The role of duck in biocontrol of weeds in organic rice-duck farming

Competition between the undesired plants and the crop was to be avoided ifreasonable yields were to be achieved. Weeds were removed first by handand then mechanically when new farming tools were developed (Le Baron,1991). During the 1950s, the first hormonal herbicides were developed;from that moment onwards, the spectrum of molecules known to havedeleterious physiological activity on weeds has increased dramatically andso has the effectiveness of new herbicides (Mortimer and Maxwell, 1994).The introduction of herbicides in agricultural systems, and their efficiencyin maintaining crops relatively free from competition, led to the idea ofweed eradication. It was soon evident, however, that weed eradication wasnot a reasonable objective and that infestation levels had not decreasedto the extent that had been expected. In fact, continuous use of herbicideled to the appearance of resistant biotypes of weeds and contaminationof the environment in Australia, Europe, and North America (Hammond,2010).