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Impact of Late Planted Soybeans
June 25, 2009
(3 minutes: 22 seconds)
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(3 minutes: 22 seconds)
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Audio/Video Script:
Jeremy Ross
Soybean Agronomist
[Title Slide Impact of Late Planted Soybeans, Dr. Jeremy Ross, Soybean
Agronomist , Number 5 - June 25, 2009, Your Arkansas Soybean Podcast, University of Arkansas Division of Agriculture, Arkansas Soybean Promotion Board]
[Jeremy Ross standing in a field with a tractor.] Im Jeremy Ross, Soybean
Agronomist with the University of Arkansas Division of Agriculture, and today we
are going to talk about the impact of late planted soybean.
[Line chart showing the effect of planting date on irrigated soybean yield by
maturity group] [Slide Late Planting Can Impact Yield - Research suggests that
planting soybeans late may result in yield loss; Yield loss potential after June
15 1% - 2% per day; After July 1 as much as 2% - 3% per day. Picture of
soybean pods.] Research findings suggest that planting after June 15 results in
a 1 to 2 percent yield loss per day, with the yield loss potential increasing to
2 to 3 percent per day after July 1. [Slide Minimize Late Planting Yield by
Changing variety; Selecting a variety with growth habits for a shorter growing
season; Selecting a good herbicide; Adjusting row spacing and seeding rate.
Picture of soybean pods. ] Some of the yield loss associated with late planting
can be minimized by changes in variety, variety growth habits, and herbicide
selection. [Picture showing soybean plant rows with a tape measure decrease
row spacing to 20 inches or less.] Additionally, research shows that decreasing
the row space to 20 inches or less and [Picture showing soybean rows with a tape
measure increase seeding rate by 10% - 15% 8 seed per foot to 10 seed per
foot.] increasing the seeding rate by 10 to 15 percent will help offset yield
losses and decrease the number of competitive weeds. [Picture of a soybean
field]
[Slide Planting After July 15 - Not recommended; Some MG IV and MG V can
produce mature seed, if emerged by August 1; Plant height and grain yields will
be greatly reduced. Picture of soybean pods.] Plantings after July 15 are not
recommended due to a greatly shortened growing season although some late MG IV
and V varieties usually have enough time to produce mature seed before a fall
frost if emerged by August 1. Plant height and grain yields will be greatly
reduced in the July plantings.
[Slide Late Planting Impacts - Number of days to flowering; Amount of time
available for vegetative plant growth and development. Picture of soybean pods.]
Soybean plants are photoperiod sensitive. Late planting impacts the number of
days to flowering, the amount of time available for vegetative plant growth and
plant development, which all are necessary for good yields. [Slide Yields are
reduced because Poor stands due to hot soil temperatures; Short day lengths;
Early flowering and reduced vegetative growth. Picture of soybean pods.]
Planting too late can reduce yields because of poor stands due to excessively
hot soil temperatures or because day lengths are too short. Short day length may
result in plants flowering early and having reduced vegetative growth.
[Slide High Quality Seed is Important Helps to establish a good stand of
vigorously growing seedings. Picture of soybean pods.] Obtaining soybean seed of
acceptable quality for planting is highly recommended. This will help ensure
establishing an optimum stand [Picture of a soybean field] of vigorously growing
seedlings. [Slide Seed Vigor is Key Especially when Planting is delayed into
June and July; Soil moisture is marginal; High soil temperatures occur. Picture
of soybean pods.] As plantings are delayed into June and especially into July,
the vigor of the seed becomes more important if marginal soil moisture and
elevated soil temperatures occur. [Slide Late Planting and Seed Quality Seed
with less than 80% germ may produce poor stands; Seed vigor, measured by the
Accelerated Aging test, may have declined to 50% or less. Picture of soybean
pods.] Seed that has less than 80 percent germination late in the planting
season may produce poor stands [Picture of a soybean field showing skippy stands
due to poor seed quality.] especially if there are significant adverse
conditions at planting due to low seed vigor. [Slide Late Planting and Seed
Quality Seed with less than 80% germ may produce poor stands; Seed vigor,
measured by the Accelerated Aging test, may have declined to 50% or less.
Picture of soybean pods.] Seed vigor, as measured by the Accelerated Aging test,
may have declined to 50 percent or less by late June and July.
[Slide Late Planted Soybeans Limited root systems that cant withstand
long periods of drought; If planted by June 15 and irrigated, 50 bushels per
acre or more; Dryland fields may have stand establishment problems. Picture of
soybean pods.] Late-planted soybeans have more limited root systems and cannot
withstand long periods of drought. With irrigation, yields of 50 bushels or
greater are possible with proper management if planted by June 15. [Picture of a
soybean field with a poor stand establishment] A late planted dryland soybean
field is often at high risk for stand establishment due to inadequate soil
moisture in mid- to late June. [Slide Late Planting/Short Season increases all
stresses to crop. Picture of soybean pods.] Also, the shortened season
associated with late planting dates intensifies the effect of any stress on the
crop.
[Slide Control Weeds Good burn down program needed; Lots of weeds could
mean yield loss. Picture of soybean pods.] To combat weed problems, a good burn
down program is needed to kill existing weeds at planting to allow soybean to
germinate and insure a good stand. Too many weeds competing with soybean could
result in yield losses.
[Slide Monitor for Insects and Diseases Late planted fields at high risk;
Scout weekly during reproductive growth stages; Apply insecticides/fungicides
only if pest pressure will have economic impact. Picture of soybean pods.] Late
planted soybean fields are at a higher risk for attack by late season insect and
disease pressure. Fields should be scouted weekly during the reproductive growth
stages to monitor for pest pressure. Applications of insecticides and fungicides
should only be made if the pest pressure is at an economic threshold.
Announcer
[Narrator] Your Arkansas Soybean Podcast is a production of the University of Arkansas Division of Agriculture and was funded in part by the Arkansas Soybean Promotion Board. For more information on soybean farming in Arkansas contact your local county Extension Office. [Title slide - For more information contact your local county Extension office. Your Arkansas Soybean Podcast, University of Arkansas Division of Agriculture, Arkansas Soybean Promotion Board]
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