Downy brome is a winter annual grass that is a problem in every Canadian province except Newfoundland. A prolific seed producer, it germinates in the fall and overwinters as a seedling. Come spring, it resumes growth rapidly.
Generally, downy brome starts heading in late April to early May. By late April, it has an extensive, fibrous root system that is hard to control with tillage, making it especially problematic in no-till or minimum till systems.
An aggressive grassy weed, downy brome is a threat to winter and spring cereals, pastures and rangeland and dry hayfields. In both Saskatchewan and Alberta, it is considered a noxious weed.
“It’s the lower category of the two,” says Nicole Kimmel, weed specialist with Alberta Agriculture and Rural Development. “If you do have downy brome you are obligated to control it so that it does not spread.”
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Identifying downy brome
In the seedling stage, downy brome can be confused with fall rye. While both are purplish in colour, downy brome does not have auricles (those small hooks that encircle the stem at the base of the leaf blade). Once fully grown, the plant has densely hairy leaves and sheaths, a soft, drooping panicle and long, thin awned spikelets.
A lot of producers don’t notice it until it’s too late, says Neeser. “It sort of has a fuzzy appearance and you don’t notice it until there’s a solid stand.”
Kimmel agrees that identification is difficult. “You’re looking for a grass in a grass. It’s not being found very easily or fast enough, so it’s getting out of control before it’s being recognized as a problem.”
When producers suspect they may have a problem with downy brome, Kimmel recommends bringing in a certified crop advisor or someone with expertise in grasses.
Controlling downy brome
Josh Fankhauser farms some 7,000 acres of cropland in Claresholm, Alta. Growing a wide range of crops — winter and spring wheat, yellow peas, canola, flax and barley — Fankhauser says downy brome has been a problem on his farm, especially in winter cereals and forage production. For control, Fankhauser has tried products like Simplicity and Everest, with a preference for Simplicity.
“In the fall cereals — because they germinate at the same time and the way you’re spraying — you don’t really have a chance to whack it with glyphosate before you seed, so it’s been pretty hard,” he says. “In the spring crops, it hasn’t been such a big problem, especially since you can spray glyphosate and set it back enough that it doesn’t rear its head until late fall.”
Downy brome is one of the earliest plants to get going in the spring, says Neeser, which makes it a particular challenge in winter wheat. Control options, he says, are limited, but he agrees that Simplicity does a fairly good job. Another option is a grass herbicide called Assure II. Its active ingredient is quizalofop. With Northstar winter wheat growers have another option, Sencor.
The seed survives for up to three years, making good control extremely important, says Neeser. And it can creep into fields from the margins along the roadside.
“A farmer should keep a close eye on the field margins and if downy brome is there then action is required,” he says.
Where possible, a pre-seed burn down herbicide is recommended; usually something mixed with glyphosate, like florasulam, says Neeser. “Glyphosate controls downy brome quite well, and so do other pre-seed burn down tank mixes that contain glyphosate and florasulam.*”
Fankhauser says that while products do work, good rotations are key when managing for downy brome.
“Our general attitude is if you’ve got too much of one weed it’s probably because your cultural practice or your rotations are out of whack,” says Fankhauser. “So if one weed starts to look worse than all of the others and starts to become a problem you better start thinking about your rotations and adjust it to combat that problem.”
According to a report issued by Alberta Agriculture, in minimum or no-till systems, glyphosate applied in late fall or early spring does provide better control than tillage, especially in cool, wet conditions. After heading, higher rates of glyphosate will be required.
* Corrections have been made to this version of the article. May 2, 2014.