North Dakota State University
NDSU Extension Service

Return to Current News, Small Grains Page

Should I Switch Wheat Varieties if the Season is Delayed?

Terry Gregoire

May 21, 2003

Generally wheat grain yield will be reduced a minimum of 0.5 bu/a each day past the optimum planting date. In the northern part of North Dakota, the optimum planting date is before May 20. Usually wheat will take 50 to 55 days to head when planted in late May. This means grain fill will occur during the warmest part of the growing season and for a cool season plant like wheat it results in smaller kernels and reduced yield potential. What options do growers have when faced with a late season planting?

Are there varieties that have more tolerance to heat stress? Yes, varieties like Ingot, Russ, and Alsen seem to handle heat stress during grain fill better than, for example, Gunner, Marshall, and AC Barrie. Research at Langdon has shown that planting Gunner and AC Barrie late will result in a larger decrease in grain yield relative to varieties like Ingot and Russ. Leaf rust damage potential increases in late plantings. In sensitive varieties like Ingot and Russ, a fungicide to protect from leaf rust should be strongly considered or plant a leaf rust tolerant variety. Review local data for other varieties that have the characteristics desired and perform well when planted late.

The Langdon Research Extension Center had a late planting trial in 2000 and 2001. The two year average yield for AC Barrie was 26.6 bushels per acre while Gunner averaged 30.9 bu/acre. All other varieties in the trial average yields were at 40 bu/acre or above. The varieties Alsen, Russ, and Parshall had average yields of 43 bu/acre. In a similar trial planted the first week of May, Gunner, and AC Barrie had yields similar to the other varieties.

When should one consider switching varieties? While each year is different, general farmer experience and research data suggest that Gunner and AC Barrie and perhaps varieties with similar genetics should not be planted after May 20 in northern North Dakota/Minnesota and perhaps earlier in southern portions of North Dakota. If planting is delayed into June, consider planting an early maturing variety if an earlier choice is available. A week earlier heading can make a difference of two weeks in harvest maturity or more when the variety is maturing in September. The risk of frost and sprout damage increases as maturity occurs in September.

Will an adjustment in seeding rate help reduce losses to late planting in wheat? Bryan Hanson, Agronomist at the Langdon Research Extension Center conducted two three year planting date and rate studies in the mid 1980's with a semi-dwarf durum, Cando and Robust barley. Seeding rates of 0.5, 1.0, 1.5, and 2.0 million seeds were used at three dates of late April, mid May and early June. There were no significant differences among seeding rates for planting dates for any measured trait. It did not help to increase seeding rate as planting date changed. However, these trials and trials with Grandin wheat in the early 1990's did show that seeding enough seed to establish a minimum of 17, 27, and 26 plants per square foot of barley, durum and spring wheat, respectfully, maximized yields. Establishing these minimums for any seeding date should be a producers goal.

NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, disability, age, Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer.
This publication will be made available in alternative formats for people with disabilities upon request, 701/231-7881.

North Dakota State University
NDSU Extension Service