Promoting Canadian Oats


Seed treatments may be used to prevent seed and soil borne diseases, especially smut. The practice of seed treatment is a farm decision and is often key to a successful oat crop. Variety breeding strategies, and on farm production strategies are like a hand and a glove. They both are part of the success story on the farm.

It might be good for growers to know that oat breeding programs in general, never use seed treatments in the years of the oat breeding cycles. Number 1 it would be very difficult to treat the thousands of envelopes of seed used each spring, number 2 all envelopes are handled closely so personal safety would be a concern, number 3 and perhaps the most significant factor to variety development, is the reality that if the breeding program allows nature to take its course regarding soil and soil microorganism impact on the oat breeding seed populations, the strongest oat varieties emerge.

Soil borne diseases such as root-rots are likely to be larger problems in cool, wet growing conditions in the spring. Hulless oats are more susceptible to seed diseases and are recommended to be treated with a seed treatment.

2017 Alberta guide to crop protection:$Department/deptdocs.nsf/all/agdex32/$FILE/606-1.pdf
2017 Saskatchewan guide to crop protection:
2017 Manitoba guide to crop protection


The importance of seed size of the seeded oat crop has been a topic of conversation for many years. Growers have their own sense of the nature and amount of grain that they wish to seed per acre. It is might be easy to think that larger seed would be stronger and better but oat specific research on the matter has been said to be limited.

From the 2005 SEED SIZE research article on the following page:

“Our results clearly demonstrate the importance of initial caryopsis [grain] size to the outcome of wild oat-oat competition, and suggest that the ability of oat to exhibit both and increased competitive response and effect to wild oat competition may be a product of specific crop traits such as caryopsis [grain] size.”

As the experiments on seed size were conducted in a greenhouse, the authors comment that:
“further investigation is needed to examine the response of oat-wild oat competition to oat caryopsis [grain] size and genotype under field conditions.


Caryopsis – also called grain, specialized type of dry, one seeded fruit characteristic of grasses and cereals
Genotype – the genetic makeup of an organism, the sum total of its genes, both dominant and recessive


Early seeding can result in increased yield and test weight. It may also result in higher quality in areas that have frequent fall moisture. However, early seeding may also result in the oats emerging at the same time as or after wild oats emerge. This may result in reduced yields and lower quality due to wild oat contamination.

Optimum seeding dates will vary province to province. The growers own understanding of the current season that is being experienced, typical climate, the soil zone, long term experience etc., all work to guide the timing of seeding.


Oats are usually seeded with a row spacing of 18-30 cm (7.5-12 inches). Research has indicated that there is very little differences in yields over a number of years within these row spacings. However, wider row spacings may result in an increased problem with wild oats and other weeds in oats.

As there is no chemical control for many grassy weed species, care must be taken using wider row spacing. In addition, wider row spacing may result in difficulty managing swaths in dry conditions as there may not be enough stubble to hold the swath off the ground.

RESEARCH PAPER (2005): Crop Science 45: 1410-1416 (2005)

“Oat Caryopsis Size and Genotype Effects on Wild Oat-Oat Competition”

Christian J. Willenborg1, Brian G. Rossnagel2, and Steven J. Shirtliffe3*.

  1. Dep. of Plant Sciences, Univ. of Saskatchewan
  2. Crop Development Center, Univ. of Saskatchewan
  3. Dep. of Plant Sciences, Univ. of Saskatchewan, *Corresponding author

“Wild oat competition causes extensive yield and quality losses in… oat”

“Traditionally, wild oat was controlled by delaying planting so that emerged wild oat could be controlled by tillage. However, delayed planting of oat causes substantial declines in grain yield, test weight, plump seed and groat percentage with a corresponding increase in thin seed percentage.”

“A key component of integrated weed management systems is to grow competitive varieties.”

“Our main objective was to assess the relative importance of oat caryopsis [grain] size and genotype in affecting wild oat-oat competition in the greenhouse….We conducted this study in a greenhouse because it provided us with a high degree of experimental control, repeatability, and precision, allowing us to isolate the effects of seed size on oat competitive ability.”

This greenhouse study was conducted during 2002 and 2003 at the University of Saskatchewan at Saskatoon. AC Assiniboia, CDC Boyer and CDC Orrin were the varieties used. All seed was sourced from the same location. The seed groupings LARGE, MEDIUM and SMALL were determined on the basis of the groat size to eliminate the effects of the size of the hull.

“Oat derived from large caryopses [grain] produced 17% more biomass and 15% more panicles per m2 than plants derived from small caryopses, irrespective of genotype or wild oat competition. Similarly, plants established from medium-seeded caryopses produced 11% more biomass and 9% more panicles than from plants established from small caryopses.” It was noted that statistically, the large and medium effects were not significantly different from each other.

RESEARCH PAPER (2004): Canadian Journal of Plant Science (2004) 84: 431-442

“Early seeding dates improve oat yield and quality in the eastern prairies”

William E. May1, Ramona M. Mohr2, Guy P. Lafond1, Adrian M. Johnston3, and F. Craig Stevenson4.

  1. Agriculture and Agri-Food Canada, Indian Head Research Farm
  2. Agriculture and Agri-Food Canada, Brandon Research Centre
  3. Potash & Phosphate Institute of Canada
  4. Private Consultant

“Traditionally, oat (Avena sativa L.) was the last crop seeded on farms in western Canada. Oat could be planted last and still be harvested or used as fodder depending on needs. The late seeding allowed farmers the opportunity to control wild oat (Avena fatua L.) in tame oat with tillage prior to planting. The harvested oat tended to be consumed locally with little attention paid to quality.”

“There have been many changes in cropping practices on the prairies since the early studies in western Canada, the most significant being the introduction of one-pass seeding and fertilizing conservation tillage systems. These new production systems increase the amount of winter precipitation that is captured by the soil, resulting in higher yield and economic return. This increase in available water may increase the yield and quality of oat since oat requires more water than the other cereals.”

In this study, conducted during 1998 to 2000, 3 locations were used: Brandon, Indian Head, and Melfort. AC Medallion, AC Juniper, CDC Boyer, and CDC Pacer were the varieties tested. Four seeding dates were chosen: early May, mid May, early June and mid June, and the target dates of these were May 01, May 15, June 01 and June 15.


  • Delayed seeding decreased the yield of all four varieties.
  • Disease resistance matters as it maintains plant health and the ability to continue using moisture for growth, while susceptible varieties suffer a decline during mid summer dampness.
  • “Two [related (1968 & 1990)] studies found that higher temperatures during development reduced seed yield.”
  • “Delayed seeding increased thin seed percentage at most locations;”
  • “Results from this study clearly show that oat producers can grow more high-quality oat if seeding is conducted in the first 2 weeks of May.”


A plant population of 20-30 plants/ft2 is desired. Seeding rates can be calculated using Thousand Kernel Weight.

Situations that require seeding rates at the higher end of the range stated above would include:

  • High fertility
  • Optimum moisture
  • Late seeding (to reduce tillers)
  • High wild oat populations anticipated

Additional on information SEEDING RATE from the research paper discussed above.

“Early seeding dates improve oat yield and quality in the eastern prairies”

RESEARCH PAPER (2004): Canadian Journal of Plant Science (2004) 84: 431-442

During the course of the experiment in this research paper a 5% field mortality was used to adjust the target plant population to 300 plants per square metre (~28 plants per square foot) of viable seeds (including adjustment for germination).

“However, field mortality for the experiment ranged from 18 to 33% …. Our results indicate that oat seeding rate recommendations should factor a field mortality rate of 20 to 30% in order to achieve a target plant population.”


Seed depth should only be deep enough to reach soil moisture and never deeper than 8 cm (3”). In direct seeding and where seedbed moisture is optimum, seed depth should be targeted towards 2-3 cm.

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