Central Valley Cooperative

Much has transpired since the last Agronomy Notes, we have had a few storms move through with rain, spotty hail and wind. The wind that came thru during the week of July 25^th did have some corn leaning and some outside rows root lodged or severely goosenecked.

 

The soybeans did get some wind too, which had some of the taller beans lodged as well. Because of the height, dense canopy and very humid moist growing conditions that we have experienced so far this growing season it would make sense that Sclerotinia Stem Rot or more commonly known as White Mold can will be a problem this fall.

 

Corn plant development ranges from Late Blister/Early Milk (R2-R3) to Early Dough (R4). The cooler nights coupled moisture from rain and heavy early morning dews have been favorable for kernel development and starch accumulation.

Planting Date	GDU’S	Plant Stage	Growth Stage
15-Apr	1775.5	Early Dough	R4
23-Apr	1727.5	Late Milk/Early Dough	R3-R4
30-Apr	1693.5	Milk	R3
08-May	1596	Late Blister/Early Milk	R2-R3

 

We accumulated 149 Growing Degree Units (GDU’s) for the week of July 28^th, 159 GDU’s for the week of August 1^st and 143 GDU’s for the week of August 8^th.

 

 

Dates	2015 GDU/Day	30 Year GDU Average/Day	Difference/Day
July 19-25	21.29	21.00	0.29
July 26-August 1	22.71	19.71	3.00
August 2-8	20.43	19.43	1.00
Dates	2015 GDU/Week	30 Year GDU Average	Difference
July 19-25	149	147	2
July 26-August 1	159	138	21
August 2-8	143	136	7

In comparing the differences by day and week, GDU’s trended very close to the 30 year average with the week of July 26 to August 1 being slightly above average for GDU’s. For the month of July we accumulated 645.5 GDU’s which is 1.5 GDU’s more than the 30 year average of 644 GDU’s.

 

Our average tassel date this year was July 20^th.

 

Average Tassel Date			Year
07-Jul			2007
23-Jul			2008
27-Jul			2009
12-Jul			2010
21-Jul			2011
08-Jul			2012
30-Jul			2013
24-Jul			2014
20-Jul			2015

 

In comparing tassel dates with Central Valley data from 2007 to 2014 our average tassel date has been July 19^th which makes this year very close to that average.

It normally takes 55-65 days from average tassel date to Physiological Maturity or Black Layer (R6). If we add 60 days to July 20^th that would put Black Layer at September 18^th.

 

A common thought is that in our area it takes about 140 days +/- from Emergence to Black Layer, with emergence to tassel taking 70-80 days and tassel to black layer 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 is:

 

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

One of the concerns that I have about our corn crop for the upcoming harvest season is Crown Rot which we have discussed earlier in the year. Crown Rot is caused by cool wet soils or other early season stress that allows the disease to enter the plant, which will cause a brown or tan colored discoloration at the base of the plant or the crown, as is shown pictured below.

 

 

Crown Rot tends to slow down and limit the amount of water and nutrients that the corn plants are able to utilize. Because of the rainfall pattern that we have been in so far this year, plants for the most part have not lacked for moisture and have been able to work thru crown rot issues.

As we get closer to harvest these plants will succumb to this disease, but prior to that the plant will pull as many nutrients out of the stalk to fill the ear and as many kernels as it possible can. Because the plant may have been unable to pull in as many nutrients as it normal does because of crown rot we will see more standability issues or down corn in those affected fields than we normally would. Keeping a close eye on fields and doing standability tests on stalks and root will be of great importance in helping to schedule harvest and limiting down corn.

 

Soybean plant development is R4 or Full Pod (Pod is ¾ inch long at one of the four uppermost nodes on main stem) to R5 or Beginning Seed (Seed is 1/8 inch long in pod at one of the four uppermost does on the main stem) for most soybean planted in April and May. For soybean that were planted in June and July they are mainly at the R3 or Beginning Pod (Pod is 3/16 inch long at one of the four uppermost nodes on the main stem).

 

Soybean Aphid and Green Cloverworm numbers have increased on fields that have not been sprayed. We are still seeing reduced aphid numbers on fields that have seed that was treated with a fungicide/insectide seed treatment. It appears that this year those treated soybeans slowed down Aphids 2-4 weeks longer than they historically have.

 

One of the concerns that I have had this growing season is the amount and frequency of moisture that we have received so far this year. We have been very fortunate for the most part when it comes to moisture we have received, which has allowed soybean plants to put on more vegetative growth. This increased growth and dense canopies has increased the probability for Sclerotinia Stem Rot or White Mold (SWM). Which we started to see show up late in the week of July 25^th in fields that have a history of it.

 

The other Soybean disease that I believe will show up will be Sudden Death Syndrome (SDS0 as well as Brown Stem Rot (BSR). Both of these diseases are accentuated by compaction issues, which are more prevalent in wetter growing seasons.

 

Central Valley Website: Past Central Valley Agronomy Notes and Agronomy Topics of the week can be found on our website www.centralvalleycoop.com under the Agronomy page.

 

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