What are my options if my winter wheat does not germinate this fall?

Poor emergence or plant stands are leaving many producers wondering if their winter wheat crop will survive the winter, what type of stands they might expect in the spring, and whether the crop will undergo the necessary processes to produce a head next year.   Unfortunately at this stage there isn’t much that can be done except understand the potential impact to crop production if the crop didn’t emerge or has just emerged.

The stage of crop development in the fall influences not only winter survival and yield potential but also crop competitiveness, maturity and the risk of infection with diseases such as rust and fusarium head blight (see Table 1 below).

Table 1:  Potential impacts of fall growth stages on winter wheat production factors

Growth Stage

Date of Germination

Yield Factor

Competition Factor*

Relative Maturity

3 leaf & tiller

Sept 5

100%

5

0 days

1-2 leaf

Sept 15

90-100%

4

+ 4

Sprouted

(not emerged)

Oct 1

80-100%

2

+ 8

Not germinated (imbibed)

Oct 15

60-100%

1

+ 10

* Competition factor: 5 = most competitive, 1 = least competitive

As the table illustrates, there may be minimal impact to yield potential of a crop that didn’t emerge in the fall but maturity will likely be delayed.  Crop competitiveness may be decreased so early season nitrogen application to encourage tillering, as well as timely weed control, will be very important.

In regards to vernalization concerns and whether the crop will produce heads next year, the key points to remember are:

  • Neither fall seedling growth nor tillering is required for vernalization to occur.  This process can begin in seeds as soon as they absorb water and swell.  Hence, late planted wheat that has not emerged prior to winter should be adequately vernalized.
  • Vernalization may also occur under cool spring conditions.

If next spring winter wheat fields whose stands are extremely variable with large patches of dead or weakened plants, replanting may become a more realistic option.  If you are considering reseeding and before destroying any wheat fields, you will need to contact your local MASC insurance agent.  For more information on winter wheat insurance information, please visit MASC’s website at: http://www.masc.mb.ca/masc.nsf/program_winter_wheat.html

There are numerous articles on MAFRI’s site dealing with dry conditions and poor germination, including “What Happens if my Winter Wheat did not Emerge?”, “Spring Germinating Winter Wheat” and “Concerned About Your Winter Wheat Stand?”.  For more information on winter wheat production, please visit MAFRD’s website at: http://www.gov.mb.ca/agriculture/crops/production/winter-wheat.html

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

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Can You Estimate Soybean Losses By Seeds on the Ground?

Questions have been coming in on the what the number of soybeans on the ground after the combine goes through means for yield loss.  For example, if you have 4 soybean seeds on the ground behind the combine, would that be about a one bushel loss?

In order to get an accurate representation on harvest losses, first you need to establish an area of 10 square feet.  Then within that area, count the soybean seeds on the ground.  Approximately 40 seeds with the 10 square foot area would equal a one bushel loss.

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What impact can rotation have on winter wheat yields?

As reviewed in a previous post on Crop Chatter, the most common rotation is seeding winter wheat into canola stubble.   However, what impact can rotation have on winter wheat yields?  Once again we can use Manitoba Agricultural Services Corporation’s (MASC) database to help try and answer this question.

The table below is a crop rotation chart, one planting season at a time, using data from MASC’s database.  It shows the potential yield of winter wheat on various stubbles, as compared to the average yield for winter wheat on all stubble types from 1998 to 2007.

The data illustrates a winter wheat on canola rotation where farmers see a relative yield response of 104% compared to the average yield of winter wheat in Manitoba.   Perhaps this is one reason why 51% of farmers reported a winter wheat on canola rotation.  If we look at a winter wheat on spring wheat rotation, yield potential drops to 91%.    We could speculate that the yield decrease may be due to increased disease pressure but can’t say for sure as yield-limiting factors are not collected in the harvest production reports.

Table 2:  Relative yield response (per cent of 1998 to 2007 average) of winter wheat sown on large acreage fields (<120 acre) of various previous crops (stubble) in rotation.

Previous Crop

Winter Wheat

Spring Wheat

Barley

Oat

Canola

Flax

Pea

Relative  Yield of Winter Wheat

76

91

91

97

104

102

90

 

The above table and all of the combinations are to provide farmers and agronomists with an additional tool to determine crop sequences and their yield benefits or risks.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

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Estimating Grain Corn Yields

The time of year is approaching where yield estimates can be done on grain corn.  Remember that grain corn yield is a function of the number of ears per acre, number of kernels per ear, and the weight per kernel.   Using the yield component method that was developed at the University of Illinois, yields can be estimated as early as the milk stage of development.

Calculating Estimated Grain Corn Yield:

Step 1.  Ear Number  – Using a row length equal to 1/1000th acre (row width 30 ” = 17′ 4″; row width 36 ” = 14′ 6”), count and record the number of ears in the length of row that are harvestable.

Step 2. Average Number of Kernels per Ear – Pick 3 representative ears and record the number of complete kernel rows per ear and average number of kernels per row.  Multiply each ear’s row number by its number of kernels per row to determine total number of kernels for each ear.  Calculate the average number of kernels per ear by summing the values for all the sampled ears and dividing by the number of ears.

Note – Don’t count the extreme butt or tip kernels, but rather begin and end where you perceive there are complete “rings” of kernels around the cob.  Do not count aborted kernels.

Step 3. Estimate yield by multiplying the ear number by the average number of kernels per ear, then dividing the result by 90:  Yield (bu/ac) = (ear number) x (average # of kernels per ear) / 90.

Note:  The value of 90  is a “fudge factor” for kernel weight and it represents the average number of kernels (90,000) in a bushel of corn at 15.5% grain moisture.  If grain fill conditions have been excellent (larger kernels, fewer per bushel), use a lower value (80).  If grain fill conditions have been stressful (smaller kernels, more per bushel), use a larger value (100).

Here’s an example:  Field has 30” rows.  You counted 24 ears (per 17’ 5” length of row).  Sampling three ears resulted in 480, 500 and 450 kernels per each ear, where the average number of kernels per ear would be (480 + 500 + 450) divided by 3 = 477.  The estimated yield for that location in the field would be (24 x 477) / 90, which equals 127 bu/ac.

Remember that yield estimates are only as accurate as the number of samples taken so repeating this exercise in several areas of a field will improve accuracy.  Since corn is in the early grain filling stages, water availability, insects, weeds, diseases, and other factors can still affect seed fill and therefore final yields.  However, as the plant approaches maturity, environmental stresses have less impact on final yield so yield estimates made that are closer to maturity should be more accurate.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture 

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