Considerations for planting winter wheat
As planting time nears, it may be helpful to review some recommendations and suggestions for planting winter wheat.
Achieving top yields requires a uniform stand of healthy seedlings. This is dependent on seeds being dropped as evenly as possible and at a uniform depth. Good seed placement, in turn, requires that fields are appropriately prepped, and drills receive disciplined inspection, necessary adjustments and deliberate calibrations.
Furthermore, because wheat planting usually coincides with row crop harvest, farmers should develop a plan that helps ensure enough attention, time and focus is placed on the planting operation. Several bushels of yield can easily be made or lost depending on the level of care taken at planting.
Highest yields are most likely to be attained when planting approximately 10 days following the Hessian fly-free-date. Of course, the reality is that planting on anyone’s preselected “best” date depends on weather conditions and when the preceding crop can reasonably be harvested. Nevertheless, it is important to be as timely as possible to insure that seedlings have sufficient time and warm weather to develop a strong root system and multiple tillers. Once 10 days have passed beyond the Hessian fly-free-date, yield potential tends to decline at least one bushel for each additional day of delay.
While the Hessian fly no longer poses a significant threat to wheat in Michigan, the Hessian fly-free-date is still a useful reference relative to wheat and disease development. Growers may do well to plant a fraction of their acreage within a few days of the Hessian fly-free-date. However, planting wheat prior to the Hessian fly-free-date is generally not encouraged as the crop may be at greater risk from viral and fungal diseases of the roots or foliage. (Suggestion: reduce fertilizer nitrogen rates to 10 lbs./acre or less when planting at or before the Hessian fly-free-date.)
|Hessian fly-free-dates for Michigan|
The best seed is certified and professionally treated. Where growers elect to plant their own seed, however, steps need to be taken to increase the odds of success.
- Eject grain from fields having any sign of a disease that can infect kernels internally, such as loose smut stinking bunt, or weeds whose seed tends to carry with the grain (for example, cheat).
- Thoroughly clean the grain to remove small and lightweight kernels.
- Submit the seed to a quality testing laboratory.
- Have the seed professionally treated with a fungicide. (The exception here is that seeds applied by airplane over soybeans should not be treated.) Reminder: it is illegal to provide bin-run or uncertified seeds to others.
Inferior grain can sometimes make acceptable seed. Examples include grain that has relatively high levels of DON or vomitoxin (assuming the seed is professionally cleaned and treated), and grain having a low level of sprouts or low falling number. In the latter case, it is important that the wheat be given a warm germination test and a stress test (Tetrazolium or Accelerated Aging), and that it is not held for the following year. Seed testing can be performed by the Michigan Crop Improvement Association (call 517-332-3546).
It is generally recommended that growers plant 1.5 to 2.2 million seeds per acre. Seeding rates on the lower end of the range should be reserved for fields being planted early (within a couple days of the Hessian fly-free-date). As the planting season goes on, the seeding rates should become progressively higher. If planting continues into the second half of October, the seed rate should be increased to at least 2.0 million per acre. The seeding rates should also be adjusted upward when seed is known to be compromised by disease, sprout damage or soil condition.
Table 1 identifies the pounds of seed that a grower would need based on the seed count per pound and his target seeding rate. For example, if the seed bags specify that there are 14,000 seeds per pound and the target seeding rate is 1.8 million seeds per acre, 129 pounds of seed would be needed per acre.
Table 1. Relating seed size and seeding rates to the amount of seed
required per acre.
|Seed size (seeds/lb.)||Target seeding rates (millions of seeds per acre)|
|Amount of seed required (lbs./ac)|
*Seeds per ac/seeds per lb. = lbs. of seed per ac.
Table 2 is useful when assessing the number of seeds being dropped by each 7.5 inch-spaced row unit. It is also helpful in observing the seedling population throughout the field (assumes a 90 percent emergence rate).
Table 2. Relating target seeding rate per acre to seed and
seedling numbers (for 7.5-inch row spacing).
|Target seeding rate (millions per acre)||Seeds per ft. of row1||Seedlings per ft. of row2|
1 Target seedling rate/43,560 X 0.625 = seeds per ft. of row
(7.5” spacing). Seeds per sq. ft. = target seedling rate/43,560.
2 Assumes 90 percent emergence.
Appropriate seeding depths usually range from 0.75 to 1.5 inches. The goal here is to achieve early and even emergence of the seedlings. Usually, a planting depth of approximately 1 inch will be deep enough to reach adequate soil moisture, provide for well anchored plants, and offer some protection against winter injury. A reasonable exception here is a grower who is working light or droughty soils and elects to plant at least 1.5 inches in order to reach soil moisture, particularly when it’s relatively early in the planting season.
Wheat establishment can be successful under conventional, minimum tillage and no-till systems.Generally speaking, no-till has won favor in recent years. It tends to result in more unevenness in the stand, but it can often provide improved moisture retention and less susceptibility to cold temperature damage. Tillage, even at a minimal level, can be helpful in distributing and incorporating residue, fertilizer and lime; and create a more uniform seedbed. Tillage can also be useful when attempting to reduce disease inoculum borne in crop residue (such as corn stubble or stalks infected with Fusarium).