Planting Sorghum or Corn in “Yellowed”
Pre-Plant Treated Fields
It
is no secret that we have had a devil of a time with weed control these past
few seasons. In response we have been
getting better and more aggressive in our use of pre-plant herbicides in our
primary row crop, cotton. This is making
for an interesting dilemma with such a long (yet welcome) period of wet weather
delaying most cotton plantings. Any more
delays in cotton planting and many of us will be outside our window for our full
potential of profitable cotton crop.
This leads many of us to consider alternate crops that do not require as
large a production window such as corn or sorghum planted slightly later. So, what can we do about our fields that were
aggressively treated with pre-plant residual cotton herbicides?
Dr.
Jordan Bell, extension agronomist district 1, Dr. Wayne Keeling, research
agronomist district 2, and myself have been wrestling with the issue in
discussions. Dr. Keeling mentioned to
Dr. Bell that, “You do not necessarily have to rule out sorghum or even an
earlier maturity class corn on Treflan (yellow) ground. Because Treflan is
bound very tightly in the soil, you can plant below the herbicide. Well, how
deep? That depends on how deep the herbicide was incorporated. Trash whippers
work well to push Treflan soil away from the seed. If you plant below the
herbicide, the cotyledon can grow through the herbicide, but if you plant on
top of the herbicide, the roots will grow through the herbicide and you will
see quick herbicide damage. This can be detected within 4 to 5 days after
planting as long as soil temperatures are ideal to promote germination. The
recent rains will not wash away the herbicide and alleviate the problem. It is
best to plant under ideal conditions with soil temperatures at 65F for 10 days
to ensure vigorous early growth. Planting in the current conditions with cool
soil temperatures will result in stressed plants that will be more susceptible
to herbicide issues in addition to the other problems such as disease and pest
problems.”
Dr.
Bell added speaking of the Amarillo region, “I do not think many of our
Panhandle producers use as much Caparol and Staple as the Southern High Plains
producers so hopefully those will not affect too many acres.”
Our
specialist’s thoughts on the issue would fit very well with what I have
witnessed in the fields over the years.
We definitely want to get below our “yellow” pre-plant cotton herbicides
with corn or sorghum plantings into really good planting conditions, and maybe
bump our seeding rates a touch. I would
caution about bumping seeding rates too much as it is very easy to get too high
a plant population by over estimating any loss due to herbicide, especially if
we successfully plant below the herbicide layer. Corn and sorghum seedlings do tend to act much
more heartily with deeper plantings compared to cotton when it comes to
emergence.
It
might also do some good to recheck the label for the applied herbicide. We might be concerned over nothing. There are a few pre-plant residual herbicides,
some of the ‘white’ herbicides by name, which have both a corn and cotton
label.
For more information, here is a link to a publication by Dr. Calvin Trostle, extension non-cotton agronomist district 2, that addresses crop restrictions for herbicide applied for
cotton: http://lubbock.tamu.edu/programs/crops/cotton/general-production/alternative-crop-options-after-failed-cotton-and-late-season-crop-planting-for-the-texas-south-plains/
Thanks,
Blayne Reed
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