Pioneer Talks Crops
Welcome to Pioneer Talks Crops. This information is provided by the Pioneer agronomist serving your community.
DEXTER, MO.
There has been a wet pattern
in early to mid-April
in southeast Missouri
with frequent showers and
short planting windows. However,
some corn acres have
been planted in the upper
mid-South, and overall the region
is experiencing slightly
above-average temperatures for this time of the
year. Hopefully, fields will dry soon so corn
planting can be completed.
Last fall was one of the wettest on record in
this region. Growers reluctantly left ruts in
many fields throughout the
whole area, and in many cases,
did not have an opportunity to
work them in. Field compaction
may be an issue this year, and
it is important to take caution in
working fields so the problem isn’t made worse.
Deep tillage and natural freezing and thawing
or wetting and drying cycles often are mentioned
as solutions to soil compaction. However,
experts point out that only the top 1 to 5 inches
of soil generally receive more than one freezing
and thawing cycle per year.
Freezing and thawing can remediate only shallow
compaction in a timely manner. Wetting
and drying cycles are more frequent, but less effective,
in relieving compacted soils. Therefore,
it may take many years for natural forces alone
to repair deep compaction. For compacted soil
layers deeper than 5 inches, soil experts usually
recommend using deep-tillage equipment to
fracture the compacted zone. This must be attempted
only when soils are dry, as deep tillage
when soils are wet will only add to the problem.
Soil conditions suitable for deep tillage on
medium to heavier soils are much more likely to
occur in the fall than in the spring in humid
areas.
Corn emergence requires 110 to 130 growing
degree units (GDUs) under ideal conditions.
That can take from five to 20 days or more depending
on soil temperature and other conditions.
Optimum temperature for corn
emergence is 80 to 90 F and emergence is reduced
or halted around 50 to 55 F. Average soil
temperatures at 9 a.m. in southeast Missouri
have now reached 60 F as reported by the University
of Missouri Delta Center. Corn emergence
at 50 F can take 20 days or longer
pending other weather factors.
Once a stand is established it
will be important to evaluate
additional herbicide needs.
Weeds need to be controlled by
the three- to five-week period
after planting to prevent competition. This is
when corn is in the V2 to V3 growth stage (four
to five leaves showing), or about 6 to 8 inches
tall. Severe weed pressure during that period,
especially from grasses, can impact corn yield
potential significantly. If either excess or insufficient
rainfall raises concerns about the performance
of soil-applied herbicides, scout
cornfields regularly to determine if weeds are
breaking through and beginning to grow normally.
Usually, the most reliable and effective
herbicide program across a wide range of conditions
is a preemerge herbicide followed by a
postemerge herbicide. Δ
GREG PFEFFER: Agronomist, Pioneer
© 2010 Pioneer Hi-Bred.