Baby-leaf Cruciferae: Improved control of Scaptomyza flava

Summary

The Problem:

During summer 2009, leaf miners caused serious economic damage to watercress and Cruciferae grown as baby-leaf salads in central, eastern and southern England. In severe cases up to 40% of leaves have been damaged. As a result, growers incurred economic losses resulting from increased pesticide applications, crop rejection and additional packhouse labour inputs. In HDC project FV 376, S. flava was identified as the pest responsible for the damage.

In FV 376, crop covers were shown to be the only effective measure for the control of S. flava and, as in FV 376 the subsequent project, FV 408, did not identify any effective pesticides in a field trial. However, in FV 408, two experimental products and spinosad (Tracer) gave effective kill of adult S. flava in leaf dip laboratory tests. This project aims to build on previous work and identify insecticides which can provide reliable control of S. flava on baby-leaf Cruciferae. The project will also provide information on the behaviour of S. flava.

Benefits to growers:

The leaf miner Scaptomyza flava remains an important pest of baby leaf Cruciferae. Only very low levels of leaf miner puncturing in salad Cruciferae are tolerated by retailers which can potentially result in total crop write-off for major producers. If a crop was written off, the cost to buy replacement material would be approximately £2.40/kg (£2,400/tonne). Therefore, replacing a typical 20 tonne weekly programme during the summer would result in a grower cost of £48,000 per week.

Use of crop covers effectively prevents access by adult flies but currently there is no effective pesticide for preventing adult leaf damage when covers are removed a few days before harvest, or on farms where covers are not used. An effective additional method for reducing damage by S. flava in baby-leaf Cruciferous crops therefore has considerable financial benefits for growers at times of high pest pressure. Growers will benefit from improved knowledge on the effectiveness of selected pesticides in controlling this pest to avoid crop rejection. Additional resources (EAMU applications) may be necessary if the products identified are not currently approved for use on baby leaf Cruciferae.

Sector:

Horticulture

Project code:

FV 408a

Date:

01 February 2014 - 30 November 2014

Funders:

AHDB Horticulture

AHDB sector cost:

£26,461

Project leader:

GEMMA HOUGH, ADAS UK LTD

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About this project

Aims and objectives:

Project aim(s):

To reduce damage associated with Scaptomyza flava on baby-leaf Cruciferae.

Project objective(s):

1: Determine the survival of S. flava adults on pesticide-treated rocket leaves under controlled laboratory conditions.

2: Record the survival and leaf puncturing damage of S. flava adults on whole rocket plants following spray application under semi-field conditions.

3: Determine whether pesticide-treated plants are repellent to S. flava adults under semi-field conditions.

4: Determine the efficacy of insecticide spray applications in reducing S. flava puncturing damage on a commercial baby-leaf cruciferous crop.
5: Communicate the results to the industry.