Because BCA encompass quite a variety of different products and active agents, which fall into different categories with different modes of action, guidance on proper application techniques has to acknowledge this product diversity. The group that shows the greatest similarities with synthetic pesticides in terms of application technique is the microbials, which also explains to a large extent their greater success in the market compared with other BCA. Nevertheless, also microbials show peculiarities that distinguish them from common pesticides. In general, handling and application of BCA will be influenced or determined by one or more of the following factors: • Nature of the agent: e.g. microscopic or macroscopic, living and self-replicating, particulate, • Specificity: usually high or higher than common pesticides’ target specificity • Shelf life & biodegradability: many BCA have reduced shelf lives and biodegradability in the environment is higher compared to common chemical products. Practical advice on how to apply microbials and botanicals was attached to the field testing protocols that were developed in the course of making these Guidelines (for the protocols, see Appendix III). This and more useful information is contained in Cornell University’s Resource Guide for Organic Insect and Disease Management (69), which is a valuable source for hands-on experience and knowledge regarding the application of BCA. It is available at http://www.nysaes.cornell.edu. In order to achieve success in the field with many microbial applications, spraying techniques are of crucial importance. Some farmers regret the withdrawal of older chemical pesticides: which were often cheaper than the substituted, ‘biorational’ products. Crude application methods, that were adequate for chemicals with a long persistence or fumigant action (now unacceptable) is often inadequate for many biological products (and some modern chemicals). There has been a convergence in need for more targeted application methods for chemicals, microbials and other biologically-based control agents (44). Applying less, by applying more efficiently, should be a fundamental maxim in IPM (whether using BCA or conventional chemicals), yet pesticide application practices have not improved over recent decades in many countries: in some, standards have actually gone down. A contributing factor may have been overzealous implementation of IPM programmes that sometimes has precluded the use of pesticides altogether, making their use an ‘unofficial’ activity and effectively deskilling (or at least not training) farmers in better techniques. Optimising efficacy in the field with BCA usually requires a ‘delivery system’ approach involving appropriate formulations and careful selection of application equipment (45). Because of their particulate nature, microbial formulations often have special application requirements. There is (i) usually a clear relationship between number of particles and biological efficacy and (ii) an essential need to keep the organism alive. If a microbial is to be delivered as a spray, the propagules must be suspended and distributed so that they have a reasonable chance of reaching the target site. In the development of a new microbial product, a careful analysis is needed of the numerical distribution of 27 2.5.3 Application techniques biochemical or volatile compound, etc. • Mode of action: delayed killing effect, antagonistic or competitive behaviour (not killing), attractant, repellent, etc.
Implementing Biological Control Agents in the ASEAN Region
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