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: April 2010
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 )
Additional Physical Form: Also available to subscribers via the World Wide Web.
Additional Physical Form: Electronic reproduction of copy from George A. Smathers Libraries, University of Florida also available.
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: VID00122
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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WFAS Exten-sion

Agronomy Notes

Volume 34:04

April 2010


Corn and Cotton
Strip Till Cotton ..................................................... Page 2
Relative Salt Index Of Commonly Used Fertilizers....... Page 2

Bahia- And Bermudagrass Warm Temperature And
Light Needs ................................... .................... Page 3
New Bahiagrass UF Riata- Update on Seed
Availability ......................................................... Page 3


Peanut Varieties And Ca Needs .......................... Page 5

Weed Control

Spring Blackberry Control..................................... Page 4
EPA Proposing New Drift Label Language................. Page 5

Calendar.................................................... ........ Page 4

"Agronomy Notes" is prepared by: Maria Gallo, Interim Chair and Y. Newman, Extension Forage Specialist
(; J. Ferrell, Weed Specialist (; F. Fishel, Pesticide Information Officer
(; B. Sellers, Extension Weed Specialist (; 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.

Kill cover crops 3-5 weeks prior to planting cotton. Cotton may be planted in warm soils in late April.
When cotton is planted in late April, it will start blooming in early July and needs to have low moisture
stress during the first 3-4 weeks of bloom to set bolls for top yields. Residual herbicides will have to be
used in most Florida cotton this year due to palmer amaranth in many of the cotton growing regions.
Cotton may be strip tilled and residual herbicides used at planting and at layby with hoods. Growers can
manage these weeds without tillage.

Dr. David Wright
Extension Agronomist
North Florida REC, Quincy

Several different types of liquid and dry fertilizer are used in corn and cotton production as starter
fertilizers. Each material has a different salt index and can result in decreased germination if placed too
near the seed. The following are salt indexes of common fertilizers used as starter fertilizer on crops in

Anhydrous ammonia 47.1
Ammonium nitrate 104.7
Ammonium phosphate 61.1
Ammonium sulfate 69.0
Diammonium phosphate 29.9
Gypsum 8.1
Dolomite 0.8
Nitrogen solution 95.0
Potassium chloride 116.3
Sulfate of potash-magnesia 43.2
Superphosphate 10.1
Urea 75.4

Nitrogen sources and nitrogen solutions should be placed about 1" from the seed furrow for each 10 lbs
N/A since they have a fairly high salt index. Potassium chloride has a high salt index but may be
applied close to the row if mixed with the soil. DAP is a granular material that is often used as a starter
fertilizer and has a fairly low salt index and is often banded near the row.

Dr. David Wright
Extension Agronomist
North Florida REC, Quincy

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 Page 2

UF Riata bahiagrass is the latest release from University of Florida that will be sold by variety name
only and has been licensed exclusively to Ragan and Massey Inc, seed company in Louisiana. This
spring small amounts of seed are available to customers who were on their list.

In July large amounts of seed will be available to interested growers. If interested contact Ragan and
Massey (1-800-264-5281).

UF Riata was developed for fall and early spring forage production by Dr. Ann Blount, forage
breeder. This bahiagrass shows lower daylength sensitivity, improved leaf tissue cold tolerance, and
increased forage production during the cools season compared to the standards cultivars. As with
Tifton 9, UFRiata is not tolerant of severe overgrazing.

Dr. Yoana Newman
Extension Forage Specialist

This winter and spring have been colder than normal. But we are in spring and we are in Florida
where weather tends to follow an oscillating pattern with wide differences between minimum and
maximum temperatures, especially during spring. This situation is confusing to many who are trying
to get ahead with their pasture fertilizer applications. With a colder than normal spring, late rather than
early might be better for fertilization practices.

Bahia- and bermudagrass are tropical plants sensitive to freezing temperatures. Temperatures below
300F kill the leaves and stems but growth will continue with night temperatures as low as 340F if day
temperatures are near 700F. Soil temperatures of 65F and above are necessary for growth of
rhizomes/roots and stolons. Wait for your fertilizer application until consistent warm soil
temperatures (650 and above) are present. Optimum soil temperature for root growth is around 800F.
Optimum daytime temperature is between 95 and 1000F. These grasses are most productive from May
to September when average daily temperatures are above 750F.

In terms of light, bahia- and bermudagrass have high light requirements. What are the implications?

They do not grow well under shady conditions like under trees, under a companion summer crop that
will shade them, or under the spring growth of ryegrass. If ryegrass or other cool-seasons have been
overseeded into bahiagrass or bermudagrass fields, they need to be removed very early in the spring
otherwise they may compromise the persistence of the warm-season grass.

Dr. Yoana Newman
Extension Forage Specialist Agronomy Notes Page 3

To follow the link, press "Ctrl" and put cursor over link, and "click. "

April 17 Equine Fair (The Hay Exchange, Inc.) Plant City

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

June 6-8 Soil and Crop Science (SCSSF) meets jointly with the
Florida State Horticultural Society (FSHS), Plantation Golf Resort

July 11-17 Caribbean Food Crops Society meeting,
Boca Chica, Dominican Republic

July 12-16 Greater Everglades Ecosystem Restoration Meeting, Naples

Aug. 1-5 Ecosvtem Restoration Conference (NCER), Baltimore, MD

This is the time of year that pastures are starting to
green up, and so are the weeds. After a long winter,
everyone is getting ready to gear up the weed
control program. This time of year we commonly
get questions about spraying blackberry. So, when
is the best time to spray this deep-rooted perennial?

Blackberry control can be accomplished if a
herbicide is applied when blooming or applied late
J in the fall. Our research has shown that applications
made when blackberry is blooming tend to be more
inconsistent than when applied in the fall. This is
because carbohydrates are moving from the root to
the shoot in the spring. If a herbicide is applied at
this time, translocation to roots can be limited and
the kill incomplete. Spraying in the fall, when the
plant is nourishing the root/rhizome, will likely
S allow more herbicide to translocate underground.

Spraying in the fall is not an instant recipe for
Blackberry in apasture during spring is most, r' r. controlled with success and regrowth of blackberry from a fall
pesticide application when the plant blooms (typically in the fall.) application is likely. However, it has been our
Photo: J. Ferrell experience that spring applications are more likely
to fail than those applied in the fall.

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

Agronomy Notes Page 4

There is a wide selection of peanut varieties available from which to choose in 2010. Most of the new
varieties are large seeded varieties that will require high Ca levels in the pegging zone. Georgia-06G,
Florida-07, and Tifguard will all need supplemental Ca for high yield and quality. We have had
relatively good soil moisture which moves Ca in soil solution to the pegging zone since the release of
these three varieties. If we have a dry year during pegging, yields and quality of these varieties may
suffer more than the smaller seeded varieties. Plan on using gypsum on these varieties to maintain yield
and quality.
Dr. David Wright, Extension Agronomist
North Florida REC, Quincy

Drift can be defined simply as the airborne movement of pesticides to non- target areas. In Florida, drift
can also have legal meaning, as there are penalties for damage caused to sensitive crops by certain
types of herbicides. Off-target movement can be in the form of:

S. Spray droplet drift
l Vapor drift
*i Particle (dust) drift

S.- Studies have shown that a significant
percentage of pesticides may never
Breach the intended target site because
of drift. It is impossible to eliminate
drift totally, but it is possible to
reduce it to a tolerable level.

Where significant drift does occur, it
can damage or contaminate sensitive
crops, pose toxicity problems to bees
l and other pollinators, pose health
Sr risks to humans and animals, and
contaminate soil and water in
'adjacent areas.

S.Applicators are legally
responsible for the damages
resulting from the off-target
. movement of pesticides.
This tree became contaminated with pesticide that was intended for a nearby field and became
airborne, ri r.i".. plants outside of the original target area. In late 2009, EPA released a Pesticide
Photo: FredFishel Registration Notice (PRN) proposing
guidance for new pesticide labeling to

Agronomy Notes Page


reduce off-target spray and dust drift. The new instructions, when implemented, are an attempt to
improve the clarity and consistency of pesticide labels and help prevent harm from spray drift. The
draft PRN contains two types of statements:
(1) A general drift statement containing a risk-
protective standard which varies according to
product type, and
(2) E\amples of product-specific drift use
Srestrictions, along with a format for presenting
these statements on product.

SDue to Worker Protections Standard regulations,
man.\ products already bear the statement "Do
not apply this product in a way that will contact
\ workers or other persons, either directly or
through drift."

Close-up of tre leaves affected by adritt In addition to protecting workers and other
Photo: F. Fishel people that may come into direct contact with
pesticide drift as covered by the WPS
regulations, EPA is concerned about human exposures to deposited drift residues, and about exposures
of non-target organisms and sites not covered by the WPS regulations. Therefore the proposal is to
have all products currently subject to WPS requirements add the following statement to their labeling
immediately after, and without removing or altering, the existing WPS statement: "In addition, do not
apply this product in a manner that results in spray (or dust) drift that could cause an adverse effect to
people or any other non-target organism or site."

If this is finalized, this presents problems to applicators of agricultural pesticides. The wording of this
new statement introduces a zero drift tolerance standard. From the beginning, EPA and FDACS have
acknowledged that some level of drift will inevitably occur, but such a level is considered to not pose
"unreasonable adverse effects." The proposed terminology, "could cause an adverse effect," is an
invitation, potentially subjecting growers to senseless litigation.

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) have set standards into place that
approve product labels through rigorous testing procedures. After years and millions of dollars,
manufacturers of pesticides currently have incorporated data and information into labels resulting
through the testing process that addresses drift mitigation measures. The current EPA proposal is
unrealistic and will "cause an adverse effect" to agricultural producers if approved.

The 23-page PRN, including the proposals concerning product-specific drift use restrictions, may be
viewed in its entirety as a pdf at

Dr. Fred Fishel
Pesticide Information Director

Agronomy Notes Page 6

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