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2018 Corn Harvest Challenges

Posted on
September 19, 2018
by
Buffy Uglow    buffy_uglow@rockriverlab.com

2018 Corn Harvest Challenges

by: John Goeser, Animal Nutrition, Research and Innovation Director

The 2018 corn harvest through much of the US is setting out to be a challenge. We've experienced everything from drought to previously unseen (record) rainfall in many areas. Iowa, southeast Minnesota, much of Wisconsin, northern Illinois and Michigan are basically a swamp.

So how much rain have we received? The following two graphics showcase the treacherous weather and moisture recently, and throughout the season:

Rainfall totals over the past two weeks

[10 to 15 inches of rain in some areas.]

September 6th 2018 14 day observed precipitation

Rainfall the past 90 days

The previously discussed areas, as well as much of Pennsylvania and into southern New York, have had a wet, wet year. [Over 20 inches of rain in many regions growing corn intended for silage.]

September 2018 90 Day Observed Precipitation

Unfortunately, the weather and excessive moisture is causing a number of challenges for the 2018 corn harvest. There is immense variation in maturity and crop conditions. I'm taking quite a few calls that follow the same script:  "What do we do with the crop now?” There are a few common answers to that question and I have a few recommendations to share based on these various situations[1].

Flooded corn

What we’re seeing

  • These fields will likely have different epiphytic bacterial populations.
  • There is mud or soil contamination and increased potential for odd fermentation, which can potentially increase the buffering capacity (harder to ferment) and contaminants.

What to do

  • Walk fields, monitor maturity, and harvest at the appropriate moisture or kernel maturity.
  • Dr. Limin Kung’s team published a paper showing flooded corn can ferment "OK".
  • Do everything you can to promote an aggressive fermentation.
    • Successful and efficient ensiling can help clean up some challenges.
    • Inoculate with lactic acid bacteria and an L. buchneri to help it be as "clean" as possible
      • Chop high as mud and silt will be heavier on the bottom.
      • Watch for denitrification (the plant can't process Nitrogen anymore) and plant death in prior flooded fields as the Nitrogen is tied up.

Tar Spot and heavily (fungi) infected fields or contamination

What we’re seeing

  • Tar Spot (mold or fungi) is showing up heavily through some of the Midwest
    • Check out this Badger Crop Doc blog post by Professor Damon L. Smith, the Extension Field Crops Pathologist at the University of Wisconsin-Madison: http://ipcm.wisc.edu/blog/2018/08/tar-spot-on-corn-in-wisconsin/
    • I spent some time with Prof Damon Smith and he shared some concerns:
      • Tar spot is not a known toxin producer but is killing plants off; some fields were hit 100%
      • Tar spot originates from Central / Latin America
      • This fungus has been combated with hybrid resistance (traditional plant breeding methods), but there are a lot of unknowns with this currently in the US
      • Secondary fungal infections are coming in as plants are dying off / decomposing from Tar Spot
      • As Damon put it, these brown leaves are a "Pandora's box"
      • Damon is seeing some Fusarium spp. and other mycotoxin producing molds come in
    • Several others have recognized new concerns with stalk integrity (standability/lodging) and ears remaining attached to the plants

What to do

  • Walk fields, monitor infestation, and harvest as close to silage dry matter (DM) or kernel maturity as possible.
  • Go out and get these crops if the plants are beginning to fall apart and severely compromised
  • Aim for appropriate DM relative to desired crop storage (i.e. corn silage at 35% DM, high moisture corn at 65 to 72% DM)
  • Kernels may be lighter test weight but are drying out anyway because the plants are dead.
  • Watch and take note of hybrids that stayed green or don't seem as heavily infected. Consider these in your lineup for next year.
  • Tar Spot likely overwinters on residue.
  • For next year, Damon and the UW Plant Pathology team will have some insight on fungicide effectiveness coming out of this season.

For other fungal infestations (other than Tar Spot) with the wet season:

  • Walk fields and monitor kernel maturity! 
    • Don't assume wet plants are stagnant for kernel maturation.
    • According to one consultant in southwest Wisconsin, some folks are seeing wet plants but kernels are at black layer.
    • Plants and kernels will continue to mature through wet, soggy weather.

Suboptimal kernel maturity for silage

What we’re seeing

  • Kernel maturity and whole-plant moisture have seemingly disconnected from one another over the past few years.

What to do

  • If kernels are well beyond half milk line, shorten chop length, this will help get kernel processing (KP) done.
  • Monitor KP with the float test or send to your lab of choice. The goal is 60 percent KP score with fresh chopped corn. 

Downed corn plants or muddy fields

What to do

  • If the corn stalks snapped and the plant is dead: go get it off ASAP.
    • Chop against the “grain” to try and pick it up.
  • If the corn stalks goosenecked and the plants aren’t dead: let it go for a bit as it will likely rebound and try to straighten itself.
    • Monitor plant DM and kernel maturity.
    • Harvest it at the optimal DM or maturity.

Inoculants

What to do

  • Research backed bugs or acid/preservative at recommended and heavy rates.
  • $1.00 to $2.00 / ton equates to $0.03 to 0.06 / cow at 20 pounds DM intake of corn silage.
    • This upfront investment might help from putting three to five times that into the diet later, in order to mitigate fermentation, stability, or contamination issues.

Bottom line

I'm expecting this year’s crop to be relatively "dirty" but we can help influence growers and farmers to make better decisions. A few weeks from now I'll follow up again with another blog post after the season has played out and we can assess feed hygiene.


[1] I'm leaning on a number of colleagues and research leaders to help learn and help answer questions. These folks include (but are not limited to): Joe Lauer, Randy Shaver, Bill Mahanna, Lon Whitlow, Limin Kung, Damon Smith, Rich Muck, Brian Holmes, and others.

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Animal Nutrition

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