Ear Rots and Soybean Lodging  08/31/18 12:31:18 PM

Crop Development: Wide-spread harvest will begin likely in the next week or two on some high moisture corn in some locations due early plant dates, short seasoned hybrids that were planted.  We have talked about how crop development has been ahead of the “normal” stages of development all season long.  We have slowed a little bit in the last week, however, we are now past 2800 GDU’s for corn planted on April 25th and black layer/physiological maturity has occurred. 
 
Growing Degree Days for Corn Growth Stages for a 113 day Hybrid
Stage                                                   GDD (Growing Degree Days--base 50)        
Emergence                                                                  120
2 leaf-V2                                                                     200
V6-tassel initiation                                                      475
V10                                                                             740
V14                                                                             1000
VT (tassel emergence)                                                1150
Silking                                                                         1400
R4 (Kernel dough stage)                                             1925
R5 (Kernel dent stage)                                                2450
R6 (physiological maturity-black layer)                     2700
*courtesy of Hollinger (University of Nebraska)
 

How Fast Will This Year’s Corn Dry?

Dry down after black layer formation varies greatly from hybrid to hybrid. Hybrid characteristics such as husk coverage and heavy test weight can have a significant impact on field drying. A general rule of thumb is that 30 GDUs are needed to lower the grain moisture each point from 30 to 25% and 45 GDUs per moisture point are needed from 25 down to 20%.  Lately we have been seeing high teens to low 20’s on a daily GDU accumulation.  Which means we currently should drop a point of moisture every 1.5 days on corn that has recently black layered. The following table indicates approximate moisture loss at various times during the fall. AGRONOMICALLY--Remember that the optimum harvest moisture, to maximize yield and minimize mechanical damage to the corn kernel, is approximately 23 to 25% moisture.   We realize there are costs involved in harvesting higher moisture corn. 
Time
Period
Moisture Loss Per Day
  %
 Mid-to-late September ¾ to 1
 Early-to-mid October ½ to ¾
 Late October to early November ¼ to ½
 Mid November 0 to ¼
 Late November 0
 
I have observed SOME ear molds and corn kernels sprouting in the ear this past week.  This is not uncommon and should not be too much of a surprise in a year with ample moisture.  This is normally a superficial development and usually does not decrease yield and/or the quality of the grain as the infections are normally not widespread in the field and/or affect much of the ear (normally just the tips). Let’s review what we can potentially look for this fall and what it can mean.
 
Diplodia. Diplodia ear rot occurs most frequently in reduced tillage fields and continuous corn. It is recognized by a white to gray mold that usually begins at the base of the ear and develops toward the tip, growing between kernels (see below).

With severe infection, the entire ear turns gray-brown and completely rots, a symptom known as mummification . Diplodia is favored by wet weather within the first 21 days after silking. Hybrids vary in the level of susceptibility to Diplodia ear rot, but because of the erratic nature of the disease most hybrids are not well characterized and any hybrid can be infected given the right conditions.
 
 
 
Fusarium. Kernels infected with Fusarium have white streaks in a starburst pattern,
scattered over the ear.

The mold is white to pink. Infection points include kernel growth cracks and ear damage from insects such as earworm or corn borer.
 
Gibberella. Gibberella is a mold that usually begins at the ear tip and progresses toward the butt of the ear.

It varies in color from red to white, but is often bright pink. Infection is favored by cool and wet weather after silking, through late summer.
maximum level of aflatoxin allowable
for a range of corn end uses in
parts per billion (ppb).
Intended Use
Aflatoxin
 
 
 
 
 
 
Penicillium. This blue-green mold grows on and between kernels

 
Infection is more likely on ears damaged by earworms, corn borers, or from mechanical injury. High moisture stored corn may develop “blue eye” as a result of this mold.
Trichoderma. Trichoderma produces mold that is green and grows on and between husks and kernels

Trichoderma usually enters the plant through insect or mechanical damage to the ear. The impact of Trichoderma is generally minor, but being able to differentiate it from other ear rots that cause mycotoxins, such as Aspergillus, is beneficial.
Kernel Sprout. Kernel sprouting can occur when moisture becomes trapped in the husk, allowing kernels to absorb it and sprout.  Hybrids having an upright ear at maturity, with an open husk may be more susceptible. Significant and continuous rainfall at harvest can favor kernel sprout on almost any ear harvest architecture.
 
Some Lodging Soybeans have already occurred and with any added heavy rainfall, might get more widespread.  Normally when soybeans achieve this kind of plant height (arm pit deep in places), it is a matter of physics that a certain amount of lodging occurs.   Heavy rain deepens the weight load on these stems.  Once the plants dry out, they stand back up to a degree.  Additionally, the plants are currently heavy with pods and leaves and when senescence begins, the stems will again try to stand back up in which a harvestable plant develops through stem and seed dry down.
 
The current forecast calls for a lot of rain in the next week---
With many soybean fields in currently the full seed (R6) to beginning maturity stages (R7), what can be expected from a yield loss and harvest management perspective?
 
Yield Impact
Heavy/Flooding rains that occurs during the early reproductive stages of soybean is more detrimental than flooding in R6 stage and beyond. Flooding at the beginning of flowering (R1) can cause potential yield losses of 2.3 and 1.5 bushels per acre on clay and silt loam soils, respectively. Potential yield losses would be expected to be larger in soybeans at the beginning pod (R3) to beginning seed (R5) stages. Stages R3 to R5 are critical in soybean yield potential as pods and seeds are set and developed. Stress occurring at R7 or later generally has a minimal effect on yield potential.
 
Keep your eyes on these hybrids and varieties this fall as they sure look to be top performers from what they have offered this year to date as well as their historic performances.
 
DeKalb DKC58-35RIB – GENDGVT2Pro and also available as a GENSS (DKC58-34RIB)
 
Description and positioning:
  • Disease Shield High end yield potential maintained even under heat and drought stress
  • Exceptional stalk and root strength very good greensnap tolerance
  • Strong foliar disease package and good Goss’ Wilt tolerance
    DeKalb DKC60-88RIB – GENDGVT2Pro and available as a GENSS (DKC60-87RIB)
    Win Percentage for DKC60-88RIB: 65% against leading competitive hybrids +/- 4 RM (238 comparisons)
    Avg. Yield Advantage for DKC60-88RIB: 7.3 bu against leading competitive hybrids +/- 4 RM (238 comparisons)
     
    Description and positioning:
  • Excellent top end yield and plant health across all environments with good ear flex
  • Excellent stalk and root strength, high greensnap tolerance, and Food Grade grain quality
  • Good overall disease package and very good Goss’ Wilt tolerance
     
    DeKalb DKC64-35RIB – GENVT2Pro and also available as a GENSS (DKC64-34RIB)
    Win Percentage for DKC64-35RIB: 82% against leading competitive hybrids +/- 4 RM (296 comparisons)                  
    Avg. Yield Advantage for DKC64-35RIB: 19.7 against leading competitive hybrids +/- 4 RM (296 comparisons)
     
    Description and positioning:
  • Disease Shield Top end yield performance with low end stability in drought and heat and Food Grade grain quality
  • Excellent stalk and root strength with very good greensnap tolerance
  • Strong agronomics, very good Goss’ Wilt tolerance, and superior Staygreen
     
     
    DeKalb DKC66-75RIB – GENVT2Pro and also available as a GENSS (DKC66-74RIB)
    Win Percentage for DKC66-74RIB: 88% against leading competitive hybrids +/- 4 RM (69 comparisons)                    
    Avg. Yield Advantage for DKC66-74RIB: 18.8 against leading competitive hybrids +/- 4 RM (69 comparisons)
     
    Description and positioning:
  • Disease Shield Excellent top end yield and plant health across all environments with moderate ear flex
  • Good stalk and root strength, high greensnap tolerance, and robust plant canopy
  • Good overall disease package and very good Goss’ Wilt tolerance
     
    Dekalb DKC70-27RIB – GENVT2Pro
    Win Percentage for DKC70-27RIB: 91% against leading competitive hybrids +/- 4 RM (44 comparisons)                    
    Avg. Yield Advantage for DKC70-27RIB: 20.9 against leading competitive hybrids +/- 4 RM (44 comparisons)
     
    Description and positioning:
  • Disease Shield Excellent top end yield and plant health across all environments with good ear flex
  • Good stalk and root strength, high greensnap tolerance, and robust plant canopy
    Good overall disease package and good Goss’ Wilt tolerance
    Asgrow AG32X8 – Class of ’18
    Win Percentage for AG32X8: 71% against leading competitive varieties +/- .4 RM (73 comparisons)
    Avg. Yield Advantage for AG32X8: 1.9 bu against leading competitive varieties +/- .4 RM (73 comparisons)
     
    Description and positioning:
  • High yield potential in a cyst bean
  • Strong PRR & BSR defense
  • Medium tall plant with excellent standability
AG33X8 – Class of ’18
Win Percentage for AG33X8: 71% against leading competitive varieties +/- .4 RM (95 comparisons)
Avg. Yield Advantage for AG33X8: 2.5 bu against leading competitive varieties +/- .4 RM (95 comparisons)
 
Description and positioning:
 
  • High yielding cyst bean adaptable to all row spacings and tillage systems
  • Excellent SDS, PRR, & BSR defense
  • Medium tall plant with good standability, emergence, and No Till adaptability
 
AG36X6 – Class of ’16
Win Percentage for AG36X6: 84% against leading competitive varieties +/- .4 RM (298 comparisons)
Avg. Yield Advantage for AG36X6: 4.7 bu against leading competitive varieties +/- .4 RM (298 comparisons)
 
  • High yielding cyst bean with good canopy closure for wider row spacings
  • Strong Southern Stem Canker, SDS, PRR, & BSR defense
  • Medium height plant with excellent standability, emergence, and No Till adaptability
AG37X8 – Class of ’18
Win Percentage for AG37X8: 70% against leading competitive varieties +/- .4 RM (77 comparisons)
Avg. Yield Advantage for AG37X8: 2.6 bu against leading competitive varieties +/- .4 RM (77 comparisons)
 
  • High yielding cyst bean adaptable to all row spacings and tillage systems
  • Good SDS & PRR defense
  • Medium tall plant with excellent standability, emergence, and No Till adaptability
 
AG39X7 – Class of ’17
Win Percentage for AG39X7: 64% against leading competitive varieties +/- .4 RM (139 comparisons)
Avg. Yield Advantage for AG39X7: 2.2 bu against leading competitive varieties +/- .4 RM (139 comparisons)
 
Description and positioning:
  • RR2Xtend/SR stacked bean with strong performance in all tested geographies
  • Medium tall tawny plant with excellent emergence and standability
  • SCN resistance and good tolerance to SDS & BSR
  • Outstanding Phytophthora package with Rps1C and solid field resistance
 
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