ND and northern MN Late Corn Planting Recommendations
 The late spring has caused concern for some North Dakota and northern Minnesota corn growers.
 Many farmers may be thinking about switching to corn products with earlier relative maturity (RM) to offset late planting.
 Yield potential can decrease with delayed planting due to several factors that include a shorter growing season, greater risk of
insect or disease infestations, and moisture stress during pollination.
 However, switching to an earlier RM corn product when planting is delayed, or deciding not to plant corn, may not be the best decision.
Corn Maturity
and fall drying conditions.
Careful consideration should be given prior to switching to an
earlier corn product. Full-season corn products for a given area
typically have the highest yield potential, which may help offset
an increase in drying costs. As planting is delayed, corn product
maturities come closer together. Corn generally requires 1.6
growing degree units (GDUs) less each day to reach flowering
and 6.8 GDUs less each day to reach physiological maturity
(black layer) as planting is delayed beyond about May 1.1
Table 1 can help with the decision of when to switch to an
earlier maturity. Based on an April 24 planting date, the number
of long-term GDUs are listed for several weeks. It can be used
to determine the potential GDUs remaining from a given
planting date to typical maturity or killing frost in a given area.
Figure 1 (page 2) is a map of average first frost dates for North
Dakota and northern Minnesota.
Therefore, corn planted in late May compared to an optimum
date may actually take 125 to 200 fewer GDUs to reach black
layer.
For an example, consider if planting was delayed until the week
of May 22 in the Carrington area. In that time, 260 GDUs would
have been lost from April 24. If the first killing frost date is
October 9, the maximum potential GDUs remaining for
Carrington is 2124 (2384 - 260). A product with a GDU to black
layer rating of 2100 GDUs can still be planted because its GDU
to black layer rating is below the 2124 potential. Additionally, a
product with a GDU to black layer rating of 2100, planted on
May 29, should only require 1903 GDUs to black layer [2100(6.8 x 29)].
When to Switch Corn Maturity
The yield for late-planted corn will vary greatly depending on the
rest of the growing season. The decision to switch maturity with
delayed corn planting is difficult because of variations in
growing seasons relative to available GDUs, first frost date,
Table 1. Average GDU accumulation in various locations in North Dakota and Northern Minnesota.
Date
Grand Forks
Fargo
Jamestown
Carrington
Minot
Eldred, MN
May 8
98
98
98
107
84
92
May 15
May 22
165
243
164
239
165
240
179
260
143
211
156
230
May 29
327
321
324
348
287
312
June 5
June 12
Sept. 25
Oct. 2
Oct. 9
Oct. 16
Oct. 23
418
519
2249
2301
2343
2373
2387
414
520
2345
2398
2441
2472
2488
414
513
2340
2394
2439
2471
2487
440
538
2277
2336
2384
2420
2441
370
458
2067
2112
2149
2174
2186
400
498
2203
2254
2295
2324
2338
GDU Base temperature of 50° F. Data shown for Grand Forks, Fargo, Jamestown, Carrington, and Minot is for 1990-2010. Data shown for Eldred, MN is for
1995-2010. Data courtesy of North Dakota Agricultural Weather Network, Fargo, ND.
AsgrowandDEKALB.com
ND and northern MN Late Corn Planting Recommendations
The numbers given are only based on averages and should only
be used as a reference. The grower must decide what is best
for the operation. Remember that the main reason for switching
corn product maturity is not so much for yield, but to reduce
the risk of immature and wet grain in the fall.
Product Considerations
Insect protection and crop safety become even more important
with later planting. Corn with Genuity® traits that offer insect
protection and herbicide tolerance, such as Genuity®
SmartStax® corn and Genuity® SmartStax® RIB Complete® corn
blend products, should be considered. Additionally, even with
delayed planting, it is still important to try and minimize the risk
of adverse weather during critical growth stages by planting a
package of product that range in GDU requirements to
flowering as well as maturity. Several new product flower early,
which helps to lower the risk of an early frost.
Switching to earlier maturity
corn products for lateplanting situations should not
always be automatic.
Sources:
North Dakota Agricultural Weather Network. Data accessed April 13, 2011.
http://www.ndawn.ndsu.nodak.edu/ (verified 4/13/11).
1
S. Brouder et al. 2008. Corn & Soybean Field Guide. ID-179. Purdue University. West
Lafayette, Indiana.
Figure 1. Average first fall freeze dates for North Dakota,
according to the North Dakota Agricultural Weather
Network (NDAWN).2
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