Current: Stewardship to support the use of Cruiser SB seed

Timescale: Annual stewardship where the VY thresholds were met (2021 was a methodology validation year, the threshold was met in 2022, 2023 & 2024).
Project Lead: BBRO. Project partners: Cambridge Environmental Assessments (CEA is part of RSK ADAS Ltd) for site management/sampling/reporting and Smithers ERS Ltd for all analysis.
Project Sponsor: BBRO, annual cost c. £175,000

Project Summary

The EU ban on neonicotinoids in 2018 fundamentally impacted the industry, with the subsequent use of Thiamethoxam treated seed only available under a Defra derogation when the ‘Rothamsted’ VY model predicted incidence above a set threshold. This stewardship monitoring programme provides robust data on thiamethoxam (TMX), and the metabolite clothianidin, residues in soil, non-crop vegetation and pollen to support the continued use of neonicotinoid seed treatments, as and when approved by Defra, until more sustainable solutions are available.

Main Objectives

Main Objectives

In 2020, when the seed treatment was not available, virus levels averaged 38%, at a cost to the industry estimated to be £67M by Defra.

Six different sites are to be selected that meet the following broad requirements:

  • Representative of soil type (3 sandy soils, 2 clay soils, and 1 silty soil)
  • Differing geographical locations (as much as possible)
  • Different climatic conditions (e.g., low/high rainfall areas), if possible
  • A full pesticide use history (5 years) of the selected sites should be available

At each site the following sampling regime for soil and field margin vegetation will be followed:


  • 3 sampling occasions: pre-drilling (baseline), within growth season (GS39), and post-harvest (within 1 month or before another crop drilled)
  • On each occasion: 15 in-field cores and 15 field-edge cores at 2 depths (0-20 and 20-40 cm)
  • At each depth, samples will be bulked to give n=3 samples (5 individual cores per bulk sample)
  • A selective bulking strategy will be used for the in-field cores
  • Randomised bulking will be used for the field-edge cores
  • Samples per occasion: 3 x 0-20 cm in-field bulk samples, 3 x 0-20 cm field-edge bulk samples, 3 x 20-40 cm in-field bulk samples, 3 x 20-40 cm field-edge bulk samples = total 12 samples
  • Samples per site = 36 (3 sampling occasions)
  • Total samples = 216 (6 sites)

Field margin vegetation

  • 2 sampling occasions: majority of plants in flower, and in advance of harvesting (Autumn)
  • On each occasion: 3 whole plant samples
  • Samples per occasion: total 3 samples
  • Samples per site = 6 (2 sampling occasions)
  • Total samples = 36 (6 sites)
  • Additionally, plant species at each site will be photographed in advance of first sampling occasion


  • 2 sampling occasions: within sugar beet growth season and just prior to harvest
  • On each occasion: Up to 1 kg of flower heads will be obtained from the field margin area
  • Samples per occasion: 1
  • Samples per site = 2 (2 sampling occasions)
  • Total samples = 12 (6 sites)

All samples are sent to the analytical lab (Smithers) for residue analysis of TMX and clothianidin under the appropriate OECD or EPA GLPs.



Latest Report

Previous Reports

Outcomes / Key Message For Growers And Industry

Please see reports issued.

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We are set up jointly by British Sugar plc and the National Farmers' Union.

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