<%BANNER%>
HIDE
 Table of Contents
 Irrigating corn
 Hardlock control in cotton
 Late season cotton decisions
 Bahiagrass decline: causes and...
 Using warm season grass hay production...
 Boron in peanut production
 Asian soybean rust
 Asian soybean rust
 Asian soybean rust
 Showy crotalaria/rattlebox
 Artificial ripening in Florida...
 Crompton crop protection and Great...
 System for certified pesticide...


FLAG IFAS PALMM UF



Agronomy notes
ALL VOLUMES CITATION SEARCH THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00066352/00060
 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: August 2005
 Subjects
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 )
 Notes
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.
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: aleph - 000956365
notis - AER9014
System ID: UF00066352:00060

Table of Contents
    Table of Contents
        Page 1
    Irrigating corn
        Page 2
    Hardlock control in cotton
        Page 2
    Late season cotton decisions
        Page 2
    Bahiagrass decline: causes and solutions
        Page 2
        Page 3
    Using warm season grass hay production to remove phosphorus (P) from P-enriched soils
        Page 4
    Boron in peanut production
        Page 5
    Asian soybean rust
        Page 6
    Asian soybean rust
        Page 6
    Asian soybean rust
        Page 6
    Showy crotalaria/rattlebox
        Page 7
    Artificial ripening in Florida sugarcane
        Page 8
    Crompton crop protection and Great Lakes chemical merge
        Page 8
    System for certified pesticide applicators
        Page 8
        Page 9
        Page 10
Full Text






AGRONOMY

UNIVERSITY OF
FLORIDA NOTES
IFAS EXTENSION
August, 2005



IN THIS ISSUE


CORN
Irrigating Corn ............................................. ........... 2

COTTON
Hardlock Control in Cotton ................................... ......... 2
Late Season Cotton Decisions ............................................ 2

FORAGE
Bahiagrass Decline: Causes and Solutions .................................... 2
Using Warm Season Grass Hay Production to Remove
Phosphorus (P) from P-Enriched Soils .................................... 4

PEANUTS
Boron in Peanut Production ................................... ......... 5

SOYBEAN
A sian Soybean R ust ......................................... ........... 6

WEED CONTROL
New Tests Screen Weed for Resistance to Major Herbicide ...................... 6
Glyphosate Resistant Palmer Amaranth ...................................... 6
Showy Crotalaria/Rattlebox ................ ............................ 7

MISCELLANEOUS
Artificial Ripening in Florida Sugarcane ..................................... 8
Crompton Crop Protection and Great Lakes Chemical Merge ..................... 8
The Florida Department of Agriculture and Consumer
Service's (FDACS) Continuing Education Unit (CEU)
System for Certified Pesticide Applicators ................................... 8


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, Interim
Dean.










Late Season Cotton Decisions


Corn grown for grain should be irrigated until
black layer formation. This is the layer that can
be seen at the base of the kernel when grain is
shelled from the cob. Black layer formation
signifies that the kernel is no longer receiving
nourishment from the plant and that seed fill is
complete. If the corn crop experiences stress
during seed fill, significant yield loss can occur.

As a general rule, irrigation will increase yield
by 25 and 50% in most years. But, in
excessively dry years the influence of irrigation
can be even greater. With increasing costs for
genetic technology and other inputs, it is
important to produce high yields in order for the
crop to remain profitable.

David L. Wright

Hardlock Control in Cotton

Hardlock is a condition that causes cotton to not
fluff out of the boll. Consequently, much of the
cotton is missed by the picker and many Florida
cotton fields look like they have not been picked
after harvest. Hardlock has been attributed to
the fungus Fusarium that infects cotton flowers
on the first day of bloom. The development of
this disease has been shown to be associated
with environmental conditions such as high heat
and humidity during the bloom period; as is
common during July and August.

FDACS and UF have worked diligently to make
fungicides available for use during this period.
Research has shown best results occur when
multiple fungicides applications are made one to
two weeks apart starting at early bloom and
continuing for several weeks during the
blooming period. If applied properly, fungicide
applications can improve cotton yield by almost
100% in those fields most severely impacted by
hardlock.

David L. Wright and James J. Marois


August is often a welcome relief and a chance to
slow down after a long season if the field. But,
there are still some decisions to be made that are
critical to finishing the season with high yields.
Late season insect control, particularly
stinkbugs, is critical to quality cotton
production. Stinkbugs are present in many other
crops through out the season and cotton
becomes especially attractive as the other crops
begin drying down. Stinkbugs often inflict the
most damage on newly developing bolls which
are susceptible for about 3 more weeks after
bloom. Since young bolls are susceptible to
damage from stinkbugs throughout the month of
August and into September, this means that
insect protection is necessary for several more
weeks.

Irrigation should be maintained throughout the
bloom period to keep cotton from shedding
squares. Many squares will shed late in the
season as fruit set continues and other factors
such as environmental stress, and insect pressure
increases. Therefore, environmental extremes
such as hot and dry or hot and wet conditions
may reduce fruit set late in the season.
Growers should begin planning for cotton
defoliation and readying equipment for harvest.
Picking cotton in a timely manner after the crop
is mature is the most effective way to retain the
highest yield and lint quality.

David L. Wright

Bahiagrass Decline: Causes and Solutions

Bahiagrass decline is a general term used to
describe the gradual deterioration of a pasture
with no apparent or specific reason. Damage in
the pasture may first appear in yellow patches
which subsequently turn brown and die. These
pastures also have virtually no root system and
plants are easily pulled from the soil by grazing
cattle or destroyed by foot traffic. The vacated
areas in pasture soon get invaded by a wide


Irrigating Corn










Late Season Cotton Decisions


Corn grown for grain should be irrigated until
black layer formation. This is the layer that can
be seen at the base of the kernel when grain is
shelled from the cob. Black layer formation
signifies that the kernel is no longer receiving
nourishment from the plant and that seed fill is
complete. If the corn crop experiences stress
during seed fill, significant yield loss can occur.

As a general rule, irrigation will increase yield
by 25 and 50% in most years. But, in
excessively dry years the influence of irrigation
can be even greater. With increasing costs for
genetic technology and other inputs, it is
important to produce high yields in order for the
crop to remain profitable.

David L. Wright

Hardlock Control in Cotton

Hardlock is a condition that causes cotton to not
fluff out of the boll. Consequently, much of the
cotton is missed by the picker and many Florida
cotton fields look like they have not been picked
after harvest. Hardlock has been attributed to
the fungus Fusarium that infects cotton flowers
on the first day of bloom. The development of
this disease has been shown to be associated
with environmental conditions such as high heat
and humidity during the bloom period; as is
common during July and August.

FDACS and UF have worked diligently to make
fungicides available for use during this period.
Research has shown best results occur when
multiple fungicides applications are made one to
two weeks apart starting at early bloom and
continuing for several weeks during the
blooming period. If applied properly, fungicide
applications can improve cotton yield by almost
100% in those fields most severely impacted by
hardlock.

David L. Wright and James J. Marois


August is often a welcome relief and a chance to
slow down after a long season if the field. But,
there are still some decisions to be made that are
critical to finishing the season with high yields.
Late season insect control, particularly
stinkbugs, is critical to quality cotton
production. Stinkbugs are present in many other
crops through out the season and cotton
becomes especially attractive as the other crops
begin drying down. Stinkbugs often inflict the
most damage on newly developing bolls which
are susceptible for about 3 more weeks after
bloom. Since young bolls are susceptible to
damage from stinkbugs throughout the month of
August and into September, this means that
insect protection is necessary for several more
weeks.

Irrigation should be maintained throughout the
bloom period to keep cotton from shedding
squares. Many squares will shed late in the
season as fruit set continues and other factors
such as environmental stress, and insect pressure
increases. Therefore, environmental extremes
such as hot and dry or hot and wet conditions
may reduce fruit set late in the season.
Growers should begin planning for cotton
defoliation and readying equipment for harvest.
Picking cotton in a timely manner after the crop
is mature is the most effective way to retain the
highest yield and lint quality.

David L. Wright

Bahiagrass Decline: Causes and Solutions

Bahiagrass decline is a general term used to
describe the gradual deterioration of a pasture
with no apparent or specific reason. Damage in
the pasture may first appear in yellow patches
which subsequently turn brown and die. These
pastures also have virtually no root system and
plants are easily pulled from the soil by grazing
cattle or destroyed by foot traffic. The vacated
areas in pasture soon get invaded by a wide


Irrigating Corn










Late Season Cotton Decisions


Corn grown for grain should be irrigated until
black layer formation. This is the layer that can
be seen at the base of the kernel when grain is
shelled from the cob. Black layer formation
signifies that the kernel is no longer receiving
nourishment from the plant and that seed fill is
complete. If the corn crop experiences stress
during seed fill, significant yield loss can occur.

As a general rule, irrigation will increase yield
by 25 and 50% in most years. But, in
excessively dry years the influence of irrigation
can be even greater. With increasing costs for
genetic technology and other inputs, it is
important to produce high yields in order for the
crop to remain profitable.

David L. Wright

Hardlock Control in Cotton

Hardlock is a condition that causes cotton to not
fluff out of the boll. Consequently, much of the
cotton is missed by the picker and many Florida
cotton fields look like they have not been picked
after harvest. Hardlock has been attributed to
the fungus Fusarium that infects cotton flowers
on the first day of bloom. The development of
this disease has been shown to be associated
with environmental conditions such as high heat
and humidity during the bloom period; as is
common during July and August.

FDACS and UF have worked diligently to make
fungicides available for use during this period.
Research has shown best results occur when
multiple fungicides applications are made one to
two weeks apart starting at early bloom and
continuing for several weeks during the
blooming period. If applied properly, fungicide
applications can improve cotton yield by almost
100% in those fields most severely impacted by
hardlock.

David L. Wright and James J. Marois


August is often a welcome relief and a chance to
slow down after a long season if the field. But,
there are still some decisions to be made that are
critical to finishing the season with high yields.
Late season insect control, particularly
stinkbugs, is critical to quality cotton
production. Stinkbugs are present in many other
crops through out the season and cotton
becomes especially attractive as the other crops
begin drying down. Stinkbugs often inflict the
most damage on newly developing bolls which
are susceptible for about 3 more weeks after
bloom. Since young bolls are susceptible to
damage from stinkbugs throughout the month of
August and into September, this means that
insect protection is necessary for several more
weeks.

Irrigation should be maintained throughout the
bloom period to keep cotton from shedding
squares. Many squares will shed late in the
season as fruit set continues and other factors
such as environmental stress, and insect pressure
increases. Therefore, environmental extremes
such as hot and dry or hot and wet conditions
may reduce fruit set late in the season.
Growers should begin planning for cotton
defoliation and readying equipment for harvest.
Picking cotton in a timely manner after the crop
is mature is the most effective way to retain the
highest yield and lint quality.

David L. Wright

Bahiagrass Decline: Causes and Solutions

Bahiagrass decline is a general term used to
describe the gradual deterioration of a pasture
with no apparent or specific reason. Damage in
the pasture may first appear in yellow patches
which subsequently turn brown and die. These
pastures also have virtually no root system and
plants are easily pulled from the soil by grazing
cattle or destroyed by foot traffic. The vacated
areas in pasture soon get invaded by a wide


Irrigating Corn










Late Season Cotton Decisions


Corn grown for grain should be irrigated until
black layer formation. This is the layer that can
be seen at the base of the kernel when grain is
shelled from the cob. Black layer formation
signifies that the kernel is no longer receiving
nourishment from the plant and that seed fill is
complete. If the corn crop experiences stress
during seed fill, significant yield loss can occur.

As a general rule, irrigation will increase yield
by 25 and 50% in most years. But, in
excessively dry years the influence of irrigation
can be even greater. With increasing costs for
genetic technology and other inputs, it is
important to produce high yields in order for the
crop to remain profitable.

David L. Wright

Hardlock Control in Cotton

Hardlock is a condition that causes cotton to not
fluff out of the boll. Consequently, much of the
cotton is missed by the picker and many Florida
cotton fields look like they have not been picked
after harvest. Hardlock has been attributed to
the fungus Fusarium that infects cotton flowers
on the first day of bloom. The development of
this disease has been shown to be associated
with environmental conditions such as high heat
and humidity during the bloom period; as is
common during July and August.

FDACS and UF have worked diligently to make
fungicides available for use during this period.
Research has shown best results occur when
multiple fungicides applications are made one to
two weeks apart starting at early bloom and
continuing for several weeks during the
blooming period. If applied properly, fungicide
applications can improve cotton yield by almost
100% in those fields most severely impacted by
hardlock.

David L. Wright and James J. Marois


August is often a welcome relief and a chance to
slow down after a long season if the field. But,
there are still some decisions to be made that are
critical to finishing the season with high yields.
Late season insect control, particularly
stinkbugs, is critical to quality cotton
production. Stinkbugs are present in many other
crops through out the season and cotton
becomes especially attractive as the other crops
begin drying down. Stinkbugs often inflict the
most damage on newly developing bolls which
are susceptible for about 3 more weeks after
bloom. Since young bolls are susceptible to
damage from stinkbugs throughout the month of
August and into September, this means that
insect protection is necessary for several more
weeks.

Irrigation should be maintained throughout the
bloom period to keep cotton from shedding
squares. Many squares will shed late in the
season as fruit set continues and other factors
such as environmental stress, and insect pressure
increases. Therefore, environmental extremes
such as hot and dry or hot and wet conditions
may reduce fruit set late in the season.
Growers should begin planning for cotton
defoliation and readying equipment for harvest.
Picking cotton in a timely manner after the crop
is mature is the most effective way to retain the
highest yield and lint quality.

David L. Wright

Bahiagrass Decline: Causes and Solutions

Bahiagrass decline is a general term used to
describe the gradual deterioration of a pasture
with no apparent or specific reason. Damage in
the pasture may first appear in yellow patches
which subsequently turn brown and die. These
pastures also have virtually no root system and
plants are easily pulled from the soil by grazing
cattle or destroyed by foot traffic. The vacated
areas in pasture soon get invaded by a wide


Irrigating Corn










variety of broad-leaf weeds including goatweed,
doveweed and dogfennel. This scenario is
usually associated with a high population
density of mole crickets. Due to the tunneling
activity of mole crickets, the surface 6 to 10-inch
soil layer in damaged pastures will be
honeycombed with numerous galleries that
cause the ground to feel spongy when stepped
on. As shown by the South Florida Beef and
Forage Program survey in 1998, mole crickets
caused a $40 million dollar loss in annual hay
revenue and cost an additional $10 million for
insect control.

Mole cricket damage to pasture and turf grasses
is mainly due to feeding on roots by 'Tawny'
mole crickets. Currently, pest mole crickets are
resident on most Florida pastures. So the
obvious question is: why don't all infested
bahiagrass pastures show a similar degree of
decline? We have identified environmental,
nutritional, and biological factors that influence
mole-cricket decline in Florida.

Since mole crickets have a one-year life span,
the yearly nymph crop population dictates the
level of activity on the pasture for that year.
With the exception of mating flights in February
and March, mole crickets spend nearly the rest
of their life cycle underground. Eggs are then
laid in clutches in underground chambers
between April and May and hatch from June to
July. Hatchlings feed in upper soil layer and
litter. Nymphs and adults occupy an extensive
tunnel system in the ground, coming out only in
the night to feed. The exclusive subterranean
lifestyle implies that pest mole crickets tend to
avoid heavy clay soils and low-lying areas that
are subjected to prolonged waterlogged
conditions. More importantly, extremely wet
summer and fall conditions tend to flush out and
expose nymphs to predators (birds, raccoons)
during daytime while normal to dry summers
promote survival of nymphs underground.
Long-term experiments have confirmed that
high summer rainfall totals result in reduced pest
mole cricket activity. A few producers who are
already aware of this relationship use controlled
summer flooding on their ranch to curtail soil
born pests in general.


Nitrogen fertilizer holds the key to bahiagrass
pasture production but here is the catch: All the
commonly used N-fertilizer materials contain
ammonium which lowers the soil pH when they
undergo nitrification. We have learned that
bahiagrass is very sensitive to changes in soil
pH. When soil pH falls below 4.5, deficiencies
of sulfur, molybdenum and boron may be
created, the root system is weakened and the
grass turns yellow during the early spring
growth flush. Likewise, a soil pH of around 7,
as a result of repeated sludge use, causes
reduced forage growth as well as iron, zinc,
manganese and copper deficiencies. A
weakened sod makes is then more susceptible to
mole cricket damage. Therefore, we recommend
that producers check the soil pH every 3 years
and lime bahiagrass pastures to maintain pH
between 5 and 6 for a healthy sod.

Grazing intensity (how low or how high)
controls how much stored energy is required to
recover and generate new leaves. Prolonged
overgrazing reduces stored energy in the sod and
could encourage further mole cricket damage to
the pasture. Most of the mole cricket-damaged
pastures in south-central Florida have been
overgrazed. It is advisable to leave a stubble
that is greater than 3" when grazing bahiagrass
and rotate cattle to other pastures when grass is
short.

The University of Florida holds a patent on a
beneficial nematode (a tiny worm) that controls
pest mole crickets. Once the parasitic nematode
enters a mole cricket, it kills the cricket within
48 hours. The nematodes then multiply and
young nematodes emerge from the dead cricket
about a week later to look for other hosts.
MicroBio (http://www.beckerunderwood.com)
is the commercial source for nematode
production. The product bears a trade name
Nematac S and cost $200/A for complete
(wall-to-wall) field coverage. However, we
have investigated methods of strip application as
means to reduce the cost for producers. It was
determined that when nematodes were applied to
13% of a field (in strips), by infected mole
crickets would spread the nematodes and fill in
gaps between the treated strips within one year.










The strip-treatment method reduced the cost of
material from $200 to $25 per acre. Three years
after strip- application of nematodes, it was
found that about 30% of mole cricket population
was infected at any particular time. The mole
cricket population then declined by 85% and
bahiagrass ground cover increased 40-95%.
Follow up surveys show that nematodes have
become successfully established on almost all
locations and continue to infect 20-30% of the
mole cricket population. Hopefully, as more
producers use the product, the nematode will
become widespread and naturalized to provide
permanent relief to bahiagrass producers
throughout Florida.


Martin B. Adjei


Research

University of Florida-IFAS conducted research
that was funded by the Florida Department of
Agriculture and Consumer Services. The
research was initiated in 2003 to evaluate the
effects of increasing N fertilizer application rates
on forage production, nutritive value and P-
harvesting capacity of bahiagrass, limpograss
and stargrass on a P-impacted dairy site in the
Lake Okeechobee Basin. A secondary objective
of that study was to determine the concentrations
of nitrates and dissolved P in surface runoff and
drainage water associated with the increased N
fertilizer application.


Research Questions


Using Warm Season Grass Hay Production to
Remove Phosphorus (P) from P-Enriched
Soils

Intensive animal feeding operations generate
large amounts of manure that can cause high
levels of phosphorus (P) in the soil and
groundwater. One way to tie up the excess P is
by applying soil amendments such as Alum.
However, approximately 35 tons of Alum is
often required and this involves huge
transportation costs of about $2,000 per acre.
There is also the question as to how Alum will
work and whether the aluminum in the material
will become toxic in the long-term. Another
alternative is the use of wetlands for treating P-
enriched water sources. This approach has been
highly successful, but wetland establishment can
cost $12,000 to $18,000 and this often proves to
be prohibitive.

Pasture production for beef, dairy and horse
feeding represents the largest land use system in
south-central Florida. Nitrogen (N) is the most
limiting nutrient to grass production and large
amounts on N fertilizer are applied to pastures
every year. Intensively managed pastures for
hay production may offer another option for
reducing the environmental risk of P.


We established and maintain field studies at the
Butler Oak Dairy in Okeechobee to answer the
following research questions: 1) What are the
effects of four rates of N-fertilization on forage
productivity and quality?; 2) What are the
responses of bahiagrass, stargrass and
limpograss to N fertilizer rates in their P-uptake
capacity?; and 3) What effects will the N
fertilizer rates have on residual nitrates and P
concentrations in the soil and groundwater?

Methods

In 2003 we re-planted the existing stargrass field
because of heavy weed infestation and installed
electrical fences around grass fields. The
bahiagrass and limpograss pastures did not have
sufficient soil P levels initially. Therefore, we
applied dairy manure to raise the initial P levels
to the desired range of 25-30 ppm of plant
available P. After manure application, we
allowed adequate time for it to break down and
the P to be redistributed within the soil top layer.
The average P levels in the upper layer in spring
of 2004 were 25, 26, and 21 ppm of plant
available P for the bahiagrass, limpograss and
stargrass, respectively.










The fertilizer treatments consisted of 0, 0.75, 1
and 1.3 times of UF-IFAS N recommendation
for each grass hay harvest. This translated into
the application of 0, 45, 60 and 90 lb of N per
acre for each hay crop. In 2004, we applied our
N fertilizer treatments to all three grasses in mid-
April. We harvested bahiagrass and stargrass to
a 4 inch-stubble and on a 30-day frequency and
the limpograss to a 6-inch stubble and on a 45-
day frequency between May and November.
There were a total of seven harvests each for
bahiagrass and stargrass and five harvests for
limpograss in 2004 and each plot received same
repeated N application following every harvest.
Runoff, shallow well (above the hardpan layer)
and deep well (below the hardpan layer)
groundwater samples were collected after each
heavy rainfall and analyzed for nitrates and
dissolved P concentrations. Soil was sampled
every spring from the top (Ap) middle (E) and
hardpan (Bh) horizons and analyzed for P and
other elements (K, Ca, Mg, Fe, Al).

Applied Questions

1) Did N Fertilizer Application Rate Affect
Forage Yield and Quality?

As expected, forage yield, crude protein
(CP) concentration and TDN of all three
grasses increased as N increased. The
annual forage production at 0 N rate
increased 2 fold (4.4-9.2 T/A) for
bahiagrass, 85% (4.8-8.9 T/A) for
limpograss and 60% (5.1-8.1 T/A) for
stargrass. Bahiagrass and stargrass
crude protein increased 4 percentage
units (12-16%) with increasing N rate,
while limpograss CP increment was
only 2 percentage units (7-9%).
Digestibility was highest for limpograss
and lowest for bahiagrass but it
increased by 3% units for all grasses
with increasing levels of N.

2) Did N Fertilizer Application Rate Affect
Soil P Removal?


Total P removal by crop increased as the
N fertilizer rate increased. At the
highest N rate, P-harvested in crop was
57, 46, and 30 lb P/A (117, 95, 63 lb
P205/A) annually, for bahiagrass,
limpograss and stargrass, respectively.

3) Did N Fertilizer Application Rate Affect
Residual Soil P and Groundwater
Quality?

Phosphorus removal by crop resulted in
an overall reduction in soil P of 6 ppm
in topsoil, 1 ppm in the mid-soil and 17
ppm in the hardpan during 2004.
Increasing N application rate did not
increase nitrate concentrations in deep
wells, but did result in appreciable
increase of nitrates in the shallow wells.
Dissolved P concentration was greater in
runoff and shallow wells for the recently
manure-amended production sites
(bahiagrass and limpograss) than for the
un-amended site (stargrass), regardless
of N fertilizer rate. These initial results
favor the use of warm-season grass hay
production for P-phytoremediation but
long term data are being collected to
substantiate this option and resolve the
nitrate problem.

Martin B. Adjei and Johannes M Scholberg

Boron in Peanut Production

All peanut producing states recommend
applications of boron (B) since it is a highly
mobile nutrient. High application rates of other
nutrients can make B deficiency more
pronounced. Deficiencies are most often found
on highly weathered, sandy soils. The symptom
we most often associate with B deficiency is
internal fruit damage called "hollow heart",
which reduces the quality and value of the crop.
However, in more severe cases, B deficiency can
result in split stems and roots (Figure 1),
shortened interodes, terminal death, and










extensive secondary branching. Leaves may be
dark green and mottled with few or no peanuts
developing on stubbed pegs. Some fields have
been observed with severe B deficiency and this
is a reminder that B is often needed even if few
observations of deficiency are seen. B may be
applied early with various pesticides to save
time and sprayer cost. However, split-
applications are desirable on sandy soils to reach
a total of 2 to 34 pound of B per acre for the
year.


Figure 1. Split peanut stems due to boron deficiency

David L. Wright and Henry (Ed) Jowers

Asian Soybean Rust

Asian soybean rust (ASR) has been found on
kudzu and in 2 sentinel soybean plots across
Florida. Therefore, it is advisable to consider a
fungicide application at early bloom. In double
cropped soybeans in Brazil, it has been observed
that the second crop is often devastated if the
early crop shows light infections. Therefore, if
there are other soybeans in the area that have
been planted earlier, late planted soybeans may
be at a higher risk to have a severe outbreak.

David L. Wright and James J. Marois

New Tests Screen Weed for Resistance to
Major Herbicide

According to a recent issue of Pesticide & Toxic
Chemical News, two rapid, nondestructive tests


have been developed by USDA-ARS scientists
to screen horseweed for resistance to glyphosate.

One method of testing resistance involves
dipping a whole leaf into a glyphosate-based
mixture and looking for signs of injury. To
achieve double confirmation of the weed's
status, a second assay can be used, taking
advantage of glyphosate's mode of action,
which involves inhibiting amino acid
metabolism. Leaf tissue samples are removed,
and amino acid levels are measured with
specialized lab equipment.

If glyphosate resistance is confirmed, the tests
should help reduce the spread of resistant weed
populations because growers will use different
herbicides to manage the resistant weeds.

FredM. Fishel

Glyphosate Resistant Palmer Amaranth

Glyphosate resistant Palmer amaranth has been
found in Houston County Georgia. Resistance
was suspected in this population last season, but
a year of diagnostic research conducted by
Monsanto and the University of Georgia has
confirmed this biotype is indeed resistant.
The resistance was documented in a field that
has been in continuous Roundup Ready Cotton
for approximately 8 years with Roundup as the
only herbicide used for weed control during this
time. Currently, only a small area (2 or 3
adjacent fields) has been confirmed to possess
the resistant biotype. However, pigweed seed
can be spread by birds and we anticipate the
spread to continue. The level of resistance in this
biotype is high with individuals surviving
multiple applications of Roundup Weathermax
totaling 88 fl. oz of product.

Can glyphosate resistant Palmer amaranth occur
in Florida? Yes, particularly if no crop and/or
herbicide rotation is observed. But, a proactive
herbicide approach can greatly reduce the
probability of this weed resistance. By simply
diversifying the herbicide program, particularly
by adding various residual herbicides to the
program, the likelihood of developing herbicide
resistant weeds decreases dramatically. Also,










extensive secondary branching. Leaves may be
dark green and mottled with few or no peanuts
developing on stubbed pegs. Some fields have
been observed with severe B deficiency and this
is a reminder that B is often needed even if few
observations of deficiency are seen. B may be
applied early with various pesticides to save
time and sprayer cost. However, split-
applications are desirable on sandy soils to reach
a total of 2 to 34 pound of B per acre for the
year.


Figure 1. Split peanut stems due to boron deficiency

David L. Wright and Henry (Ed) Jowers

Asian Soybean Rust

Asian soybean rust (ASR) has been found on
kudzu and in 2 sentinel soybean plots across
Florida. Therefore, it is advisable to consider a
fungicide application at early bloom. In double
cropped soybeans in Brazil, it has been observed
that the second crop is often devastated if the
early crop shows light infections. Therefore, if
there are other soybeans in the area that have
been planted earlier, late planted soybeans may
be at a higher risk to have a severe outbreak.

David L. Wright and James J. Marois

New Tests Screen Weed for Resistance to
Major Herbicide

According to a recent issue of Pesticide & Toxic
Chemical News, two rapid, nondestructive tests


have been developed by USDA-ARS scientists
to screen horseweed for resistance to glyphosate.

One method of testing resistance involves
dipping a whole leaf into a glyphosate-based
mixture and looking for signs of injury. To
achieve double confirmation of the weed's
status, a second assay can be used, taking
advantage of glyphosate's mode of action,
which involves inhibiting amino acid
metabolism. Leaf tissue samples are removed,
and amino acid levels are measured with
specialized lab equipment.

If glyphosate resistance is confirmed, the tests
should help reduce the spread of resistant weed
populations because growers will use different
herbicides to manage the resistant weeds.

FredM. Fishel

Glyphosate Resistant Palmer Amaranth

Glyphosate resistant Palmer amaranth has been
found in Houston County Georgia. Resistance
was suspected in this population last season, but
a year of diagnostic research conducted by
Monsanto and the University of Georgia has
confirmed this biotype is indeed resistant.
The resistance was documented in a field that
has been in continuous Roundup Ready Cotton
for approximately 8 years with Roundup as the
only herbicide used for weed control during this
time. Currently, only a small area (2 or 3
adjacent fields) has been confirmed to possess
the resistant biotype. However, pigweed seed
can be spread by birds and we anticipate the
spread to continue. The level of resistance in this
biotype is high with individuals surviving
multiple applications of Roundup Weathermax
totaling 88 fl. oz of product.

Can glyphosate resistant Palmer amaranth occur
in Florida? Yes, particularly if no crop and/or
herbicide rotation is observed. But, a proactive
herbicide approach can greatly reduce the
probability of this weed resistance. By simply
diversifying the herbicide program, particularly
by adding various residual herbicides to the
program, the likelihood of developing herbicide
resistant weeds decreases dramatically. Also,










extensive secondary branching. Leaves may be
dark green and mottled with few or no peanuts
developing on stubbed pegs. Some fields have
been observed with severe B deficiency and this
is a reminder that B is often needed even if few
observations of deficiency are seen. B may be
applied early with various pesticides to save
time and sprayer cost. However, split-
applications are desirable on sandy soils to reach
a total of 2 to 34 pound of B per acre for the
year.


Figure 1. Split peanut stems due to boron deficiency

David L. Wright and Henry (Ed) Jowers

Asian Soybean Rust

Asian soybean rust (ASR) has been found on
kudzu and in 2 sentinel soybean plots across
Florida. Therefore, it is advisable to consider a
fungicide application at early bloom. In double
cropped soybeans in Brazil, it has been observed
that the second crop is often devastated if the
early crop shows light infections. Therefore, if
there are other soybeans in the area that have
been planted earlier, late planted soybeans may
be at a higher risk to have a severe outbreak.

David L. Wright and James J. Marois

New Tests Screen Weed for Resistance to
Major Herbicide

According to a recent issue of Pesticide & Toxic
Chemical News, two rapid, nondestructive tests


have been developed by USDA-ARS scientists
to screen horseweed for resistance to glyphosate.

One method of testing resistance involves
dipping a whole leaf into a glyphosate-based
mixture and looking for signs of injury. To
achieve double confirmation of the weed's
status, a second assay can be used, taking
advantage of glyphosate's mode of action,
which involves inhibiting amino acid
metabolism. Leaf tissue samples are removed,
and amino acid levels are measured with
specialized lab equipment.

If glyphosate resistance is confirmed, the tests
should help reduce the spread of resistant weed
populations because growers will use different
herbicides to manage the resistant weeds.

FredM. Fishel

Glyphosate Resistant Palmer Amaranth

Glyphosate resistant Palmer amaranth has been
found in Houston County Georgia. Resistance
was suspected in this population last season, but
a year of diagnostic research conducted by
Monsanto and the University of Georgia has
confirmed this biotype is indeed resistant.
The resistance was documented in a field that
has been in continuous Roundup Ready Cotton
for approximately 8 years with Roundup as the
only herbicide used for weed control during this
time. Currently, only a small area (2 or 3
adjacent fields) has been confirmed to possess
the resistant biotype. However, pigweed seed
can be spread by birds and we anticipate the
spread to continue. The level of resistance in this
biotype is high with individuals surviving
multiple applications of Roundup Weathermax
totaling 88 fl. oz of product.

Can glyphosate resistant Palmer amaranth occur
in Florida? Yes, particularly if no crop and/or
herbicide rotation is observed. But, a proactive
herbicide approach can greatly reduce the
probability of this weed resistance. By simply
diversifying the herbicide program, particularly
by adding various residual herbicides to the
program, the likelihood of developing herbicide
resistant weeds decreases dramatically. Also,










many herbicides control Palmer amaranth and
can easily (and often inexpensively) be
incorporated into the current weed control
program. For example, all the herbicides listed
below are known to control pigweeds and many
possess both preemergence and postemergence
activity.

Postemergence Postemergence
Preemergence (foliar) (directed)

Prowl Staple MSMA

Treflan Dual Cotoran

Cotoran Diuron

Zorial Valor

Diuron Prowl

Staple Layby Pro
(linuron +
diuron)

Cobra

Caparol

It is important that we return to the time-tested
principles of crop production. Weed
management is a season-long practice and the
easiest solution may not always be the best.
Yes, the new genetic technologies that have
been developed are excellent tools. However,
even the best of tools can be broken if abused.

Jason A. Ferrell

Showy Crotalaria/Rattlebox

Rattlebox, or showy crotalaria (Crotalaria
spectabilis), is an annual weed that is often
found in isolated areas of pastures, rangeland,
and roadsides (Figure 2). Although showy
crotalaria is not a highly competitive or invasive
weed, it is important to monitor this pest since it
is toxic to most livestock. The primary toxins in
showy crotalaria are the alkaloids pyrrolizidine
and monocrotalamine. These toxins are found


throughout the plant, but seeds contain the
highest concentration of these toxins. Acute
death sometimes occurs when livestock eat large
quantities (about 3% of their body weight) of the
seeds or the plant, but more typically animals
will develop signs of wasting due to liver
disease and photosensitization with symptoms
lasting from a few days up to 6 months. In
severe cases, monocrotalamine can also cause
acute damage to the lungs.


How is showy crotalaria identified? Showy
crotalaria is an erect, annual legume (can act as a
perennial in some environments) with simple,
alternate leaves. Although the plant fixes
nitrogen, it tends to have a slightly off-green to
yellow color. Leaves can be hairy, but are often
hairless. The stem of the plant becomes angled
as the plant matures. Flowers are yellow and are
typical to that of the legume family, except that
the flowers are attached to a long stalk at the top
of the plant. The fruit looks similar to that of the
pea pod, but it is much wider. There are
approximately 10 to 20 heart-shaped seeds in
each pod. At maturity, the seeds become
detached inside the fruit, giving the fruit a
rattleboxx' sound when shaken.

How is showy crotalaria controlled? Very little
data exist for this species and no herbicide labels
list Crotalaria species as a controllable weed.
However, any type of growth regulator herbicide
(2,4-D, Weedmaster, Remedy, etc.) should give
some activity on showy crotalaria. Personally, I
think PastureGard at 3 pints of product per acre
would have good control of this weed. If spot-
spraying, a 1-2% (v/v) solution can be applied
directly to the plant. Other products such as
Weedmaster and Outlaw may also have good
activity, but the rate would likely need to be
higher. Alternatively, glyphosate can be spot
sprayed onto individual plants.



























ure 2. Showy Crotalaria. Photo credit, Allen
Boatman (www.plantatlas.usf.edu)

Brent A. Sellers

Artificial Ripening in Florida Sugarcane

Sugarcane harvest in Florida requires a full 5
months due to the ratio of sugarcane acres to
mill processing capacities. Consequently, some
sugarcane is harvested in October when warm
temperatures, adequate soil moisture, and high
nitrogen levels limit early season natural
ripening. Mature, or ripe, sugarcane plants
contain a higher percentage of sucrose and as a
result produce more pounds of sugar per acre.
In order to overcome this lack of natural early
season ripening, sugarcane is treated with
herbicides or plant growth regulators to induce
ripening. In the past, Polado L and Touchdown
(glyphosate is the active ingredient in both) were
the only products labeled for sugarcane ripening
in Florida. Roundup Weathermax (glyphosate)
recently received a label for sugarcane ripening
and will be available for the 2005-2006 harvest
season. In Florida, glyphosate can only be
applied in the final ratoon. Application to
earlier ratoons can result in reduced stand counts
and yields in subsequent years. Applications
should be made 3 to 6 weeks prior to harvest.
Rates are 5 to 14 oz/A for Polado L, 5 to 12
oz/A for Roundup


Weathermax, and 8 to 18.5 oz/A for
Touchdown. Trials at EREC have shown that
Polado and Touchdown perform similarly.
Monsanto data indicates that Polado and
Roundup Weathermax are also similar when
applied at equivalent rates.

Curtis Rainbolt

Crompton Crop Protection and Great Lakes
Chemical Merge

Crompton Corporation and Great Lakes
Chemical Corporation have combined to form
Chemtura Corporation. Chemtura (pronounced
chem-choo'-ra) will be based in Middlebury,
Connecticut and will be the fourth largest
publicly-traded U.S. specialty chemicals
company. The product line of the new company
will combine the fumigants of Great Lakes
(Methyl-bromide, Terr-O-Gas and Chlor-O-Pic)
with the insecticide/growth regulators
(Diamond, Dimilin, and Micromite), acaracides
(Acaramite, Comite and Omite), fungicides
(Procure and Terraclor), herbicides (Alanap and
Casoron), and plant growth regulators
(Harvade,Leafless, and Royal MH-30) of
Crompton.

Richard K. Sprenkel

The Florida Department of Agriculture and
Consumer Service's (FDACS) Continuing
Education Unit (CEU) System for Certified
Pesticide Applicators

Applicators must become recertified in order to
renew their pesticide applicator licenses. To
become recertified, individuals have the option
of either retaking the certification exams or
earning CEUs. CEU credits are earned by
attending professional meetings, seminars or
completing online or correspondence courses.

The Pesticide Information Office has received
questions concerning the new CEU system for
certified applicators. It's inevitable that these
recent changes have caused some confusion with
many applicators. Since few applicators opt



























ure 2. Showy Crotalaria. Photo credit, Allen
Boatman (www.plantatlas.usf.edu)

Brent A. Sellers

Artificial Ripening in Florida Sugarcane

Sugarcane harvest in Florida requires a full 5
months due to the ratio of sugarcane acres to
mill processing capacities. Consequently, some
sugarcane is harvested in October when warm
temperatures, adequate soil moisture, and high
nitrogen levels limit early season natural
ripening. Mature, or ripe, sugarcane plants
contain a higher percentage of sucrose and as a
result produce more pounds of sugar per acre.
In order to overcome this lack of natural early
season ripening, sugarcane is treated with
herbicides or plant growth regulators to induce
ripening. In the past, Polado L and Touchdown
(glyphosate is the active ingredient in both) were
the only products labeled for sugarcane ripening
in Florida. Roundup Weathermax (glyphosate)
recently received a label for sugarcane ripening
and will be available for the 2005-2006 harvest
season. In Florida, glyphosate can only be
applied in the final ratoon. Application to
earlier ratoons can result in reduced stand counts
and yields in subsequent years. Applications
should be made 3 to 6 weeks prior to harvest.
Rates are 5 to 14 oz/A for Polado L, 5 to 12
oz/A for Roundup


Weathermax, and 8 to 18.5 oz/A for
Touchdown. Trials at EREC have shown that
Polado and Touchdown perform similarly.
Monsanto data indicates that Polado and
Roundup Weathermax are also similar when
applied at equivalent rates.

Curtis Rainbolt

Crompton Crop Protection and Great Lakes
Chemical Merge

Crompton Corporation and Great Lakes
Chemical Corporation have combined to form
Chemtura Corporation. Chemtura (pronounced
chem-choo'-ra) will be based in Middlebury,
Connecticut and will be the fourth largest
publicly-traded U.S. specialty chemicals
company. The product line of the new company
will combine the fumigants of Great Lakes
(Methyl-bromide, Terr-O-Gas and Chlor-O-Pic)
with the insecticide/growth regulators
(Diamond, Dimilin, and Micromite), acaracides
(Acaramite, Comite and Omite), fungicides
(Procure and Terraclor), herbicides (Alanap and
Casoron), and plant growth regulators
(Harvade,Leafless, and Royal MH-30) of
Crompton.

Richard K. Sprenkel

The Florida Department of Agriculture and
Consumer Service's (FDACS) Continuing
Education Unit (CEU) System for Certified
Pesticide Applicators

Applicators must become recertified in order to
renew their pesticide applicator licenses. To
become recertified, individuals have the option
of either retaking the certification exams or
earning CEUs. CEU credits are earned by
attending professional meetings, seminars or
completing online or correspondence courses.

The Pesticide Information Office has received
questions concerning the new CEU system for
certified applicators. It's inevitable that these
recent changes have caused some confusion with
many applicators. Since few applicators opt



























ure 2. Showy Crotalaria. Photo credit, Allen
Boatman (www.plantatlas.usf.edu)

Brent A. Sellers

Artificial Ripening in Florida Sugarcane

Sugarcane harvest in Florida requires a full 5
months due to the ratio of sugarcane acres to
mill processing capacities. Consequently, some
sugarcane is harvested in October when warm
temperatures, adequate soil moisture, and high
nitrogen levels limit early season natural
ripening. Mature, or ripe, sugarcane plants
contain a higher percentage of sucrose and as a
result produce more pounds of sugar per acre.
In order to overcome this lack of natural early
season ripening, sugarcane is treated with
herbicides or plant growth regulators to induce
ripening. In the past, Polado L and Touchdown
(glyphosate is the active ingredient in both) were
the only products labeled for sugarcane ripening
in Florida. Roundup Weathermax (glyphosate)
recently received a label for sugarcane ripening
and will be available for the 2005-2006 harvest
season. In Florida, glyphosate can only be
applied in the final ratoon. Application to
earlier ratoons can result in reduced stand counts
and yields in subsequent years. Applications
should be made 3 to 6 weeks prior to harvest.
Rates are 5 to 14 oz/A for Polado L, 5 to 12
oz/A for Roundup


Weathermax, and 8 to 18.5 oz/A for
Touchdown. Trials at EREC have shown that
Polado and Touchdown perform similarly.
Monsanto data indicates that Polado and
Roundup Weathermax are also similar when
applied at equivalent rates.

Curtis Rainbolt

Crompton Crop Protection and Great Lakes
Chemical Merge

Crompton Corporation and Great Lakes
Chemical Corporation have combined to form
Chemtura Corporation. Chemtura (pronounced
chem-choo'-ra) will be based in Middlebury,
Connecticut and will be the fourth largest
publicly-traded U.S. specialty chemicals
company. The product line of the new company
will combine the fumigants of Great Lakes
(Methyl-bromide, Terr-O-Gas and Chlor-O-Pic)
with the insecticide/growth regulators
(Diamond, Dimilin, and Micromite), acaracides
(Acaramite, Comite and Omite), fungicides
(Procure and Terraclor), herbicides (Alanap and
Casoron), and plant growth regulators
(Harvade,Leafless, and Royal MH-30) of
Crompton.

Richard K. Sprenkel

The Florida Department of Agriculture and
Consumer Service's (FDACS) Continuing
Education Unit (CEU) System for Certified
Pesticide Applicators

Applicators must become recertified in order to
renew their pesticide applicator licenses. To
become recertified, individuals have the option
of either retaking the certification exams or
earning CEUs. CEU credits are earned by
attending professional meetings, seminars or
completing online or correspondence courses.

The Pesticide Information Office has received
questions concerning the new CEU system for
certified applicators. It's inevitable that these
recent changes have caused some confusion with
many applicators. Since few applicators opt










to retake the exams, let's review the recent CEU
changes that affect those who work in
agronomic settings (a complete listing of current
CEU requirements for all applicator categories is
provided in UF/IFAS EDIS document PI-40).

Before January 1, 2005: All applicators
who renewed their licenses with CEUs
before January 1, 2005, were required to
earn at least 2 Core CEUs for each
primary category that was being
renewed, and at least half the required
number of CEUs earned for each
category must have been approved for
the specific category. The remainder of
the required CEUs could have been
earned in either Core or the specific
category. If licensed in more than one
category, the applicator would have
been required to earn at least 2 Core
CEUs per category (the same 2 Core
CEUs could not be used for all
categories) and the total CEUs earned
must have been the sum of the CEUs
required per category. As an example,
an applicator who had 3 categories
would have needed 6 Core CEUs to
renew.

After January 1, 2005: Commercial and
public applicators who renew their
licenses with CEUs after January 1,
2005, must have 4 Core CEUs plus the
number of category CEUs shown in the
table below. Only 4 Core CEUs are
required per license not 4 Core CEUs
per category. The new system is much
more straight-forward. Beginning in
2005, all category CEUs must be
approved for the specific category.
There will no longer be a requirement
for having 2 Core CEUs per primary
category, and Core CEUs can no longer
be used to meet the required number of
category CEUs. Example: After January
1, 2005, private applicators must earn 4
Core CEUs plus 4 CEUs approved for
the Private Applicator Agriculture
category. No substitutions of other types
of CEUs will be allowed.


Table of CEU Requirements


The table below lists the number of CEUs
required for applicators who choose to recertify
with CEUs. Effective January 1, 2005, all
applicators must earn 4 Core CEUs in addition
to the category CEUs listed below.

Number of Category
Cat=e ries CFITs Renqiired
Aerial 16
Agricultural Row Crop 8
Pest Control
Agricultural Tree Crop 8
Pest Control
Private Applicator 4
Agricultural Pest Control
Raw Agricultural 4
Commodity Fumigation
Seed Treatment 4
Soil & Greenhouse 4
Fumigation
Demonstration & 4
Research

No Core CEUs are required and cannot be used
to renew the secondary category of
Demonstration and Research. To renew the
Demonstration and Research category, the
license holder must earn 4 CEUs approved for
Demonstration and Research (no Core CEUs).

Aerial CEUs

Aerial License Renewal. Aerial applicators
must earn 4 Core CEUs plus 16 Aerial CEUs to
renew the Aerial category no substitutions
allowed.


Using a Combination of CEUs and Exams to
Renew

Applicators may recertify by re-taking and
passing the certification exams if they do not
have enough CEUs for renewal. If an applicator
has earned the required category CEUs but not
enough Core CEUs, the Core exam may be re-
taken. Applicators may also choose to re-take
the category exam(s) providing 4 Core CEUs
have been earned, regardless of the number of










categories being renewed. Applicators who are
licensed in more than one category may choose
to renew some categories with CEUs and other
categories by exam.

Example 1: Private applicators are
required to have 4 Core CEUs plus 4
CEUs approved for the Private
Applicator Agriculture category. A
private applicator who has 4 Private
Applicator CEUs and only 2 Core CEUs
may choose to re-take the Core exam
instead of earning 2 additional Core
CEUs, if desired.


Example 2: A commercial applicator
licensed in both the Agricultural Row
Crop category and the Agricultural Tree
Crop category has earned 8 Ag Row
Crop CEUs, 2 Ag Tree Crop CEUs, and
3 Core CEUs. The applicator will need
to earn 6 more Ag Tree Crop CEUs plus
1 more Core CEU. To recertify in both
categories, the applicator has the option
of re-taking the Ag Tree Crop and Core
exams instead of earning additional
CEUs, or take either of those exams and
earn the required CEUs for the other.

Additional information may be obtained from
FDACS at http://www.flaes.org/ and the
University of Florida Pesticide Information
Office at http://pested.ifas.ufl.edu/.

FredM. Fishel


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
products.
Prepared by: J.M. Bennett, Chairman; M.B. Adjei, Forage Agronomist (mbadjei@ifas.ufl.edu); J.A. Ferrell, Extension Agronomist
(jaferrell@ifas.ufl.edu); F.M. Fishel, Pesticide Coordinator (weeddr@ifas.ufl.edu); B.A. Sellers, Extension Agronomist
(sellersb@ifas.ufl.edu); E.B. Whitty, Extension Agronomist (ebw@ifas.ufl.edu); D.L. Wright, Extension Agronomist (dlw@ifas.ufl.edu).