ISSUE 11
Spring 1995

Controlling Wild Oats
in Small Grains


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Prairie Grains is the
official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain
Growers Association,
South Dakota Wheat,
Inc., and the
Minnesota Barley
Growers Association.


Cool, wet conditions the last few growing seasons turned many wheat fields into a playground for wild oats. To get the upper hand on this prolific weed in 1995, Bev Durgan, University of Minnesota extension weed scientist, offers the following tips:
  • Barley is more competitive with wild oats than spring wheat. Also, warm season row crops such as sunflowers, soybeans, and corn should be considered in fields with heavy wild oat populations.
  • An early soil cultivation will stimulate wild oat germination and another one or two subsequent cultivations will control emerged wild oats prior to crop seeding. But beware the drawbacks of delayed seeding: wheat yield reductions of up to 40 percent compared to early seeding, and possible foxtail population increases.
  • Most crucial for good wild oats control with any herbicide: Proper timing. Postemergence wild oat herbicides require application at precise leaf stages.
  • An accurate leaf count is important for optimum wild oats control. Leaf number on wild oats is determined by counting the leaves on the main stem and disregarding the tillers. The youngest leaf is counted as a full leaf only when another leaf becomes visible. Lower leaves which may have died from various stresses, such as frost, should also be counted in the total leaf number.
  • Another big control factor: Moisture conditions. Some wild oat herbicides work better under dry conditions than others. The drier the conditions, the harder it is to control wild oats. Thus, use upper herbicide rates for best control in dry conditions.
  • Early wild oats control can mean better yields because the weed has less time to compete with the crop. However, when a herbicide treatment is applied early, odds are greater that a later flush of wild oats will require a second herbicide application, or that some wild oats might escape treatment.
  • Any uncontrolled wild oats can reduce yields, and will produce seed that contributes to problems in the following growing season. In general, under heavy wild oat pressure (over 30 plants/sq. ft.) research has shown that a herbicide treatment should be applied as soon as possible to prevent high yield losses.
  • Follow strategies to prevent herbicide resistance in wild oats, a growing problem in Minnesota. Key practices: Rotate crops, combine tillage with herbicide treatments, and rotate wild oat herbicides with different modes of action.

WILD OAT HERBICIDES CURRENTLY LABELED IN MINNESOTA

FAR-GO (trillate) -- Can be preplant or preemergence applied in the spring. Incorporation needed except with fall granular applications. May be applied along with Treflan for foxtail control in wheat and barley. Granules perform best when applied in the fall; liquid formulation better in the spring, according to U of MN research.

ASSERT (imazamethabenz) -- Gives consistent wild oat control, and will also control wild mustard, according to U of MN research. Apply with non-ionic surfactant to wild oats in the 1 to 4-leaf stage. Add crop oil concentrate (but not if 2,4-D is in the tank mix; crop injury risk) in addition to surfactant in dry weather or heavy wild oat pressure.

Can be tank mixed with 2,4-D ester, MCPA ester, Bronate, and Harmony Extra. There are rotational restrictions, since Assert may persist in the soil for more than one year. Some crops at risk: sugarbeets, potatoes, and canola.

AVENGE (difenzoquat) -- Barley tolerates Avenge, although some wheat varieties will be injured by it. Sharp, Grandin, Gus not on the Avenge label. There is a supplemental label that allows Avenge to be applied to 2375 at 3 pints/A; serious injury may result at rates higher than that. See label for further varietal restrictions.

Apply to wild oats in the 3 to 5-leaf stage. In Minnesota research trials, Avenge gave the best control in 4 to 5-leaf wild oats. Can be tank mixed with 2,4-D, MCPA, Harmony Extra, Express, Buctril, Curtail, and Bronate.

CHEYENNE (fenoxaprop, MCPA ester, thifensulfuron, tribenuron) -- Labeled for postemergence control of foxtails and wild oats and most annual broadleaf weeds in hard red spring wheat. Cheyenne is not labeled for use in durum, barley, or oats.

Apply to spring wheat crop from the 3-leaf stage to the end of tillering, or 6-leaf. Apply when grass weeds are 4 inches tall or less. Do not apply to crop after jointing or injury may occur. Do not apply by air, and do not tank mix with other compounds.

Good to excellent control of wild oats, foxtails, kochia, pigweed, and several other annual broadleaf weeds.

HOELON (diclofop) -- Can be applied to all varieties of wheat, barley, and durum, when wild oats are in the 1 to 4-leaf stage. Best control when applied before the 3-leaf stage.

Wild oat control with Hoelon is increased by cool temperatures following application, but reduced on moisture-stressed wild oats. Increasing the rate used can somewhat overcome the latter problem.

Do not apply to barley after tillering or in cool, wet conditions. Hoelon is sensitive to many broadleaf treatments, but can be tank mixed with Buctril or a low rate of MCPA ester plus Buctril.

TILLER(fenoxaprop, MCPA ester, 2,4-D ester) -- Apply after spring wheat begins to tiller (3-4 leaf stage) but prior to jointing (6-leaf) for control of wild oats and larger foxtails (3-leaf to 2-tillers). To decrease injury potential, do not apply after spring wheat jointing.

Do not apply to durum, barley, oats or rye. Tiller can be applied by air. Do not apply more than one application per season, or within 70 days of harvest. Can be tank mixed with Stinger, Buctril, and Tordon.

For any herbicide treatment, follow label rates and directions. Contact a dealer or your county extension educator for more specific information on controlling wild oats, and managing for herbicide resistance.

Copyright Prairie
Grains Magazine
Spring 1995