Planting Winter Wheat

By Daniela Carrijo

The time for planting winter wheat is approaching. Here are some basic planting considerations based on The Penn State Agronomy Guide.

Planting time

Ideal planting dates are (see map in Figure 1):

• Area 1: September 20 – October 3
• Area 2: September 25 – October 8
• Area 3: October 1- October 15

Figure 1. Crop management areas in Pennsylvania.

Rotations

Avoid planting winter wheat continuously or following other cereals such as corn, rye, or barley. These crops can become volunteers and can be difficult to control in the wheat crop. More importantly, these crops are hosts to fungi causing the wheat diseases take-all and head scab (also called Fusarium head blight), which can severely impact wheat yield. The risk of these diseases can be almost entirely avoided through a rotation with soybeans or another broadleaf crop.

Variety Selection

A big decision is what variety to plant. Varieties can vary as much as 30bu/acre based on side-by-side replicated plots. In addition to industry reports, producers can use University reports to compare the performance of varieties across a range of seed companies and breeding programs. See the latest results from Penn State, Cornell, Virginia Tech, and University of Maryland. When interpreting these reports, it is important to note the general management practices (e.g., whether fungicide applications were made) and weather conditions (e.g., whether severe drought or storms were experienced) for each trial. Some reports include lodging/standability and disease tolerance ratings. Give preference to varieties that were tested and yielded well over more than one year and more than one location within your region. Lastly, if planting saved (non-certified) seed is a consideration, be informed of all the risks (read more about it in this article). Research shows that saving wheat seed does not pay off in most cases.

Seed Depth

Seed 1 to 1 and 1/4 inches deep and strive to maintain uniform seeding depth. If planting into residue, first, make sure that the residue is evenly spread across the field to avoid seeding depth issues, and secondly, be sure to rule out the residue when setting seed depth – there should be at least 1 inch of soil (not residue) above the seed. Fungicide seed treatments are strongly recommended to protect against seedling diseases and promote rapid seedling growth.

Seeding Rate

The ideal plant population for winter wheat is 1.3 to 1.5 million plants/acre. Assuming a typical 85% emergence rate, this requires a seeding rate between 1.5 and 1.7 million seeds/acre (see Table 1 to convert to seeds per foot of row). Use the number of seeds per lb noted on the seed bag to convert the desired seeding rate from seeds/acre to lb/acre. For example, if the bag indicates 10,000 seeds/lb and my target seeding rate is 1.5 million seeds/acre, then I would need 150 lb of that seed to plant one acre. Use the lower rates in Area 3 (lower winterkill risk) and the higher rates in Areas 1 and 2. Increase these rates when:

• Planting under poor conditions such as a cloddy seedbed.
• Planting late: when planting more than 2 weeks past the fly-free date, increase the seeding rate by 10% for each week delayed past that date
• Under no-till: if planting into heavy residue, increase the seeding rate by about 15% to compensate for seed to soil contact issues

Table 1. Conversion chart between seed/plant population on an area basis (per acre or per square foot) to a linear foot of row for different row spacings.

Fall fertilization

Determine lime, P and K needs from a soil test. Maintain pH between 6.0 and 7.0. Winterkill may be more severe if pH is below 6.0 and/or phosphate availability is low. Up to 20 lb of N per acre and all of the P₂O₅ and K₂O may be broadcast prior to planting, or a portion can be applied with a drill and the remainder broadcast. To minimize fertilizer burn, do not apply more than 15 lb of N or 30 lb of (N + K₂O) per acre in the row with the seed.

Fall grazing?

If using the winter wheat crop for grazing in the fall, plant one to two weeks earlier and apply 40 lb of N per acre in addition to recommended fall rates. Allow plants to accumulate 3 to 4 inches of top growth before going dormant in the fall. In the spring, the animals should be removed, at the latest, when the plants are at growth stage Feekes 5. At this stage, the leaf sheaths are fully elongated and erect but the plant has not begun jointing (see this visual guide).