We received some scattered rain showers throughout the week with totals ranging from .25-1”. Daytime temperatures during the week were in the upper 70’s°F to lower 80’s°F with nighttime temperatures in the mid 50’s°F to low 60’s°F.
Soybean plant development ranges from R5 (Beginning Seed) to R7 (Beginning Maturity) on some early planted, early maturing varieties. When soybeans are at R7 one pod on the main stem has reached its mature pod color.
I noticed a few more fields during the week versus last week that had leaves that had started to turn color and had pods that were doing the same. In most situations, 3-4 weeks after leaves start to turn color they will be combined.
I am still hearing reports of some small pockets of white mold occurring, but have not seen any as of yet. I am still seeing areas of Sudden Death Syndrome (SDS) but also seeing more Brown Stem Rot (BSR).
SDS infects the roots early in the season, with symptoms normally showing up in late July or early August, while BSR symptoms tend to show up late in August into September. Early symptoms of SDS and BSR are yellow chlorotic areas in the field as shown below on the left.
As you look at plants you will see yellow spots in between the veins (as shown above on the right) that progress to yellow with brownish lesions (as shown below on the left) to mainly brownish lesions with yellow chlorotic areas in between the lesions (as shown below on the right).
As the disease progresses further, leaves will fall off the plant and grey and brown areas will develop on the lower stem. If you cut into the stem and into the roots, the pith should remain white. If the pith is not white and is brown you have Brown Stem Rot (BSR). Brown Stem Rot and Sudden Death Syndrome have the same symptoms except for the color of the pith. Sudden Death Syndrome may also cause a root rot that may leave a bluish type of fungal growth on the roots.
Sudden Death Syndrome is more apt to happen in early planted fields that have cool and wet soils. It also appears that the soybean plants need to be affected by a Soybean Cyst Nematode and or compaction prior to the plant developing Sudden Death Syndrome. Once you have had SDS and, if conditions are right, you will get the disease. The best way to limit yield reductions from these diseases are to plant resistant varieties the next time that field is in soybeans.
Corn plant development ranges from late Dough (R4) to Early Dent with some early planted earlier maturing hybrids approaching 50% milk line.
| Planting Date | GDU’S | Plant Stage | Growth Stage |
| 25-Apr | 2206 | Early Dent | R5 |
| 05-May | 2186 | Early Dent | R5 |
| 11-May | 2138 | Early Dent | R5 |
| 17-May | 2104 | Late Dough to Early Dent | R4-R5 |
| 24-May | 2046 | Late Dough to Early Dent | R4-R5 |
We accumulated 123 Growing Degree Units (GDU’s) during the week which is 7 GDU’s more than the 30 year average of 116 GDU’s for that time frame. The average daily GDU accumulation for the week was 17.57 GDU’s per day which is 1 GDU more per day than the 30 year average of 16.57 GDU’s.
| Dates | 30 Year GDU Average/Day | 2014 GDU/Day | Difference/Day |
| August 31 to September 6 | 16.57 | 17.57 | 1 |
In comparing GDU accumulation for 2014 to 2013 we are slightly ahead for every planting date except April 25. In comparing 2014 to the 30 year average we are behind for the April 25 planting date, virtually even for the May 5 and 11 planting date and slightly ahead for the May 17 and 24 dates.
| 2014 | 2013 | 30-Year | |
| Planting Date | GDU’S | GDU’S | GDU’S |
| 25-Apr | 2206 | 2243 | 2254 |
| 05-May | 2186 | 2179 | 2188 |
| 11-May | 2138 | 2128 | 2135 |
| 17-May | 2104 | 2068 | 2073 |
| 24-May | 2046 | 1976 | 1988 |
Depending on the planting date we are 2.9 days behind for the April 25 date and 3.1 days ahead for the May 24 planting date compared to the 30 year average. The average GDU’s used for this comparison is 18.6 GDU’s per day, which is an average accumulation of GDU’s from late July to early September.
The GDU range for hybrids in our area is 2300-2700 (92-108day.) The most common day length of hybrids planted in our area is 98-101 day, most of these hybrids reach R6 at about 2475 GDU’s. If you use 2475 GDU’s as your R6 target it will take 14 to 23 days from September 6 to reach R6 or Black Layer. (The table below provides an estimated R6 date, by planting date.)
| Planting Date | GDU’S | GDU’S to R6 | Days to R6 | Date of R6 |
| 25-Apr | 2206 | 269 | 14 | 20-Sep |
| 05-May | 2186 | 289 | 16 | 21-Sep |
| 11-May | 2138 | 337 | 18 | 24-Sep |
| 17-May | 2104 | 371 | 20 | 25-Sep |
| 24-May | 2046 | 429 | 23 | 29-Sep |
Frost Insurance- A supplemental weather coverage is available to protect against frost or other weather events. My understanding of this coverage is that the grower purchases the coverage but picks the day that coverage is needed to. Considering where we are at with GDU’s this may be worth investigating with your local crop insurance representative.
If by chance you are unable to get the information you need contact your local Central Valley Agronomist and they will put you in contact with someone who could help provide some answers regarding this “Frost Insurance”.
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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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