Most of Kansas wheat has been planted by this time of the year. However, some producers may have delayed planting for different reasons, including harvesting a summer crop during late October, or waiting for significant precipitation to occur. Planting wheat in early November is within the acceptable range in southeast and far south central Kansas. In other areas of the state, this is later than desirable, and later than the cutoff date for full crop insurance benefits.
Although good yields may still be achieved if wheat is planted outside the optimal planting window, late-planted wheat is often subjected to colder fall temperatures and has less time to tiller prior to winter dormancy, which can reduce wheat yield potential and increase the risks of winter injury. Under these circumstances, some management adjustments can be made to try to compensate for the consequences of late planting:
Increase seeding rate
As mentioned above, late-planted wheat tends to produce fewer tillers during the fall than wheat planted at the optimal time. Fall tillers are generally more productive than spring tillers, contributing more to the crop’s yield potential. Therefore there is a need to compensate for the reduced tillering by increasing seeding rates to get more seed per row foot. Wheat seeding rates for Kansas vary depending on the precipitation zone, and increase from west to east (Table 1). Likewise, seeding rates should be increased every week that planting is delayed after the end of the optimal planting date range by about 150,000 – 225,000 seeds per acre (or 10 to 15 lb/acre) in western Kansas, or 225,000 – 300,000 seeds per acre (15 – 20 lb/acre) in eastern Kansas. Final seeding rates should not be above 90 pounds per acre in western Kansas and 120 pounds in eastern and central Kansas.
Table 1. Seeding rates for different Kansas regions for optimum planting date. Upward adjustments to these rates are needed when planting wheat late.
|
Region within Kansas |
Seeding rate |
|||
|
Optimum planting date |
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|
seeds/acre |
seeds/sq. ft.* |
|||
|
Min. |
Max. |
Min. |
Max. |
|
|
Western |
750,000 |
900,000 |
17 |
21 |
|
Central |
900,000 |
1,125,000 |
21 |
26 |
|
Eastern |
1,125,000 |
1,350,000 |
26 |
31 |
|
Irrigated |
1,200,000 |
1,500,000 |
28 |
34 |
* To determine row length needed for one square foot based on row spacing, divide 12 by the row spacing of your field. For example, if row spacing is 7.5 inches, 12/7.5 = 1.6 feet, or 19.2 inches of row are needed to be equivalent to one square foot.
Maintain the optimal planting depth (1 to 1.5 inch deep)
Wheat needs at least 4-5 leaves and 1-2 tillers prior to winter dormancy for maximum cold tolerance. Late-planted wheat will most likely have fewer tillers and leaves than wheat planted at the optimal timing, and therefore will be more susceptible to winterkill. To increase the chances of winter survival, it is important to plant wheat at the normal planting depth (1 to 1.5 inches below the soil surface). This will ensure good root development and anchorage, as well as good soil insulation during the winter. Shallow-planted wheat is at greater risk of winter injury. If the seed is placed too deeply, it may not have enough vigor in cold soils to emerge well.
Place starter phosphorus (P) fertilizer with the seed
Phosphate-based starter fertilizer promotes early-season wheat growth and tillering. Additionally, P is less available under colder temperatures, which can result in P deficiency under cold weather conditions. When planting late, producers should strongly consider using about 20 lbs/acre of P fertilizer directly with the seed, regardless of soil P levels. This placement method is more effective at that time of year than other application methods. The later the planting date, the more fall root development is slowed. The closer the fertilizer is to the seed, the sooner the plant roots can get to it.
Use fungicide seed treatment or plant certified seed
Late-planted wheat is typically sown into colder soils, which generally increases the time needed for germination and emergence to occur. As a consequence, there is increased potential for seed- and soil-borne diseases that affect seedlings and early-season wheat development. Fungicide seed treatments can protect the seed and seedling during the extended time it is subjected to potential seedling diseases, improving stand establishment under poor growing conditions. It is important that the seed treatment thoroughly coat the seeds to ensure good protection. For fungicide seed treatment options, please refer to the most current version of the K-State fungicide seed treatment chart available at: https://www.bookstore.ksre.ksu.edu/pubs/MF2955.pdf
Consider variety selection
It is probably too late to make any changes in varieties this fall. However, a few points to consider in variety selection when it is known that wheat will be planted late (e.g. when planning to sow wheat following soybeans) are tillering ability and maturity. A variety that has good tillering ability may offset some of the consequences of late planting, as it might produce one or two tillers during the fall when planted late whereas a low tillering variety may produce none. Also, late-planted wheat is typically behind in development going into the winter, which might translate into slower development in the spring. This delay can result in plants being exposed to drought and especially heat stress during grain filling, reducing the duration of the grain filling period. Thus, selecting an early-maturity variety with good yield potential may offset to some extent the consequences of late planting by decreasing the chances of having a grain filling period subject to drought and heat stress.
Romulo Lollato, Wheat and Forages Specialist
lollato@ksu.edu
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