Every producer hopes for a good, uniform stand of wheat by the end of October, but not everything goes perfectly every year.
There are always some fields with poor or uneven stands, said Jim Shroyer, Kansas State University Research and Extension crop production specialist. Sometimes the field can´t be planted at the optimum time, due to wet soils, late row crop harvest, or some other factor.
When planting at this point in the season, producers will have to use a slightly higher seeding rate -- 75 to 90 pounds per acre in western Kansas and 100 to 120 pounds in eastern and central Kansas, Shroyer said. It would also be a good idea to include some starter fertilizer at planting time to help the roots get started in cold, wet soils.
Where emergence is uneven or poor, producers will have to decide whether to replant. The decision is not always clear-cut, but some guidelines can help with the decision, he said.
"The producer will have to determine if the stand count is below normal; and if so, by how much. But first you have to know what a normal stand count should be," said Shroyer. He provided these tips:
If a producer uses a drill with 12-inch row spacings, plants at a 60-pounds-per-acre seeding rate with a variety that has 15,000 seeds per pound, and expects a germination and emergence rate of 75 to 80 percent, there should be 675,000 to 720,000 plants per acre. This amounts to about 15.5 to 16.5 plants per foot of row.
If a grower planted 60 pounds of seed per acre using 7.5-inch rows, and a germination rate of 75 to 80 percent, that would be about nine plants per foot or row.
The next step is to determine the average number of plants per foot of row that is present by taking numerous plant counts across the field, Shroyer said. This assumes the stand is more or less uniform throughout the field, with no large gaps.
"Generally, if the average number of plants is about 50 percent or more of normal, the recommendation is to keep the stand. With less than 40 percent of normal, the recommendation is to replant the field. With a stand that is between 40 and 50 percent of normal, the decision is more difficult," the agronomist said.
Loss of yield potential is not the only consideration, he added. Where stands are less than 40 percent of normal, the potential for blowing and weed infestations also become major concerns.
Where the stand is 30 to 40 percent of normal, cross-drilling with 30 to 40 pounds per acre in western Kansas and 40 to 60 pounds per acre in central and eastern Kansas, using a double-disc opener drill might be advisable, Shroyer said. If a hoe drill is used, however, the seeding rate should be slightly higher than what was originally planted, because the hoe drill will destroy much of the original stand.
"If possible, replanting should be done at a 45-degree angle to the original stand to minimize damage to the existing stand. If stands are less than 30 percent of normal, increase the seeding rates by 20 pounds per acre," he said.
Determine cause of poor wheat emergence before replanting
If little or no emergence of wheat occurred this fall, producers should dig through the soil crust to determine the problem before replanting, said Jim Shroyer, K-State Research and Extension crop production specialist.
"The most common emergence problems are crusting, dry soils, poor quality seed, and seedling rot diseases," he said.
Where crusting has occurred, producers should determine whether the seeds or seedlings are still viable or the coleoptiles have become bent or crinkled due to the crusting, the wheat specialist said. Sometimes a light rain on crusted soil will soften the crust so seedlings can emerge. Otherwise, a rotary hoe will break up the crust, allowing them to emerge.
If dry soils are the problem, replanting will do no good unless the seed has partially germinated and stalled out before emerging.
"If the seeds are still hard and viable, or have a very short coleoptile emerging from them, the best advice is to leave the field alone and wait for rain," he said.
If there has been adequate moisture and no crusting, but little or no emergence, poor quality seed or seedling rot diseases are possible causes of the problem, Shroyer added. In this case, the field will need to be replanted with good quality, treated seed.