In the UK, most brassica crops are grown within the Assured Produce Scheme. The Assured Produce crop protocols are designed to help growers identify and manage the risks involved in crop production, by following a systematic approach. Regular systematic crop walking to monitor pest levels is recommended as part of the strategy. However, although most growers walk their crops regularly, keep records, and make decisions based on their findings, there is no sound statistical basis for their various approaches. In addition, the concept of ‘nil tolerance’, propounded by the multiple retailers, does not fit easily into a sample-based system, since all plants in a field would need to be sampled to be sure that none was infested. Thus growers require a rational, statistically-sound approach to crop walking and decision-making which is in line with the quality control procedures developed and used regularly by other industries.
The first aim of the project is to develop a robust cost-effective management system for foliar pest control in brassica crops, from sowing until harvest. The project will produce a flexible approach to managing pest control, strongly based on statistical theory, and taking account of variability in the pests, the crop, the control measures available and grower requirements. The project will evaluate the robustness of action thresholds and the overall economic viability of management systems. A second major aim of the project will be to transfer the technology to growers, consultants and multiple retailers and to instill them with a basic understanding of the statistical principles that underpin the use of sampling to make decisions.
This work will have a wide application for the management of foliar pests of brassicas and will indicate ways in which sampling strategies, action thresholds and risk management systems for the pests of other horticultural crops may be developed. The greater use of threshold-based pest management systems is in line with MAFF Policy Objectives for Programme AU HH19. Such systems will reduce pesticide usage, by better targeting of insecticide treatments, without causing a reduction in crop quality.