Production : Biotic Constraints : Pests, Diseases and Weeds

Grasshoppers / © Paul Roux

Pests, Diseases and Weeds

The ways in which pests, diseases and weeds, collectively known as “biotic stressors,” affect the lives of the world’s poorest farmers is a primary concern of the HarvestChoice project. Biotic stressors decrease agricultural yields, raise the production costs of managing these diseases, and limit the storability and marketability of food. They also raise the riskiness of farming as a livelihood strategy or a commercial enterprise. As living organisms, biotic stressors exhibit complex behavior, leading to difficulties in understanding where they might be found, and what their crop productivity impacts might be. HarvestChoice and its partners are conducting spatially-explicit assessments of the prospective productivity and economic gains from ameliorating the effects of these biotic stressors on crop production, with special emphasis on the biotic cropping constraints confronting agricultural systems on which the world’s poor so heavily depend.

Nature of the Problem

Pest, disease and weed problems have strong site- and time-specific dimensions. The crop loss impacts of one particular pest on a particular crop growing in a particular location may be entirely different from the losses incurred by the same pest on the same crop in other locales. Further, pest population dynamics, migration, invasion and damage are driven by local conditions, such as temperature and rainfall. Thus, a crucial first step in determining where, when and how agricultural systems might be affected by biotic constraints is to determine where pests, weeds and diseases might be. Earlier efforts by Dennis Hill (1983, 1987), the Centre for Agricultural and Biosciences International, CABI (2006), Oerke and colleagues (1994) and others have provided important information about the distribution of biotic stressors worldwide. Unfortunately, most of the available data and information on pest, weed and disease occurrence are relatively coarse. CABI , for example, provides maps of pest occurrence, but these show only that a pest or disease occurred in a country at some, usually unknown, time in the past. The spatial extent and severity of the infestations are also not typically recorded, meaning such data and information are not sufficiently spatially or temporally explicit to capture the important local conditions that drive biotic constraint problems.

References

CABI. CABI Crop Protection Compendium. 2006 <Data Disk>.Wallingford, UK, CAB International.
Ref Type: Data File

Hill, D.S. Agricultural Pests of the Tropics and their Control, 2 ed. New York: Cambridge University Press, 1983.

____. Agricultural Insect Pests of Temperate Regions and their Control. New York: Cambridge University Press, 1987.

Oerke, E.C. et al. Crop Production and Crop Protection: Estimated Losses in Major Food and Cash Crops. Amsterdam: Elsevier Science, 1994.

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