Table of Contents
 Weed control


Agronomy notes
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00066352/00107
 Material Information
Title: Agronomy notes
Uniform Title: Agronomy notes (Gainesville, Fl.)
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Florida Cooperative Extension Service
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
Place of Publication: Gainesville
Creation Date: December 2008
Subjects / Keywords: Crops and soils -- Florida   ( lcsh )
Crop yields -- Florida   ( lcsh )
Agriculture -- Florida   ( lcsh )
Agronomy -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
periodical   ( marcgt )
serial   ( sobekcm )
Statement of Responsibility: Florida Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences.
General Note: Description based on: January 1971; title from caption.
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Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000956365
notis - AER9014
System ID: UF00066352:00107


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Table of Contents
    Table of Contents
        Page 1
        Page 2
        Page 3
    Weed control
        Page 4
        Page 5
        Page 6
        Page 7
Full Text
IFAS Extension Agronomy A tes

agronomy Fotes
Volume 32:12 December 2008


Cover Crop Value to Cotton
Cotton Price and Rotation .......................... .................... Page 2

Hay and Haylage Use ..................... .....................................Page 3
Soil Testing for Forage Production ......................................Page 3

Weed Control
Pre-Harvest Intervals, Tolerances and Residues .............Page 4
Control of Woody Brush ............................ .....................Page 5

Large differences in nitrogen prices......................................Page 6
Oil Crops ..................................................................... Page 6
Calendar .................................................................................Page 6
Fuel Prices Projections Encouraging News .......................Page 7

^^J) 0^I

Conservation tillage has become an accepted practice for all row crops. Research has confirmed that
yields can be increased by an average of 10% from cover crops vs. fallow or bare ground. Much of this
has to do with moisture and temperature impacts on cotton during the growing season.

Recent research has shown the value of cattle grazing winter
Sc fir Yie c annuals prior to planting cotton. Two years of research comparing
oat and rye mixtures as winter grazing shows that lint yields for
increased by an average of 10% cotton are increased by 175-300 lbs/A when cattle are grazed vs.
from cover crops not grazed and then cotton planted. Even though there is some
surface compaction of soil by cattle during the winter in the
grazed areas as compared to the ungrazed areas, there is an
advantage in more nitrogen being available to the cotton from
manure which shows up in petiole and leaf samples throughout the season. Grazed areas also have higher
soil moisture content deep in the soil profile than ungrazed areas leading to less plant stress even though
cotton is strip tilled into killed cool season winter forage in both areas.

Utilization of winter annuals by livestock is an example of how land can be utilized year round with
benefit both to the following cotton crop and can provide a source of income so that the cover crop pays
for itself and perhaps adds profit to the farming operation through cattle sales. This is a decision that has
to be made ahead of time if temporary fencing and water are to be made available for livestock in areas
that have not had fences for years.

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

Agronomy Notes Pa

"Agronomy Notes" is prepared by: J.M. Bennett, Chairman and Yoana Newman, Extension Forage
Specialist ( !ic ,i11 c.Ii.n J. Ferrell, Extension Weed Specialist (i !nilc, Li1. .. i c i F.M. Fishel,
Pesticide Coordinator (weeddr@ifas.ufl.edu); and D. Wright, Extension Agronomist (wright@ufl.edu).
Designed by Cynthia Hight (chight@ufl.edu). Photos, except where designated otherwise, by Tyler
Jones (tylerljones@ufl.edu) in the UF/IFAS photo department. 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.

Soil Testing for Forage Production
Supplying adequate soil fertility and the correct pH to your forages is one of the keys to a successful
forage production. If your are a hay producer, plant annual forage crops every year, or overseed in
winter time, then you need to soil test every year. If your operation is based on perennial forages, you
could do so less frequently. One of the first action to get ready for the upcoming season in terms of
fertilizer needs should be to have your soil tested. Now more than ever, a soil test will save you
money because it will indicate those nutrients that are in your soil in sufficient amounts. Soil testing
followed by the proper fertilization, is one of the practices that will possibly have the most long-term
effect on your forage production per acre. There is no other way to find out the status of your soil
nutrients but to soil test. Keep in mind that the recommendations coming back from the soil test report
are based on efficient fertilizer use and environmentally sound nutrient management without losses of
yield or crop quality. Use these months prior to spring time to test your soil and correct soil pH if
necessary; acidic soil condition is a tendency for many Florida soils. If lime is needed it will be
indicated on your soil report. If needing assistance on how to collect a sample, contact your county
agent. You will find a listing of all county extension offices at the following link:

Yoana Newman, Extension Forage Specialist

Hay and Haylage Use

With the recent frost experienced in most of Florida and while cool-season forages are still becoming established,
there is not much forage available. During this time, hay and haylage can provide forage of the quality required
to support many different types of livestock. Both hay and haylage, are means of forage preservation, and these
products can be used to supplement livestock when pastures are insufficient or in poor condition. Despite both
being forms of conserved forage, they are not technically the same. Hay (squares or round bales) is baled when
the forage has less than 18% moisture and this forage conservation method renders a dry product that is
biologically stable. In the case of hay production, the hay is left on the field to dry naturally for a couple of days
(forage dries under exposure to air or aerobic conditions). When baled at the right maturity and with a moisture
content of approximately 18% or less, it is a fine product that can meet the nutritional requirements of many
classes of livestock.

Haylage or grass silage, is a conservation method that occurs in anaerobic conditions (absence of air, technically
is absence of oxygen), which requires wrapping the bale or chopped material to minimize exposure to oxygen
while the moisture content is still high (50-65%). The product is a 'fermented' forage that is preserved by the acid
produced by anaerobic microbes and a resultant drop in pH.

Both hay and haylage are safe to feed to livestock; however, either can result in a poor quality product if proper
conservation practices are not followed. In the case of hay, if it is baled too wet, it will develop mold and spoil.
Cattle, being less sensitive to mold than horses, may consume moldy hay without serious consequences; however,
for horses this type of hay should be avoided because the problems can be more severe.

In the case of haylage, if the material put into the bag is of poor quality or too wet then a spoilage phase may
follow the normal fermentation. Spoilage-phase products make the haylage unpalatable and they can be
dangerous, especially to horses.
Thus, poor techniques of forage conservation will result in a product of low quality or in rare cases ones that can
negatively impact animal health. When managed properly, both hay and haylage are excellent sources of feed
for your animals during times of shortage of fresh pasture.

Yoana Newman, Extension Forage Specialist

Agronomy Notes Pag

Pre-Harvest Intervals, Tolerances and Residues

I The United States has the safest and most abundant food supply in the world. A major reason why it is the safest
is that pre-harvest intervals are established and listed directly on pesticide product labels. The pre-harvest
interval refers to the minimum time that must
Crop Minimum Time elapse from application to harvest, usually
from Application to expressed in days (see chart on the left.) Whenever
Harvest (PHI)(Days) pesticides are applied, their residues will remain on
Apples 25 treated surfaces for a time. The chemical
Apricots1 300 properties, frequency of application, rate applied,
Schemes' 300 and environmental factors determine how much
Citrus 7 residue will be present.
Cranberries2 21
Grapes 7 Residues are important in certain circumstances
Nectarines 7 and necessary for some types of pest control where
Peaches 7 their presence provides continuous control.
Pears (including oriental) 7 Herbicides applied where crop rotation is not a
Pistachio 7 factor or in areas where total long-term weed
Plu ms 7 control is desired, such as fence-rows and adjacent
Prunes 7 to buildings, are examples of this phenomenon.
Brazil, Butternut, Cashew, Chestnut, Protecting structural foundations from termites is
Chinquapin, Filbert, Hickory, another desirable feature of pesticide residues.
Macadamia, Pecan, Black Walnut and However, residues are undesirable when they
English Walnut) expose people, domestic animals, or wildlife to
unsafe levels of pesticides. Acceptable levels of
residues for any pesticide are known as its tolerance and set by government agencies. The tolerance is the
maximum amount of a pesticide that may remain on or in raw agricultural commodities. Research is conducted
using laboratory and animal tests to establish tolerances. From this research, amounts of pesticides which remain
are determined to be harmless to consumers. A conservative margin of safety is included in tolerance levels
when established by the Environmental Protection Agency (EPA). Each pesticide that is registered for a food use
must have an established tolerance, and their levels will vary depending upon the pesticide's mode of action,
toxicity and all uses of the pesticide. In establishing the tolerance of a pesticide, researchers consider the total
diet of the consumer and their nonfood exposure over a lifetime of 70 years. State and federal agencies monitor
produce to ensure that growers do not exceed pesticide residue tolerances. Any produce that is found to exceed a
tolerance is seized.

This past month, a strange occurrence that FDACS investigated was brought to our attention. An inspection of a
Florida commercial agricultural production facility revealed illegal residues of dieldrin in pumpkins. Dieldrin, an
organochlorine insecticide, was first patented in 1948. However, all uses were cancelled in 1986 due to its long-
term persistence. A similar regulatory fate occurred with other organochlorines, including DDT, aldrin,
chlordane, heptachlor, and endrin.

Although the recent dieldrin incident described is very unusual fortunately, but occasionally, pesticides can be
erroneous present due to:
0 The crop absorbing pesticides that were applied to the site previously;
0 A grower applying pesticides to an unregistered crop;
0 A grower applying a rate of pesticide that exceeds the label recommendations;
0 The pesticide is applied too close to the crop's harvest; or
0 Drift of a pesticide from another site.

The pumpkin producer will no doubt face strict legal sanctions for those decisions and actions with dieldrin use.
Although that incident is a blatant misuse, simply checking product labels and obeying pre-harvest intervals
listed can save expense, both in legal fees and from having a crop embargoed.

Dr. Fred Fishel, Pesticide Information Officer weeddr@ufl.edumy Noes
Agronomy Notes

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

Persimmon, cherry, Chinese tallow and other "weedy" trees can often be
found growing along fencerows. A foliar application of glyphosate (5 to
8% solution) made prior to leaf color change can be effective, but total
coverage can be difficult and retreatment will often be necessary.

Another procedure that is effective and more consistent than foliar
application is basal treatment. Basal application combines the herbicide
with basal oil (not water) and applies the mixture directly to the bark of a
standing tree (see photo.) This procedure results in rapid uptake and loads
a great deal of herbicide into the plant. However, it is important to use a
basal oil/herbicide mix; a herbicide/water solution will simply not work.

Basal oil mixed with herbicide is being The basal application technique is for trees that are less than 6-inches in
applied directly to the bark of the standing diameter and have smooth bark. It is important that the lower 12 to 18
tree. inches of the stem be treated on all sides with the herbicide/oil mixture.
Photo: J. Ferrell Adequate coverage is essential, since treating only one side of the stem
will result in controlling only half of the tree. Basal applications can be
made any time of the year, but are most effective during the dormant season when leaves are not

It must be noted that basal applications will not provide rapid control. Herbicide injury is often not
observed for several weeks after treatment and total control may require several months. Additionally,
basal treatment is not effective on older trees with thick bark. For older trees, other application
techniques should be employed.

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

For more information on brush control, please reference Herbicide Application Techniquesfor
Woody Plant Control, http://edis.ifas.ufl.edu/AG245.

Dr. Jason Ferrell
Extension Weed Specialist

Agronomy Notes Pag

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Employment Opportunity-
Affirmative Action Employer authorized to provide research educational information and other
services only to individuals and institutions that function without regard to race, color, sex, age,
handicap or national origin. For information on obtaining other extension publications, contact your
county Cooperative Extension Office. Florida Cooperative Extension Service/Institute of Food and
Agricultural Sciences/University of Florida/Larry Arrington, Dean.

Large Differences in Nitrogen Prices

Nitrogen prices vary from about 55 cents/lb of N to as much as 80 depending on the source. Urea prices
have dropped from the season high at a faster rate than ammonium nitrate.
Consider using some ammonium sulfate to get about 30 lbs/A of S along with urea to get the required N
rate for small grains. Ammonium sulfate is about 21% N and 23% S, therefore, all of the N should not
come from this source due to its acidifying effects. Small grain for grain will need N at planting followed
by 75-90 lbs/A in late January for top grain yields. Winter grazing planted in October or early November
should have split nitrogen applications such as 20-30 lbs/A at plant followed by another 40-50 lbs/A in
January to stimulate growth. Applications every 6-8 weeks of 40-50 lbs N/A keeps winter annuals
growing well without exposing large amounts of fertilizer to leaching.
Herbicides may be applied with liquid nitrogen (28-0-0-5) to control most broadleaf weeds. Liquid N is
typically the cheapest form of N but was higher during 2008. If clovers are present in the winter grazing,
broadleaf herbicides should not be used. Check prices for Nitrogen when needed each time since the
price has been changing rapidly depending on the source.
Dr. David Wright, Extension Agronomist

Oil Crops

Several growers have been experimenting with growing crops to produce some of their own biodiesel for farm use.
There are certain strategies that can work well when double cropping while still maintaining good rotations. If
certain acreage is dedicated to oil crops consider canola followed by sunflowers followed by small grain followed
by either peanut or soybean. Oil content of these crops varies widely as well as the value of the meal. This
rotation works well getting as many as 3 oil crops in 2 years. If the oil crops are used for oil, check to see where
they can be crushed and the amount of oil that can be expected along with value of the byproducts and the cost of
production. Equipment has to be set up differently for different crops when extracting oil.

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

Dec. 3-4 National Organic Standards Training
Quincy, FL North Florida REC; contact: (352) 273-3508 isefton(@ufl.edu

Jan. 15 2009 Florida Cattleman's Institute and Allied Trade Show
Kissimmee, FL

Agronomy Notes PaP L

Fuel Prices Projections-Encouraging News

Forage and hay producers, amid all the uncertainty with the economy, here are some cheering news on
the fuel prices projections in what remains of 2008 and 2009.

The Energy Information Administration, EIA, anticipates that regular-grade gasoline prices will average
$3.56/gal in both 2008 and 2009. In the October update, EIA projected total U.S. gasoline inventories at
180 million barrels, 23 million barrels below the five-year average and the lowest since August 1967.
Next year, EIA expects inventories will recover to 205 million barrels, about four million barrels below
the previous five-year average. The change will be due to continued weakness in motor gasoline
markets and growth in domestic fuel ethanol production. EIA also projects that on-highway diesel fuel
retail prices will average $3.91/gal in 2009, down from a projected $4.01/gal this year. Full report on
www.eia. doe. gov/emeu/steo/pub/contents.html

U.S. Gasoline and Distillate Inventories



0I .I .I .I .I
Jan 2004 Jan 2005 Janan 200 Jan 2007 Jan 2008 Jan 2009
NOTE0 Colored bands represent "nonwima range published in EIA WeelJy Petroleum Status Report, AppendixA.
Shon-Term Energy Outlook, October 2008 (

Yoana Newman
Extension Forage Specialist

Agronomy Notes Pc