Integrated weed management

On each arable field the crop will be accompanied by a weed community with a certain composition as to species and number of individuals per species. The composition of the community is an indication of the conditions in the field. It is the result of the selective forces exerted by the production system. The origin of the vegetation is hidden in the soil seedbank. The floral composition and abundance of the weed species are potential factors of harmfulness of the weed vegetation. Cultural measures determine the actual speed of emergence and relative growth rate of the weeds. Various biological, physical and chemical techniques are available to control the competition between weed vegetation and crop and to manage weed problems throughout the rotation cycle. Different systems have different impacts on the degree of weed control within one season and within a rotation period, and on the pollution of the farming system and its environment. Knowledge about the effects of different weed control techniques may lead to an Integrated Weed Management (IWM) system. Economic, environmental and political reasons are steering the actions of a farmer within a season. Integrated Weed Management results in lower input of chemical compounds, but demands more labour. The net result of costs and benefits is positive, but depends on the possibilities of each farmer to adopt elements of IWM strategies.