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Frequently Asked Questions – Seeding Winter Wheat Which steps
should I take in growing winter wheat? To get an answer to your own question, click here
August 2005 Which steps should I take in growing winter wheat? Producers who intend to grow winter wheat should consider the undertaking as part of the whole farm operation and not in isolation. Several management decisions and operations should be taken, including:
Is “stubble-in” seeding the only choice? Due to the harsh winters in Saskatchewan, it is imperative that winter wheat is direct seeded in standing stubble to ensure sufficient snow cover. At least eight cm of un-packed snow is needed to maintain winter temperatures at crown level above critical levels for winter survival. Which stubble is best suited for winter wheat? Canola or mustard stubble is preferred as it provides the lowest disease, insect and weed risks, and usually provides adequate stubble for trapping snow. Barley and oat stubble may be used. If planted on wheat stubble, disease issues become pronounced. Dry beans, lentils, and field peas have poor snow-trapping abilities and should be avoided. Can I seed winter wheat on chem-fallow? Yes you can as long as there is enough stubble to capture and maintain sufficient snow cover. However, this may not always be the case since the stubble becomes brittle and loses snow-trapping ability. In a study in which 65 winter wheat fields were surveyed, the lowest average snow trapping potential (STP) of 17 was observed on chem-fallow (Fowler, 2000). In this study, winter wheat had a high risk of winter-kill when seeded into fields or areas within fields that had a STP of less than 20, where: STP = [stubble height (cm) x standing stems per m2] ÷100. The target STP prior to seeding should be greater than 40. Post-seeding STP should be greater than 20. Seed with equipment that preserves stubble.
How can I handle excessive crop residue prior to seeding winter wheat? Crop residue management begins at harvest. Cut the crop at a height that would provide STP of more than 40. Spread the straw and chaff uniformly. Harrowing before seeding can be an effective way of spreading excess straw; however, harrowing can reduce STP. If a hoe drill is to be used in seeding winter wheat, the straw must be well chopped and spread uniformly. Most no-till drills should be able to seed into stubble left for snow trapping without plugging. What is the optimum time for seeding winter wheat? Optimum seeding dates range from August 20 in the northeast to September 15 in the southwest corner of the province. As a guide, the Winter Wheat Production Manual shows the optimum date for no-till seeding winter wheat into standing stubble as: August 27:
Meadow Lake/Prince Albert/Nipawin areas How late or early can I seed winter wheat? The recommended optimum seeding dates are based on seeding dates that provide optimal growth for highest winter hardiness. Plants should have three to four leaves with one tiller, and well developed crowns, by freeze up in order to attain maximum cold tolerance and optimum energy reserves. In general, this should be within 7 to 10 days of the optimum seeding date. Seeding too early results in excessive growth in the fall and loss of winter hardiness consequently leads to increased winter injury. Late seeding results in poorly established plants, with low winter survival potential. Hence, both situations result in poor stands and decreased yield potential. What is the optimum seeding rate for winter wheat? Optimum seeding rates for winter wheat are similar to those of spring wheat. However, because of winter mortality, the target plant populations should be between 25 and 30 to achieve a spring stand of 18-24 plants per square foot. Base your seeding rate on seed size (thousand kernel weight - TKW), germination percentage, seedling mortality and the target plant density. The calculation is performed as shown below: Seeding rate (lb./ac.) = [(Plants/ft.2 x TKW g x 10) ¸ (% Survival)] Note that % survival is a product of % germination and mortality rate. Seeding rate will also vary by region, but an approximate rate is 2 bu./acre. What is the optimum seeding depth for winter wheat? Shallow seeding (0.5 to 1 inch or 1.3 to 2.5 cm.) is generally recommended. This ensures that the seed germinates and emerges without expending too much energy. Ensure that the seed is in good contact with the soil. Unlike spring seeding when farmers may seed deeper hoping to place seed in moist soil, there is no advantage gained by seeding deeper than recommended, since fall stubble soil moisture rarely increases with soil depth. Shallow seeded winter wheat can germinate from a small amount of rainfall. If soil is dry, shallow seeding increases the odds of germination.
Which varieties of winter wheat are best suited for my area? Refer to the Saskatchewan Seed Guide for the best varieties for your area. Choose a variety that would provide you with the best yield and resistance to lodging, winter damage, stem rust, leaf rust and bunt. When selecting varieties, marketing should also be considered. The Canadian Wheat Board has a Market Development Contract Program for selected varieties – contact the CWB for more information. How much fertilizer should I apply in winter wheat? Apply nutrients based on soil test recommendations using a reasonable target yield. Previous soil test results from that field can be used as a guideline for P and K, but a current soil test is the best tool for determining the amount of N required. Expected price of winter wheat and fertilizer should also be considered for determining economic fertilizer application rates. Which N fertilizers can I use in winter wheat? Commonly available forms of nitrogen are: urea (46-0-0); liquid urea ammonium nitrate (28-0-0); anhydrous ammonia (82-0-0); and ammonium sulphate (21-0-0-24). For details on the characteristics and usage of these fertilizer options, see SAF fact sheets Nitrogen Fertilization and Guidelines for safe rates of fertilizer applied with the seed. Can I broadcast N and P fertilizers in winter wheat? Phosphate fertilizer must be banded with, or very near, the seed to be effective. The higher the amount of N placed with seed, the higher the risk of seedling damage and winter-kill. Side or mid-row banding of N gives the best results both in terms of protecting the seedling from toxicity and salt effect and increasing N use efficiency. Generally, fall broadcasting N results in increased risk of losses of N to the environment. If seeding is done with double shoot openers, don’t sacrifice seedbed quality for fertilizer placement. There are several effective methods of applying N early in the spring. What is the optimum timing for applying N fertilizer in winter wheat? Winter wheat growers like to assess their winter wheat fields for winter-kill in early spring before applying the nitrogen fertilizer. Whatever the case, ensure that the N fertilizer is applied by early spring for optimum results using soil test recommendations. Side banding or mid-row banding all the N fertilizer in the fall is one option, and early spring application using one of several methods is another option, for managing fertility in winter cereals. Logistically, winter wheat should be fertilized prior to spring seeding to avoid conflict with seeding operations. Can I spray my winter wheat in the fall? Pre-seeding weed control, including pre-harvest management, with a glyphosate product is an effective control measure for biennial and perennial weeds. There are no herbicides recommended for fall post-emergent application to winter wheat with the exception of Sencor for downy brome control and bromoxynil based products. Low rates of 2,4-D for broadleaf winter annual weed control can be applied safely (Fowler, 1987). Recommendations out of the U.S.A. suggest that 2,4-D can only be used in the fall if winter wheat is sufficiently tillered. Research conducted in 2001 by the Western Australian Department of Agriculture shows that: 1) there is great varietal variability in the level of sensitivity of wheat to phenoxy herbicides; 2) even the very low rates of phenoxy herbicides applied prior to tillering can result in high yield losses; and 3) wheat exhibits a range of tolerance to the different phenoxy products with 2,4-D causing more injury than MCPA and ester formulations causing greater losses than amine formulations (Newman and Nicholson, 2001). Research conducted at the Agriculture and Agri-Food Canada station in Lethbridge, found that late application of phenoxy herbicides increased the amount of winter-kill (Freyman and Hamman, 1979). Canadian labels recommend spring application only, and many indicate NOT to apply in the fall. As a result, the optimum time to treat winter annual broadleaf weeds in winter wheat is as early in the spring as feasible when both winter wheat and winter annual weeds have begun to grow. References AB Ag. 1998. Fact Sheet
on Direct
Seeded Winter Wheat. For more information,
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