Oats is a small-acre crop that has tended to fall behind in terms of agronomy research. That’s changing as more oat varieties become available and new niche markets continue to develop and offer premiums to growers meeting their specifications. For anyone trying oats for the first time, or considering adding oats to their rotation, Grainews has rounded up the latest oat-related agronomy information.
1. Diseases in oats
One of the most pressing issues for growers is disease resistance, in particular resistance to crown rust, which is especially prevalent in Manitoba and some areas of south-east Saskatchewan. “We’re seeing more crown rust in oats and the genes that we have been using up until now for resistance seem to be breaking down,” says Jennifer Mitchell Fetch, an oat breeder at Agriculture and Agri-Food Canada’s (AAFC) Brandon Research and Development Centre in Manitoba. “We are monitoring the races that are coming up through the United States because we need to stay ahead with genetic resistance.”
Crown rust can reduce yields and increase lodging. The disease bearing spores can be blown in from the southern U.S., and can also be produced locally on buckthorn bushes, the alternate host, where the fungus can undergo crossing and changes in genetics.
It’s important to know the resistance rating of the seed you’re planting and choose the most resistant varieties if they are in an area prone to crown rust.
Don’t jump the gun on fungicides. “There are some oat variety cultivars like AC Morgan that are susceptible to disease and growers should pencil in a fungicide application when growing them, but there are others that have good disease packages and fungicides aren’t going to be of benefit to them,” says William May, a research scientist at AAFC’s Semiarid Prairie Agricultural Research Centre at Indian Head, Saskatchewan. May’s research has found that the use of a fungicide did not increase the oat’s ability to yield when the oat was not susceptible to disease.
- Read more: New oat varieties on the horizon
Only consider applying fungicide when the yield potential and value of the crop is high, and when leaf diseases develop early in the season and continued moist weather conditions are forecast. The best time to apply fungicide is at the late flag leaf to boot stage. Provincial Crop Protection Guides provide details of registered products.
Researchers are also keeping an eye on barley yellow dwarf virus (BYD) which seems to be spreading northwards through the Central Great Plains. “There seems to be more BYD occurring in the southern part of Minnesota,” says Mitchell Fetch. “I don’t know if that’s something we need to worry about coming into Manitoba with a vengeance. It’s transmitted by infected aphids that get blown up into Manitoba and if conditions are milder we don’t know if they will be able to over-winter There’s a lot of those things that are unknown.”
2. Weed Management
Oat growers are urged to use many different control options to help manage weeds. Wild oats remain a major concern for oat growers and there are still no herbicide products registered for in-crop wild oat control. Careful field selection is important — only plant oats in fields that have low wild oat populations. If growers plan their rotations well in advance, they can control wild oat populations in preceding crops. Farmers can use tillage or herbicides to control the first flush of wild oats just before emergence of the oat crop or can delay seeding until after the wild oats have emerged and been controlled. But under drier summer conditions, farmers should expect yield and quality loss if seeding is delayed. There can also be more than one flush of wild oats anywhere from May through to mid June. Higher seeding rates and banding fertilizer adjacent to the seed can increase plant populations and make them more competitive, but growers should choose varieties with good lodging resistance as there is a higher risk of lodging at higher seeding rates.
Herbicides containing 2,4-D should be avoided on oats as they have been shown to cause considerable yield reduction. Products containing dicamba should be used according to the stage restrictions on the label and should be avoided under stress conditions.
3. Seeding oats
Seeding oats earlier generally results in increased yields and quality, although optimal dates vary by location. In general, seeding by the middle of May in Manitoba, Saskatchewan and southern Alberta will give optimum yield and quality. Soil temperature should be above 5 C.
Seed treatments can help prevent soil borne diseases such as smut, and in cool, wet growing conditions will also help prevent root rot. Seed treatments are recommended for hulless oats as they are more susceptible to seed diseases. (See the POGA website at poga.ca for information about registered seed treatments for oats).
Seeding rates recommended by Canadian oat researchers vary from 300 to 325 plants per square metre (28 to 31 per square foot) with some data suggesting that seeding up to 375 plants per m2 (36 per ft./sq.) may help control wild oat and achieve uniform, high yielding stands. However, some producers report good yields with a seeding rate as low as 220 plants per m2 (22 plants per ft./sq.).
Seeding rates can be calculated based on the intended plant density, thousand kernel weight (TKW) and per cent survival (the percentage of seeds expected to germinate and produce vigorous seedlings). For example, under normal conditions growers should expect around 95 per cent germination, but if planting in cold, wet soil, they should reduce the expectation to 90 to 93 per cent germination because three to five per cent of the viable seed will likely not produce a plant.
The thin seed coat of hulless oats make them more fragile, which can lead to lower germination. Hulless oat growers may need to increase the seeding rate to achieve a minimum plant population of 300 to 325 plants per m².
Oats should be seeded at a depth of one to two inches — just deep enough to reach soil moisture — and never deeper than three inches.
Oats are usually seeded with a row spacing of 7.5 to 12 inches but research has shown that in no-till systems a wider row spacing up to 14 inches has no detrimental effect on plant numbers or tiller development, although wider row spacing may result in an increased problem with wild oats and other weeds.
4. Fertilizing oats
Nitrogen is the most yield limiting factor in oats. There has been a lot of research into optimum N rates, which vary according to location. A soil test is always recommended to allow growers to accurately calculate the amount of N they need to apply.
Too much N will reduce test weights, plump kernels and increase lodging; too little N will reduce tillering and yield.
Water availability is crucial to oat yield and is closely tied to the N rate. Research at the University of Montana has shown it takes four to five inches of water to produce the first bushel of oats, after which yield increases by 12 to 14 bushels per acre with each inch of additional water. The more moisture that is received, the more N will needed to achieve the increased yield potential. Under these circumstances a 100 bu./ac. crop of oats will require 97 to 117 lbs./ac. of N.
Research done by May and others has shown that under normal conditions around 89 lbs./ac. total N (soil + applied) provided optimum yields, which translates to between 36 to 71 lbs./ac. of applied N depending on the soil residual.
A phosphate (P) application may be necessary in certain situations such as on newly broken land, fallow fields, or early seeding into cold, wet soils. Again, soil testing will determine phosphate levels in the soil. An application of 18 to 28 lbs./ac. applied with the seed is usually adequate to produce optimum yields.
Oat response to potassium (K) usually occurs when soil test levels are below 280 lbs./ac., and soils that are sandy to sandy-loam or poorly drained are more prone to K deficiency. In cold, wet soils, an application of 15 lbs./ac. of K chloride (0-0-60) in the seed row, even when soil test levels are sufficient, may result in a crop response. Applications higher than18 lbs./ac. should be side-banded or broadcasted to avoid seedling damage.
Oats have one of the highest requirements for sulphur (S) so soils which test low in S may require an application of sulfate to correct the deficiency if growers want to obtain optimal yields.
Recommended fertilization rates for specific areas can be found on provincial government and POGA’s websites.
5. Harvesting oats
Most oats are swathed and then threshed by a combine with a pickup attachment to avoid losses from shattering; growers need to be careful with timing to avoid damage to oat hulls that can reduce yield and quality. There can be a lot of variability in maturity across the field but generally oats are ready to swath when moisture content is about 35 per cent and the greenest kernels have changed to a cream colour.
Swathed oats should be threshed as soon as they reach the correct moisture level. Oats left too long in the field can weather, resulting in lower quality, and will shatter during rain or wind storms.
Straight combining oats may be an option in some circumstance such as on even, uniform land or when a crop matures early, but growers should make sure no green hulls are present or the oats will not make milling grade. If the oats are left too long in the field before straight cutting weather may cause the stems to break down and reduce yield.
Reducing cylinder speeds to around 900 r.p.m. and allowing wider concave clearances will help to prevent damage to oat hulls.
Growers should be cautious about using a pre-harvest glyphosate application on oats. Major oat buyer, Grain Millers recently announced that they will no longer accept oat shipments that have received pre-harvest glyphosate because of concerns about the functionality of the oat during processing.
“It’s a major concern that people have to be aware of,” says May. “If they do a pre-harvest growers have to be very careful on their timing. My perspective is that if the crop is not mature enough to combine in August, you should swath it. I’m not a big pre-harvest person in oats because you’ve got that big panicle with different levels of maturity. It’s supposed to be a weed control measure and if you’re using it as a harvest desiccant, I don’t think you’re doing anybody any favours.” There could also be issues with glyphosate residues depending on where the oats are being sold.
Find more information about growing oats at the Prairie Oat Growers Association website, poga.ca.