Determining Economic Threshold of Downy Brome (Bromus Tectorum L.) in Wheat (Triticum Aestivum L.)

Abstract

Weed economic threshold in a specific crop serves as a tool for employing cost-effective management program. The response of wheat (Triticumaestivum L.) yield to varying densities of downy brome (Bromus tectorum L.) was tested during winter season of 2014-15. Increasing densities of B. tectorum (0, 5, 10, 20 and 40 plants m-2) increased B. tectorum dry weight up to 322%. Wheat plant height, tillers m-2 , spike length, grains spike-1 , 1000-grain weight, biological, grain and straw yields were reduced at downy brome density at and above10 plants per m 2. Grain yield losses of wheat varied from3 to 19% with B. tectorum density between5 and 40 plants per m 2. Maximum plant height, tillers m-2 , grains spike-1 of downy brome were observed in its lowest (5 plants m-2) density. The economic threshold of B. tectorum as determined by prediction model was 2.6 plants per m 2 indicating that downy brome weed in wheat should be managed at this density level.