), caused by the fungus Cercospora beticola, can cause significant yield losses (up to 50%) in sugar beet crops around the globe. In the UK it has been a sporadic problem, due to the nature of the disease, which requires favourable environmental conditions (warm and wet for a prolonged period) to thrive and cause significant levels of defoliation. In seasons where CLS is damaging, as was seen in 2020, it can rapidly strip leaves from plants and impact the entire national crop. Damaged sugar beet respond by utilising their sugar reserves from the root to promote new canopy growth, and thus, yield of these beet is reduced.

Main Objectives

As it is a relatively new threat in the UK, our understanding on the range of types and severity of damage it can cause is limited. BBRO must develop a new programme of research in order to manage CLS into the future.

Short term, understanding how current and new fungicides can offer protection to CLS is important to prevent and manage any future epidemics. Unlike other major foliar diseases (rust and powdery mildew), the UK sugar beet crop currently lacks a diverse range of fungicides for CLS control. Caligula, introduced in 2022, is understood to offer some protection, but cannot be applied until 1st September. By this time severe yield loss to CLS may already have occurred. Therefore, we need a method to investigate efficacy of alternative/new active ingredients in a reliable, repeatable and rapid fashion. This will equip BBRO with the techniques to further investigate CLS and answer important questions, such as whether populations of Cercospora found in the UK have become adapted to our climatic conditions, before we embark on more ambitious field research programmes.2024 BBRO Crop Monitoring Extension:

The trial of the BBRO’s expanded crop monitoring network in 2023 was successful and gathered important insights into how the crops grew around the country. The enhanced equipment and extended visit period to the fields provided information of beet moth, foliar disease, canopy health and growth will all feed into future BBRO projects and underpin KE and research activities. There was a great deal of interest in our monitoring activities in 2023, and it is important that we continue to develop our sites to leverage the greatest amount of data from each site.

This research is fundamental to gain an understanding of Cercospora types found in the UK before BBRO begins invests in developing a dedicated CLS research site. We must begin to understand the diversity and resistance profile of CLS and then use representative isolates to gather useful and meaningful insights into fungicide use and variety resistance in field trials.

The findings from this pilot project will also be developed to provide UK sugar beet growers with an early warning system, identifying when CLS spores are arriving in fields as well as when spots are first appear. We will then be able to use these observations with the existing BBRO Cercospora early warning system to validate whether the model it uses is accurate for UK strains, whilst also building a reference collection of isolates to monitor the evolution of Cercospora into the future. This will be especially of interest should CR+ (CLS resistant) varieties enter the market in the future. 

All methods which are proposed are already established in other parts of the world and were seen in action during Alistair’s recent visit to North Dakota. As a result, we should be confident that we can gain results in this first-year pilot, before full roll-out in 2024 (when a further application will be submitted to BBRO SHC).

Currently we do not have any idea of the diversity of Cercospora populations found in British sugar beet crops, or their sensitivity to current and future fungicides. This pilot study will build the foundations to gather this understanding before a full scale roll-out.

The project will combine air-trapping for spores of sugar beet pathogens alongside isolation of populations from infected leaves which will be collected by hand.

Up to ten monitoring sites will be established in 2023 (utilising the BBRO aphid trapping sites) which will consist of:

Spornado sampler – this will capture spores in custom-made mesh cartridges. These will be changed on a bi-weekly basis for ten weeks before witching to weekly for a further ten weeks. These cartridges will be sent to BBRO for testing via qPCR to confirm CLS presence and abundance.

Weather sensors: Leaf wetness, rain and PAR sensors (Sencrop)

Time-lapse camera – Will be set up to regularly take photos so we can work out exactly when spots appeared in the crop for the first time and record disease development.

Project Extended

In 2024, we hope to extend the number of sites we monitor which will give better coverage across the growing area and refine the measurements which are obtained. This will increase the total number of sites from 12 to 17. Each factory area will have an advanced monitoring hub, which will be equipped with the new Delta-T weather stations. Regular observations will be made on the growth, development and health of the crops during regular visits and logged on the web-form system to collect the data. This will include Aphid counts, which will be made from 20 plants at each site and used to relate any relationships between yellow water pan catches and reaching threshold (possibly important data for devising any new treatment thresholds for aphids).


Outcomes / Key Message For Growers And Industry

Under review
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BBRO is a not for profit making company.
We are set up jointly by British Sugar plc and the National Farmers' Union.

British Sugar
National Farmers' Union