Integrated Weed Management 

Integrated weed management consists of the combination of different control methods, in order to ensure good control of weeds. Combination of methods does not mean that they are simultaneously applied. There are preventive and curative methods, and the combination of different practices will depend on the weed species present, the severity of the problem, and on the crop and plot conditions, but also on the farmers' socio-economicenvironment and on his technical level of expertise. For technical and economic reasons, integrated management should be used rather than any single method on its own.

Go here to get more details on the two methods.