Late Corn Planting Recommendations in Minnesota

  • As planting time approaches and wet soils remain across much of Minnesota, many growers may be thinking about switching to earlier maturity corn products to offset late planting.
  • Yield potential can decrease with delayed planting due to a number of factors, including a shorter growing season, insect and disease pressure, and moisture stress during pollination.
  • Switching to earlier maturity corn products for late-planting situations should not be an automatic decision.
 

Corn Maturity

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 can help offset an increase in drying costs.  As planting is delayed, corn products actually reduce their GDD (growing degree day) needs.  GDD accumulation increases as the the growing season progresses.  As a result, the number of GDDs required from planting to physiological maturity (black layer) decreases by nearly 7 GDDs per day as planting is delayed beyond May 1st.  This means that late-planted products mature in fewer than expected GDDs.  Therefore, corn planted in May compared to an optimum planting date may require 125 to 200 GDDs less to reach black layer.  Recommendations from your local agronomist regarding full-season corn relative maturity (RM) groups and RM switch dates for Minnesota are listed in Table 1. 

 

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 GDDs, the first frost date, and fall drying conditions. 

Table 2 lists average accumulated GDDs, at several locations over several weeks, based on an April 28th planting date.  This information can help with the decision of when to switch to an earlier maturity by determining the potential GDDs remaining from a given planting date to typical maturity or killing frost in a given area. Table 3 shows average first frost dates for some cities in Minnesota.

10;   10;
For example, consider if planting was delayed until the week of May 15 in the Lamberton area.  If the first average killing frost date is October 10, the maximum potential GDDs remaining for Lamberton is 2454 (2604-150).  Therefore, a product with a GDD to black layer rating of 2400 GDDs can still be planted becuase it39;s rating is below the 2454 estimated GDD potential that may occur before the first killing frost.  If the reduced GDD requirement after May 1st is also taken into consideration, the product is even less likely to encounter a killing frost before physiological maturity:  
10;   10;
2400 GDD requirement - (7 less GDDs  per day X 15 days) = 2295 GDDs
10;   10;
The numbers given are based on averages and should only be used as a reference.  Growers must decide what is best for their 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.  
 Table 1. Local Monsanto agronomist recommendations for switching corn maturities in Minnesota 
 Minnesota Region
 Full-season RM
 "Switch-to" Dates
 
 
 
 May 15
 May 25
 
--------Days--------
 Southern1
 106-111
 100-105
 94-99
 Central2
 100-104
 94-99
 89-93
 Northern3
 98-102
 94-96
 85-89
1Southern zone = east to west line SOUTH of U.S. Highway 212
2Central zone = east to west line NORTH of U.S. Highway 212  
3Northern zone = line from Morris to St. Cloud, MN and north
 

Product Considerations

Corn with Monsanto traits that offer insect protection and herbicide tolerance, such as SmartStax®RIB Complete® for the Corn-Growing Area and Genuity®VT Triple PRO®RIB Complete®corn blends, should be considered.  Additionally, even with delayed planting, it is still important to try to minimize the risk of adverse weather during critical growth stages by planting a package of products that range in GDD requirements to flowering as well as maturity.  

 
 
 
 Table 2. Average GDD accumulation from six locations in Minnesota, based on an April 28th planting date. 
 Date
Montevideo 
Morris 
Lamberton 
St. Cloud 
Waseca 
Rochester 
 May 8
77
72 
80 
72
77
 74
 May 15
143
133
150 
132
145
139
 May 22
225
212
236 
206
225
213 
 May 29
308
292
324 
284
311
293
 June 5
406
388
426
376
413 
388
 June 12
517
493
542
478
527
495
 Sept. 25
2417
2312 
2477
2288
2469 
2347 
 Oct. 2
2482
2372 
2550
2343
2570
2411 
 Oct.  9
2528
2414
2604
2383
2592 
2470
 Oct. 16
2568
2449
2648
2416
2632 
2499
 Oct. 23
2596
2473
2680
2438
2661
2526
 Source: The University of Minnesota Climatology Working Group.1 30-year history (1981-2010)
Table 3. Average first frost date (28°F) 
 Region
City 
Date 
 West Central 
 
 
 Morris
10/8 
 Montevideo
10/9 
 Fergus Falls
10/10
 Central
 
 
 Hutchinson
10/13 
 St. Cloud
10/9
 Willmar
10/12 
 Southwest
Lamberton 
10/10 
 Southeast
Rochester 
10/8 
 Source: The University of Minnesota Climatology Working Group.230-Year History (1981-2010)