News Story

Agronomy Notes for the week ending August 5, 2017

 

                     

We had spotty showers move through the area early in the week. Temperatures ranged from the upper 50°F’s to low 60°F’s for the lows, with some areas experiencing temperatures in the upper 40°F’s on Friday morning. High temperatures ranged from the upper 70°F’s and 80°F’s almost ideal growing conditions, especially if there is adequate moisture.

Corn plant development ranges from R3 or Milk stage from corn planted in mid-April to just completing silking and starting to Blister (R1) for corn planted in early June.

Planting Date

GDU'S

Growth Stage

Growth Stage

12-Apr

1677

Milk

R3

24-Apr

1612

Blister/Early Milk

R2-R3

5-May

1576

Blister/Early Milk

R2-R3

12-May

1508

Blister/Early Milk

R2-R3

2-Jun

1291

Silking/Blister

R1-R2

 

We accumulated 118 Growing Degree Units (GDU’s) during the week and 76 GDU’s during the first five days of August which is 20 and 22 GDU’s less than the 30-year average. During the week and the first five days in August we averaged 16.86 and 15.2 GDU’s per day which is 2.86 and 4.4 GDU’s less than the average.

Dates

2017 GDU Average/Day

30 Year GDU Average/Day

Difference/Day

July 30 to August 5

16.86

19.71

-2.86

August 1-5

15.20

19.60

-4.40

Dates

2017 GDU

30 Year GDU Average

Difference

July 30 to August 5

118

138.0

-20.00

August 1-5

76

98.0

-22.00

 

In the latter part of July and first few days of August we have experienced days with less sunlight, these days were warm but some days were partly cloudy to cloudy for a large percentage of the day. We need temperatures between 50-86°F for corn to accumulate GDU’s, with that being said, when we experienced days with less sunlight we can start to lose yield. It is my belief that on cloudy days with less than 50% sunshine during daylight hours, we can lose .25-.5 bushels/day. Where this potentially becomes a bigger concern is that from August 1 to the middle of the month we will lose 34 minutes of daylight.

            A widely held belief is that in our area it takes about 140 days +/- from Emergence (VE) to Black Layer or Physiological Maturity (R6). With Emergence to Tassel/Silking (R1) taking 70-80 days and Tassel to Black Layer taking 55-65 days

Growth Stage

Time Frame

Emergence to Tassel

70-80 days

Tassel to Black Layer

55-65 days

           

The Breakdown of days by reproductive stage from Tassel to Black Layer is as follows:

Growth Stage

Days After Silking

Tassel / Silking

R1

0

Blister

R2

10-14 days

Milk

R3

18-22 days

Dough

R4

24-28 days

Dent

R5

35-42 days

Black layer

R6

55-65 days

 

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.

Planting Date

GDU'S

GDU'S to R6

Days to R6

Date of R6

12-Apr

1677

798

42

16-Sep

24-Apr

1612

863

46

19-Sep

5-May

1576

899

48

21-Sep

12-May

1508

967

51

25-Sep

2-Jun

1291

1184

63

6-Oct

            In walking corn fields during the week I am starting to see some nutrient deficiencies show up, in particular Nitrogen, on fields that did not add a supplemental treatment of Nitrogen. What concerns me about deficiencies showing up now, is not just the yield loss, but also the potential for plants starting to cannibalize their stalks, and moving those nutrients to the ear and kernels. By scavenging the stalk for nutrients, standability/harvestability is greatly reduced. Some of these deficiencies were discovered earlier in the growing season by tissue sampling, but were not yet visible at that time.

Soybean plant development ranges from Beginning Pod  (R3- when pods on one of the four uppermost nodes on the main stem are 3/16” long) for beans planted in late June to Beginning Seed (R5-pod has seed 1/8” at one of the four uppermost nodes on the main stem) for beans planted in late April.

Planting Date

Plant Stage

Growth Stage

25-Apr

Beginning Seed

R5

10-May

Beginning Pod/Full Pod

R3-R4

27-May

Beginning Pod/Full Pod

R3-R4

3-Jun

Beginning Pod/Full Pod

R3-R4

28-Jun

Beginning Pod

R3

 

Soybean aphid numbers are climbing with certain areas growing faster than others. We most generally tend to find Soybean Aphids sooner in fields that:

  • The first or last planted soybeans
  • By wooded areas such as creek/river bottoms that have buckthorn in them
  • Soybeans with Seed Treatments with absent or less active insecticidal properties
  • Fields with lower Potash (K) levels (150 PPM or less)
  • Fields with higher Soybean cyst nematode levels

 

Upcoming Events:

  • Central Advantage Field Technology Days September 6-7 Farm America Waseca

 

***We have added the video portions of our Agronomy Updates to the Central Farm Service Website***

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