Winter wheat planting recommendations

Improving wheat yields depends on achieving uniform wheat stands this fall.

Much of wheat’s yield potential is determined at planting. To attain top yields, the goal of the planting operation needs to be an even and uniform stand of seedlings. This, along with timely planting, is critically important if improving wheat performance is the goal.

Field preparations

The chance of achieving a consistent stand is greatly improved by insuring that residue from the previous crop is spread uniformly. Particularly for no-till operations, bunched-up residue is the most common threat to evenness in wheat stands. In some cases, the coulters are unable to cut through the thick residue or the emerging wheat simply rots below the layers of plant material. Adding weight to the drill may help in penetrating crop residue (or hard soil). In some cases, the only alternative would be to use tillage to help disburse and bury the residue.

Planting date

Highest yields are most likely to be attained when planting within two weeks following the Hessian fly-free-date (Table 1). Of course, the reality is that the preceding crop and current weather largely dictate when wheat is actually planted. Nevertheless, it is important to be as timely as possible to insure that seedlings have sufficient time to develop a strong root system and, preferably, initiate multiple tillers. Once a couple weeks have passed beyond the fly-free-date, yield potential tends to decline at least one bushel for each additional day of delay.

Table 1. Hessian fly-free-dates for Michigan

Hessian fly-free-dates for Michigan

County

Sept.

County

Sept.

County

Sept.

County

Sept.

Alcona

6

Eaton

16

Lapeer

15

Ogemaw

10

Allegan

20

Emmett

4

Leelanau

8

Osceola

10

Alpena

9

Genesee

17

Lenawee

25

Oscoda

7

Antrim

4

Gladwin

12

Livingston

16

Otsego

6

Arenac

13

Grand Traverse

8

Macomb

18

Ottawa

19

Barry

18

Gratiot

15

Manistee

13

Presque Isle

8

Bay

14

Hillsdale

19

Mason

13

Roscommon

7

Benzie

16

Huron

13

Mecosta

12

Saginaw

16

Berrien

23

Ingham

17

Midland

15

Sanilac

15

Branch

19

Ionia

16

Missaukee

9

St. Clair

16

Calhoun

19

Iosco

7

Monroe

21

St. Joseph

23

Cass

22

Isabella

11

Montcalm

15

Shiawassee

16

Charlevoix

3

Jackson

16

Montmorency

7

Tuscola

15

Cheboygan

4

Kalamazoo

20

Muskegon

18

Van Buren

22

Clare

12

Kalkaska

5

Newaygo

15

Washtenaw

18

Clinton

17

Kent

18

Oakland

16

Wayne

18

Crawford

6

Lake

13

Oceana

16

Wexford

9

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 fly-free date. However, planting wheat prior to that date is generally not encouraged as the crop may be at greater risk from viral and fungal diseases.

Seeding depth

Attaining a consistent depth and thus even emergence is often more critical for achieving high yields than fine-tuning actual seeding depth. 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. An exception, however, is where the soil is exceptionally dry. In this case, the seed should be placed as deep as necessary to find moisture.

Planting rate

The recommendation is to plant between 1.4 and 2.2 million seeds per acre. Seeding rates on the lower end of the range should be reserved for fields being planted within a couple weeks of the fly-free-date. Higher rates at this time are discouraged as overly thick stands may encourage lodging, as was experienced by some growers during the 2010-2011 season. 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 million per acre. The seeding rates should also be adjusted upward when seed is of questionable quality.

Table 2 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 bag specifies 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 2. 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)

1.6

1.7

1.8

1.9

2.0

2.1

Amount of seed required (lbs/ac)

10,000

160

170

180

190

200

210

11,000

145

155

164

173

182

191

12,000

133

142

150

158

167

175

13,000

123

131

138

146

154

162

14,000

114

121

129

136

143

150

15,000

107

113

120

127

133

140

16,000

100

106

113

119

125

131

17,000

94

100

106

111

118

124

18,000

89

94

100

106

111

117

* Seeds per ac / seeds per lb = lbs of seed per ac.

Table 3 is useful for assessing the number of seeds being dropped by each row unit (7.5-inch row spacing) and for evaluating actual emergence.

Table 3. 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 row 2

1.4

20.1

18.5 (92%)

1.6

23.0

20.7 (90%)

1.8

25.8

22.7 (88%)

2.0

28.7

24.7 (86%)

2.2

31.6

26.5 (84%)

1 Target seeding rate/43,560 X 0 .625 = seeds per ft of row (7.5” spacing). Seeds per sq ft = target seeding rate/43,560.
2
An estimated emergence rate is given in brackets as percent. (The rate tends to decline as seed rates increase.)

Fall fertilization

Approximately 10 to 25 pounds of fertilizer nitrogen is recommended at the time of planting. However, because of this season’s drought, growers may be able to forego nitrogen when planting relatively early following a high nitrogen crop such as corn silage, as there may be plenty of residual nitrogen in the soil (see MSU Extension News article Planting wheat following drought-stricken corn).

All phosphorus and potash should be applied in the fall with rates determined by soil test levels. In general, soils having medium test levels of phosphorus (25 to 40 ppm) require approximately 50 pounds per acre of phosphate. For soils testing medium for potassium (75 to 100 ppm), approximately 100 pounds per acre of potash may be sufficient.