Downy brome (bromus tectorum) and cheat (bromus secalinus) are two weed species often misidentified. Yet, categorizing these weed species incorrectly can result in the difference between suppression and control.
Despite similarities, downy brome and cheat do have distinct differences. For starters, downy brome is more common than cheat in winter wheat fields. According to the University of Nebraska, cheat always heads out before the wheat.1
Identifying weed species in the field is critical to determine the best weed management program. Growers who have downy brome, the more likely of the two, will want to consider a fall herbicide application for control versus a spring application that only suppresses the species.
“It’s easier to scout in the fall because we can still find mature seed heads from last season in the fields or on the borders,” says Abe Smith, market development specialist, Dow AgroSciences. “Downy brome seed heads have long awns and can get easily caught in clothing and socks. Cheat has a less hairy stem.”
Downy Brome is the more prevalent and threatening species in the Southern Plains region. If downy brome is in fields, Smith recommends a fall application of PowerFlex® HL herbicide for control. When applied in spring, PowerFlex HL suppresses downy brome.
“If downy brome is an issue, we would encourage people to consider a fall application verses spring because their success will be better overall,” Smith says.
Both downy brome and cheat can decrease yield significantly depending on the population, Smith says.
“Growers are becoming much more sensitive and likely to treat cheat and downy brome now versus 10 years ago. They understand the impact these weeds have on yield and the difficulty they have on management over the years,” he says.
These cheat and downy brome families of grass tend to cause a lot of seed spreading on the ground. This causes dense populations of weeds that can dominate and outcompete the crop specifically for moisture, Smith says. Yield potential can be significantly affected if the weeds outcompete the wheat crop.
“They are competing with the grass, not only for nutrients but for moisture, especially in these dryland areas,” Smith says.
University of Nebraska Extension NebGuide found at Alliance and North Platte, moderate (one to two plants per square foot) to heavy infestations of downy brome have reduced wheat yields 30-80 percent.
(Source – http://www.dowagro.com/en-us/usag/news-and-resources/newsroom/2015/november/03/misidentification-of-downy-brome-can-result-in-reduced-yields)