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Agronomy notes
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Permanent Link: http://ufdc.ufl.edu/UF00066352/00083
 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: December 2006
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.
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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: UF00066352:00083


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Vol. 30:12

December 2006



Increasing C otton Y ields....................................................................................2


C control of W oody B ru sh ............................................................................ ....... 2


K udzu and Soybean R ust ............................................................................. 2
Summary of Aldicarb Rule Changes .................................... ......................3
Select Crop V varieties Early......................................................... .............. 5
W heat Planting.................................................................... ......... 5

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.

Increasing Cotton Yields

Research over the past few seasons has shown
that cotton yields are reduced by hardlock/boll
rot. Through several years of investigations we
found Fusarium to be the main organism
involved in hardlocked bolls. With 4 years of
study, we found that spraying fungicides and
insecticides during the 8 weeks of bloom (July
and August), we have been able to harvest from
200 to 700 lbs/A more lint as compared to the
untreated. In many cases insecticides resulted in
higher yields than fungicides even though no
insect reached the threshold level necessary for
treatment. This is because thrips and other
insects are carrying the Fusarium and infect the
boll on the day of pollination (white flower).
Therefore, insects (both pests and beneficial)
could be setting the crop up for hardlocked bolls.

It appears that treating cotton every two weeks
starting at first bloom for 4 total applications
could result in average yearly yield increases of
300-400 lbs/A of lint. Applications at these
timings will also control stinkbugs and other
pests that cause boll and square shed. There is
only one fungicide currently labeled for
application to control Fusarium hardlock,
Topsin M. Applications of the fungicide may be
made along with the insecticide application to
help control hardlock as well as leaf diseases.

David Wright and Jim Marois

Control of Woody Brush

The coming of winter is often seen as a time to
suspend weed control efforts. However, these
months are ideal for performing some much
needed brush control.

Persimmon, cherry, Chinese tallow and other
"weedy" trees can often be found growing along
fencerows. A foliar application ofglyphosate (5
to 8% solution) made prior to leaf color change
can be effective, but total coverage can be
difficult and retreatment will often be necessary.
Another procedure that is highly effective and
more consistent that foliar application is basal
treatment. Basal application combines the
herbicide with a penetrant oil (not water) and

applies the mixture directly to the bark of a
standing tree. This results in rapid uptake and
loads a great deal of herbicide into the plant.
However, it is important to use a basal oil or
diesel fuel/herbicide mix; a herbicide/water
solution will simply not work.

The basal application technique is for trees that
are less than 6-inches in diameter and have
smooth bark. It is important that the lower 12 to
18 inches of the stem be treated on all sides with
the herbicide/oil mixture. Adequate coverage is
essential, since treating only one side of the stem
will result in controlling only half of the tree.
Basal applications can be made any time of the
year, but are most effective during the dormant
season when leaves are not present. It must be
noted that basal applications will not provide
rapid control. Herbicide injury is often not
observed for several weeks after treatment and
total control may require several months.
Additionally, basal treatment is not effective on
older trees with thick bark. For older trees, other
application techniques should be employed.

Herbicides that work best for basal application
are triclopyr ester (Remedy, Garlon 4, Tahoe 4)
and Chopper. A triclopyr product should be
mixed with basal oil to form a 25% solution (1
quart of herbicide in 3 quarts of oil). This
product is highly effective on most all woody
brush, including Chinese privet. Chopper is a
more potent herbicide and only requires the
addition of 8 to 12 oz of herbicide per gallon of
basal oil.

For more information on brush control, please
reference Herbicide Application Techniquesfor
Woody Plant Control,

Jason A. Ferrell

Kudzu and Soybean Rust

The Soil Conservation Service (SCS) promoted
kudzu for erosion control during the 1930s and
farmers were paid an incentive to plant kudzu as
forage during the 1940s. However, because of
its weedy tendencies, the SCS stopped
recommending kudzu in the early 1950s. In the
early days no herbicides were available to

control this weed, but livestock grazing kept it
under control to some extent.

It has been estimated that there are over 7
million acres of kudzu in the Deep South with an
average infestation size of 14 acre. This means
that there may be 30 million sites in the South.
Kudzu vines are known to grow 1 foot per day
and often grow more than 60 feet during the
season. Livestock numbers have declined since
the 1940s and 50s and kudzu patches have
expanded rapidly and taken over fences and

Specific kudzu sites were monitored in 2005 and
2006 for presence of soybean rust. Monitoring
was done primarily by the Department of Plant
Industry in 2005 and by the University of
Florida soybean rust team in 2006. We wanted
to monitor the same sites and new sites both
years to determine if rust was spreading and if
we could detect higher levels of infection. We
assumed rust would be limited to southern
Florida during the winter months, but could
move north quickly as the weather warmed.
Eighty three specific kudzu sites were monitored
for soybean rust in 2005 and 2006. Ten percent
of the monitored sites were positive in 2005, and
an additional 30% were positive in 2006. In
general, weather conditions were not as
conducive to spread in 2006 as in 2005 until late
in the season when rainfall levels were higher
and temperatures lower.

Soybean rust on kudzu is able to over-winter
further north than expected due to plants being
sheltered from harsh temperature conditions
around houses, in culverts, or other sheltered
places. The results of the surveys done in
Florida in 2005 and 2006 indicate that soybean
rust is becoming more widespread. It is
expected that more sites will become infected in
the future, especially in the coastal and south
Florida areas. This may lead to a greater chance
of rust spreading into the Midwest on storms
that occur early in the season. There are no
fungicides registered for controlling rust on

Infected kudzu leaves are often found in shady
areas out of direct sunlight early in the season.
However, infection increases rapidly late in the

season when days get shorter and temperatures
are cooler, and infected plants may be found in
many different areas including areas that are
exposed to extended periods of sunlight.

Summary of Kudzu Sites
Monitored in 2005-2006
Number of
Infection Status Sites
Negative 2005, 47
Negative 2006
Negative 2005, 24
Positive 2006
Positive 2005, 9
Positive 2006
Positive 2005, 3
Negative 2006

David Wright and Jim Marois

Summary of Aldicarb Rule Changes

Aldicarb is a granular carbamate insecticide
applied to more than 400,000 acres of Florida
citrus to manage citrus rust mite, whiteflies,
citrus nematode, aphids, and citrus psyllid. The
use of aldicarb has increased in importance as a
result of the finding of citrus greening in the
state, which is vectored by citrus psyllid.

Aldicarb is soluble in water and is readily
absorbed into the roots and is transported
throughout the plant. There are indications that
aldicarb can be highly mobile in certain soil
types, such as those with relatively high sand
content and little organic matter, and its
detection in groundwater demonstrates that
leaching can occur. Aldicarb has high acute
toxicity and carries the signal word, "DANGER
POISON" on its label. Acute toxicity and
groundwater contamination concerns are the
criteria for its restricted use classification.
Highly publicized incidents involving
contaminated cucumbers and watermelons
occurred in the mid 1980s. In those cases,
misapplication led to adverse effects in people.
For these reasons, there is a statewide
stewardship rule regulated by the Florida
Department of Agriculture and Consumer
Services (FDACS) for aldicarb's use. Several
amendments to the regulation have recently

Effectively immediately, the time period for
application of aldicarb to citrus has been
changed from the period January 1 April 30 to
the period November 15 April 30. The rule
states that the use of aldicarb on citrus is limited
to one application per tree per use season.

Effectively immediately, there is no longer a 10-
day delay between submission of a permit
application and the earliest start date for the
aldicarb application. The aldicarb application
may be made as soon as the permit has been
approved, but is still limited to the period
November 15 April 30.

Effectively immediately, when multiple
application sites are submitted together, FDACS
may reject selected application sites, if
necessary, and approve the others. Each
application site is now considered a separate
permit, and the whole set of application sites
will be assigned only one FDACS #. For
applicators using paper forms, the "Application
for Permit to Apply Aldicarb" has been modified
so that only one application site may be listed on
each form. When multiple paper forms are
submitted together, the top part of the form
(licensed applicator information) needs to be
completed on only one form, and any additional
forms just need to list the applicator's name and
the specific site information for each additional

Effectively July 1, 2007, drinking wells inside
an application site or within the appropriate
buffer zone (300 or 1,000 feet) around an
application site must be identified with Global
Positioning System (GPS) latitude and longitude
coordinates in decimal degrees. Latitude and
longitude coordinates must be accurate to at
least five decimal places. Applicators are
encouraged to begin reporting GPS coordinates
as soon as possible. If GPS coordinates are
provided, a verbal description of the well
location is not necessary but may be provided if

Effective July 1, 2007, application sites for all
crops to which aldicarb is applied must be
identified to the /4 of /4 section. This is in
addition to the following information which
must still be provided for each application site:
county, township, range, section, and site/block

name or description. Paper forms have been
modified to accommodate the change and
applicators are encouraged to provide such
section information as soon as possible.

Effective July 1, 2007, in order to reduce the
buffer zone around cased drinking wells from
1,000 feet to 300 feet, cased well documentation
must contain all of the following information:
well location, casing depth, static water level at
time of well completion (if not continuously
cased to a depth of 100 feet or greater), and
name of the water management district of
Florida-Licensed well contractor that issued the
document. Well location must be identified by
county, range, township, and section; and,
effective July 1, 2007, GPS latitude and
longitude coordinates in decimal degrees to five
decimal places are to be used.

The rule change clarifies that well location must
be provided only for drinking wells that
determine application setbacks based on the
300-foot and 1,000-foot setback requirements.
The number of non-drinking wells within the
application site must still be reported but no well
location information needs to be reported for
non-drinking wells, provided they are posted
with a conspicuous warning notice stating "NOT

The rule now specifies that FDACS may deny
permit applications that list application sites in
areas determined by the department to be
unsuitable for aldicarb application, based on a
pattern of detections of aldicarb or aldicarb
residues that exceed the Florida Department of
Environmental Protection water quality
standards in potable well water samples from
that geographic area. Individuals may petition
for the reversal of such determinations, and
FDACS will review and evaluate such petitions.
Petitioners must provide written permission to
reverse the unsuitability determination from all
property owners affected.

For information and obtaining permits, see

Fred Fishel

Select Crop Varieties Early

Variety tests should be studied as soon as the
data becomes available. The best varieties are
often in short supply the first year or two that
varieties are out. This has been true for peanuts
and small grain in the past couple of years. Corn
and cotton seed supplies have been good for the
best varieties in the last few years. Check our
website and websites of neighboring states for
http://www.griffin.peachnet.edu/swvt/ on row
crop variety testing. It will be very important to
look at variety test information for peanuts
http://edis.ifas.ufl.edu/AG247 during the coming
year since the best varieties will be in short

David Wright

Wheat prices have been higher this fall than at
any time recently. This has led to an increased
interest in planting. Since the wheat acreage has
been low for the past several years, there will
not be enough seed of the recommended
varieties to go around. Be aware that if old
varieties are planted, the disease resistance is not
good and that fungicides will have to be used.
Wheat can be planted from mid-November to
mid-December with good results. Wheat should
not be planted later since yields are usually
reduced. This is because late planted wheat will
not accumulate enough chill hours for proper
head development and because diseases are
much worse on late maturing varieties.

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; J.A. Ferrell, Extension Agronomist i.i,., ii i l ..I I F.M. Fishel, Pesticide Coordinator
-.I.Ih .I, ,I, .i..i C.R. Rainbolt, Extension Agronomist I ....1..1 1, I i ..Il ..,i B.A. Sellers, Extension Agronomist
,i. i., 1.1 ,11i .1.,i D.L. Wright, Extension Agronomist (dlw@ifas.ufl.edu).

Wheat Planting