V O L U M E 1 0 • I S S U E 5 • M A Y 2 0 1 5 Agronomy
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(Photo: Dulaney Seed) The Importance of Uniformity If you want to maximize
yield, you must strive for uniform stand establishment.
Research data from AgVenture and several leading
research institutes prove the importance of uniform stand
establishment to yield potential.
Big swings in daytime vs. nighttime temperatures stress
germinating corn. In the study represented in the graphic, a
25 percent stand loss was observed due to stresses
experienced in germination and stand establishment.
Reduced stands can be expected when planting in to cold, wet soils or directly before cold,
wet weather is expected. To avoid losing your yield potential, consider:
! Stop planting 1 or 2 days in advance of a cold spell. Allow seed to begin hydration in
warmer soils in order to minimize damage due to cold
imbibition.
! Nighttime temps can dip more dramatically in sandy fields,
pushing temperatures below advisable planting levels.
Excess residue in fields absorbs heat from sunlight and keeps
soils cooler and damper. A comparison in the same field where
one area had residue removed and an area of high residue proves
the dramatic difference. Even with the crop emerged in late May,
there was an 11-degree midday temperature difference. The residue coverage resulted in the
cooler, wetter environment for seedling establishment, reducing opportunity for an ideal stand
(Sources: AgVenture, Pioneer, University of Wisconsin).
Soybeans Planting Uniformity A uniform soybean stand yields better. AgVenture’s Jeff
Shaner reminds growers to always start by planting into an ideal seedbed. “Often overlooked
are the specifics of uniformity, and that includes soil moisture uniformity.” Shaner says yields
can be reduced by 8-10 percent where soil moisture is uneven in the seed zone. Variability in
soil type also can greatly influence moisture conditions. Shaner adds, “Make sure you are
planting into optimal conditions for seed moisture absorption. Check to be sure you have
consistent seeding depth and perfect seed spacing. Finally, planting into a well-prepared
seedbed allows for ideal seed-to-soil contact to assure the seed can absorb the moisture it
needs to initiate germination.”
Young Corn Plant Herbicide Injury Growers are more likely to see corn plant injury from
pre-emergence residual herbicides in cool and wet springtime conditions. That’s because that
young seedling is ready to grow. It takes up herbicides faster than it can metabolize them. In
addition, injury may occur when those herbicides come in direct contact with the seed. Where
soil-applied grass herbicides are used including metolachlor, acetochlor, alachlor and various
atrazine pre-mixes, malformed seedlings or other signs of injury may appear.
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Soybean Herbicide Injury Considerations Controlling
Amaranthus species is an important mission for many
growers. While many have found that soil-applied PPOinhibiting herbicides, including saflufenacil, flumioxazin,
and sulfentrazone, are very effective for control of
Amaranthus species, they may see some soybean injury
left in the wake. Hypocotyls and cotyledons that show
browned or burned symptoms were likely exposed to a
high concentration of herbicide as they were emerging in the herbicide’s presence. Often,
injury symptoms can appear where herbicide was applied after planting, and rain event
occurred within a few days of soybean emergence. Cool conditions (both air and soil) also
tend to slow the rate of herbicide metabolism which can exacerbate the problem. Crusted soils
also prolong exposure of hypocotyls and cotyledons within that high herbicide concentration
zone. Talk with your AgVenture Yield Specialist if you have questions on soybean injury
(sources: AgVenture, University of Illinois: http://bulletin.ipm.illinois.edu/?p=2183).
Black Cutworm Activity A single Black cutworm
larvae can cut up to four corn plants in its lifetime. High
capture numbers have been reported already this
spring in Minnesota, Missouri, Kentucky, and Illinois,
with peak flights reported in Indiana. Cornfields most
at risk include weedy fields and no-till ground. They
typically feed at night or while overcast. Sample fields
to assess damage and note the percentage of cut or
damaged plants, the corn growth stage, and the
average development stage of the cutworm larvae. Control may be needed if 3-5 percent of
the plants show leaf feeding and 2 or more cutworms can be found per 100 plants.
Assessing Soybean Seedlings
for Flower Color Did you know
that you can assess soybean
seedlings now to determine the
flower color? As the picture
indicates, young soybean stems
that are purple now will bear purple
flowers. Those with white stems
will bear white flowers at
reproduction.
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