Review: The phenomenon of crop-weed competition; a problem or a key for sustainable weed management?

Author: Aspasia P. Efthimiadou, Anestis C. Karkanis, Dimitrios J. Bilalis ^* and Panagiotis Efthimiadis

Received 22 January 2009, accepted 9 April 2009.

Abstract

Herbicide resistance in weeds is rapidly expanding phenomenon around the world resulting in higher costs of production and greater weed impact. With current pressures to reduce herbicide usage but maintain cost-effective weed control, the innate ability of crops or cultivars to suppress weed growth has become increasingly important. The increasing appearance of herbicide-resistant weeds in the fields may force breeders to consider breeding for competitiveness as a high priority. Moreover, knowledge of competitive ability of weeds is desirable for development of economically and environmentally acceptable weed management systems. It is well established that weed species vary in their competitive effects on crops. Effective weed control management has been dependent upon farmers gaining knowledge of the characteristics of the weeds they were managing. The objective of this review was to examine the role of seed persistence, morphological traits of weeds, environment (i.e. water stress, soil properties) and cultural practices (fertilization, crop density and pattern, competitive crops and cultivars) in weed-crop competition. Characters such as growth rates, shading ability, tillering capacity, crop height, leaf area, upright growth, long stem, high biomass and allellopathy affect crop:weed interactions. Although we cannot eliminate the use of herbicides (synthetic or organic), their use can be reduced by selection of crop species and cultivars with superior weed suppression potential. Cultivars which are able to tolerate or compete strongly with weeds in combination with increased seed rates would make a significant contribution to productivity and yield stability on farmer’s fields.

Key words: Weed, weed suppression, competition, competitive ability, seedbank, cultivars, allelopathy, water stress, crop density, fertilization.