Written by Bob Fanning, former SDSU Extension Plant Pathology Field Specialist.
Recent rain and snow across much of South Dakota has improved the prospects of planting winter wheat in some of the dry areas, but will also delay planting in fields yet to be seeded.
In South Dakota, the recommended time to plant winter wheat is Sept. 15 through Oct. 10. The October 15 deadline to receive full crop insurance coverage and winterkill protection provides incentive to get fields planted by that date. Producers can still purchase crop insurance on fields planted after October 15, but will sacrifice 1% of coverage for each day after that date, up to 25 days. All fields planted after Oct. 15 are ineligible for winterkill protection.
There are good reasons for the Sept. 15 to Oct. 10 planting date recommendations, but winter wheat can be planted after Oct. 10, or Oct. 15 and still raise a respectable crop. The primary disadvantages to planting late are that the plants are typically behind in development going into the winter and slower getting going in the spring, which leads to delayed maturity compared to earlier planted wheat. That delay can shorten the grain fill period, and often results in the plants being subjected to moisture and heat stress during this stage. Date-of-planting studies have shown that late planted winter wheat can produce just over 20% less than wheat planted at the ideal time. Late planting also presents higher risk of winterkill and erosion, particularly when not seeding into protective cover.
There are management strategies you can use to help compensate for planting late. Use narrow row spacing if you have the equipment. If not, try to rent or hire equipment from someone who does. Ten inches or wider would be considered wide spacing. If wider spacing is your only option, increase the seeding rate by 1.5 times. Even if using narrow row spacing, also increase the seeding rate. While 960,000 – 1.2 million pure live seeds per acre is the recommended seeding rate when planting during the recommended time, raising that to 1.6 million seeds per acre or even higher is suggested when planting late. Planting depth of 1 to 1.5 inches is recommended, as both shallow and deep planted wheat is more susceptible to winterkill. Plant into fields with protective cover, especially when planting later then the recommend dates. Apply phosphorus with the seed. Apply 20 Lbs/A of phosphorus if soil test levels indicate none is needed, and add 20 Lbs/A to recommendations. Phosphorus promotes root growth and improves winter survival. Plant certified disease-free, treated seed. A final suggestion would be to plant an early maturing variety with favorable agronomic characteristics and good yield potential. Maturity, winter survival ratings, and yield for most varieties planted in South Dakota can be found in the 2013 Winter Wheat Variety Trial Results.
If winter wheat planting gets delayed past November 1, producers should consider waiting until spring to plant spring wheat, or consider dormant planting spring wheat. Late planted winter wheat often matures later and yields less than dormant or early planted spring wheat. True dormant planting occurs when the seed is planted just before the ground freezes. Spring wheat that is properly dormant planted will lie in the soil as hard seed until the soil warms enough in the spring to begin germination, approximately 34-37° F.
For more information on wheat production in South Dakota, check out the following resources available for online purchase at the iGrow Marketplace!