Evaluating Corn Stands  05/11/17 9:44:39 AM

Mynard Plot Tour—MAY 16TH IS CANCELLED—Given the delays this spring, we will skip our first date next Tuesday May 16th.  WE will have the first tour on WEDNESDAY May 31st—Hopefully, planting will be completed and we have a chance to take a breath over Memorial Day Weekend.


2017 Mynard Tour Dates

Date                            Location                      Time                            Guest Speakers/Topic

Wednesday  May 31th Mynard Plot                9-10:30 a.m.                Tim Mundorf_Midwest Labs

Fertility Observations

Planting Re-Cap


Tuesday June 13th       Mynard Plot                9-10:30 a.m.   

Tuesday June 27th       Mynard Plot                9-10:30 a.m.               

Tuesday July 11th        Mynard Plot                9-10:30 a.m.

Tuesday July 25th        Mynard Plot                9-10:30 a.m.

August 2nd-6th              Springfield                                                      Sarpy Co. Fair

Tuesday August 8th     Mynard Plot                9-10:30 a.m.

August 9th-12th            Cass Co. Fairgrounds                                      Cass Co. Fair

Tuesday August 22nd  Mynard Plot                9-10:30 a.m.                Corn Breeder/Corn Lineup

                                                                                                            Soybean Breeder/Soybean Lineup

Tuesday August 29th   Cass Co. Fairgrounds                                      Late Summer Clinic


It is not unlikely that as our corn crop emerges this spring, the chances or cork-screw or twisted corn may exist.  In extreme cases, the corn may TRY to leaf out under-ground.  Given the spring we have had, there is some chance of this, so, as you scout your fields to evaluate stand establishment, consider the following to understand what may be some of the causes to this phenomena.  This does not appear at this time to be widespread or extreme, however, you may see this as the corn emerges.


Like many crop problems, multiple possible causes of this phenomenon exist. The challenge is to identify the most likely cause for your situation. Corn emergence occurs through mesocotyl elongation that pushes the coleoptile to the soil surface. Corn planted early can twist and form a corkscrew shape or have curved mesocotyl growth due to kernel position in the furrow compared to the normal vertical path upward through the soil. Fortunately, the problem is usually limited to a small number of plants within a few problem fields.


A Key Source For Local Agronomic Information
Herbicide Injury. Abnormal mesocotyl development can also be caused by cell growth inhibiting herbicides, such as the acetanilide family. Injury, due to these herbicides often resembles adverse effects due to soil crusting and generally affect corn shoot development when weather or soil conditions are not adequate for rapid plant growth. Often when plant twisting is being blamed on herbicide injury, cool soil temperatures and soil crusting are contributing factors.

Soil Crusting. Heavy rains shortly after planting can result in soil crusting. Severe crusting results in increased resistance for the coleoptiles of the corn plant to push through the soil surface. This resistance can result in corkscrewed or deformed mesocotyl/coleoptile development. Excessive press wheel compaction and seed furrow sidewall compaction resulting from planting

in wet conditions can also restrict coleoptile emergence.


Soil Temperature Effects. Abnormal mesocotyl or coleoptiles development can occur with large fluctuations in day and night soil temperatures. Studies have shown that abnormal corn development occurred most often when day and night soil temperatures fluctuated from 80 F to 55 F, respectively. Now, we did not have temperature swings to that degree, but soil temperatures swings can increase the chances of cork screwed corn. 


Management Options. You should conduct stand counts in your fields to evaluate the severity of crop damage. In most cases, the best option will be to do nothing. Leaving the existing crop will likely be more economical than replanting this far in the planting season. Additionally, pre emergence corn herbicides already on the field will likely restrict you from replanting the field to soybeans.


Source: B. Nielsen. 2004. Corkscrewed Corn Seedlings. Purdue University Ext.

May 1.


As you evaluate your stands, a few considerations IF you are considering a replant due to weather, etc.    1) Many herbicides restrict replant options and producers should use caution and consult the herbicide label prior to replanting.  2) Replanting corn at this time of the season can still maximize your total yield potential.  It is not late enough in the season to think about changing maturities of hybrids or changing to soybeans entirely for the areas needing replanting.   This conversation changes however, after May 16th.   It is documented that yield potential in corn is reduced one percent for every day after May 15th that corn is planted. If your fields have stand losses of 30-40% or less after May 15th, it is still better to leave the field alone than replanting the entire field.  If stand loss is greater than 50% across the entire field re-planting to corn or planting soybeans may be a better option.  This is of course unless you intend to harvest and dry high moisture corn immediately after black layer development has occurred.  Even then, you would be in a race with the average frost date of early October to get the corn to maturity.  3) Prior to re-planting, you may be provoked to re-apply pre-emergence herbicides and a supplemental dose of fertilizer in eroded areas where the soil particles which have bound to the herbicides/fertilizer has been physically moved through erosion from the storms.  The important things to remember are that not all areas of the field had the treated soil layer removed through erosion. Re-application could promote increased herbicide carry-over potential for the rotation crop of next year in these areas.  We don't know how much of the herbicide or fertilizer was lost unless a soil analysis of the area in question is preformed.  I believe the most important thing to consider is getting the area re-planted and growing without further delay or possible added stress from additional applications.  The best choice is to treat weed issues with post-emergence applications and if additional side dressed nitrogen if needed.  .4) Soybeans can maintain much of their maximum yield potential even if stand is reduced 40 percent.  5) Historically, soybeans can be planted up to June 5th without a statistical yield reduction---Some academic research will debate this.

Corn Replant--Early Season--Example #1:  Using the below table—(optimal planting date of April 30th):  If you planted a 113 Relative Maturity hybrid at 30,000 on April 30th and have a viable stand now of 15,000, the yield potential is 82%.   This table is useful for all replanting decisions (hail, soil crusting, insect damage, etc)


Planting                                                          Population (1000/ac)

Date          10                         15                    20                    25                    30                    35

Apr. 1          62                       76                    86                    92                    94                    93

Apr. 20        67                       81                    91                    97                    99                    97

Apr. 30        68                       82                    92                    98                    100                  98

May   9        65                       79                    89                    95                    97                    96

May 19        59                       73                    83                    89                    91                    89

May 29        49                       63                    73                    79                    81                    79

                         % of maximum yield


from Nafziger,E.D. 1994. Journal of Production Agriculture. &:59-62

Based of research in the Central Corn Belt by the University of Illinois.


Corn Replant--Late Season--Example #2--The following table from Purdue University using 113 RM day hybrids demonstrates late season planting yield potentials.

                                                            Population (1000/ac)

Planting Date                         16                    18                    20                    22.5                 25


May 16                                    86                    90                    93                    96                    98

May 21                                    83                    87                    91                    94                    95

May 26                                    80                    84                    87                    90                    92

May 31                                    75                    79                    82                    85                    87

June 5                                      69                    73                    77                    80                    81

June 10                                    63                    67                    70                    73                    75       

                        % of maximum yield

At a population of 25,000 planted on June 10th a yield reduction of 25% has occurred before you have pulled out of the field.  The chances of seeing a 15-20% yield reduction due to early frost/light test weight, etc. is also very real. Planting grain or forage sorghum has more yield and economic potential at this calendar date if your location and management practices would permit this to take place.   I realize that previous corn herbicide applications or management practices may have you locked into replanting corn on certain acres.  I would suggest that you don’t go more than 10 days earlier in relative maturity if you do decide to change the maturity of corn planted.  Research and experience suggest that you are still better off using the same maturity hybrids you normally plant in your region due to their aggressive plant growth will allow the corn to “catch up faster”.  Hope for a hot summer and a late frost.


Fertilizing/Re-fertilizing, Nitrogen Loss to corn and soybeans should also be avoided until the crops have a chance to resume active growth. Increasing fertility to injured plants can amplify the injury and delay the recover period. Nitrogen leaching is always a question in cool, wet springs. The amount of nitrogen lost depends on the form of nitrogen used. Solution nitrogen (28% or 32%), or ammonium nitrate are more subject to leaching because they contain nitrate-N which is not readily held in the soil and moves with the soil water. Ammonia N (anhydrous) has to go through nitrification (conversion to nitrate), in order to be leachable and plant available. With the “rollercoaster” temperature swings, cooler soil temperatures, nitrification has been slow and most ammonia N is still present as ammonium and not subject to soil leaching. The result of this might be that corn has emerged and is yellow. One reason for this is obviously lack of sunlight, but usually it is a result of the nitrogen being unavailable for plant uptake or it has been leached out of the germination zone. The only way to tell is to soil test for residual nitrate in the top two feet after the corn has reached to V10 (8-leaf) stage. At that time, if needed, additional nitrogen can be applied through side-dress or fertigation applications. In-season uses of chlorophyll meters are generally the best approach to determining fertility needs.



Soil Compaction during planting after rain is certainly more an issue now than it was 2 weeks ago.  As the calendar approaches May 15th this week, producers may/will plant into wetter than normal conditions in order to complete corn planting in a timely fashion.  Surface and sidewall compaction from tillage and planter passes across wet fields certainly increase the chances of having restricted root growth in the seed slot and added discoloration to the corn and soybean plant.  This is most common in fine-textured soils and aggravated by continued cool and wet conditions.  Sidewall compaction is a product of the force of the disk openers of the planter smearing the sides of the seed slot when the soil conditions are too moist at the seeding depth. Since early root growth is restricted laterally to the width of the seed slot, the plant's ability to extract water and nutrients from the soil is compromised and the plant will fall under stress.

Some growers believe that as long as the press/closing wheels aren't picking up mud on the tread that it is dry enough to plant.  That may be true however, digging to seeding depth and making sure that the soil is friable--crumbles in your hand with little to no soil sticking in you palm, will insure that the soil is not too wet to plant to promote added compaction.  Waiting the extra day is hard to do but, can pay you in the end!




John W. McNamara


Wiles Bros. Inc.

606 Wiles Road

Plattsmouth NE. 68048

(402) 298-8550--Office

(402) 499-3870--Cell

(402) 298-7174--Fax



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