Biological control of weeds: a review of principles and trend

Abstract

The biological control of weeds can be practiced in three different ways, i.e. by introduction of control agents (classical approach), conservation of existing control agents and the numerical augmentation of native control agents by inundative releases. The main principles, general consideration and the methodology of each of these approaches are shortly reviewed, as well as their potentials and limitations. Classical biological weed control, the approach most frequently employed, provided an overall success rate of about 30%, has a positive cost to benefit ratio and is ecologically rewarding. It is pointed out that its great potentials are not yet fully realized because of limited financial support, but that the socio-economic benefits deriving from it could be important in the future. Special attention is also being paid to the inundative approach, especially to the development of bioherbicides, a novel method of biological weed control employing mainly native plant pathogens. It is expected that this control method will gain in importance in the future, after the presently existing limitations will be overcome. Biological control of weeds should be considered as one of the available options in all weed situations. It offers great socio-economic benefits and is environmentally safe and therefore should be the favoured weed control method in the future.