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Wild Oats

Pest Profile: Wild Oats

One of the leading weed pests in Western Canada, wild oats are grassy annual weeds prone to the development of herbicide resistance. Their seeds can persist in the soil for up to a decade and can be toughest to deal with during wet years, when they emerge from the soil in large numbers.
Wild Oats

TYPE

  • Annual
  • Grassy

IDENTIFICATION

Plants grow up to 5 feet tall with smooth, erect stems. The head is an open panicle with spikelets typically containing 2 – 3 florets (and occasionally up to 7). The panicle may contain up to 250 seeds, ranging from black, brown, grey, yellow to white. At the seedling stage, the plant has a counter-clockwise leaf twist and no auricles, with hairs on the leaf margins.

KEY CHARACTERISTICS

Common in cultivated agricultural land. 

Germination:  

  • Optimum temperatures between 16 – 22 ℃. Slows at <4℃ and >33℃. Generally, from 2 to 5cm depths assuming adequate moisture. 
  • Seeds will not germinate if exposed to the sun, they must be covered.
  • Wild oat seeds tend to germinate within two years, but they can remain viable in the soil for 8± years

Seed Production: 

  • With the presence of crop competition 20-50 seeds/plant. In absence of competition up to 250 seeds/plant.

Seed Dispersal: 

  • Mature Wild oat seeds will fall from panicle of the parent plant. 
  • Newley produced seeds are typically dormant. Dormancy is broken by temperature, and if adequate moisture the seeds will germinate. Dry conditions will cause the seeds to return to a dormant state.

Root System: 

  • Fibrous

PLANT GROWTH

Key distinguishing features: 

  • No auricles, a membranous ligule  and a counterclockwise leaf twist as seedling. A tall stem that can reach up to 4 feet. At maturity, Wild oat seeds have a distinctive 3-4 cm long, black awn.

Leaf Structure: 

  • Long slender leaves. Leaf blade margins have short hairs, most prominent close to the base.

Scouting ID: 

  • If ever in doubt, dig out the plant and identify the seed.

CONTROL TIPS

  • When scouting, check low spots in fields for wild oats, and keep an eye out for herbicide-resistant patches.
  • Summerfallow increases the number of seeds that break dormancy, and weeds will emerge after each tillage operation. Fall tillage also helps reduce wild oat populations.

RESISTANCE OVERVIEW

  • Repeated use of the same herbicide groups, lack of crop rotation, and the adoption of herbicide-tolerant crops have led to increasing herbicide resistant populations of Wild oats. 
  • New research indicates that tank mixing herbicides with multiple sites of action is better at delaying herbicide resistance than rotating herbicide sites of action annually (Renton et al., 2024).

CONFIRMED HERBICIDE RESISTANCE

Confirmed herbicide resistance to: 

  • Group 1 ACCase inhibitors
  • Group 2 ALS Inhibitors
  • Group 14 PPO Inhibitors
  • Group 15 Inhibitors of cell growth and division. 

REPORDUCTIVE BIOLOGY

  • Most Wild oats self-pollinate, but a small fraction (1-2%) are cross pollinated by wind.
     

TRENDS

  • 10 Wild oats/m² left untreated can reduce yield by 10%.
  • Wild oats that emerge before the crop, present a greater yield loss potential.
  • The spring after Wild oat seed production typically sees 80% of seeds germinate. The second spring generally has up to 97% of the seed germinate.

ADAMA PRODUCT OPTIONS

Crop Product  Group
Wheat CAZADO®  Group 1 & 2
BRAZEN®  II & BRAZEN ALL IN®  Group 1
LADDER ALL IN®  Group 1
Barley BRAZEN®  II & BRAZEN ALL IN® Group 1
Canola (All Types) ARROW ALL IN® Group 1
LEOPARD® Group 1
Canola (Glufosinate tolerant varieties only) ADAMA Glufosinate 150 SL Group 10
Peas, Lentils, Dry Beans & Soybeans (All types)  ARROW ALL IN® Group 1
LEOPARD® Group 1
SQUADRON® (peas & lentils only) Group 5
Peas, Dry Beans, Soybeans & Imi-tolerant Lentils (ie: Clearfield)  DAVAI® 80 SL  Group 1
DAVAI® A PLUS  Group 1 & 2
DAVAI® Q PLUS  Group 1 & 2
Peas, Soybeans & Dy Beans  PHANTOM® 240 SL Group 2
PYTHON® Group 2 & 6

Always read and follow each label to determine which herbicide is appropriate for the crop affected. 

INTEGRATED PEST MANAGEMENT PLAN

Effectively manage herbicide resistant Wild oats.

Seeding Rates: Increase seeding rates to promote crop competition.
Crop Rotation and Competition: Ensure adequate crop rotation to promote effective chemical rotations, plant, and soil health. Plant crops that grow quickly and densely, such as barley or canola, to out compete Wild oats for nutrients, water, and light. Seed as early as the soil is fit.
Tillage: Use strategic tillage in areas with suspected resistance. Spring tillage is more effective than fall tillage at reducing Wild oat emergence. Tillage can bring seeds to surface and expose to sunlight and move seeds into the drier surface soils.
Cultural Tactics: Methods such as mowing, burning, or using cover crops, to help prevent Wild oats from setting seed.
Herbicide Rotation and Mixtures: Rotate herbicide mixtures and use different modes of action. Combine herbicide groups, or use combination premixes, when possible, to help ensure no seed production occurs. Ensure correct timing of herbicide applications for optimal Wild oat control.
Keep Records: Track what you’ve done and record successes and failures.
Scout Fields: Regularly monitor fields for weed emergence patterns and herbicide performance. Look for irregularly shaped weed patches or patches with no clear boundary, which could indicate herbicide-resistant Wild oats. 

REFERENCES

Government of Alberta. (2011). Wild, Oats. Retrieved January 21, 2025, from https://www.agric.gov.ab.ca/app107/loadPest?action=display&id=90

 Government of Manitoba. (n.d.). Volunteer barley (Hordeum vulgare). Retrieved January 21, 2025, from https://www.gov.mb.ca/agriculture/crops/weeds/volunteer-barley.html

 Renton, M., Willse, A., Aradhya, C., Tyre, A., & Head, G. (2024). Simulated herbicide mixtures delay both specialist monogenic and generalist polygenic resistance evolution in weeds. Pest Management Science.

Saskatchewan Pulse Growers. (2023). Weeds to watch: Wild oats. Retrieved January 21, 2025, from https://saskpulse.com/resources/weeds-to-watch-wild-oats/?download-pdf

 Western Grains Research Foundation (WGRF). (2023). Herbicide-resistant weed management: Factsheet. Retrieved from https://www.prairieweeds.com/wp-content/uploads/2024/05/2024_WGRF_ICAC_Factsheet.pdf

 Integrated Weed Management (IWM). Resource Center. (2024). Tank mixing or herbicide rotation: Which strategy is best? Retrieved January 21, 2025, from https://growiwm.org/tank-mixing-or-herbicide-rotation-which-strategy-is-best/

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