Oats, Wild


Pest Information
Common Name: Oats, Wild
Family Name: Grass
Latin Name: Avena fatua
Provincial Designation: Common
Life Cycle: Annual
Mode of Spread: Seed

Detailed Information
Provincial Situation: In Alberta, it is present in almost municipalities from Letbridge to Fort Vermillion. It is most prevalent in the Black, Dark Brown and Grey-wooded soil zones (Table 1) Table 1. Relative abundance and ranking of wild oats in various agricultural ecoregions of Alberta
Agricultural EcoregionRankFrequency1 (%)Uniformity2Density3 (m-2)Relative Abundance
Mixed Grassland141.429.87.368
Moist Mixed Grassland138.834.413.554.1
Fescue Grassland15035.56.546.4
Aspen Parkland352.641.911.534.2
Boreal Transition35040.89.227.1
Peace Lowland935.829.8613.9
Alberta (All regions)245.637.710.133.1


1 Frequency = Percent of fields in which wild oats occurred
2 Density = Average number of wild oats in occurrence fields.
3Uniformity = percent of quadrates in which wild oats occurred
Source: Thomas et al (2002). Alberta Weed Surveys. Cereal, Oilseed and Pulse Crops 2001s.

Growth and Development (Life Cycle): Emergence: Most wild oat germinates and emerges in early to mid spring. Cool wet conditions promotes maximum emergence, so crop that are seeded early are usually the most heavily infested. Fall or early spring applications of nitrogen fertilizer simulate germination. Growth of roots and shoots of wild oats is slow for the first 2 weeks, but increases quickly from then on. Most wild oats tillers within a month of emergence.
Seed Production: In the absence of competition, average seed production is 100-150 per plant; however, under severe competition it is only 20-30 seeds per plant.
Seed germination: The optimum soil temperature for the germination of wild oats is between 16 and 22 degrees Celsius. Germination is slow at 4 degrees Celsius and very slow at 33 degrees Celsius. Most germination occurs at depths of 2 to 5 cm if soil moisture is adequate. However, if the surface layer is dry, germination can occur at depths up to 20 cm. The wild oat seed will not germinate while exposed to light; it must be buried. Seed can be buried naturally by wind drifted soil, soil washed by water or through its unusual self-burial process. When wild oat seed is moistened, the awn unwinds. As the seed dries out the awn twists again. Alternate wetting and drying enables the wild oat to bury itself, thereby satisfying one condition for germination.
Dormancy: Mature seeds of wild oats are usually dormant when they shatter. Dormancy is broken by warm, dry conditions after the seeds ripen. If moisture is available when dormancy is broken, the seeds will germinate; otherwise they become dormant again. (a)
Longevity in the soil:
Dispersal:
Reproduction (Dispersal): Seed: Mature seeds of wild oats are usually dormant when they shatter. Dormancy is broken by warm, dry conditions after the seeds ripen. If moisture is available when dormancy is broken, the seeds will germinate; otherwise they become dormant again. The annual rates of seed germination are: The spring following seeding - up to 80 per cent. The second spring following seeding - up to 97 per cent. The remaining 3 per cent may have what is termed deep-seated dormancy and can germinate for up to 12 years.
Vegetative:Though not a major method of reproduction, wild oats are capable of vegetative regeneration. Wild oat plants can be transplanted and regrown if cultivation is incorrectly or incompletely carried out, and field and weather conditions are good for plant growth. Even severely injured (mutilated, sectional or segmented) wild oat plants are capable of vegetative propagation.
Origin: It was introduced in Canada from Europe in the early 1800s.
Flowering: Wild oats usually start to flower in early July and may continue to flower for up to six weeks. Seeds at the tip of the main axis of the panicle may ripen and fall to the ground before the seeds at the base are filled. Seeds shatter as they mature and are shed by mid-August, generally before the crop is harvested.
Yield Losses: Competition is greatly influenced by the relative emergence dates of wild oats and the crop. If wild oats emerge before the crop, yield losses are greater than when the crop emerges first. Density and rates of growth of the weed and the crop alone influence competition. Increased growth rates and densities of wild oats increase crop yield losses. The following table shows the estimated yield losses caused by various densities of wild oats in four crops. The actual losses may vary from year to year depending on climatic conditions.
Agricultural EcoregionRankFrequency1 (%)Uniformity2Density3 (m-2)Relative Abundance
Mixed Grassland141.429.87.368
Moist Mixed Grassland138.834.413.554.1
Fescue Grassland15035.56.546.4
Aspen Parkland352.641.911.534.2
Boreal Transition35040.89.227.1
Peace Lowland935.829.8613.9
Alberta (All regions)245.637.710.133.1


*The time of emergence information was developed experimentally for barley and wheat only. However, it may also be accurate for canola and flax. Add or subtract the appropriate number for every day wild oats emerge before or after the crop. For example, if wild oats at 2 plants per square foot emerge 3 days before barley, the yield loss changes from 11 to 14 per cent.

How to Control: Tillage: Tillage is not compatible in direct seeding system. However, in intensive tillage systems tillage can be used to reduce wild oats populations.
Summer fallow: Summer fallow increases the number of seeds that break dormancy. A new stand of wild oats will emerge after each tillage operation. Summer fallow can be grazed to control wild oats. Seed fall crops in the same year as the fallow to provide competition against wild oats that germinate in the spring.
Pre-seeding tillage :Till as early as possible after spring thaw. This warms and aerates the soil and stimulates early germination of wild oats. Early tillage of heavy, wet soils is particularly important. Tillage prior to seeding should be done before weeds reach the three-leaf stage. This minimizes the moisture and nutrients they use. Tillage should be to a depth of 2.5 to 5 cm during warm, dry weather so the wild oats cannot re-establish. Post-seeding tillage -
Post-seeding tillage:Post-seeding tillage is valuable because wild oats that emerge before the crop are more competitive than those that emerge with or after the crop. Till before crop emergence to prevent any crop damage. A shallow cultivation with a rod-weeder or harrows will eliminate wild oat seedlings. Fall tillage - Fall tillage is useful if wild oat seeds have been exposed to two or three weeks of warm dry weather. A shallow tillage will lightly cover wild oat seeds and promote early germination in the spring. A cultivator is more suitable than a discer or harrow. If fall weather is cool and moist, avoid tillage so that dormant wild oat seeds remain on the surface exposed to the elements.
Mowing: When an infestation of wild oats is moderate to heavy, and the crop is of low density, mowing is an effective preventive measure. Wild oats should be mowed at the shot-blade stage. Early mowing can result in wild oat regrowth and seeds can still be produced. Mowed wild oats can be used for greenfeed or, if some of the seeds have set, for silage. The fermentation process will destroy wild oat seed viability.RotationFall-seeded crops emerge early the next spring and can smother the emerging wild oats. Fall rye is generally more vigorous and competitive than winter wheat. Land seeded to perennial forage for three or more years can provide good control for heavy infestations of wild oats. However, some wild oat seeds can survive under sod and germinate when the sod is broken. A green-feed crop such as oats can be seeded early to enable a competitive advantage over the wild oats. To prevent weed seed production, cut the crop before the panicles of wild oats start to emerge from the sheath. Silage effectively destroys any seeds produced. Use annual crops in the rotation, especially the more competitive crops so that yield losses are minimized and the wild oats are suppressed. In descending order, barley, canola and wheat are the most competitive small grains.Delayed seedingDelay seeding to allow time for wild oat seedlings to be destroyed by tillage before or at seeding. Seed an early maturing crop such as barley. Yields may be reduced if seeding is delayed by more than 10 to 14 daysHeavier
Seeding rate: Research carried out at Lacombe Research Station has shown that a high seeding rate reduces wild oats populations
Chemical Control: Spring Pre-seeding Weed Burndown Application: In direct seeding system, emerged wild oats can be controlled in the early spring with the use of burndown herbicides, provided weeds are small, actively growing and environmental conditions are favorable for herbicide uptake and translocation
Herbicide resistant crops: The use of herbicide resistant crops such as Roundup Ready canola, Liberty Link canola and CLEARFIELD canola and wheat provides another option for the control of wild oats. For best results, applications should be made early, when wild oats are in 1 – 4 leaf stage In-crop Application Large number of herbicide are available for selective control of wild oats in cereals, oilseed and pulse crops. For detailes on these herbicide see Herbicide Selector Tool on Roping the Web


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Last Modified: 2011-12-22 11:16:57.894

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