Features
Agronomy
Cereals
Assessing winter wheat survival
Each spring, winter wheat growers evaluate how well their crop has come
through the winter. Sometimes they face the difficult choice of whether
to keep a struggling stand or reseed the field to another crop. Two
specialists provide some practical tips to help with that decision.
April 30, 2010 By Carolyn King
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| When assessing winter wheat survival, check the plant’s crown to see if it is white and healthy looking with new roots. Photos courtesy of Ducks Unlimited Canada.
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Each spring, winter wheat growers evaluate how well their crop has come through the winter. Sometimes they face the difficult choice of whether to keep a struggling stand or reseed the field to another crop. Two specialists provide some practical tips to help with that decision.
Mark Akins, a winter wheat agrologist with Ducks Unlimited Canada in Regina, says the first thing to keep in mind is, “Winterkill is generally not a large percentage of the winter wheat acres. Most years, winterkill reseeding is less than five percent from what I’ve seen through Saskatchewan crop insurance. So usually it’s not a big risk, especially if you had a good establishment in the fall and good insulation with snow cover.”
Pam de Rocquigny, a cereal specialist with Manitoba Agriculture, Food and Rural Initiatives, notes, “According to Manitoba crop insurance, in Manitoba from 1986 to 2007, the average winterkill rates in winter wheat are approximately nine percent.”
The biggest mistake Akins sees growers make when they assess winter wheat survival is to give up too early on the crop. “They check their stands before they start spring seeding and see a crop that isn’t responding quite as quickly as they’d like and they decide the stand is not good enough. But it’s amazing how winter wheat plants can recover if you give them some time.”
He recommends, “You may want to have a plan B for that piece of land, perhaps have some seed ready in case you need to reseed. And you want to check the stand through the spring if you can. But don’t make a final decision on your winter wheat crop until you’re two-thirds to three-quarters of the way done seeding your other fields. In southern Saskatchewan, that could be May 15 or a little later.”
This delay can help a winter wheat crop recover without much risk. He says, “Even if you decide that the crop isn’t good enough, what are you going to do about it on May 5 when you’re right in the middle of seeding? And for the small percentage of growers that reseed, if they decide to reseed two-thirds of the way through spring seeding, there’s still time to get a spring crop in and grow a decent crop.”
| Improve winter survival by getting winter wheat off to a good start “The biggest thing a grower can focus on to avoid winterkill is good establishment in the fall. If you can do that, you’ve gone a long way to a successful winter wheat crop,” says Mark Akins, a winter wheat agrologist with Ducks Unlimited Canada, adding that early seeding, shallow seeding and seeding into stubble are key to establishing a strong stand. “You need to seed early enough to have a plant that’s at the three-leaf stage with a couple of tillers before winter. The recommended seeding window is Aug. 20 to Sept. 15. And the more I work with winter wheat and grow it on my own farm, the more I think the earlier the better during that window. If it’s dry and you’ve got the seed in the ground, then you have a wider window to receive rain to get that plant started. If it’s moist, then you have a longer time for that plant to grow, so it will be a strong plant that can withstand winter conditions and have a vigorous start in spring.” Pam de Rocquigny, a cereal specialist with Manitoba Agriculture, Food and Rural Initiatives, notes, “The recommended seeding depth is usually an inch or less. If you seed any deeper it takes quite a while for the plants to emerge and that can result in weaker, more spindly seedlings.” Akins adds, “In southern Saskatchewan if you’re seeding with the calendar, almost 50 percent of the time you may not have enough moisture in the soil for the seed to germinate. But if you seed it shallow, a small shower of rain will get it started.” “Adequate stubble is important for that snow-catching capacity so the plants receive the insulating snow cover they need to survive our cold winters,” says de Rocquigny. To keep that stubble up, Akins advises, “Reduce your traffic at harvest and seeding time. Typically, the worst winterkill is on the headland areas, which have been abused at harvest and at seeding because the stubble was knocked down and the ground was compacted.” De Rocquigny notes two other considerations for the fall. About fertilizer management, she says, “You want to consider your phosphorus fertility program; phosphorus will help to get that crop through the winter.” About variety selection, she says, “There can be differences between varieties in terms of winter hardiness. However, if you seed into correct conditions in terms of stubble density, then variety differences should not be that evident.” |
De Rocquigny explains how to check a stand in early spring. “The most common way is crown examination. You dig up individual plants in random areas throughout the field. If the plant’s crown appears white and healthy looking and new roots are coming out from the crown, then you can usually consider the plant is in good condition and growth has resumed. Depending on the weather, normally you can start checking at the end of April or early May.”
She notes, “If you do the sampling randomly throughout the field, this method will give you an idea of what you can expect. But you won’t know for sure until the plant is actively growing and producing new green shoots to what the variability will be within the field.”
Plant density is an important factor to consider, but it tells only part of the story, according to Akins. “Compared to spring wheat, winter wheat will intensely tiller, and the crop will really fill in. With Saskatchewan crop insurance it’s optional for a grower to reseed a spring cereal at eight to 12 plants per square foot, while with winter cereals it’s optional for a grower to reseed in the spring at five to seven plants per square foot. So you can have a thinner stand and still end up with a good crop,” says Akins. “That’s nice to say, ‘five to seven plants and you’ll still be okay.’ The problem is, I’ve never seen a field where there were five to seven plants per square foot all across the field. Usually the problems occur in patches like headlands where the stubble was knocked down or hilltops that were bare in the winter.”
It comes down to one’s comfort level
“The decision on patchy stands really goes on a field-by-field basis, and what producers are willing to accept in terms of plant stands and the increased management practices that they need to follow,” says de Rocquigny.
She explains, “If you have a field with small patches of poor stands, but overall it is a field that you’re going to keep, you will need to focus on management strategies such as controlling broadleaf and grassy weeds and applying nitrogen early to encourage more tillering. And throughout the year you’ll have to increase your scouting because plants with delayed growth are at a higher risk of rust and fusarium head blight infection and you may need to control or suppress those diseases.”
Even if a field has large patches of poor stands, some growers choose to keep the winter wheat and follow the same strategy of increased management. De Rocquigny says alternatives might be to till the large patches for weed control or to seed the patches to a cover crop.
She cautions, “Seeding spring wheat into the large gaps is not recommended. For western Canadian wheat, growers need to sign a declaration form saying which class of wheat they are delivering to the elevator. If they seed a spring wheat into these larger patches, it obviously increases the possibility of mixing spring and winter wheat, which can be two different classes, and that can result in downgrading.”
Akins emphasizes the importance of an early spring nitrogen (N) application, even if a grower is not sure about keeping the winter wheat crop. “If the stand is a little shaky in the spring, people may say, ‘I won’t fertilize it because it doesn’t look really great.’ But if you don’t fertilizer it, then you’ve got a weak crop that is trying to recover but doesn’t have the nutrients that it needs, so you’re putting it at an even greater disadvantage. My advice to growers is, no matter what your crop looks like, put on the nitrogen fertilizer that it needs. If necessary, do the weed control that has to be done. And wait and see.”
He explains that a grower could split the spring nitrogen application. “Let’s say if the winter wheat doesn’t work out, the grower is planning to reseed his field to flax. For a winter wheat crop, he would apply 100 lbs of N per acre, but for a flax crop he would only apply 60 lbs of N per acre. So he can put 60 lbs of N on in the middle of April before he starts seeding his spring crops. Then when he makes a final decision to keep the winter wheat on May 20, he can apply the other 40 lbs.”
Akins adds, “I understand that growers may be worried about putting money into a crop when you don’t know whether it’s going to work out, but mid-April is too early to decide whether your winter wheat stand is going to be good or not. So apply nitrogen and control weeds if needed. If you don’t keep the winter wheat, the nutrients are there for the crop you reseed. Then you haven’t starved the winter wheat plants that are trying to recover.”
If you do reseed
“If you are looking at reseeding, the first thing is to contact your local crop insurance agent. In Manitoba it is Manitoba Agricultural Services Corporation, and in terms of crop insurance they will lead you through the steps of what your options are,” says de Rocquigny.
Akins strongly recommends not reseeding to durum or spring wheat because of the risk of disease transmission and the risk of grade loss due to winter wheat volunteers mixing with the durum or spring wheat. He suggests crops like barley, oat, flax or canaryseed can be good options.
De Rocquigny adds, “Remember that winter wheat is hard to kill. Tillage or a burndown herbicide probably will not provide complete control. Select a crop to reseed where there may be in-crop weed control options for those winter wheat volunteers.”
