Originally published in Purdue Pest Management & Crop Production Newsletter (6 September 1996)

Frost-Mongering Update for Corn as of September 9th

R.L. (Bob) Nielsen , Agronomy Department , Purdue University, West Lafayette, IN 47907-1150
Internet address: rnielsen@purdue.edu

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.

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