News Story

Agronomy Update Aug 4, 2018

Brian Weller, Lead Agronomist

The temperatures during the week were in the upper 70°F’s to low 80°F’s for highs during the day and mid-50°F’s for lows during the night, almost ideal for pollinating crops. We did receive some spotty showers later in the week, but prior to that we were starting to see lighter soils and soils that had compacted areas showing signs of water stress.

Corn plant development is late R3 (Milk) to early R4 (Dough) for corn planted in late April. Corn planted in late May is at R2 (Blister).

Planting Date

GDU'S

Growth Stage

28-Apr

1777.5

R3-R4 Dough

5-May

1709.0

R3 Milk

13-May

1638.0

R2 Blister -R3 Early Milk

19-May

1547.0

R2 Blister -R3 Early Milk

26-May

1432.0

R2 Blister

 

We accumulated 118.5 Growing Degree Units (GDU’s) during the week, which is 19.5 GDU’s less than the 30-year average. We averaged 16.93 GDU’s per day during the week which is 2.79 GDU’s less than the average. We accumulated 611 GDU’s for the month of July, which is 33 GDU’s less than the 30-year average, or 1.06 GDU’s less per day than “Normal”.

Dates

2018 GDU Average/Day

30 Year GDU Average/Day

Difference/Day

July 29-August 4

16.93

19.71

-2.79

July 1-31

19.71

20.77

-1.06

Dates

2018 GDU

30 Year GDU Average

Difference

July 29-August 4

118.5

138.0

-19.50

July 1-31

611.0

644.0

-33.00

 

We did experience a few days during the week 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, 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 1st to the 15th of the month we will lose 35 minutes of daylight. For the month of August, we will lose 77 minutes of sunlight, every hour is needed to maintain or increase yield.

Lack of sunlight is a concern on both yield loss but also standability or harvestability. If a corn plant is not producing enough energy to fulfill the plants needs it will start taking nutrients away from the leaves as well as the stalk, the less energy you produce from the sun the more is taken away from the stalk and consequently you increase the potential for standability or harvestability issues.

A common thought 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 date to Physiological Maturity or Black Layer (R6). If you were to add 60 days to our average tassel date this year of July 14, it would put Black Layer at about September 12th.

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” rainfall and GDU accumulation between now and R6.

Planting Date

GDU'S

GDU'S to R6

Days to R6

Date of R6

28-Apr

1777.5

697.5

37

10-Sep

5-May

1709

766

41

13-Sep

13-May

1638

837

45

17-Sep

19-May

1547

928

49

22-Sep

26-May

1432

1043

55

28-Sep

 

Soybean plant development ranges from R3 (Beginning Pod-Pod is 3/16” long at one of the four uppermost nodes on the main stem with a fully developed leaf) for soybean planted in late May. We do have early maturing soybeans that were planted in late April that are at R4 (Full Pod-pod ¾” long at one of the four uppermost nodes on the main stem, with a fully developed leaf).

Soybean Aphid numbers grew exponentially in the last few weeks with Japanese Beetle numbers starting to decline in many areas. We are starting to see Green Cloverworms in some fields as well. Both the Japanese Beetle and Green Cloverworms can be major defoliators, which in tandem with Soybean Aphids can reduce yield potential quickly.

Central Farm Service Website: Central Farm Service Agronomy Notes and Updates 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.

We are also on Facebook and Twitter with links to both on the Central Farms Service website www.CFSCOOP.com

Central Farm Service Agronomy Videos have been posted on Twitter and Facebook, these video updates will be appearing from time to time.

If you have been receiving our Agronomy Notes of the week via mail and would like them emailed to you, contact your local Central Farm Service Agronomist or myself at bweller@cfscoop.com Use the same procedure if you would like to be taken off this list.