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Seeding wheat on time pays yield rewards

Seeding date can have a major effect on winter wheat yields. Wheat seeded too early in the fall uses more soil water in the fall and in 2004 had more freeze injury in the spring because of the soil water it used in the fall. Drier soils cooled down faster and hence there was more freeze injury to the wheat.

In one University of Nebraska-Lincoln test, a replication located in a low area yielded 70 bushels per acre while the entire plot averaged 21 bushels per acre because it had less soil water.

The recommended seeding dates for Nebraska winter wheat vary substantially from one end of the state to the other -- from Sept. 1 in the extreme northwest area to Oct. 1 in the southeast tip -- and have been proven and verified through years of research and farmer experience. In some years, an earlier seeding may have an advantage and in other years, a later date may have an advantage. In the long term, the suggested seeding dates will give the highest average yield.

The recommended seeding date represents a goal for seeding completion. As farm size and the number of acres increases for individual farmers, so does the length of time needed to complete seeding. The goal should be to have all the wheat planted by the ideal date. Plan your field order for planting accordingly. For example, plant higher elevation fields and those containing sandy soil first and leave lower fields and those with higher clay content until last.

If the seeding date is delayed or growing conditions prevent or delay root growth to the dual placement fertilizer band, seed fertilizer placement is the preferred application method. Poor root growth, for whatever reason, limits root fertilizer contact and tillering, which affects yield. Much of the grain yield of winter wheat occurs on tillers that develop from buds in the axils of lower leaves. Under normal conditions, as much as 70% of the grain yield comes from tillers. Tillering also enables the plant to adapt to different conditions. Few tillers develop when moisture, nutrition and other conditions are poor. Numerous tillers that increase the yield potential form when conditions are favorable.

Seeding date greatly affects development of tillers in winter wheat. Seeding during the optimum period enables wheat to form sufficient but not excessive tillers. Early seeding results in too many fall tillers that may compete with each other, become diseased and deplete soil moisture so that grain yields are low. Late seeding gives plants little time to develop tillers, resulting in an inadequate numbers of spikes (heads) for high yields the following spring.

Senescence and death might eliminate excessive tillers that form during the fall. Conversely, if too few tillers develop during fall, additional tillers may form during spring; however, the yield potential may differ between tillers that develop during fall and those that develop during spring.

Several factors are considered when developing the recommended seeding dates. In the Nebraska panhandle, the dates depend on elevation. Producers can determine the ideal date for each field by knowing the elevation. Using a starting point of Sept. 15 for 3500 feet, one day should be added for each 100 feet of elevation decrease and subtracted for each 100-foot elevation increase. For the rest of the state, Sept. 25 or later seeding dates are recommended to avoid Hessian fly infestation.

Delayed planting dates also may be due to a need to avoid wheat streak mosaic virus, Russian wheat aphid, crown and root rot and too much fall growth. Excessive fall growth causes excessive moisture use and stress.

There are several other reasons for planting early. One is to get adequate ground cover to avoid erosion from wind and water. Another is to get adequate plant growth to assure winter hardiness. A third reason is to quicken maturity the following summer and avoid excessive heat stress. The map is a guide rather than an absolute deadline.

Each producer should make changes to ensure the planting dates fit the conditions of his or her farm.

Seeding date can have a major effect on winter wheat yields. Wheat seeded too early in the fall uses more soil water in the fall and in 2004 had more freeze injury in the spring because of the soil water it used in the fall. Drier soils cooled down faster and hence there was more freeze injury to the wheat.

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