Grower Summary

Horticultural

Development

Company

Grower summary

PC 284

Review of pest control in UK pepper crops
Final Report 2008

Disclaimer

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 results and conclusions in this report may be based on an investigation conducted over one year. Therefore, care must be taken with the interpretation of the results.

Use of pesticides

Only officially approved pesticides may be used in the UK. Approvals are normally granted only in relation to individual products and for specified uses. It is an offence to use non-approved products or to use approved products in a manner that does not comply with the statutory conditions of use, except where the crop or situation is the subject of an off-label extension of use.

Before using all pesticides check the approval status and conditions of use.

Read the label before use: use pesticides safely.

Further information

If you would like a copy of the full report, please email the HDC office (), quoting your HDC number, alternatively contact the HDC at the address below.

Horticultural Development Company

Tithe Barn

Bradbourne House

East Malling

Kent

ME19 6DZ

Tel: 01732 848 383

Fax: 01732 848 498

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.

Headline

The project has pulled together information from members of the Pepper Technology Group and project collaborators (Fargro, Koppert Biological Systems, Syngenta Bioline, BCP Certis). The review highlights the need for new and more robust biocontrol programmes to achieve the Pepper Technology Group’s aim of pesticide free production.

Background and expected deliverables

· The current use of biological control agents within protected pepper crops has been subject to problems and disruption among many growers. These changes include increasing problems in controlling familiar species and the occurrence of new species of pest.

· Aphids are becoming an increasing problem, and the subsequent need for control using chemical treatments frequently results in the disruption of other biological control programmes. The species of aphid currently causing problems is the glasshouse and potato aphid Aulacorthum solani. Rapid growth of large populations of this species has been experienced and the current programme of biological agents is ineffective.

· Thrips populations are also beginning to become an increasing problem for growers at planting. For other growers, unexpected growth in the pest population later in the season means that the current biocontrol programme fails to provide adequate control.

· In addition pepper growers are increasingly experiencing problems with the glasshouse leaf hopper for which the currently available biological agents are limited in their success. Mealybug (Pseudococcus viburni) has also become a pest for some pepper growers.

Summary of the project and main conclusions

· This project provides a first step in the review of pest control in UK peppers. The project’s aim is to identify the main concerns and problems for UK pepper growers and thereby provide an overview of the different problems and possible solutions.

· The review highlights possible solutions to provide robust systems for pest control.

· The review explores the possible interaction of the different growing regimes for peppers and the growth of pest populations.

· The project has discussed with collaborators appropriate changes to current, or the development of new, programmes that could provide more robust solutions for growers.

· The effectiveness of predators and parasitoids as biological control agents can be constrained by a range of factors including the availability of prey/hosts; lack of alternative food sources, as well as various mortality factors. In Conservation Biological Control we seek to support natural enemies by modifying the agro-environment in a way that removes or minimizes these impediments. This review considers the potential for improving biological agents and pest reduction through nutritional improvement.

· The project identifies new chemistry that could contribute to effective pest reduction in conventional and organic crops.

Improvement to biological control programmes

· A common disruption to successful biocontrol programmes is the use of insecticides. Frequent over-use of some products has caused resistance in pests for some nurseries. In addition some products that are used for specific pests have produced an increase in non-target pests, usually as a consequence of the lethal and sub-lethal effects on the biocontrol agents.

· Before using an insecticide, the possible side effects on biological control agents should be considered. Anticipating the side effects of insecticides could benefit biological control programmes. However, as mentioned above the data on the effects of insecticides on beneficials is incomplete and conflicting and will vary with the screening methods employed. Even products with a short persistence can have a deleterious effect on the numbers of beneficials that have built up over time within a crop, and to achieve an equivalent population of biological control agents could either take too long or be too expensive.

· There is a range of predatory mites available and their performances are affected by temperature and humidity. Improvements in their efficacy may be achieved through adjusting the selection of agents to meet the changing temperatures/humidities within the crop. Similarly some parasitoid species perform more efficiently at different temperatures.

· Most biological control agents require a suitable food source to increase life span and numbers of offspring produced. Pepper flowers have pollen and nectar, but the quality, quantity and accessibility to all beneficials needs to be verified, and also whether additional food sources could improve some biological control systems.

Problems in biocontrol programmes

Pest control programmes have been developed for most pest species in protected peppers, but some programmes are not proving to be sufficiently robust and reduced chemical input would present a challenge for controlling some pest species. Section B of the Science Section discusses the biological programmes and their gaps for most commonly occurring pest groups.

Over several growing seasons, changing climate will affect external insect populations and, as a consequence, the most prominent pest problem for growers changes. The following three groups of pest have been the most troublesome in recent seasons.

Aphid control

· A common problem to all growers is the control of aphids, especially the aphid Aulacorthum solani, and particularly where growers wish to pursue a chemical free practice.

· To achieve sustainable aphid control in pepper crops the addition of other species of predators and/or parasitoids may be required. The review has provided information on additional agents that could be considered but the benefits of adding these to general aphid control programmes needs verification. The industry could also benefit from the introduction of new aphid parasitoid/predator species, some of which may be non-native and therefore would require the pursuit of a licence.

· Hyperparasitism presents an increasing problem for some growers. Part of this problem may be accounted for by the crops (and weeds) and their pests that are grown in the vicinity if the glasshouse. There is also a possible contribution to the hyperparasitoid population from banker plants. Aphid control could be improved if methods for eliminating hyperparasitism were developed.

Leafhopper control

· Leafhoppers present a problem in some crops, particularly for growers in the south of England. The uses of chemical products against leafhopper have disrupted the biological control programmes for other pests. However recent applications of Steward (Indoxacarb) would appear to have produced effective all round control.

· There are currently no consistently effective biocontrol agents for leafhopper. Information on available agents and rates are discussed in Section B of the Science Section. However, further work on effective biological control is required. Physical methods, such as sticky traps and suctioning systems will contribute to the overall control of leafhopper.

· Leafhoppers move into glasshouses from the surrounding vegetation and the management of these external areas may also provide part of the solution to the pest populations.

Thrips control

· The breakdown of the thrips control programmes has several sources: invasion of the glasshouse from external crops, reduction in biocontrol agents due to chemical programmes for other pests, large thrips populations at the end of the season results in and subsequent high infestation levels at start of the following season. It is also speculated that Mypex may allow better survival of thrips between crops.

· High rates of Orius laevigatus have succeeded in reducing large thrips populations for several growers, and have achieved control for growers with TSWV problems. However, the costs of such programme are extremely high and therefore more cost-effective biocontrol programmes for high or virus transmitting thrips populations are required. (Section B of the Science Section discusses these issues and possible solutions.)

· Research suggests that virus problems can be alleviated through the management of vegetation surrounding the glasshouse, assuming that plants from propagation are virus free.

External controls

· Pest problems do vary with individual growers and certainly the sudden occurrence of pests is usually correlated to external crops to that particular glasshouse and therefore can be very specific to a grower.

· Entry into the LEAF scheme requires that growers should maintain areas around the glasshouses for increasing biodiversity. Management of field margins is beginning to be developed in horticultural field crops across Europe. Management of these margins meets the requirements of farmers to reduce pest pressure/insecticide input through the increase of beneficials whilst maintaining low labour. It is possible that the applications for these methods may provide some glasshouse growers with similar benefits by reducing pests and increasing beneficial insects.

· However large pest invasions due to external crops will always remain a problem for some growers. Screening vents, which has been shown to prevent pest infestations in protected lettuce crops (HDC PC132) whilst effective can prove to be prohibitively expensive. Therefore programmes with reduced or no chemical input for such influxes needs to be further investigated.

Action points for growers

· The review provides growers with an overview of pests, biocontrol agents and insecticides in protected peppers.

· Growers can use the review for information on additional biocontrol agents that may provide solutions to pest problems, discussions with representatives from biocontrol agencies and further evaluations of these biocontrol agents would be required.

· The PTG goal of achieving pesticide free production requires more robust biological control programmes to be developed for some pests, such as aphids.

· Biological control programmes need to be developed for some pests, eg leafhopper.

· The review also lists approved chemicals for protected peppers.

· The reports provides information on the longer term use of chemical products listed in relation to the replacement Directive for 91/414EC. This is an ongoing situation and developments have occurred since the submission of this report, for a more recent product status growers can look at the following web site: http://www.pesticides.gov.uk/uploadedfiles/Web_Assets/PSD/Revised_Impact_Report_1_Dec_2008(final).pdf