ENID, Okla. —
Over the last 10 years, wheat producers have had access to plant protection products that have done a much better job of controlling the brome species in wheat.
In fact, cheat, Bromus secalinus, had seen several new products released to control its damaging impact on northwest Oklahoma wheat. With the emphasis on controlling cheat, there have been several other brome species that have taken cheat’s place as “the most difficult weed in wheat.” Two that are highest on most producers’ lists would be rescuegrass and downey brome. In this segment of Extended Forecast, I would like to take my shot at controlling downey brome.
Downy brome, Bromus techorum, is a winter annual. Many producers could argue that statement because in dry years they see it germinate in the spring and so have I. This plant has a shallow root system and can be easily pulled out of the ground in the spring when chasing rye in wheat fields. Just like wheat, downy brome can produce an intense amount of tillers that produce seed panicles that are dense and drooping with several spikelets 3⁄4 of an inch to 11⁄2 inches in length. Often times, during the maturing stage of growth, the plant takes on a purple to reddish color. Once again, anything that is reddish in wheat is bad news.
About 99 percent of the time, seed will shatter out prior to wheat harvest and rarely would there be a dockage issue with downy brome. Since the seed shatters out prior to harvest, all the seeds remain in the field to cause problems next year. The biggest impacts to the wheat crop are moisture utilization and nutrient loss to the developing wheat crop. While downy brome will produce some forage, it is not as productive as wheat in a grazing system.
Those who listen to me discuss weed control know crop rotation and utilization of different herbicide modes of action in the crop rotation systems are my favorite methods of downy brome control. Research at Oklahoma State University will indicate downy brome seed could lie dormant in soils for up to three years, so crop rotation is but one tool for control. During fallow periods of time, glyphosate and fall applications of atrazine are very effective and tillage where appropriate will be an option.
Most of the brome species herbicides on the market can do a good job of controlling light to moderate downy brome infestations if applied early in the growth cycle. OSU research will indicate when wheat has one good tiller and is actively growing and temperatures are mild for a few days, fall treatments of downy brome have been successful. Later applications of these same products generally are less effective than the fall treatments.
At this time, there are no confirmed cases of ALS-resistant downy brome in Oklahoma. However, ALS-resistant cheat has been confirmed in northwest Oklahoma and being in the same family as cheat, downy brome could be one of those weeds to watch for in your wheat production system.
Additional information about downy brome control can be obtained from your Oklahoma Cooperative Extension Service office. Your ag educator would be glad to provide you with options for control.
Gribble is Oklahoma Cooperative Extension Service northwest area agronomist.