FINAL REPORT

To:

Horticultural Development Company

Bradbourne House

Stable Block

East Malling

Kent

ME19 6DZ

AYR tomato production:

Phase 2 of the development and implementation

of a robust IPM programme

June 2008

______

Commercial – In Confidence

Project Title: AYR tomato production: Phase 2 of the development and implementation of a robust IPM programme

Project number:PC 251a

Project leader: Dr R. Jacobson, RJC Ltd

Report: Final report, May 2007

Principal experimental

worker:Dr R. Jacobson

Other contributors:Ms L. Aitken, Syngenta Bioline

Ms G. Rochester, J. Baarda Ltd

Locations of Project:J. Baarda Ltd,

BelasisPark, Billingham, Teeside, TS23 4HR

Library facilites at LancasterUniversity.

HDC Project Co-ordinator:Mr D. Hargreaves, Horticultural Consultant

Date Commenced:1 July 2007

Date completion due:30 June 2008

Key words:Tomato, all year round production, supplementary lighting, integrated pest management, biological pollination

Whilst reports issued under the auspices of the HDC are prepared from the best available information, neither the authors nor the HDC can accept any responsibility for inaccuracy or liability for loss, damage or injury from the application of any concept or procedure discussed.

The contents of this publication are strictly private to HDC members. No part of this publication may be copied or reproduced in any form or by any means without prior written permission of the Horticultural Development Company.

The results and conclusions in this report are based on information gathered from the scientific and horticultural literature, study tours to the Netherlands and Finland, and crop monitoring at three commercial sites in the UK. The conditions under which the studies were carried out and the findings have been reported with detail and accuracy. However, because of the biological nature of the work it must be borne in mind that different circumstances and conditions could produce different results. Therefore, care must be taken with the interpretation of the results especially if they are used as the basis for commercial product recommendations.

Authentication

I declare that this work was done under my supervision according to the procedures described herein and that this report represents a true and accurate record of the results obtained.

Signature………………………………………………………………………….

Dr R. J. Jacobson

Director

RJC Ltd

5 Milnthorpe Garth, Bramham, West Yorks, LS23 6TH

Tel: 07752 874162

E-mail:

Date …………….

CONTENTS

Page

Grower Summary

Headlines 5
Background and expected deliverables 5
Summary of work to date 6
Financial benefits to growers 11

Action points for growers 12

Science Section

General introduction to project

Background14

Approach15

Financial implications16

Principle differences between AYR and conventional tomato
production17

Summary of work completed in phase 1

Preliminary studies18

Pollination studies20

Monitoring pests and natural enemies21

Further observations on the biological pollination strategy 23

An IPM strategy based on Macrolophus

Background25

The chosen site26

The cropping and IPM strategies27

Monitoring procedures in 2007 / 0829

Results of crop monitoring31

Summary of costs42

Conclusions44

References45

Acknowledgements47

GROWER SUMMARY

HEADLINES

  • A Macrolophus-based IPM programme was effective and financially viable in inter-planted AYRtomato crops.
  • Where AYRcrops were completely replanted in the autumn, a similar IPM programme was successful but more expensive than conventional season crops.
  • Biological pollination was successful if bees were released when natural light became available and confined to their hives before it became limiting.

BACKGROUND AND EXPECTED DELIVERABLES

British tomato growers and retailers share the common goal of pesticide-free crop production. Prior to the start of this project, supplies of home-grown glasshouse produce were only available between late January and October, leaving a gap of three winter months to be filled by produce imported from southern Europe. The latter were grown under considerable pressure from invading pests and most of the growers were still dependent on intensive pesticide applications to supply produce of the quality demanded by the UK market. The potential risk of chemical residues being detected in tomatoes on supermarket shelves during the winter period was therefore greater than during the rest of the year. As a consequence, retailers encouraged UK growers to develop methods of producing tomatoes all year round using artificial lighting when natural light is limiting.

AYR production and artificial lighting can affect the behaviour of both herbivorous and beneficial insects and mites directly via light intensity, photoperiod and spectral range, and indirectly via the plant due to changes in the glasshouse climate, agronomic practice, plant nutritional status and plant defence mechanisms. It was therefore clear that the IPM and pollination programmes currently used by British tomato growers would have to be modified for use in AYR cropping. The overall aim of this project was to develop and implement robust programmes that would provide reliable results under artificial lighting in the UK.

The project was designed with two distinct phases. The first phase was one of rapid information gathering from all available sources; i.e. literature searches, study tours and detailed crop monitoring. This enabled the initial IPM and biological pollination programmes to be modified very quickly. Throughout this phase, any abnormal behaviour by pests, beneficial insects and bumble bees was noted and the programmes were fine tuned to overcome the difficulties.

Glasshouse whiteflies proved to be the most difficult pest to manage using biological techniques. The parasitic wasps, Encarsia formosa, became established in all crops under high pressure sodium (SON/T) lamps but failed to provide satisfactory control of the pest populations. This was addressed in phase two of the project.

SUMMARY OF WORK TO DATE

Information gathering:

The Annual report for phase one provides a review of the information gathered from preliminary literature searches, contact with overseas IPM practitioners and study tours to Finland and the Netherlands. Thishighlights the following ways in which IPM and pollination could be affected by AYR production and artificial lighting:

Possible advantages:

  • Inter-planting crops provides continuous production runs which could result in long-term stable relationships between pests and beneficial species.
  • The performance of parasitoids in glasshouse crops is normally restricted by low temperatures and short days in the early season. However, this may not be the case in crops with artificially extended days if the intensity and spectrum of artificial light is adequate to enable the parasitoids to search efficiently.
  • Pest species (eg. spider mites) and beneficial species (eg.Orius majusculus) that enter a resting phase known as diapause during the winter under natural conditions should breed continuously in AYR crops.
  • Changes in the duration and intensity of light can have an impact on plant biochemistry and morphology, possibly leading to an increase in resistance to pests.

Possible disadvantages:

  • AYR production may create an additional challenge because there is no extended period when the glasshouse is empty and can be thoroughly disinfested.
  • Unsubstantiated reports from Finland suggested Encarsia were attracted to the SON/T units where they were killed by the hot bulbs.
  • Continuous illumination can negatively affect dusk / dawn active or night-active insects such as Feltiella acarisuga.
  • The lights could attract certain pests (eg moths) into the glasshouse, thus creating additional problems in the late summer and autumn.
  • Spider mites breed more successfully than their predators in the tops of plants during hot weather and this often leads to control failures in the summer. It was anticipated that this could occur at other times of the year in crops receiving artificial light from above due to vertical temperature and humidity gradients.
  • Bumble bees may become disorientated under SON/T lamps due to the lack of natural UV light.

Pollination studies:

During the study tour to Finland, it was noted that many tomato growers who used bumble bees for pollination did not expect the colonies to remain active for more than 2-3 weeks (i.e. compared to 8-12 weeks in a conventional crop grown in the summer in the UK). The colonies rapidly became depleted because the adult bees failed to return to the hives and the immature bees died of starvation. The partners in this project looked towards developing a system better suited to their own needs. The study was done in late January / early February 2006 in a tomato crop (cv Temptation) which was artificially lit (15,000lux) from midnight to 17.00hrs. Natural light was available from about 07.45 to 17.00hrs. Flower opening and pollen flow was monitored over a 24 hour period and the implications in terms of bumble bee activity were determined.

The results showed that pollen flow began 5-6 hours after the lights were switched on and continued for a further 8-9 hours, indicating that the correct biological pollination strategy was to release bumble bees when natural light became available (in this case from about 08.00hrs) and close the hives before natural light became limiting (in this case from about 15.00hrs).This approach became the basis of the biological pollination strategy in the UK study crops and wassuccessful in a range of tomato types and cultivars throughout the winters of 2006/07 and 2007/08.

Crop monitoring in Phase 1

Dedicated staff were employed to record numbers of specific pests and natural enemies at regular intervals from autumn 2006 to spring 2007. The sampling was done at fixed sample stations so that population trends could be monitored over time.

Encarsia were released at weekly intervals throughout phase one of the project at higher rates than in conventional crops. Although parasitised whitefly scales could be found in all the crops, they rarely exceeded 30% of the whole whitefly population and did not keep the pest under control. This was consistent with experiences in Finland where it was reported that Encarsiaadults were attracted to the SON/T lamp units and killed by the hot bulbs. The latter may have been the case where some of the lamps were hung vertically among plants in Finnish crops but we found no evidence of pest or beneficial species being killed on bulbs positioned above UK crops.

A large leaf miner infestation developed in one of the monitored crops in November 2006. A total of 2.5 Diglyphus isaea parasitoids were released per m2. The parasitoids established very quickly and the leafminer population crashed within a few weeks. Although this was a very worrying period in terms of potential crop damage, the final results showed beyond any doubt that Diglyphuscould be very effective under these environmental conditions.

Spider mites were found throughout the winter and there was no evidence of them entering diapause under the artificial lights. It was concluded that the biological control programme against spider mites could be continuous and would not have to restart each spring.

The spider mite population growth was generally constrained by Macrolophus caliginosus and / or occasional applications of spiromesifen (Oberon) against whiteflies. As a consequence, suppression of spider mites did not depend on Phytoseiulus persimilis and the feared breakdown in biological control in the tops of the plants was not encountered in any of the monitored crops.

There is no doubt that many species of moths are attracted to illuminated glasshouses when it is otherwise dark outside. However, for the moths to be attracted and gain entry to the glasshouse, the lights must be switched on at the same time as the ventilators are open, which doesn’t usually happen during natural darkness. Crops are commonly ventilated to reduce temperature during the “pre-night” period but the risk of moths being attracted into the glasshouse at that time is relatively small because the lights are switched off. When the lights are turned back on at around midnight, black out screens are usually drawn to prevent light pollution and so the attraction to moths is greatly reduced. It is unusual for ventilators to be open during that period of natural darkness but it does happen under some circumstances; eg on mild nights the heat from the lamps may raise the air temperature above the set point thus triggering the ventilators and black out screens to open by about 10% to allow air exchange. In fact, only one problem occurred with caterpillars and this may have originated from moths that invaded during the summer. This population of tomato looper caterpillars was successfully controlled with repeated applications of Bacillus thuringiensis. If growers wish to entirely exclude moths, then it will be necessary to screen glasshouse ventilators at a cost of £80k to £100k per hectare depending on the type of structure.

A Macrolophus-based IPM strategy:

The approach

The crop monitoring results of phase one of this project indicated that Macrolophus had the potential to form the basis of an IPM programme in AYR tomato crops. Until recently this option would have been rejected by growers because Macrolophuswere known to cause extensive damage to tomato trusses after they had killed the invertebrate prey. However, a method of culling Macrolophuspopulations with applications of natural pyrethrins had been developed in another HDC project and this greatly reduced the risk of the predators causing economic damage to the crop.

It was decided that phase two of this project would design and implement an IPM programme based on Macrolophus. The studies were done at J. Baarda Ltd (Teeside)as this site offered the opportunity to explore different scenarios in six almost identical 1.45ha glasshouses.

The target population for Macrolophusentering the autumn period was an average of 2-3 individuals per sample point (i.e. on one leaf positioned 5-6 down from the growing point). Manipulation of the population with natural pyrethrins was required in some crops during late summer to achieve thistarget.

Four blocks were inter-planted so that the new plants were grown alongside the old plants for about 6-8 weeks. In these situations, both pests and natural enemies were able to gradually transfer to the new plants. All inter-planted blocks had adequate populations of Macrolophuswhen the new plants arrived and no further releases were required.

The ability of parasitoids to contribute to IPM of whiteflies was investigated in two crops. One crop received prophylactic releases of Encarsia and the other receivedEretmocerus eremicus.

In all cases, Diglyphus parasitoids were released if crop monitoring indicated that this control measure wasrequired against leafminers.

Results and conclusions

Interplanted crops:

  • Compared to the previous season, the IPM programme based on Macrolophusfor inter-planted crops was very successful.
  • In two inter-planted crops of cv Piccolo, whiteflies were controlled throughout the winter by Macrolophuswithout any intervention with chemical pesticides.
  • Encarsia and Eretmocerus performed poorly throughout the monitored period and only made a minimal contribution to the control of whiteflies.
  • In two interplanted crops, Macrolophushad to be supplemented by a single application of the IPM compatible insecticide, pymetrozine (Chess), in mid-winter. However, this was considered acceptable.
  • Leafminers were controlled by a combination of Macrolophusand Diglyphus.
  • Although spider mites had been present in the previous season, they were not seen in any of the crops during this monitored period. It is believed that they were suppressed by the ever present Macrolophus.

Replanted crops:

  • The situation was more difficult in the two crops which were completely replanted in the autumn.
  • Whiteflies and leafminers established quickly on the new plants but there was very little carry over of natural enemies.
  • All pests were eventually brought under control with minimal use of chemical pesticides but the programme was more expensive and the plants suffered more damage than the inter-planted crops. This was almost certainly because so few Macrolophuswere carried over from the previous crop. In future, much larger releases of Macrolophuswill be required to protect autumn replants.

FINANCIAL BENEFITS TO GROWERS

The overall cost of IPM in the four inter-planted crops ranged from 5.1p to 16.4p per m2 with an overall mean of 12.1p per m2. The whitefly parasitoids appeared to contribute little to the programme and where they were omitted the mean cost was reduced to 10.5p per m2. Diglyphushad the greatest impact on the overall IPM cost but we believe that this component can be reduced by further fine tuning of monitoring methods and release strategies.

IPM costs incurred by growers of conventional natural season crops vary depending on the cultivars grown and the range of pests that must be controlled on each nursery. Figures provided by Gerry Hayman of the Tomato Working Party (TWP) provided a useful comparison with AYR production because they covered a wide range of scenarios. The average cost of the TWP IPM programmes in 2006 was 22p per m2.

At the start of this project, biocontrol programmes in AYR crops in Finland were reported to be 1.5 to 2.6 times more expensive than conventional crops. Using the TWP figures, we mighttherefore have anticipated that our AYR IPM programmes would cost between 33p and 57p per m2. In fact, our Macrolophus-based IPM programmesin the inter-planted crops were considerably less expensive than this and compared very favourably with conventional natural season crops.

Where crops were terminated and completely replanted in the autumn, the cost of the IPM programmes ranged from 28.3p to 41.6p per m2 with an overall mean of 34.9 per m2. These programmes were considerably more expensive than the inter-planted crops because populations of all biological control agents had to be re-established. The population growth of released Macrolophuswas very slow during the early stages of the new crops which led to an almost total dependence on purchased Diglyphusfor the control of leafminers. As a consequence, the overall cost of the IPM programmes in the replanted crops was more in line with those reported in Finland.