With the cooler than average temperatures, questions have come up regarding growing degree units and how far behind the accumulation might be. The accumulated GDUs for the KSRE Research fields are reported daily on the K-State Weather Data Library web page at http://www.ksre.ksu.edu/wdl/Text%20files/text/GDU.TXT
Below is a table that shows the current accumulated GDU for Sorghum, how far behind that is, the average freeze date, and how many GDUs on average accumulate from the 15th through the average freeze date:
|
GROWING DEGREE ACCUMULATION from April 1 - August 15, 2013 |
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|
Division |
Location |
Current Sorghum GDU |
Average Sorghum GDU |
Departure |
Approx No. Days |
Average Freeze Date |
Average number of GDU’s remaining from Aug. 15 through first freeze |
|
Northwest |
Colby |
3909 |
4126 |
-217 |
-11 |
2-Oct |
1679 |
|
Southwest |
Garden City |
4192 |
4361 |
-169 |
-8 |
13-Oct |
2232 |
|
Central |
Hays |
4279 |
4460 |
-181 |
-9 |
10-Oct |
1957 |
|
South Central |
Hutchinson |
4232 |
4813 |
-581 |
-29 |
17-Oct |
2225 |
|
Northeast |
Manhattan |
4328 |
4591 |
-263 |
-13 |
15-Oct |
2032 |
|
East Central |
Ottawa |
4231 |
4831 |
-600 |
-30 |
17-Oct |
2231 |
|
Southeast |
Parsons |
4498 |
4834 |
-336 |
-17 |
23-Oct |
2380 |
|
Northeast |
Rossville |
4173 |
4591 |
-418 |
-21 |
11-Oct |
1942 |
|
South Central |
St. John |
4321 |
4848 |
-527 |
-26 |
22-Oct |
2279 |
|
North Central |
Scandia |
4051 |
4535 |
-484 |
-24 |
16-Oct |
2034 |
|
Northeast |
Silver Lake |
4207 |
4637 |
-430 |
-22 |
11-Oct |
1941 |
|
West Central |
Tribune |
4058 |
4117 |
-59 |
-3 |
7-Oct |
1717 |
|
**Sorghum GDU: (Maximum temperature + Minimum temperature)/2-35, when minimum temperature is greater than 32 oF |
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Most sorghum hybrids need about 1,900 GDU’s from half bloom to physiological maturity, using the 35 degree minimum temperature (or 1,500 if a 42 degree minimum temperature is used in the calculation). Comparing that to the last column in the chart above, that means there is still time for the sorghum to reach physiological maturity in most areas if the sorghum is now, or soon will be, at half bloom – assuming average weather and average dates of the first freeze.
Mary Knapp, State Climatologist
mknapp@ksu.edu
Kraig Roozeboom, Cropping Systems and Crop Production Agronomist
kraig@ksu.edu
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