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Agronomy notes
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Permanent Link: http://ufdc.ufl.edu/UF00066352/00089
 Material Information
Title: Agronomy notes
Uniform Title: Agronomy notes (Gainesville, Fl.)
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Florida Cooperative Extension Service
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
Place of Publication: Gainesville
Creation Date: June 2007
Subjects / Keywords: Crops and soils -- Florida   ( lcsh )
Crop yields -- Florida   ( lcsh )
Agriculture -- Florida   ( lcsh )
Agronomy -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
periodical   ( marcgt )
serial   ( sobekcm )
Statement of Responsibility: Florida Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences.
General Note: Description based on: January 1971; title from caption.
 Record Information
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000956365
notis - AER9014
System ID: UF00066352:00089


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Vol. 31:6 June 2007

Junt 5 Bef for:ric field d:i\ N FL REC NUlruinui. FL
June 9 Pcreiuiual PC:IIllI Field D:i\ Noullin GA
June 25-2" Southern conscnraion till.ie conficrnce N FL REC O(IIII FL
Junt 27-28 For:,ic \\orkcls Toml H.iudi Co E\ciisiOll O)ffi. \\ijclihl;i. FL


C orn after C orn ...................... ..... ............................................ .. 2
Nitrogen and Boron Applied at Tassel on Corn................... ............................. 2

Extended Deadline for 2007 Crop-loss Program...................................................2
Growth Regulators for Cotton in a Dry Year .............. .........................................4

Fall Armyworm in Pastures and Hayfields Control...........................................4
M managing Pastures after D brought ........................................ ....... ............... 5
Manage Now for Your Winter Hay Quality ........................................................5

24C label for Strongarm Postemergence in Peanuts..............................................5

Cover Crops and Strip Till in D ry Y ears ........................................ .....................5
Planting Date for Cotton and Peanuts............................................... ...............6
Spread of A sian Soybean Rust....................................... ............................ 6
W ater N eeds for C rops.......... ..... .................................................. ........ ... .. .... .6

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Employment Opportunity _Affirmative Action Employer authorized to
provide research, educational information and other services only to individuals and institutions that function without regard to race, color,
sex, age, handicap or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension
Office. Florida Cooperative Extension Service/ Institute of Food and Agricultural Sciences/ University of Florida/ Larry Arrington, Dean.

Corn after Corn

There are very few corn hybrids that can be
planted in June without major damage from
insects and disease. Growing a Bt corn is
critical for planting this late. Even most Bt
hybrids will succumb to disease pressures of
southern corn rust and corn leaf blight.
However, there is one main corn hybrid
(Pioneer) that is currently being grown for a late
crop that has done well. Otherwise, the next
best choice for silage as a second crop may be
forage sorghum which usually has good disease
resistance and will produce good yields with
irrigation or rainfall. If corn is to be planted
after corn, a soil insecticide should be used.
Anytime that planting is done into green weeds
or living crop roots, a soil insecticide is critical.
It takes about 4 weeks between crops when the
field is weed free to reduce the insect
population. This is the reason for soil
insecticide use at planting and there needs to be
enough moisture to activate the pesticide and to
be taken up by the crop.

David Wright

Nitrogen and Boron Applied at Tassel on

There are always questions about the application
of additional N to corn late in the season after
tassel. Our research has shown that there is little
value in applying N after tasseling. If corn is N

deficient until the tassel period, yield will be
reduced no matter what rate is applied after this
time. Late N has been shown to increase protein
content of the grain but is not an economical
protein supplement. If corn is dark green at the
tassel stage, no yield increase is expected from
additional applications even if the corn crop can
take up an additional 100-150 lbs/A during this
time until maturity; most of the N will go into
the grain. Timing of N during the vegetative
period is the key to high silage or grain yields.
Boron helps to translocate sugars in the grain
and most of Florida's sandy soils are deficient in
boron. Boron may be applied with nitrogen
applications during the growing season and may
be more beneficial at the last application near
tasseling. One pound of actual boron is usually
adequate in split applications since the crop will
not take up more than 1/3rd pound for the total
crop and is as easily leached as nitrogen.

David Wright

Extended Deadline for 2007 Crop-loss

Due to the drought conditions Monsanto has just
published the following letter which is of
importance to cotton producer.

David Wright

Letter from Monsanto on following page.


May 24, 2007

Dear Cotton Producer,

The prolonged drought conditions in the southeastern cotton belt have prevented the planting of
thousands of acres of cotton, and put a lot more cotton under early season stress. In response to recent
discussions with a number of cotton producers, Monsanto will be implementing a change in the Trait
Crop Loss Refund criteria for the 2007 crop year.

The current Trait Crop Loss Refund portion of the Roundup Rewards program reimburses cotton
farmers for trait fees paid for a crop that is lost or fails to make an acceptable stand in the first 60 days
after planting. With the current dry conditions and in response to producer needs, Monsanto is extending
its 2007 crop-loss program deadline for cotton acres lost due to drought to August 10th, in the
states of Alabama, Florida, Georgia, Mississippi, North Carolina, South Carolina, Tennessee, and

This 2007 program change will provide producers who plant prior to June 10th with additional days,
beyond the normal 60 day period, to work with the insurance industry regarding claims and file for
Monsanto's Crop Loss Refund, should the drought conditions continue to stay dry and a crop loss occurs
due to the drought. As before, this program can be used under Roundup Rewards program guidelines for
any cottonseed with Monsanto traits.

If you have a crop loss claim, you should report your claim to your seed retailer immediately. This needs
to be done in a timely manner to allow for field visits and claim processing. Remember that your
Monsanto Trait and Seed Representative will need to see your field prior to replanting or plowing-up your
crop. Claims must be received by the August 10, 2007 deadline to be serviced in accordance with the
Roundup Rewards requirements and guidelines. If you have any questions about requirements or
qualifications for Roundup Rewards, call 1-800-ROUNDUP or talk with your local seed retailer.

We greatly value your business and hope this added benefit is a help to you in the event you need to
utilize the Trait Crop Loss Refund portion of the Roundup Rewards program.


Ernesto Fajardo
Vice President, U.S. Crop Production

Growth Regulators for Cotton in a Dry Year

Cotton begins rapid growth in June in most
years if moisture is not limiting. This is the
period when the height needs to be regulated and
some data has shown that growth regulators will
help with square retention. If cotton is being
grown in fields that normally have excessive
growth, consider using half rates this year to
slow growth. Otherwise, if summer rains begin
it will result in very tall cotton. Cotton normally
has about 20 total nodes and no more than 2
inches is desired between any node. During
periods of high rainfall and high fertility, node
length can stretch to 3-4 inches between nodes.
If high moisture conditions happen, cotton can
get so tall that pesticide application will not
penetrate through the canopy. There are many
management factors that can influence
vegetative growth and they include N fertility,
soil moisture, weed control, plant population,
and insect control. Good fruit and boll retention
will slow vegetative growth. However, most of
the cotton growers in Florida use DPL 555
cotton which tends to set fruit a little later and
have excessive vegetative growth under good
growing conditions. Most research does not
show a yield increase to growth regulators but it
will keep the crop shorter and easier to manage.
If cotton is under severe stress, do not apply
growth regulators.

David Wright

Fall Armyworm in Pastures and Hayfields -

Armyworm worms are cyclical pasture pests that
are present in pastures every year. They appear
usually in the fall, but also in the short period at
the beginning of summer rains. In the past,
exceptionally dry years like the one we are
experiencing have recorded damaging
populations in pastures, usually, after the initial
rains that follow the drought conditions. Based
on these facts, it is good to be prepared and
know the chemical control options that are
available if this year happens to be one year
where conditions will favor the build up of

armyworms after initial rains. Always follow
product label directions for application and rates.

A relative new couple of products and options
for control of armyworms are Tracer,
manufactured by Dow AgroSciences and
Dimilin 2L, manufactured by Chemtura. Tracer
insecticide works better when used at the higher
recommended rate of 2 oz/acre and worms are
present. Tracer is toxic to bees but the label
indicates that bees foraging sprayed crops will
not be affected once the spray deposit has dried.
To avoid developing insect resistance, Tracer
manufacturer recommends not applying the
product more than 3 times in any 21-day period.
The second option, Dimilin 2L is an insect
growth regulator that is registered for use in
Florida at the rate of 2 oz per acre. Use of
Dimilin might be more appropriate whenever
there are many eggs being laid and no damage is
evident on the grass, as it takes a couple of
weeks to kill the insect; if larvae are present it
needs to be used when larvae are small (< V2
inch). The difference in products is that Dimilin
has a very long residual activity, probably 6-7
weeks versus 1 week at best with Tracer. The
restrictions (or period of wait prior to use for
grazing or hay production) when using Tracer
are 3 days for hay and if grazing you need to
wait until it has dried (usually few hours, 3-6 h).
Dimilin 2L has no restrictions for grazing.
There are some data to suggest that animals
feeding or grazing on Dimilin treated grass will
have a suppression of flies (such as face and
horn flies) because the active ingredient of the
product will pass through the digestive tract and
end up on the manure from that treated grass. In
some tests, the product was very effective on the
fly control and 100% suppression of these flies
occurred for 2-3 weeks as long as the animals
were feeding on the Dimilin treated grass.

If we are spared the trouble of dealing with these
insects in this first half of the year, still keep the
recommendations at hand for they will be useful
in the fall when they will very likely infest

Yoana C. Newman and Richard Sprenkel

Managing Pastures after Drought and Fire

This year Florida has received a good share of
these two devastating conditions. Paying
attention to some critical practices will help
ranchers and farmers ease the impact of drought
and/or fire:

a. Wait longer than usual before turning cattle
into pastures. Allow a 'generous' stubble
height in order to build up the needed
reserves that are critical for long term
recovery. If you have some burnt areas, the
green-up with the burnt soil background
may give the impression that you have more
forage than you really do. Do not fall into
this visual illusion and allow the proper
additional weeks for resting the pasture
before grazing or cutting them. Buying hay
for a couple more weeks will offset the
potential damage and expense (due to weed
control and replanting) that will result from
overgrazed conditions.
b. Make sure to have proper fertilization to
guarantee root development. Drought brings
an associated lack of growth and the natural
pool of nutrients in the soil may be higher
than in previous more wet years. However,
if you need to fertilize assure that potassium
levels are moderate.
c. Make sure you control your weeds once the
rains start. A weed-free condition will
benefit your pasture plant and will give it a
'heads up' start after stressful conditions.

Yoana C. Newman

Manage Now for your Winter Hay Quality

Summer time is when most of they hay will be
put up to be used mainly in the winter time. Do
not place your efforts just on getting your
tonnage levels up but think critically about how
to raise the nutritive value of your hay.
Timeliness in forage fertilization and herbicide
application affects not only your yield but also
your forage quality. The main factor affecting
the quality of your hay is the stage at which is
cut. Higher quality forage will result from
harvesting at an earlier stage of maturity. Avoid
cutting your hay when it is mature with well

developed seedheads present because the quality
will be significantly reduced.

Yoana C. Newman

24C label for Strongarm Postemergence in

A special use label to allow Strongarm herbicide
to be applied postemergence in peanuts was
approved earlier this month by the Florida
Department of Agriculture. This label allows
for Strongarm to be applied up to 28 days after
planting for the control or suppression of
tropical spiderwort (Commelina benghalensis).
The 28 days after planting restriction is in place
due to concern of Strongarm carryover to cotton.
Peanuts are very tolerant to Strongarm applied

Strongarm is effective on tropical spiderwort if
plants are small when the application is made.
Larger plants will be severely injured and
remain stunted for several weeks, but will rarely
die. Strongarm will often not provide tropical
spiderwort control as long into the season as
Dual Magnum, but it will provide some
postemergence control if that is necessary.
Strongarm applied postemergence is also
excellent on common ragweed, cocklebur,
eclipta, bristly starbur, and wild radish, among
other weeds.

Jason Ferrell

Cover Crops and Strip Till in Dry Years

Strip tillage is used widely for corn, cotton and
peanut production in many of the north Florida
counties. Florida research has shown that
moisture in the soil can be improved under
conservation tillage and that soil temperature
can be reduced. However, in very dry years,
conservation tillage cannot compensate for lack
of moisture during planting and stand
establishment. This year would have been one
to kill out the cover crops early so that surface
organic matter would reduce the amount of
moisture evaporating from the soil. Growers
who bedded their cotton fields this year may
have been better off since they can knock the top

layer off the bed and plant into moisture.
Another problem in dry years with strip tillage is
getting a smooth seedbed without pulling up
clods of dry soil while planting and getting a
uniform seed depth. Rows can be stripped off
early in the season (Jan.-Mar.) while there is
usually good moisture; then to obtain stands, a
planter can be run at planting time with row
cleaners. Many of the conventional till fields
had clods brought up from tillage and will
require many tillage passes to have a smooth
seedbed for planting cotton which requires to be
planted shallow (1/2 inch deep).

David Wright

Planting Date for Cotton and Peanuts

Since many growers have not had adequate rain
to plant either cotton or peanuts, the question
becomes: when is it too late to plant either
crop? Many fields of peanuts and cotton that
were planted this spring have spotty stands if
they were not irrigated. This dry condition can
result in more TSWV in peanuts while cotton
can compensate to some degree if rains come
later in the year. Generally, both cotton and
peanuts should be planted no later than the
middle of June since they both require 150 days
or more to mature. Frost can damage peanut and
unopened cotton bolls; and bolls will never
open. If crop insurance is carried, there is a
requirement to have crops planted by a certain
date. Farmers need to take this into
consideration. If peanuts and cotton were
planted and herbicide applied but stand failures
prevent taking the crop to yield, be aware of
plant back restrictions in other crops that can be
planted later than these crops including soybean,
peas, sunflowers, corn, and other shorter season

David Wright

Spread of Asian Soybean Rust

Asian soybean rust had been present every
month for 2 years at certain locations in north
Florida until the late freeze in February. This
freeze knocked back the kudzu and the soybean
rust has not been found in many northern
locations as of this point due to dry weather

since late February. However, we expect to see
rust start up on kudzu soon in areas that are
conducive to its development and it is still
present in one of the sites that have continued to
be positive for rust. Louisiana has received
more rain than Florida and has had several
positive sites identified. Research is continuing
on soybean rust in Florida since it can have such
a tremendous impact on the mid west. Plant
breeding and management studies are being
done here to prepare for the disease hitting the
Midwest early in the season.

David Wright

Water Needs for Crops

This year is one for the record books for
growers. Growers who have water to irrigate
will find it expensive to grow the crop with high
energy prices for pumping water. Producers
with no irrigation find it difficult to plant or do
any management since stand establishment,
tillage and weed control are influenced by dry
weather. Crops require different amounts of
water at different growth stages. All crops
require good moisture for stand establishment
and most have low water requirements until late
vegetative stages. Corn has a high water
requirement starting about 42 days after planting
until tassel but the highest requirement is during
the ear fill period. Corn does not need to be
under stress when it is silking and tasseling or
ears will not be pollinated and this occurs over a
short period of a week to 10 days. Other crops
like cotton and peanuts need the most moisture
during the bloom period and the bloom period
for cotton is about 8 weeks long. The first 3-4
weeks of bloom are the most critical for cotton
since 95% of the yield can be set during these
weeks. Peanuts need moisture during bloom to
help move calcium into the pegging zone for
kernel development and for the pegs to enter the
soil. Some insect problems are much worse in
dry years and any damage that the plant receives
will make recovery longer. Water is essential
for good yields and quality crops. High numbers
of spider mites have been noted on crops this
spring due to the drought.

David Wright

The use of trade names does not constitute a guarantee or warrant of products named and does not signify approval to the exclusion of similar
Prepared by: J.M. Bennett, Chairman I.I.I, 1l .... J.A. Ferrell, Extension Agronomist I Il,.il, ... ,.I.. Y.C. Newman, Extension
Forage Specialist ... niil .Ih.. and D.L. W right, E ...i .i ..i ..m 1.11 .1i 11 .1.