CABI - Biocontrol News and Information 23(2) June 2002 News

Biocontrol News and Information

June 2002, Volume 23 No. 2

IPM Systems

This section covers integrated pest management (IPM) including biological control, and techniques that are compatible with the use of biological control or minimize negative impact on natural enemies.

Droplets of Wisdom

Concerns in the media about pesticides are often largely misplaced: with some problems over-stated and real issues not addressed. Various proposals to cut down pesticide use are impractical and clearly have been rejected by 'the market'. The total value of world sales increased some 2.5 times to US$30 billion during the final two decades of the 20th century, and the agrochemical industry has attributed the lack of growth over the last 3-4 years as a temporary problem, related to low prices for agricultural produce.

Misdirection of public concern is unfortunate, because real problems with pesticides remain, including: hazards with human health (especially with insecticides and where regulatory standards are poor), environmental contamination, possible residues on food (food safety), and failures in control due to pest resistance or resurgence. However conflation of pesticide issues can lead to inappropriate measures being taken; for example, restrictions adopted in Europe (where food safety and environmental concerns are major issues) are often unsuitable in tropical countries (where food security and human health predominate). Impartial information can be difficult to find, especially data relevant to developing countries and information that focuses on practical measures to reduce (but not necessarily eliminate) pesticide use. Since the late 1980s, this area of R&D has been constituted a 'no man's land' for funding and support [see BNI 21(4), 96N-100N (December 2000), 'Rational pesticide use: an alternative escape from the treadmill'].

Farmers are concerned about the high costs of pesticides, yet generally little is done to improve the quality of application, which is almost always highly inefficient. Spray drift has been identified as a problem (which indeed it may be), but many so-called solutions may also reduce efficiency of dose transfer, thus increasing rather than decreasing the pesticide consumption. Many of the problems could be alleviated by implementation of known technologies, within an appropriate infrastructure of education and policy. Rational Pesticide Use (RPU) is a concept that focuses on their better selection and utilization (applying safer agents more efficiently), as opposed to promotion of pesticides.

The DROPDATA website pages describe current and future activities of the CABI Bioscience RPU Unit, and collaborating partners including the International Pesticide Application Research Centre (IPARC) at Silwood Park. We aim to develop linkages between research groups and extension workers and have two primary objectives:

To give technical information on application techniques (the DROPDATA resource pages)
Examine wider issues related to pesticide use (advocacy and description of RPU techniques)

Recent developments include:

Publication (for the first time) of the British Crop Protection Council (BCPC) protocols for evaluating agricultural spray nozzles
Provision of presentations about RPU, downloadable utilities and linkages with other webpages promoting similar objectives
Advice on biopesticide delivery systems, including information on the 'MycoHarvester', a device that can revolutionize the formulation of beneficial fungal agents by small- to medium-scale enterprises
Information on improving pesticide application to tropical tree crops such as cocoa (cacao)

The way in which the DROPDATA website is developing as a practical resource for stakeholders, from farmers to researchers, is illustrated by the information being added on tree crops. The second part of this article describes a project which is contributing new understanding and knowledge on the tricky problem of effective pesticide application in these crops.

Collaborative Cocoa Disease Control

Techniques used by smallholder farmers for applying pesticides to tree crops, such as cocoa, are often especially poor. In practice it is common to encounter farmers who use knapsack sprayers, fitted with cone nozzles, to 'squirt' the tank mixture onto higher branches; most of the liquid then falls back onto the ground and is wasted. The information in the cocoa section of the DROPDATA website has been distilled from a project in Costa Rica and Brazil involving CABI Bioscience, CATIE (Centro Agronómico Tropical de Investigación y Enseñanza, Costa Rica), and a number of partners in Brazil, the UK and the USA. The project is funded by the United States Department of Agriculture (USDA).

Fungal diseases are a principal constraint to world cocoa production and two of these - witches' broom (Crinipellis perniciosa) and frosty pod rot (Moniliophthora roreri) - pose a special threat to livelihoods in Latin America and their management remains problematic. Chemicals such as copper fungicides are poisonous, have limited efficacy and a long-term impact on the environment (in spite of being permitted for restricted use in 'organic' agriculture). While biological control agents may offer the most sustainable long-term solution, there are many technical, commercial and conceptual issues of development yet to be resolved. What both synthetic and biological pesticides have in common currently is an inadequate standard of application to crops: poor formulation, spray droplet size and coverage substantially affect their efficacy.

The CABI-CATIE-USDA project aims to improve delivery systems (especially formulation and application techniques) for promising microbial agents, such as isolates of hyperparasitic fungi in the genus Trichoderma. However, techniques developed may also be used in the application of conventional chemical fungicides, which are being used as standards in the field-testing programme. Ultimately, the goal is to assemble a 'toolkit' of practical, efficient and safe solutions to key problems, and encourage farmers to adopt them. This will have multiple benefits: improving the efficacy of control and operator safety, while reducing control costs and adverse environmental impact.

Recent laboratory and field work has enabled project partners to make provisional recommendations on operational settings for the two most commonly used fungicide application techniques: portable hydraulic sprayers and motorized knapsack mistblowers. Work on optimization continues to further reduce volume application rates (and thus increase work rates) for hydraulic sprayers, and more field evaluations are aimed at minimizing dosages of chemical fungicides and maximizing the potential of microbial biocontrol agents.

Websites:
www.dropdata.net
www.cabi-commodities.org

Contact: Roy Bateman, CABI Bioscience UK Centre (Ascot), Silwood Park, Buckhurst Road, Ascot, SL5 7TA, UK
Email: r.bateman@cabi.org
Fax: +44 1491 829123

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