For Oklahoma wheat growers who are battling feral rye and jointed goatgrass incursions, wheat variety selection can be a particularly important consideration when trying to produce a crop with sufficient yields and protein content.
“The only practical option for managing feral rye and jointed goatgrass in wheat is to utilize the Clearfield system,” said Josh Bushong, Oklahoma State University Cooperative Extension agronomy specialist for the state’s northwest district.
By sowing a Clearfield wheat variety, the wheat producer can apply the herbicide Beyond. This herbicide will kill wheat varieties without this trait.
“The newer Clearfield Plus system allows the use of an adjuvant called methylated seed oil – often referred to as MSO – or HSOC, high surfactant oil concentrate,” Bushong said. “Only Clearfield wheat varieties designated with a ‘2’ or a ‘Plus’ such as Doublestop CL Plus can tolerate the addition of the oil adjuvants.”
In addition to MSO or a non-ionic surfactant, it is recommended to also include a nitrogen-based fertilizer with the herbicide Beyond. These include ammonium sulfate and urea ammonium nitrate (UAN 28 percent or 32 percent N) at a rate of 2.5 gallons per 100 gallons or 2.5 percent V/V of spray.
“Spray-grade ammonium sulfate can be used at 12 to 15 pounds per 100 gallons,” Bushong said. “To increase control, it is recommended to increase the urea ammonium nitrate rate up to 5 percent V/V, or if ammonium sulfate is used, increase it up to 20 pounds per 100 gallons.”
Liquid fertilizer can be used as the carrier only for Clearfield Plus systems. While the Clearfield or Clearfield Plus systems are great options, do not expect 100 percent control of feral rye. The Beyond herbicide label only gives it a suppression designation for rye.
“To improve control, it is recommended to use sequential applications of Beyond,” Bushong said. “The first application should be done in the fall and the other applied in the spring.”
Bushong added producers need to be aware that applications of the herbicide Beyond can cause a reduction in weed control when air temperatures are below 40 degrees Fahrenheit. If air temperatures drop below 40 degrees Fahrenheit within a week of application, crop injury can occur.
“Control of these weeds can be troublesome, especially if the wheat is to be harvested for grain,” Bushong said. “Often the only option is to either graze out the crop or harvest it for hay, mainly because if the wheat is harvested for grain, the price reductions from dockage and foreign material typically will be too high. The bottom line is to start with the best available variety and then use best management practices.”
Doublestop CL Plus’ two gene technology offers improved control of feral rye and jointed goat grass, yield stability across a wide range of environments such as drought-stressed and high-yield systems, excellent test weight in a late-maturity wheat with good protein content and quality, a high tolerance to acidic soils and Endurance-type grazing aspects with forage production and late first hollow stem.
Additional information about OSU-developed wheat varieties, weed control in wheat and best management practices that enhance yields and protein content is available through all OSU Cooperative Extension county offices, typically listed under “County Government” in local directories.