growing winter wheat

seed early

Seeding early is the most important thing a grower can do to produce a vigorous plant with improved chances of winter survival. Plants that enter winter with greater than three leaves usually have well-developed crowns. The crown is the area at the base of the shoot from which the plant regrows in the spring.

Seeding too early, however, could promote excessive growth by winter, which can increase the risk for winter injury. Larger plants may also be at risk of snow mould. Despite these risks, seeding early is preferable to seeding too late.

The optimal seeding window across most of the Prairies is between September 1 and 15. If the crop is to be used for fall grazing it should be seeded by mid August. Seeding past the optimal date is ok and many growers still produce profitable yields.

The exceptions to this rule include:

• The Peace Region of Alberta where ideal seeding dates are earlier than the rest of the Prairies due to cooler fall temperatures. Producers in this area should aim to seed around August 25-31.
• The Chinook belt where seeding can be postponed because of long falls and milder winters. Producers in this area can seed into late September.

Producers should not wait for moisture prior to seeding. Winter wheat needs very little moisture to germinate. Under dry conditions, seeding into dry soil and waiting for rain to germinate the crop has been a far more successful strategy than delaying seeding until after rainfall. Research has demonstrated that postponement of seeding until after the middle of September can result in a five to ten per cent yield penalty for each week delayed.

There are many factors involved in deciding when to plant your winter wheat. Contact the agronomist for your area to discuss what is right for you.

seed heavy

Seed size can vary between different and similar varieties of the same crop from field to field and year to year depending on many factors such as growing conditions, soil conditions, and integrated pest management practices. Because of this variation in seed size, the number of plans in a pound or a bushel of a seed is also highly variable.

The proper way to calculate seeding rate is determined using target plants per square foot in conjunction with 1000 kernel weight (TKW) and seedling survival rate. Higher seeding rates create a denser, more uniform stand and are especially important in high moisture areas and are critical to winter survival, crop competitiveness, and yield potential. Idea target target plant stand for winter wheat is 30-35 plants per square foot.

To calculate seeding rate:

• Seeding rate (lb/ac)=target plant population/ft2 X 1000 kernel wt. (g)/seedling survival rate (0.70) / 10
• TKW in grams is used as the average number
 of seeds per pound varies
• Seedling survival rate of 0.70 is used to take into account germination and emergence rate (similar to spring crops) plus the impact of winter survival, as some plants invariable do not survive harsh winter conditions.

seed shallow

Soil moisture in most stubble fields in the fall has been depleted, leaving a very dry seedbed for winter wheat. Under these conditions, seeding shallow (1/2 to 1 inch) allows the seed to take advantage
 of moisture provided by fall rains. Research has shown that as little as 1/3 inch of rain is often enough to successfully establish winter wheat that was seeded shallow. Conversely, deep seeding delays emergence and often results in a spindly plant that is more susceptible to winterkill. Research has consistently shown that shallow seeding is much more successful than deep seeding.

It is also important to ensure that the seed is well packed in soil when planted for adequate seed to soil contact. This helps to keep the much needed fall moisture for germination.

seed slowly

Just like canola, winter wheat performs better if seeded at speeds closer to 4 mph than 6 mph.

use a seed treatment

Based on seed quality, crop rotation, and weather conditions, determine whether you are at a high risk for seedling disease development. If so, use a fungicide/insecticide seed treatment to minimize the effects of the disease. Recent research conducted by Agriculture and Agri-Food Canada indicates that use of a fungicide/insecticide seed treatment increases the chance of seed survival and spring plant vigour in winter wheat.

winter wheat stage timing

Winter wheat is seeded in late August or early September into a shallow seedbed to allow the plant to access enough water to germinate quickly and grow for four to five weeks. The next four to eight weeks (October to November) allow the plant to vernalize (giving the plant the signal to flower next spring) and acclimate to the cold (harden off for the winter). Ideally, this plant would be three to four leaves, have a tiller or two with developed crown tissue and would be ready to achieve winter wheat’s maximum yield potential next spring.

In extremely dry conditions, establishment can look quite different. Seeds could be anywhere from lying in dry dirt not germinated, to sprouted and not quite through the ground, to emerged crop in the one to three leaf stage in wet areas around sloughs or in low spots. In these delayed germination situations, vernalization may occur under cool spring conditions. The stage of crop development in the fall influences not only winter survival and yield potential but also crop competitiveness, maturity, and the risk of infection with diseases such as rust and fusarium head blight. The table below gives the best idea of what to expect from variable crop stages.

Please be aware that later-germinating winter wheat still has the potential to achieve high yield and profitability but management becomes more critical as the crop is often not as competitive.

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seeding into standing stubble

Direct seeding into standing stubble is important for winter wheat production. Standing stubble helps to trap snow that insulates crown tissue from cold winter temperatures. Snow cover ensures the soil temperature at the crown (1/2 to 1 inch deep) stays well above killing temperatures, even with air temperatures at -40°C. Optimally for winter survival, stubble needs to hold four inches or more of snow. This amount of snow will prevent soil temperatures from dropping to lethal temperature.

Snow trapped in the stubble not only reduces the risk of winterkill but also improves soil moisture reserves in the spring.

Tall, dense stubble provides optimal snow trapping capability. Canola, barley, oat, flax, or the stubble of a forage crop all consistently provide this type of stubble. Wheat stubble also provides tall dense stubble but is not recommended due to the potential risk for wheat streak mosaic virus. This disease may develop from a “green bridge” created when a previous cereal crop and the emerging winter crop are too close together, allowing the movement and survival of the disease vectoring mites. At least seven to ten days between the dry-down of spring cereal crops and the emergence of winter wheat is necessary to prevent problems with the disease, as the wheat curl mite needs a live cereal plant for a host at all times. Radiant is currently the only winter wheat variety resistant to the wheat curl mite. Crops that do not provide tall dense stubble such as field pea and lentil are not recommended. However, many winter wheat growers seed into these stubbles with an increased risk of winterkill.

Harvest management of the previous crop including cutting height and straw/chaff spreading also plays a role. Producers should strive to minimize stubble disturbance during harvest and subsequent seeding operations.