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Integrated Pest Management (IPM) is the phrase used to describe a set of crop protection measures that balance the economic production of crops with the needs of a sustainable environment (Tucker and Sage, 1999). The majority of work done in relation to IPM has been done for wood crops, particularly willow. However, general and common sense approaches identified for willow can also apply to non-wood biomass crops. Tolerance to pest and disease within biomass crops is set at a higher level than for food crops because the aesthetic aspect of a biomass crop does not affect its value. It is only in the yield that pest damage becomes important and undesirable. Rough, tussocky grassland containing herbaceous flowering plants provide the right conditions for natural enemies of leaf beetles. These enemies include spiders, ground beetles, flies and parasitic wasps. Overuse of pesticides can seriously damage the potential for natural control by such animal groups. This is also true of control measures taken against other defoliating insects such as sawfly larvae. Modern farming achievements may not have been possible without the chemical control of pests and large infestations that cause crops to be uneconomical. However, many are now realizing that the arbitrary use of such techniques can be both environmentally and economically harmful, because destruction of one pest may provide the opportunity for another pest to fill the niche. Also, pest species are often short lived and highly fecund. This type of life cycle can aid in the development of resistance to anti-pest chemicals. Beneficial insects that prey upon a variety of pests may also be destroyed in the process of modern pesticide application regimes. Other strategies exist to combat excessive yield reduction. All invertebrate pests have multiple natural enemies (predators, parasites and infectious agents). Monoculture crops encourage pest species populations to become artificially large. Natural enemies, as a whole, often require a diversity of vegetation species and structure in order to take full advantage of their pest prey. Therefore in wood crops; ground cover vegetation should be maintained as diverse grassy-herbaceous rides around and through plantations; cutting regimes should be designed to avoid the development of scrub but maintain relatively deep and diverse ground cover; hedgerows should be managed to remain diverse in species and structure. This will act to encourage a diverse range of natural enemies of pest species. Large scale insecticide use is not recommended for the control of chrysomelid beetles. Under situations of excessive yield loss the life cycle of the beetles can be used to guide managed insecticide use (Sage et al., 1999). Beetles spend winter in trunk and fence post crevices etc. They re-colonise plantations edges in spring before moving further into the crop. This opens a window of opportunity to insecticide only the crop edges, thus minimizing destruction of natural pest enemies. Also a sacrificial edge of susceptible varieties of tree will increase the concentration of beetles into a manageable area. Beetles will tend not to colonize young growth, therefore, leaving a sacrificial strip unharvested will further concentrate pest beetles for a longer period after harvest. In general, planting multiple varieties at one site will reduce the risk of high losses as susceptibility varies greatly between varieties and under different conditions. Rust control measures can be integrated into the above practices for insects. Tucker and Sage (1999) recommend plantations to be situated away from larch plantations as this is an alternative host for willow and poplar rusts; single variety plantations should be avoided; mixed variety planting should be encouraged to delay and reduce spread of damaging rust complexes. There is not the opportunity for mixed planting and ground cover through the crop within non-wood biomass plantations (although Miscanthus can sustain a high level of ground cover in its early stages, Semere and Slater, 2005). However it is possible to maintain a grassy/herbaceous ride around the edge of the crop. This, along with good hedge management will provide habitats for natural enemies that will disperse into the crop to find prey. ------------------------------------------------------------------------------------------------------------- Sage R.B., Fell D., Tucker K. & Sotherton N.W. (1999) Post hibernation dispersal of three leaf-eating beetles (Coleopteran: Chrysomelidae) colonizing cultivated willows and poplars. Agricultural and Forest Entomology. 1, 61-70. Semere T. & Slater F.M. (2005) The effects of energy grass plantation on biodiversity. Tucker K. & Sage R. (1999) Integrated pest management in short rotation coppice for energy: A growers guide. Game conservancy Ltd. Fordingbridge, UK. |
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