Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

Horticultural brassics: development of economic thresholds for aphids and caterpillars - HH2501SFV

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.
O1 Determine the influence of pests on the quality of marketable crops

O2 Relate infestation levels at harvest to whole plant infestation levels during crop growth

O3 Develop practical monitoring approaches for pest infestations during crop growth

O4 Develop sequential sampling protocols to assess whether the level of infestation exceeds that determined to be acceptable

O5 Determine the consistency of the efficacy and persistence of control measures

O6 Determine the effects of pest immigration and population development rate on pest infestations

O7 Develop a framework for producing monitoring and control systems for individual crops
Project Documents
• Final Report : Horticultural brassics: development of economic thresholds for aphids and caterpillars   (1473k)
Time-Scale and Cost
From: 2001

To: 2004

Cost: £245,996
Contractor / Funded Organisations
ADAS UK Ltd., Horticulture Research International
Pest Control              
Plant Pests and Diseases              
Fields of Study