Density effect and economic threshold of Japanese brome (Bromus japonicus Houtt.) in wheat
Japanese brome (Bromus japonicus Houtt.) is a winter annual weed commonly found in the wheat (Triticum aestivum L.) fields of China. It is prevalent in northern China and produces obvious wheat yield losses. Information on the interference of Japanese brome on wheat density and its economic threshold (ET) is unknown; this information is useful to manage Japanese brome. Two-year field experiments were designed to determine the ET of Japanese brome in wheat. The dry weight of Japanese brome with a density of 320 plants m-2 was similar to the ’natural weeds including Japanese brome’ treatments and higher than other Japanese brome densities, except for the 640 plants m-2 density which had the highest weed dry weight and yield loss. In the absence of Japanese brome, natural weed infestation was less competitive. The ET of Japanese brome in wheat was between 4 and 5 plants m-2 with 80% efficiency for the herbicide flucarbazone. It predicted that 4 plants m-2 of Japanese brome can cause 2.11% to 2.24% yield losses. This information can contribute to decision making for Japanese brome management. Given several production factors, this ET is more precise and reliable than the ET determined with only yield losses and can be used to develop better control strategies.