For several weeks now, I've been describing how Indiana corn growers and consultants can assess the fall frost risk of any particular field based on the grain development stage and estimates of remaining GDD in the growing season (see p&c9641.htm, p&c9643.htm, or p&c9644.htm). This week, I decided to simply publish the pertinent tables instead of repeating all the accompanying text. If you have questions about the tabular information, review my previous articles.
Table 1. Approximate GDDs from specific grain fill stages to kernel black layer for corn hybrids that typically require 2700 GDDs from planting to black layer. | ||
Grain fill stage | Description | GDDs to black layer |
R1 | Fresh silks | 1300 |
R2 | Blister | 1040 |
R3 | Milk (roasting ears) | 900 |
R4 | Dough | 775 |
R4.5 | Late dough/early dent | 510 |
R5 | Fully dented | 250 |
R6 | Black layer | 0 |
Adapted from Table 3, NCH-40, Growing Season Characteristics and Requirements in the Corn Belt, Ralph E. Neild and James E. Newman, 1986. | ||
Click for a description of corn grain fill stages. |
Table 2. Grain fill stages of development and frost risk assessment for various planting dates at the Purdue Agronomy Research Center near West Lafayette, IN, as of September 2, 1996. | ||
Planting date | Grain fill stage on Sep 2 | Will the grain mature before frost? |
April 19 | Full dent | Yes |
May 2 | Full dent | Yes |
May 14 | Mid-dent | Yes |
May 17 | Mid-dent | Yes |
May 20 | Mid-dent | Yes |
May 31 | Late dough/early dent | Likely yes |
June 5 | Dough | Maybe |
June 15 | Late milk/early dough | Likely not |
June 21 | Milk (roasting ear) | Likely not |
Median frost date for westcentral Indiana is October 13. |
Table 3. Estimates of youngest safe grain fill stage relative to fall frost risk in Indiana. Estimates valid for crop development as of September 9, 1996 and median fall frost dates. | |||
Indiana Crop Reporting District | Median frost date (50 % probability) | Estimated GDD remaining from Sep. 9 to fall frost | Approximate youngest safe grain fill stage |
Northwest | October 6 | 359 | Mid-dent |
Northcentral | October 6 | 347 | Mid-dent |
Northeast | October 6 | 349 | Mid-dent |
Westcentral | October 13 | 454 | Early dent |
Central | October 13 | 440 | Early dent |
Eastcentral | October 6 | 350 | Mid-dent |
Southwest | October 20 | 575 | Late dough |
Southcentral | October 13 | 485 | Early dent |
Southeast | October 13 | 491 | Early dent |
Click for a description of corn grain fill stages. |
Return to the the Chat 'n Chew Cafe.
The Corn Growers Guidebook , a WWW resource for corn management systems in Indiana and the eastern CornBelt.
Purdue University Agronomy Extension WWW Home Page.
Purdue Agronomy On-Line! , Purdue's Agronomy Department WWW Home Page.