Group Title: Agronomy Notes
Title: Agronomy notes
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 Material Information
Title: Agronomy notes
Uniform Title: Agronomy notes (Gainesville, Fl.)
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Agronomy Department
Florida Cooperative Extension Service
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
Place of Publication: Gainesville
Publication Date: November 2009
Subject: 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 )
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
Bibliographic ID: UF00066352
Volume ID: VID00118
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000956365
notis - AER9014


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IFAS Extension

Agronomy Notes

Volume 33:11



Impact of Soybean and Peanut on N Needs of
Winter Forages......................... ............................. Page 2
Annual Ryegrass Fertilization.............................................. Page 2
Winter Rye and its Weed-Killing Properties ..................... Page 7

Weed Control

Disulfoton and Methamidophos Voluntarily Canceled ......Page 4
EPA Begins New Scientific Evaluation of A trazine ...... Page 5
Candle Bush: Another Weed to Watch in Pastures,
Natural Areas, and Roadsides .......................................Page 6


Fall Soil Sampling..................................... ................................ Page 3
Fall Tillage For Small Grain .......................... .................... Page 3

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/Millie Ferrer-Chancy, Interim Dean.

"Agronomy Notes" is prepared by: Maria Gallo, Interim Chair and Y. Newman, Extension Forage
Specialist (; J. Ferrell, Extension Weed Specialist (; F.M. Fishel,
Pesticide Coordinator (; B. Sellers, Extension Weed Specialist (;
and D. Wright, Extension Agronomist ( Designed by Cynthia Hight (
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.

November 2009

If no N is applied to winter forages or cover crops, forage yields can be increased by 80% by having
soybeans or peanuts immediately prior to planting small grain. This may be enough for a good cover
crop. However, when grazing is needed and 75 lbs/A of N are applied to the winter cover crop or
grazing, a well nodulated soybean crop can increase yields of winter forage by about 20%. Most of the
nitrogen is available from both peanut and soybean during the first 30-45 days and may be leached out
of the root zone over the winter if a cover crop is not planted. Additional nitrogen is needed for plant
growth after the first 45 days in most cases.

Dr. David Wright, Extension Agronomist
North Florida REC, Quincy,

Annual Ryegrass Fertilization

\\ ith the right temperatures and moisture
S. conditions. annual ryegrass will be vre.
responsih e to N fertilization. Fertilization should
be based on a soil test since the initial le els of soil
nutrients %will depend on p)re,,ioIus fertilization
practices, rainfall, and soil texture. Based on your
soil test results. P and K should be applied either
at planting or soon after. ir needing K
fertilization on sandy soils, it is recommended to
do a split application. particularly if the
recommendation or requirement is high, split
half in late rall and the other hall in late %winter.

ir planting on a prepared seedbed, 30 Ib'acre N is
usually applied at planting. and then topdress
with 50 Ib'acre after each culling or grazing
period (anywhere bet" een 2 or 3 times during the
growing period.

If the r. grass has been oVerseetded on a warln-
season i)erelnlllial like bahiagra .'or
Sbermluhdagrass, Ihe first N application should be
postponed unlil after tile first frost to a% oidl .N
., tuplake by the warmn-season grass.

Dr. Yoana .Newiiian. Extension Forage Specialst

Photo: Riegra%4 field

Agronomy Notes Pa

Fields should be sampled every year for nutrient levels and for detection of nematode levels in the field.
November is normally a good month since crops are mostly out of the field and are easy to traverse to get
samples. This will help determine what nutrients are needed and especially if fields need to be limed.
Nematode levels can help determine what crops to grow the following year and if treatment is needed.
Likewise, certain cover crops can increase nematode levels and knowing species in the field will help
determine what cover crops to grow.

Dr. David Wright, Extension Agronomist

Coastal plain soils have a natural compaction
layer that inhibits root growth which reduces
the amount of nutrients and water available
to plants. Small grain and winter grazing
respond to deep tillage in much the same way
that row crops do. During dry or wet periods
small grain yields can be much higher due to
being able to root deeper or watler ima. drain
through the soil faster allowing crops to grown

'SiAceqipnatriAin for grain and rapiAg is *
...n.ted i'tih a drill in 0J:rro r.a chis el
.plow. or similh:o ee' tg mpl eVItri is I.:.
e ._.rh M ,oi1 .j -:...
'" ,-- 'o PIgwrJ

Disulfoton and Methamidophos Voluntarily Canceled

EPA has issued a final order approving the voluntary cancellations, requested by the registrants, of
pesticide products containing disulfoton and methamidophos. Disulfoton and methamidophos are both
used as insecticides/miticides. Uses of importance in Florida for disulfoton include control of spider
mites, aphids, thrips, mealybugs, and other sucking insects in cotton, ornamentals, potatoes, and other

Methamidophos has been used for control of chewing and sucking insects and spider mites on potatoes
and cotton. The order, published in the Federal Register on September 23, 2009, cancels the last
disulfoton and methamidophos products registered for use in the United States. These organophosphate
insecticides are registered for use on a variety of food crop and non-food sites, including disulfoton use
on residential ornamentals. EPA received no comments in response to a July 22, 2009 notice announcing
the agency's receipt of the requests for voluntary cancellation.

For all methamidophos products and most disulfoton products, the cancellations are effective December
31, 2009; two disulfoton products will be canceled effective December 31, 2010. Use of the disulfoton
and methamidophos products canceled by this order may continue until existing stocks are exhausted,
provided that use is consistent with approved product labeling. The registrants may sell and distribute
existing stocks of most disulfoton products and all methamidophos products until December 31, 2010;
two disulfoton products may be sold and distributed by the registrant until June 30, 2011.

Dr. Fred Fishel
Pesticide Information Director

November 1-5 ASA, CSSA, SSSA annual meeting, Pittsburgh, PA.

November 7 "Livin' the Country Life Land and Animal Ownership" Conference
Bert Harris Agri-Civic Center, Sebring; Contact: Manatee County Extension Service
Christa Kirby, 941-722-4524; Sponsor: South Florida
Beef-Forage Program in UF IFAS Extension

November 9 UF/IFAS York Distinguished Lecture, 2:00 p.m., Gainesville
UF Emerson Alumni Hall, President's Room
Featuring Congressman Adam Putnam. Parking in O'Connell Center

November 14 Florida 4-H Centennial Gala, Jacksonville

November 15-17 Energy Conference, Orlando

December 13-16 Conference on Grazing Lands, Reno/Sparks, NV

February 24-26, 2010 UF Water Institute Symposium, Gainesville

May 3-6 Aquatic Weed Control Short Course, Coral Springs

May 5-7 Florida Beef Cattle Short Course, UF Gainesville, Hilton UF
Agronomy Notes Pa

EPA Begins New Scientific Evaluation of A trazine

In an October 7th news release from the U.S. Environmental Protection Agency (EPA), it was announced
that EPA is launching this year a comprehensive new evaluation of the pesticide atrazine to determine its
effects on humans. At the end of this process, the agency will decide whether to revise its current risk
assessment of the pesticide and whether new restrictions are necessary to better protect public health.
One of the most widely used agricultural pesticides in the U.S., atrazine can be applied before and after
planting to control broadleaf and grassy weeds; EPA will evaluate the pesticide's potential cancer and
non-cancer effects on humans. Included in this new evaluation will be the most recent studies on atrazine
and its potential association with birth defects, low birth weight, and premature births.

"One of Administrator Jackson's top priorities is to improve the way EPA manages and assesses the risk
of chemicals, including pesticides, and as part of that effort, we are taking a hard look at the decision
made by the previous administration on atrazine," said Steve Owens, assistant administrator for EPA's
Office of Prevention, Pesticides and Toxic Substances. "Our examination of atrazine will be based on
transparency and sound science, including independent scientific peer review, and will help determine
whether a change in EPA's regulatory position on this pesticide is appropriate."

During the new evaluation, EPA will consider the potential for atrazine cancer and non-cancer effects,
and will include data generated since 2003 from laboratory and population studies. To be certain that the
best science possible is used in its atrazine human health risk assessment and ensure transparency, EPA
will seek advice from the independent Scientific Advisory Panel (SAP) established under the Federal
Insecticide, Fungicide and Rodenticide Act. EPA will engage the SAP to evaluate the human health
effects of atrazine over the coming year. Below is the timeline:

November 2009 EPA will present SAP its plan for the new atrazine evaluation.

February 2010 EPA will present and seek scientific peer review of its proposed plan for
incorporating population studies into the atrazine risk assessment.

April 2010 EPA will present and seek peer review of its evaluation of atrazine non-cancer
effects based on animal laboratory toxicology studies, selection of safety factors in
the risk assessment, and the sampling design currently used to monitor drinking
water in community water systems.

September 2010 EPA will present and seek peer review of its evaluation of atrazine cancer and
non-cancer effects based on animal toxicology studies and epidemiology studies.
This review is intended to include the most recent results from the National Cancer
Institute's Agricultural Health Study, anticipated for publication in 2010.

At the conclusion of this process, EPA will ask the SAP to review atrazine's potential effects on
amphibians and aquatic ecosystems. The SAP meetings will be open to the public.

In addition to the scientific review of the effects of atrazine, EPA plans to meet with interested groups to
explore better ways to inform the public more quickly about results of atrazine drinking water

Dr. Fred Fishel
Pesticide Information Director

Agronomy Notes Pa

Candle bush (Senna alata), also named candlestick, Emperor's candlestick, Christmas candle, popcorn
senna and ringworm shrub, is a shrub or small tree, but often grows as an annual in cooler climates (see
photo.) In tropical climates, candle bush can grow up to 30 ft tall and 15 ft wide. In climates that support
only annual growth of this plant, reports of up to 10 ft tall and 4 ft wide are common (see photo on left.)

Candle bush plants are usually highly branched
and the degree of branching is similar to that of
Brazilian peppertree. Leaves are pinnate with 7
to 14 pairs of leaflets. Individual leaflets are
rounded at the apex, up to 2.5 inches long, and
are t\ pically larger near the leaf tip. Flowers are
. el low, arranged closely on an upright spike
somewhat resembling a candle. Seed pods are
thick. straight, narrow, and 4-angled and split
open to reveal approximately 60 tan to brown
flattened seeds at maturity. Late in the season,
the inflorescence will have dry, brown pods at
ti, hI. tftrm rrrpn r;nnnrri nnrlc abqn lthat

opein flowers, followed by unopened flowers at

Candle bush is found in many habitats, but prefers high water tables and is fairly drought tolerant once
established. It prefers open areas and sunlight, but can survive in partial shade. It often forms thickets
where it has escaped cultivation. In Hawaii, it has been observed to form dense stands in pastures. In
Australia, candle bush is found along creeks and drainage canals, and occasionally on disturbed and
overgrazed areas. It is commonly found along roadsides, old abandoned field, and other weedy localities
in Guam.

According to the Atlas of Florida Vascular Plants, candle bush has been recorded in 11 Florida counties,
with the northern most being Orange and Brevard counties. In addition to Florida, candle bush is found
in Alabama, Mississippi, Louisiana, Texas, and Hawaii. Recently, we have observed candle bush plants
growing in open pastures in Hardee, Manatee, and Polk Counties.

Candle bush is a tropical plant, therefore, probably only overwinters well in extreme south Florida and
along the coasts. Although the top growth of the plant is killed by frost, regrowth from the root stock is
quite common throughout Florida. Considering Florida's climate it is likely that this plant will continue
to persist and may become problematic in various habitats.

Control of candle bush does not appear to be difficult. Research in Hawaii has determined that it is
extremely sensitive to triclopyr (Remedy Ultra, etc.) and 2,4-D. Considering that candle bush is a
member of the legume family, aminopyralid (Milestone/Grazonnext) may also provide good control.
Mechanical controls are usually ineffective due to regrowth from the root system.

Dr. Jason Ferrell, Weed Specialist

Dr. Brent Sellers, Extension Weed Specialist
Range Cattle REC, Ona

Agronomy No es Pc



Rye (Secale cereale), is a winter grain
not to be confused with annual
Ryegrass (Lolium multiflorum). Rye is
one of the small grains together with
oats, wheat, barley, and triticale. This
grass is popular in Florida because of
its multipurpose use. It has an
extensive and heavy root system, and
the ability to grow in sandy and low
fertility soils. It is also the winter
hardiest of all small grains; it will
grow at lower temperatures where .
other winter grains usually will not.
Rye plants are often used as ground
cover and to reduce erosion. Of Rye .,a a
particular interest, is the weed-killing
capability of this crop. Rye suppresses
weeds without herbicides, making it a common cover crop on organic farms.

Photo: Y. Newman

Depending on where it is planted in the state,
it will provide grazing from late November to April

., f*. . .

[t I *., 4

I Ryefield.

Scientists with the Agricultural Research Service
(ARS), John Teasdale and Cliff Rice and their
research team, are trying to understand why Rye
works as a cover crop. The studies are the first
attempts to measure organic compounds known as
'benzoxazinoids' released from rye, and their
impacts as weed suppressors. The goal of these
researchers is to continue the experiments until
more light is shed on the compounds involved and
their relation to soil chemistry properties.

Dr. Yoana Newman
Extension Forage Specialist

Agronomy Notes Pc

Photo: Y. Newman I

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