News Story

Agronomy Notes for the week ending August 26, 2017

The week started out with a warm and sunny Sunday, almost a perfect day, and ended as cool, cloudy, drizzly Saturday, which seemed like an early fall day. Temperatures ranged from the 50°F’s and 60°F’s for the lows, with some reports of upper 40°F’s in areas, and 70°F’s for the highs.

A few signs of fall that I always seem to notice are back to school sales flyers and Oak trees that have acorns that are falling. I first started to notice acorns on the ground, on Thursday August 10. I believe that is about the time we normally see them.

The other sign of fall that always get my attention are tree leaves on the ground and soybean plants that are starting to turn color. In both instances, I started to see tree leaves fall and soybean leaves change late in the week. The photo below shows an experimental 1.2 maturity soybean on the left, that is starting to change color, side by side with a 1.4 maturity soybean on the right that has not. (Once beans start to change color they are in the R6.5 growth stage.)

Soybean plants vary from R4 or Full Pod (Pod is 3/4" of an inch long at one of the four uppermost nodes on the main stem with a fully developed leaf), to R6 or Full Seed (Pod containing a green seed that fills the pod cavity at one of the four uppermost nodes on the main stem with a fully developed leaf)

 

Planting Date

Plant Stage

Growth Stage

25-Apr

Full Seed

R6

10-May

Beginning Seed

R5-R5.5

27-May

Beginning Seed

R5

3-Jun

Beginning Seed

R5

28-Jun

Full Pod

R4

 

By the time the soybean plant reaches the R6 growth stage (shortly after R5.5) the soybean plants have:

  • Ceased to flower
  • Reached their tallest height, maximum node number, and leaf surface area
  • Reached their peak level of nitrogen fixation
  • Seeds that begin rapid accumulation of dry matter and nutrient accumulation from leaves and stems

The rapid accumulation of dry matter and nutrients will continue until after R6.5, at that stage the soybean plant will have accumulated 80% of its nutrients, and total dry seed weight. Root development is almost complete at R6.5 and will cease by R7 (Beginning Maturity).

The item to remember about growth stages is an earlier maturing soybean will enter the reproductive stages sooner and will reach new “R” stages faster than a later maturing soybean planted on the same day. This item is sometimes forgotten until soybean plants begin to drop leaves and change colors, but is very important especially when making recommendations based on growth stages, such as when to spray a fungicide or insecticide. 

As was discussed in the last few weeks we are seeing more instances of Sclerotina Stem Rot or White Mold (SWM), Sudden Death (SDS) and Brown Stem Rot (BSR). With these diseases, the actual infection occurres earlier in the growing season. SWM and BSR are more likely to be infecting the soybean plant during the early reproductive phase R1-R2. SDS on the other hand infects the plant soon after the plant emerges from the soil and is a seedling.

Corn plant development ranges from R2 (Late Blister- kernels are light yellow in color, and starch accumulation is turning the clear liquid inside the kernel to a milky white color) to R3 (Milk Stage-kernels are yellow in color and endosperm is milky white in color and in later stages of R3 will become more and more pasty in its consistency).  for corn planted in late May into early June. Corn planted in mid to late April is the late R4 (Dough-endosperm pasty in texture and in later stages will start to dent at the top of the kernel) to early R5 (Dent-kernels are accumulating more and more starch which causes a “Milk Line” to form at the top of the kernel. As the starch accumulation increases, this Milk Line will advance down the kernel to the cob and once it does, the kernel will reach R6 or Physiological Maturity or Black Layer.)

Planting Date

GDU'S

Growth Stage

Growth Stage

12-Apr

1991

Late Dough-Early Dent

R4-R5

24-Apr

1926

Late Dough-Early Dent

R4-R5

5-May

1890

Dough/Early Dent

R4-R5

12-May

1822

Dough

R4

2-Jun

1605

Blister/Early Milk

R2-R3

 

At the beginning of R5, kernels have approximately 55-60% moisture content. As the Milk Line advances down the kernel the moisture level drops and will be at 30-35% moisture content when the kernel reaches R6 or Black Layer. The closer you get to R6 prior to a frost, the less likely you are to experience yield loss.

The photo below and on the left, shows a corn ear at the R5 growth stage, with the photo on the right showing the advancing Milk Line on the kernel. I would estimate the Milk Line to be at 10-15% on this kernel.

                                 

We accumulated approximately 111 Growing Degree Units (GDU’s) during the week which is 19 GDU’s less than the 30-year average. For the first 26 days of August we have accumulated 390 GDU’s which is 104 GDU’s less than the 30-year average. In analyzing the GDU information at a daily level we averaged 15.86 GDU’s for the week and 15 GDU’s so far in the month of August. In both instances, we were less than the 30-year average, 2.71 less GDU’s for the week and 4 GDU less for the month of August compared to the 30-year average.

 

 

Dates

2017 GDU Average/Day

30 Year GDU Average/Day

Difference/Day

August 20-26

15.86

18.57

-2.71

August 1-26

15.00

19.00

-4.00

Dates

2017 GDU

30 Year GDU Average

Difference

August 20-26

111

130.0

-19.00

August 1-26

390

494.0

-104.00

 

The table below compares our GDU’s by planting date to the 30-year average. We currently are 50 to 123 GDU’s behind the 30-year average for all planting dates, with the April 24 planting date being the furthest behind the average at 123 GDU less, and the June 2 planting date the closest at 50 GDU’s less. If we use the 30-average of 18.8 GDU’s/day for August, we are currently 2.7 to 6.5 GDU’s behind the average.

Planting Date

2017 GDU'S

30 Year GDU'S

Difference

Day +/-

12-Apr

1991

2095

-104

-5.5

24-Apr

1926

2049

-123

-6.5

5-May

1890

1978

-88

-4.7

12-May

1822

1916

-94

-5.0

2-Jun

1605

1655

-50

-2.7

 

Last week was the fifth week in a row where we accumulated fewer GDU’s than the 30-year average. These cooler temperatures were coupled with cloudy days, these cloudy days reduce the amount of photosynthesis that take place which forces the plant to pull starch and energy from the stalk to fill the kernel which negatively reduces standability/harvestability.  Another aspect of cloudy days is when we experience days with less sunlight we start to lose yield, it is my belief that on cloudy days with less than 50% sunshine during the daylight hours, we can lose .25-.5 bushels/day. Where this issue become more of a concern is as we get further into the month of August we will lose more daylight.

For the month of August, we will lose 80 minutes of daylight, sunrise is 34 minutes later and sunset is 46 minutes earlier from August 1st to August 31st. As the calendar advances, for the month of September we will lose another 86 minutes, sunrise will be 33 minutes later and the sunset will be 53 minutes earlier.

 It normally takes 55-65 days from the Tassel/Silking date (R1) to Physiological Maturity or Black Layer (R6). The anticipated date of Black Layer by planting date is listed in the table below. This is calculated with the belief that a 100-103 day hybrid was planted, and that we will receive “normal” temperatures and GDU accumulation between now and R6.

**** The following data is based on GDU accumulation as of August 26, 2017****

Planting Date

GDU'S

GDU'S to R6

Days to R6

Date of R6

12-Apr

1991

484

26

20-Sep

24-Apr

1926

549

29

24-Sep

5-May

1890

585

31

26-Sep

12-May

1822

653

35

29-Sep

2-Jun

1605

870

46

11-Oct

 

With our below average GDU accumulation for the week, our anticipated date of Black Layer or R6 was pushed back another day by planting date.

In comparing GDU information from 2001-2017, the average GDU accumulation for a planting date of April 25 is 2061 GDU’s. When comparing 2017 to that average we are about 145 GDU’s less than that or 7.7 days. There are only 2 years that have fewer GDU’s than 2017, with those being 2004 and 2009. The year of 2013 and 2014 were only slightly higher in GDU accumulation than 2017.

Year

GDU

2017

1885

2014

1971

2013

1939

2009

1801

2004

1788

 

Insurance Reminders- Contact your Crop Insurance agent if you are chopping corn for silage, so your silage tons can be converted into bushel equivalents. This can also be used on revenue claims if Chicago Board of Trade (CBOT) future prices remain low.

Other Insurance reminders would be to contact your agent if you still have old crop in the bin prior to harvest and are going to put this year’s harvest on top of your old crop. If you do not measure prior to harvest it could be counted as new crop and would affect any claims, you may have.

Upcoming Events:

  • Answer Plot Thursday August 31 Start time 11 AM 5 miles south of Claremont
  • Central Advantage Field Technology Days September 6-7 Farm America Waseca
  • Answer Plot Tuesday September 12 Truman

 

Central Farm Service Website: Central Farm Service Agronomy Notes, Updates and Videos can be found on our website www.CFSCOOP.com at the bottom of the home page. Past Agronomy Notes and Updates can be found under the News tab and Agronomy News.

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