Cropland, Pasture

Wild Oat (Avena fatua)

Monica Pokorny

Richard Old, Bugwood.org Papery membrane at base of blade.

USDA PLANTS Database Seed with bent, twisted awn.

Steve Dewey, Bugwood.org Wild oat plant

Identification and Life Cycle. Wild oat is an introduced annual grass (Poaceae). The seedling leaves are slightly hairy and twisted counter-clockwise. Hollow stems grow 1 – 4 feet tall or taller. Leaf blades are flat, 8- 12 in. long, broad (0.5-0.75 in. wide), and have tiny hairs on the leaf blade margins. A papery membrane is visible at the base of the leaf blade. The fruiting head has drooping spikelets in a loose, open panicle. Each spikelet has a pair of large papery scales. Flowering and seed production is from June to August. All seeds have a dark, bent, twisted awn about 1 inch long. Seeds are hairy at the base with a circular scar at the point of seed attachment. Wild oat has an extensive, fibrous root system. Cultivated oats resembles wild oats but wild oats are much larger and have long bent awns.

Habitats. Wild oats occurs in croplands and disturbed areas such as grain fields, oilseed crop fields, fallow fields, roadsides, waste places, and gardens.

Impacts. Wild oat infestations reduce crop productivity through competition and decrease the grain quality. Infestations also lead to increased costs for grain cleaning and weed control. Long awns on the seed can injure livestock. Wild oats is also an alternative host for virus diseases of grains and alfalfa.

Biology and Ecology. Wild oats most commonly germinate in the spring or autumn, but it can germinate throughout the growing season during cool, moist conditions. Roots and shoots develop quickly. Flowering may last up to 6 weeks, with seed-set and seed shedding occurring over a prolonged time. Plants reproduce by seed with each plant producing 20 to 250 seeds. Seeds are initially dormant and most germinate in the first and second spring but some can remain dormant and viable for up to 12 years. Seeds are shed around the parent plants and dispersed during harvesting. Cultivated oats and wild oats hybridize readily.

Management Approaches

Biological Control. None

Mechanical and Cultural Control: Plants can be managed with cultivation at germination and before seed-set. Tilling is most effective at the 3-leaf growth stage. Mowing can prevent seed-set in heavy to moderate infestations. Burning windrows of straw immediately after harvesting can reduce viable seeds as seeds are not tolerant to high temperatures. Competitive, autumn-seeded crops such as fall rye and winter wheat can reduce wild oat infestations on cropland, especially if a dense cover crop establishes. Forage crops used in a crop rotation also are effective. A competitive stand of perennial vegetation will discourage wild oats on pastures.

Chemical Control: Numerous herbicides are registered for wild oats control. Overuse of some herbicides has resulted in a major increase in herbicide resistant populations.

Example of herbicides that can be used to manage wild oats. Consult herbicide labels for additional rate, application and safety information. Additional herbicide information can be found at http://ces.uwyo.edu/WeedManagementHandbook.asp

Herbicide Trade Name chemical name	Product per Acre	Comments
Croplands
Aatrex^R atrazine	3.2 – 4 pt/ac	In corn and sorghum, apply preplant surface (up to 45 days before planting - MT or WY), or preplant incorporated, at planting, preemergence, or postemergence before crop is 12 in. tall or weeds exceed 1.5 in. height.
Assert imazamethabenz	1.2 –1.5 pt/ac	Apply when wild oats are in the 1- 4 leaf growth stage and from the 2-leaf to internode stage for barley and wheat.
Assure II quizalofop	5 – 12 oz/ac	In alfalfa, apply when grasses are small (2 – 8 inches tall). In canola, dry beans, peas sugarbeets and lentils apply within height ranges specified on label. For best results, apply when grasses are in the 3-leaf to early tillering stage.
Avenge difenzoquat	2.5– 4 pt/ac	In small grains apply when wild oats are in the 3- to 5-leaf stage.
Basis Gold rimsulfuron + nicosulfuron + atrazine	14 oz/ac	In corn and sorghum apply when weeds are 1– 3 inches tall. Corn: up to 12 inches tall or 6-collar stage.
Clarity dicamba	0.5– 1 pt/ac (corn); 0.5 pt/ac (sorghum)	Corn: preplant, preemergence, or early postemergence before crop is 5-leaf stage or 8 in. tall. Or, late postemergence when weeds are small and corn is between 8 –36 in. Sorghum: preplant, or after crop is in the spike stage but before 15 in.
Discover clodinafop	3.2– 4.0 oz/ac	In wheat and barley apply to actively growing weeds at the 2-leaf to pre-boot stage. Do not apply to winter wheat in fall.
Dual Magnum metolachlor	1 – 2 pt/ac	In peas and lentils apply preplant incorporated or preemergence in spring.
Eptek, Eptam EPTC	2.25–4 pt/ac Eptek; 3.5– 4.5 pt/ac Eptam	Apply and incorporate Eptek just before planting alfalfa, or apply to established stands (metered into the irrigation water) prior to weed emergence. Use lower rates on very coarse textured soils. In dry beans and safflower apply Eptam preplant incorporate or lay-by incorporated treatment.
Everest flucarbazone-sodium	0.41– 0.6 oz/ac	Apply to spring wheat when the majority of plants have1 leaf to a maximum of 4 leaves on the main stem plus 2 tillers. For winter wheat apply either in the fall or spring when the majority of the plants have between 1 and 6 leaves on the main stem plus 2 tillers.
FarGo	3 pt/ac	In sugarbeets preplant incorporated spring or fall.
Gramoxone Max^R paraquat	1.3 – 2.7 pt/ac	In peas and lentils apply to seedbeds before, during, or after planting, but prior to crop emergence.
Hoelon diclofop methyl	2– 2.66 pt/ac	In wheat and barley apply when the wild oat or green foxtail are in the 1- to 4-leaf stage.
Kerb pronamide	1 – 4 lb/ac	Apply in the fall to new fall- or spring-planted forage legume seedlings after they have reached at least the trifoliate leaf stage, or, apply to established forage legumes in the late fall or early winter after soil temperature falls below 55º F, but before freeze-up.
Liberty glufosinate	28– 34 oz/ac	Apply between dawn and 2 hours before sunset. Apply until corn is 24 in. tall or in the V-7 stage.
Lightening imazethapyr + imazapyr	1.28 oz/ac	In corn and sorghum apply early postemergence when most weeds are actively growing and generally 1 to 3 inches tall.
Poast sethoxydim	1.5–2.5 pt/ac (canola); 0.5–1.5 pt/ac (dry beans); 0.5–2.5 pt/ac (peas, lentils, potatoes)	In canola, peas, lentils, potatoes and dry beans, apply to actively growing grasses at the stage of grass growth indicated on the label.
Princep simazine	2.2– 4.4 lb/ac	In corn and sorghum apply before, during, or after final seedbed preparation, but before weeds and crop emerge.
Puma fenoxaprop	0.66 pt/ac	Apply to wheat from the 1-leaf to recommended days before harvest. Apply to barley from crop emergence up to the 5-leaf stage. Do not apply after jointing.
Raptor imazamox	4 oz/ac	In dry beans apply postemergence after crop has at least one trifoliate leaf and weeds are < 2 inches. In peas and lentils apply by indicated growth stage.
Roundup and Roundup UltraMax glyphosate	12 oz–5 qt/ac	Apply to actively growing weeds before planting, or any time prior to emergence of crop.
Scythe pelargonic acid + related fatty acids	3 – 10 % by volume	Apply to small emerged weeds prior to crop emergence or after harvest.
Select, Arrow, Prism clethodim	Prism: 13–34 oz/ac; 6 –16 oz/ac Select, Arrow	Applied to seedling or established alfalfa. In alfalfa, potatoes, sugarbeets and dry beans apply postemergence to weeds that are actively growing and at the appropriate growth stage listed on the label.
Sencor metribuzin	Alfalfa: 0.33–2 pt/ac; peas, lentils, grass seed: 0.25-.75pt/ac	Apply in fall or spring when alfalfa is dormant. In peas and lentils preemergence applied after or before seeding; or apply postemergence when weeds are < 2 inches high but before crop is 6 inches tall. In grass seed, apply when crop is dormant and prior to active spring growth.
Tiller fenoxaprop + 2,4-D +MCPA	1.0– 1.7 pt/ac	Apply to spring wheat from the beginning of tillering or to winter wheat with a minimum of 3 tillers. Apply prior to jointing in both.
Treflan trifluralin	1–2 pt/ac	In canola, apply preplant incorporated in the spring (Utah, Wyoming, and Montana) or in the fall (Utah and Wyoming). In peas and lentils apply preplant incorporated in the spring.
Pasture, Rangeland, and Non-crop areas
Roundup glyphosate	12 oz – 5 qt/ac	Apply to actively growing weeds.
^RRestricted Use Product.
Disclosure. The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

Categories: Weed, Crop, Pasture

Date: 11/28/2007