|Carrington Research Extension Center
North Dakota State University
NDSU Extension Service
North Dakota Agricultural Experiment Station
20 May, 1999
POST-EMERGENCE HERBICIDES FOR FLAX
A limited number of post-emergence herbicides are labeled for weed control in flax. Bromoxynil (tradenames include Broclean, Buctril, Moxy) is labeled at 1 pint per acre to 2- to 8-inch tall flax for broadleaf weed control. Bromoxynil will provide good or excellent control of numerous weeds including wild buckwheat, cocklebur, kochia, lambsquarters, marshelder, eastern black nightshade, common ragweed, annual smartweed, sunflower, and Russian thistle. MCPA applied at 1 pint per acre (4 pound per gallon concentrate) to 2- to 8-inch tall flax will provide good or excellent control of broadleaf weeds including cocklebur, flixweed, lambsquarters, marshelder, wild mustard, common ragweed, and sunflower. Bromoxynil and MCPA may be tank-mixed to increase the spectrum of broadleaf weed control. Potential for flax injury exists with either herbicide used alone or as a mixture. Poast at 0.5 to 1.5 pints per acre is labeled for grass control in pre-bloom flax. A second application is recommended to provide fair-to-good control of quackgrass. Apply Poast with one quart per acre of an oil additive to actively-growing grasses. Poast may be tank-mixed with bromoxynil or MCPA ester for broad spectrum weed control. Crop injury and reduced grass weed control may occur with the tank mixtures. Refer to herbicide labels and NDSU Extension Service circular W-253 "1999 North Dakota Weed Control Guide" for required information on use.
VOLUNTEER SUNFLOWER CONTROL IN WHEAT AND CORN
Volunteers from last year's sunflower fields are emerging in fields planted to wheat and corn this season. Emergence of volunteer sunflower may occur over an extended period of time depending on previous tillage operations, current soil conditions, etc. Volunteer sunflower is quite competitive with grass crops. NDSU studies have indicated a sunflower density of 50 plants per square yard can reduce wheat yield by 40 percent. Post-emergence herbicides should be applied before sunflower is four-inches tall and a second treatment may be needed for late-emerging sunflower.
Post-emergence herbicides rated by NDSU that provide good-to-excellent or excellent control of volunteer sunflower in wheat include the sulfonylurea herbicides + 2, 4-D, dicamba or dicamba + MCPA amine, bromoxynil or bromoxynil + MCPA, Cheyenne (HRS wheat only), Curtail or Curtail M, Starane + 2,4-D or MCPA, Tiller (HRS wheat only), Tordon + 2,4-D or MCPA (HRS wheat only), and 2, 4-D.
Post-emergence herbicides rated by NDSU that provide good-to-excellent or excellent control of volunteer sunflower in corn include Accent Gold, Banvel or Clarity, Basagran, Bladex + oil, Celebrity, Curtail, Distinct, Hornet, Liberty (Liberty tolerant corn only), Permit, Scorpion III, Stinger, and 2,4-D.
Refer to herbicide labels and NDSU Extension Service circular W-253 "1999 North Dakota Weed Control Guide" for herbicide rates, correct weed and crop stages for herbicide application, and other specific information regarding herbicide use.
Greg Endres, Area Extension Specialist/Cropping Systems, Email: firstname.lastname@example.org
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