IMPACT OF SOIL-MICROORGANISMS ON WEED BIOLOGY AND ECOLOGY

While weed populations have traditionally been controlled by chemical and cultural methods, inundative biological control with microbial age nts offers an additional strategy for managing weeds. Foliar pathogens have long been sought after as potential biocontrol agents, but rhizo sphere microorganisms and their influence on weed growth and developme nt have been ignored until recently. Rhizosphere soil is replete with a variety of microorganisms such as rhizobacteria, pathogenic soil-bor ne fungi, and arbuscular mycorrhizal fungi, all of which have a direct or indirect impact on weeds and their competitive ability. In some ca ses, specific microbes have a detrimental effect on the weeds and can be exploited as biological control agents. The ubiquitous mycorrhizal fungi are beneficial symbionts that can impart a competitive advantage to their plant hosts, particularly if mycorrhizal dependency is exhib ited in weeds as opposed to crops. It may be possible to exploit vario us soil microbes by directly or indirectly reducing weed competition a nd tipping the competitive advantage in favor of the crop. However, in formation available on microbial/weed/crop relationships is limited an d research efforts are required to explore the use of soil microorgani sms as another weed management tool.