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: June 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: VID00124
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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June-2010-issue-Agronomy-Notes ( PDF )

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IFAS Extension

- S S A S



Corn Response To Nitrogen ...............................Page 3


Regulating Cotton Height ................................ Page 2


New Bahiagrass: UF-Riata Update ................ Page 3

Targeting High Quality Grass Hay ................... Page 4

Pearl Millet: SummerAnnual.......................... Page 4

Weed Control
EPA's Endocrine Disruptor Screening Program... Page 6

Strip T Crops .......................................... Page 7

Calendar ....................... .......... ........... .. Page 2
Natural Soil Compaction Layer ......................... Page 5
B :.. Crop Field Day ................................. Page 7

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 ... r.t ..ii. 1.1 A. Blount, Forage
Breeding Specialist 1. .' ,,.t !..I I. F. Fishel, Pesticide Information Officer ...I.l.t ..I ..I. D. Wright, Extension Agronomist iili ,,II. 1..,
Designed by Cynthia Hight i.. i II.. i, 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.

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

Regulating Cotton Height

Growers in Florida have been growing DPL 555 cotton on almost 1(0H ",, of the acreage for the past 7 years or more. This is an
aggressive-growing cotton variety and had to be managed to keep the height down to be able to do various management practices
as well as to aid in defoliation and harvest. Cotton begins rapid growth in June in most years when moisture is not limited. This is
the period when height needs to be regulated and square retention is important. There are many management factors that can
influence vegetative growth, and they include N fertility, soil moisture, weed control, plant population and insect control. Good
fruit and boll retention will slow vegetative growth. However, we do not know very much about many of the new cotton
varieties that are replacing DPL 555. In most cases their growth will not be as aggressive and lower rates of growth regulators
may be applied.

In general, growth can be managed with the use of mepiquat materials sold under trade names of Pix, Mepex, Topit, Mepichlor,
Pentia, and others. These materials will generally shorten the internode length and reduce the leaf area where stem and leaf
expansion are occurring. Some research has shown a slight increase in early fruit retention and earlier maturity. Yields are not
necessarily increased but plants will definitely be shorter and may be easier to manage. Knowing the fields that normally have
rapid and excessive growth and the varieties along with early fruit set will help ensure growth control.


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

June 2-3 SAF/SFRC Spring Symposium Sustaining Forests,
Fisheries and Aquatic Resources in a Changing World
Paramount Plaza Hotel, Gainesville

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

July 13-15 American Peanut Research and Education Society Meeting
Clearwater, 979-845-8278

Inquisitive goat at the SmallFarms July 15 Bioenergy Crop Field Day, Plant Science REC, Citra
Academy Field Day, North Florida REC
on April29, 2010 in Live Oak. Refer to July 22-24 Southern Peanut Growers Conference,
the calendar on the rightfor related and Edgewater Beach Resort, Panama City Beach
upcoming conferences: Florida Small Farms
J j 31) and Goats (Sept. 12.) July 31 Aug. 1 Florida Small Farms & Alternative Enterprises Conference
Photo: TlerL. Jones Osceola Heritage Park, Kissimmee
IFAS Communications
Aug. 1-5 Ecosytem Restoration Conference (NCER), Baltimore, MD

Sept. 12-15 National Goat Conference, Leon Civic Center, Tallahassee

Oct. 11-14 UF-CTA Potential Invasive Pests Workshop
Coconut Grove (Miami), Mayfair Hotel

Corn Dr. David Wright, Extension Agronomist
North Florida REC, Quing

Corn Response To Nitrogen

Every year is a new year for farming. New challenges arise from pests or weather
events (too wet or dry). This year has been no different with heavy rains on corn
during the vegetative stage of growth. Corn may often be lacking in sufficient N
fertilization in the early part of the season if too little N is applied at planting and
weather delays a sidedress application. Root systems are limited during the first 4-6
weeks so little N can be scavenged from row middles.

The picture shows N deficiency along with S deficiency symptoms on corn that
had 10 inches of rain during the early vegetative period. During the first 4 weeks of
growth at normal planting dates corn will take up about 1 lb of N/A/day. During
the next 3 weeks corn will take up about 1.4 lbs N/A/day, followed by the period
Nitrogen and sulfur deficient corn after heaiy rains of 2-3 weeks prior to tassel when vegetative growth is rapid and uptake peaks
resulted in a loss ofplantN. around 3.5/lbs/A/day or about 25 lbs/N/week. The early N applications are
important for high yield even though corn will continue to take up N at the rate of
Photo: D. Wright 2.5 lbs/A/day from tassel until maturity. Nitrogen applications made after the tassel
stage does little for yield but can increase grain protein.

Forage Dr. Ann Blount, Forage Breeding Specialist
North Florida REC, Marianna

Dr. Yoana Newman, Extension Forage Specialist

New Bahiagrass: UF-Riata Update

UF-Riata will be available this year. UF-Riata is a novel diploid bahiagrass developed for fall and early spring forage production
for the southeastern U.S. This bahiagrass exhibits lower photoperiod sensitivity, improved leaf tissue cold tolerance, and
increased forage production during the cool season compared to the standard bahiagrass cultivars Argentine and Pensacola.
Multi-location variety trials show UF-Riata is similar in total season yield to Tifton 9, with an improvement in seedling vigor and
leaf tissue cold tolerance that promotes late fall-season growth and early spring-season growth. UF-Riata seasonal forage yields
have been greater than 25% compared with Argentine and Pensacola, and 5-1( ., compared with Tifton 9 in north Florida. UF-
Riata is well adapted throughout the southern Coastal Plains and Peninsular Florida.

Management of UF-Riata is similar to that of Tifton 9. While Argentine and Pensacola bahiagrass are tolerant to 0- c h-,i
UF-Riata is not, and spot grazing will result in stand loss and subsequent weed encroachment. Rotational grazing is a good
approach since it allows UF-Riata pastures to recover from livestock! -i i i and producers should rest the pasture and allow
for regrowth to a 6 inch stubble height between grazing events.

Hay harvests of UF-Riata should be made several times throughout the growing season. Forage should not be allowed to grow
rank. Digestibility decreases with plant age and fungal leaf diseases may harm the health of the stand. Should weather conditions
prevent timely hay harvests, then options for i i 'I n mowing or ensiling the forage should be considered.

It is important to purchase seed of UF-Riata from a licensed seed source. This insures the purity of the cultivar, high percent
germination and freedom from weed seed. UF-Riata will be sold by variety name and marketed by Ragan-Massey Seed (800-264-
5281). The seed is in stock and ready to ship via UPS.


Dr. Yoana Newman, Extension Forage Specialist

Targeting High Quality Grass Hay and Minimum Losses

Forage quality is associated with nutrients, high i _, protein, and digestibility, and low fiber. Weather conditions and
forage maturity are the primary factors affecting quality of a stand.
Maturity, or stage of growth, is the principal factor responsible for declining forage nutritive value. As the plant advances in
growth beyond the first couple of weeks (where protein and digestibility are highest), stem growth continues, as well as
deposition of fibrous components at the plant cell level.

During the summer, if the weather forecast calls for a few days without rain, it is advisable to harvest early than anticipated,
even if the regrowth is not at the targeted 4 or 5 week schedule. Harvesting early at 21 or 24 days, will provide even highest
nutritive value and will avoid the rain-associated losses. Take advantage of dry weather forecast and harvest early, you will get
back in track (4 to 5 week harvest) later in the season.

Typical hay production practices in Florida to minimize losses include 'tedding and raking'. Usually, tedding shortens the
curing time by about 1/2 day. Tedding scatters the forage over the entire field in order to capture all the solar radiation; tedding
uses more efficiently the i -_ of the sun. Tedding also makes a thinner layer, which produces a more uniform drying.
Raking should be done at 35-4, ,".. moisture to keep dry matter losses under 4".. If raking is done too late (when crop is at
bailing moisture) losses can exceed 21 .. Also, to minimize losses, hay should be raked in the same direction that it was

Pearl Millet: Summer Annual

This quality forage with abundant leaves is similar in
adaptation to sorghum sudans. There are several differences,
though. The soil temperature requirement is higher (65 to
70degrees F) for pearl millet than those for sorghum (60 to 65
degrees F). Pearl millet is safe to feed to horses, and does not
produce prussic acid (which makes it a safe forage when there
is the possibility of frost later in the season).

Pearl millet is used as a high quality summer crop for growing
or lactating animals, and often as an emergency feed for all
type of livestock.

Grazing should occur at 18 to 24 inches, and harvested at boot
or pre-boot stage.

Some quick facts


Planting Date:

Planting Depth:
Seeding Rate:

Seed Cost:

Mid March to June. In North
Florida, earliest planting is April 1st.
1/4 to 1/2 inch (seed is very small)
12 to 15 lb/acre in rows, or
30 to 40 lbs/acre if broadcast
Hybrid i(., )1 1/lb; $7 to 9/acre)
5000 to 10000 lb/acre

Growth Habit:

Production Season:


4-8 feet tall, erect. Abundant tiller
after establishment.
Sandy-loam, moist but well drained;
tolerates drought and
very short term flooding.


* Possibility of nitrate poisoning.
* Different from Sorghum, does not cause prussic acid
* Safe to feed horses.
* Hay is difficult to cure because of thick stems.
* Affected by fall armyworm and leaf rust.

For additional information, visit Forages of Florida webpage millet&type= G

Improving Soil

Dr. David Wright, Extension Agronomist

North Florida REC, Quiny

Natural Soil Compaction Layer

Coastal Plain soils have a natural compaction layer that has the highest rate of compaction about 6 inches deep as
shown below, and compaction falls off dramatically after 12-15 inches deep as shown in the photo. Therefore, deep
tillage is necessary to prevent restricted root growth and reduced yields.






0 500 1000 1500 2000 2500 3000 0 500 1000 1500 2000 2500 3000
Soil Resistance (kPa) Soil Resistance (kPa)
Soil Mechanical Resistance (n = 150)

Graphic and Photo: D. Wright

Our research has shown that ripping
underneath corn rows can add 20-60 bu/
A of corn and 8-10 bu/A of soybean.
This practice has a similar effect on other
summer crops as well as winter grain

The picture below shows a dark line
above the B horizon (red soil) with roots
running laterally. This is an indication of
a compacted layer; some of the roots
were not able to penetrate the
compacted layers and started growing
laterally. All Coastal Plain soils exhibit
this trait and can be found in pine woods
where no equipment traffic has
influenced it. Roots of crops like
bahiagrass can penetrate this compacted
layer and following crops can use these
root channels for root growth and water

Roots run laterally above
this dark line. Bahiagrass
can penetrate the
compacted (red) layer thus
creating root channels for
subsequent crops.






- Sod-based Peanut
S Cony. Peanut

- Sod-based Cotton
- Conv. Cotton 1
- Conv. Cotton 2

Weed Control

Dr. Fred Fishel, Pesticide Information Director

EPA's Endocrine Disruptor Screening Program (EDSP)

The endocrine system is responsible for regulating important biological processes, including metabolism, blood sugar levels,
growth and function of the reproductive system, and the development of the brain and nervous system. All birds, fish, and
mammals possess an endocrine system. It's a complex system consisting of three basic components:
SMore than 50 hormones produced by the glands which function as chemical messengers; and
SReceptors in various organs and tissues that recognize and respond to the hormones.

The EPA Targets Pesticides

All pesticide active ingredients are required to undergo extensive toxicological testing prior to being granted U.S. Environmental
Protection Agency (EPA) registration. Some industrial chemicals have undergone extensive toxicological testing; however, it is
unclear whether this testing has been adequate to detect the potential for both groups of these chemicals to be endocrine
disrupters. It's also uncertain or what additional testing is needed for the EPA to assess and characterize both human health and
ecological risk. Recent legislation including the reauthorization of the Safe Drinking Water Act (SDWA) and passage of the Food
Quality Protection Act (FQPA) has mandated that such a screening and testing program be developed by EPA. The overall
objective is to reduce or mitigate risk to human health and the environment.

The EDSP Process

EPA's EDSP has been involved in a validation process for several tiers of assays with their accompanying protocols and the
policies and procedures for use in the EDSP testing process. In late 2009, EPA issued the first test orders for pesticide chemicals
to be screened for their potential effects on the endocrine system. At this same time, EPA made available the battery of scientific
assays and test guidelines for conducting the assays, as well as a schedule for issuing test orders to manufacturers for 67 chemicals
that will serve as the first group to enter the initial phase. Of the 67 chemicals, there are 58 pesticide active ingredients and 9 high
production volume chemicals used as inert ingredients. Because this list of chemicals was selected on the basis of exposure
potential only, it should not be construed or characterized as a list of known or likely endocrine disruptors.

List of 58 Chemicals
used as Pesticide
Active Ingredients:

isoindole-1,3 (2H)-dione
Benfluralin aka benefin

Fenbutatin oxide
Gardona (cis isomer) aka

Methyl parathion
Piperonyl butoxide
Propyzamide aka pronamide

Quintozene aka PCNB

List of 9 Chemicals
used as Inert

Butyl benzyl phthalate
Dibutyl phthalate
Dimethyl phthalate
Dimethyl phthalate
Di-sec-octyl phthalate
Methyl ethyl ketone


UF IFAS Plant Science Research and Education Unit invites you to:

Bioenergy Crop Field Day .

July 15, 2010 Focus on Grasses:
8:30 a.m. 1:00 p.m. Elephantgrass
Citra, FL Energycane

Event is Free; Register by July 8 Miscanthus

Link to: Rejistration Sugarcane

Link to: Directions Sweet Sorghum

Field Tours of Ongoing Bioenergy Grass Crop Research
Most Recent Data From Statewide Experiments
Updates on Bioenergy Crop Breeding Efforts
IFAS Scientists on-hand for Small Group and One-on-one Interaction
Comp mentary Lunch Provided

Weed Control Dr. David Wright, Extension Agronomist
North Florida REC, Quiny

Strip Tilling Crops

Strip tillage is used widely in many areas of the southeast U.S. There has been
some concern among many people about weed resistance especially from
palmer amaranth with the impact of possibly decreasing the area planted with
conservation tillage. However, many growers still have hooded or shielded
sprayers for direct spraying and there are many effective, residual herbicides
that can be used in cotton, peanut, corn and soybean.

Rope wick applicators can be used in peanut fields late in the season. Strip
tillage has reduced time in the field and fuel costs as well as preserved stands
from sand blasting and fields from erosion. Most growers who have adopted
this method of planting have found that it is not necessarily easier but has Peanstilledinto bahiagrass with no erosion and
economic as well as timeliness advantages and do not want to go back to residual herbiddes to help prevent weed resistance.
conventional tillage practices. For years, weed control was the main
disadvantage to planting crops using strip tillage methods and directed spray Photo: D. Wlight
equipment was necessary for late emerging weeds. However, Roundup Ready
and other genetic technology have often been relied upon for all of the weed and pest control without using residual chemicals at
planting and at layby thus creating a weed resistance problem. Growers must rely on several modes of action for weed control as
well as residual herbicides to help prevent weed resistance.

Many fields were plowed this winter and spring to help control glyphosate resistant weeds and heavy rains washed many fields to
levels unseen in many years. Take care not to create a worse problem by turning ground. Many of these washed fields have
sanded areas that will take decades if ever to reach the yield potential of pre rain/erosion levels. There are enough residual
herbicides in the arsenal to control weeds with strip tillage without resorting to turning ground or other intensive tillage


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