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: July 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: VID00114
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

Igronom y Notes

Volume 33:7


Cotton Nitrogen Requirement .......................... .................... Page 2
Row Crops and Cover Crops: Corn, Cotton,
Soybeans, Peanuts ........................................................ Page 2


9aleage an Alternative to Manage Moisture ........................ Page 3

Weed Control

Grazonnext: A "New" Herbicide for Pastures .....................Page 4
Crabgrass and Sandbur Control in Bermudagrass ............ Page 4
EPA Announces Safety Measures for Soil Fumigant Use ...... Page 5
EPA 's Arsenical Decision ................................. .......................Page 6
Carbofuran Tolerances ............................................................. Page 7


Calendar & Field Days ...... ...................................................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/Larry Arrington, Dean.

July 2009


Cotton Nitrogen Requirement

Cotton needs nitrogen in the square to early bloom period. Most cotton planted on time will start
blooming in early July and should have the N out before the 3rd week of bloom. Cotton does not require as
much N as many crops. Normally 50-60 lbs/A are required for a bale of cotton. However, there may be 20
-50 lbs/A of nitrate N available to the plant over the season in the soil and applications of 60-90 lbs/A of
N may be adequate for 2-3 bale yields. Sandy soils do require more N than heavier soils and it should be
applied no later than the 3rd week of bloom. Sulfur is especially important on sandy
soils. Recommendations are 30 lbs/A even when yield responses are as much as a bale per acre. Late
foliar applications ofN are not recommended unless there is not a good boll set.

Dr. David Wright, Extension Agronomist

Crop response to cover crops and conservation tillage

Our research has shown that cover crops cool soil surfaces by as
much as 25 degrees over bare ground planted crops. Plant
canopy temperatures can likewise be reduced by 5 degrees or

This can have tremendous impact on final yield of crops.

Corn, cotton, peanut and soybean respond well to dense
cover crops and may be especially helpful for non
irrigated crops.

Conservation tillage works well with all of the row crops and
helps reduce soil erosion on sloping land as well as reducing
moisture loss and wind erosion.

Agronomists tand in afield of cotton planted into a dense oat 1 hen is it too late for planting row
cover crop in Quincy, Florida. crnp
Photo: Dr. David Wright r

Soybeans may be planted in July if drilled and irrigated. Yields may prove very satisfactory and MG V-VIII
may be used. There are many high yielding varieties and you must keep in mind that they grow very fast and start
blooming earlier as the planting date is delayed into late summer. The latest planting date for soybean may be as
late as the middle of August if irrigated.

Peanuts will probably not yield enough to make them profitable from plantings made in July and can be
damaged from late frosts when dug in November.

Corn may be planted as a second crop for grain or silage if a Bt (slows damage from armyworm corn ear worm)
hybrid is used that has good disease resistance. The latest planting date for corn should be July 15-20 to make
satisfactory yields.

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

This summer seems to be shaping as a typical Florida summer with very humid days and afternoon
showers that usually do not allow for the 3 drying days usually needed for hay production. These
showers although short often delay harvest and cause field losses. At the same time, maintaining a
regular harvest schedule (every 4 to 5 weeks) during the summer months is essential for good forage

Round bale silage is an option to
S manage this moisture situation and
keep with the harvesting schedule.
.. ....... Baleage is the harvesting of the forage
t with the same equipment used to make
hay with the additional step of
wrapping the bales with a plastic film
and the aid of a piece of equipment
known as a 'plastic wrapper'. This
technique where the bale is wrapped
wet for fermentation in the absence of
oxygen (also known as anaerobic
conditions) has been used successfully
in Europe and has been in practice in
the United States for over two

What is the wait period from cutting to
Bale wrapping (I; .. A in North Central Florida.
Photo: Dr. Y. Newman bailing? For grasses is usually a
couple of hours. How long should one
wait from baling to wrapping bales? The quicker the better. Field observations show that wet bales will
heat if allowed to sit a few hours before wrapping. Air exposure and high moisture allows plant
respiration and fungus (mold) growth, producing heat that is not dissipated once the wet forage is in a

When bailing legumes, the ideal moisture is about 45 to 50% Dry Matter (DM) (or 50 to 55% moisture).
The wait between cutting and bailing to achieve this percent DM under Florida conditions is about 4-5
hrs. It is not really all that difficult to do, just cut and let dry. With the short dry down there is not even
a need to turn. If you bale at that moisture there is little leaf shatter worries. One issue to be careful, as
with any legume, is potential for spoilage because of low soluble carbohydrates (or sugars) and high
buffering capacity (that may interfere with the desired drop in pH). For example, perennial peanut
relative to other legumes does very, very well.

Yoana Newman
Extension Forage Specialist

Agronomy Notes Pa

"Agronomy Notes" is prepared by: J.M. Bennett, Chairman and Yoana Newman, Extension Forage
Specialist (; B. Sellers, Extension Agronomist (1 c.lic! ,, Il! i'..i. J. Ferrell, Extension
Weed Specialist (; F.M. Fishel, Pesticide Coordinator (; 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.

A couple of weeks ago, new herbicide was launched by Dow AgroSciences called Grazonnext. In all actuality, this
really is not a new herbicide, but a new name. Grazonnext contains aminopyralid and 2,4-D at the same
concentration as that of ForeFront herbicide. A quick look at the labels for both ForeFront and Grazonnext will
show that the only difference is the name itself, as everything else remains the same.

A question we are getting a lot already is "Why?" Dow AgroSciences is phasing out Grazon P + D, a product
we have never had in Florida, but is widely used in the rest of the Southeast and elsewhere. They are replacing
this product with Grazonnext, due to the environmental concerns with picloram in Grazon P + D.

What about the price? Grazon P + D is an effective and economical herbicide in states where it is approved for
use. Since Grazonnext has been released as a means to phase out Grazon P + D, Dow AgroSciences had to be sure
that Grazonnext was also an economical choice as well. As a result, Grazonnext is approximately $20/gallon
cheaper than Forefront herbicide. Therefore, at the 2 pt/acre rate, ranchers can expect the herbicide to cost between
$8.50 to $10/acre.

Currently, our recommendations for pasture weed control recommend ForeFront for many weed species. Since
Grazonnext and ForeFront are exactly the same, one can replace the name ForeFront with Grazonnext wherever it
is seen in our recommendations. If you have any further questions about this product, then feel free to contact us.

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

The high temperatures and frequent rainfall of summer is great bermudagrass growth, but it also creates ideal
conditions for annual grasses like crabgrass and sandbur. Crabgrass has excellent forage quality and can be ideal
for grazing. However, the delayed drying time and off-color often causes problems for those attempting to
produce high-quality bermudagrass hay. Sandbur can be even worse by filling the bale with extremely sharp burs
that can render the hay inedible.

Control of crabgrass can be difficult to achieve. For several years it has been rumored that pendimethalin (Prowl
H20) is close to receiving a registration for preemergence control crabgrass and sandbur in bermudagrass
hayfields. But to date, this registration has not been finalized. Until this occurs, there are no preemergence
herbicides labeled for annual grass control. This leaves us with postemergence options which are few.

One choice is imazapic (Plateau, Impose, etc). Imazapic is highly effective on several grass and sedge species,
but can also be injurious to bermudagrass. Generally speaking, you can expect to see bermudagrass stunted for 3
to 4 weeks and this may result in the loss of one hay cutting. To minimize this impact, applications should not be
made until the bermudagrass is actively growing and rainfall is common. Early season applications can be highly
injurious, resulting in delayed growth for much of the season. Although imazapic can be injurious, proper use of
this herbicide can result in premium, weed free, bermudagrass hay.

Another choice is between-cutting glyphosate use. Glyphosate can be applied at 8 to 10 fl. oz/A immediately after
hay is removed from the field, but prior to bermudagrass regrowth. Generally speaking, this application should
be made within 1 or 2 days after hay removal (or 7 to 10 days after cutting). Delaying this application until
bermudagrass regrowth has occurred can result in bermudagrass stunting, but using low glypohsate rates as
recommended here will generally not cause severe injury. The drawback to this option is that total crabgrass and
sandbur control is rarely achieved. These low rates, coupled with applications to plants with little leaf surface
area, results in fair levels of control. But, this application is relatively inexpensive and avoids much of the
bermudagrass injury issues associated with imazapic.

Dr. Brent Sellers, Extension Weed Specialist and
Dr. Jason Ferrell, Weed Specialist
Agronomy Notes Pag

EPA Announces Safety Measures for Soil Fumigant Use

This past May 27, The Environmental Protection Agency (EPA)
announced its plan for strengthening safety measures for soil fumigant
use. The safety measures intend to reduce fumigant exposures to
bystanders, including people who live, work, attend school, or spend time
I near agricultural fields that are fumigated and increase overall safety of
fumigant use by requiring greater planning and compliance.

SSoil fumigants are pesticides that, when injected or incorporated into soil,
form a gas that permeates the soil and kills a wide array of soil-borne
--- pests. The gas can migrate from the soil into the air. Off-site workers or
bystanders exposed to these pesticides may experience eye, nose, throat,
or respiratory irritation, or more severe poisonings, depending on the
fumigant and level of exposure. Some of the new safety measures

>Creating Buffer Zones
>Enforcing Posting Requirements
>Adding measures to Protect Agricultural Workers
S>Strengthening Training Programs

EPA took extensive public comments on the safety measures, announced initially in July 2008, to
refine the measures as needed and develop an implementation strategy. This included many public
meetings and visits with state agencies and agricultural, farm worker, and public health constituents.
Adjustments to the 2008 proposal have been made based upon new scientific data and improved
information on certain technological capabilities. EPA will continue to work with state agencies,
growers, farm workers, and public health officials to achieve the new protections while minimizing
costs and burdens on growers. The EPA plans for the measures to be implemented starting in the 2010
and 2011 growing seasons (see Table 1).

Table 1. Timeline for soil fumigant risk mitigation steps.

Time Action
Summer 2009 EPA sends letters to fumigant registrants outlining label schedule.
Fall 2009 Registrants submit revised labels to EPA.
2010 EPA reviews and approves new soil fumigant labels before the growing season, implementing
most measures (except those related to buffer zones) to achieve improved protections.
2011 EPA implements remaining measures relating to buffer zones to gain full protections.
2013 EPA begins reevaluating all soil fumigants under the Registration Review program.

Fumigants are used on a wide range of crops, primarily potatoes, tomatoes, strawberries, carrots, and
peppers. The soil fumigants methyl bromide, chloropicrin, dazomet, metam sodium, metam potassium,
and iodomethane are all subject to the new requirements.

More information on these measures may be viewed at:
soil fumigants/.

Dr. Fred Fishel, Pesticide Information Director
weeddr@ufl.eduomy Notes P
Agronomy Notes


EPA 's Arsenical Decision

EPA has finalized its decision on the arsenicals (MSMA, DSMA, CAMA, and cacodylic acid).

For cotton, applications are:

Limited to 1 postemergent application at 2 lbs ai/A with a second application at 2 lbs ai/A only
if needed as a salvage operation (i.e. if pigweed escapes the first application).
A 50-foot buffer zone must be maintained around permanent water bodies, such as rivers,
streams and lakes.
Pre-plant cotton use must be deleted.

Uses on golf courses, sod farms and highway rights-of-way will be canceled
December 31, 2012, with the use of existing stocks allowed until December 31, 2013. The labels must
have the following:
Golf course use is limited to spot treatments only (100 square feet per spot), not to exceed 25%
of total golf course acreage per year. One broadcast application is allowed for newly
constructed golf courses only.
Sod farm use is limited to 1-2 broadcast applications per season. A 25-foot buffer zone must be
maintained around permanent water bodies.
Two broadcast applications per year are allowed for use on highway rights-of-way only.
A 100-foot buffer zone must be maintained around permanent water bodies.
Other rights-of-way uses must be deleted.

All other uses of MSMA and currently registered uses of DSMA, CAMA, DMA (cacodylic
acid and its sodium salt) must be deleted effective December 31, 2009. In addition, MSMA product
registrations must be amended to delete the following uses:
Residential Turf
Non-bearing Fruit and Nuts
Citrus (bearing and non-bearing)
Bluegrass, Fescue and Ryegrass grown for seed
Drainage Ditch Banks
Utility Rights-of-way
Fence Rows
Storage Yard and similar Non-crop Areas
Existing stocks of these uses may be used until December 31, 2010. After the end dates for existing
stocks, uses of these products will be illegal.
Dr. Fred Fishel
Pesticide Information Director

Agronomy Notes


Carbo furan Tolerances

EPA has revoked all tolerances for carbofuran as of I dU dIE -
December 31, 2009. The trade name of this' c l i I a tid'
pesticide registered in Florida is Furadan. Residues On..LI EPAs ONE NUMER
found on food after December 31, 2009 will be Aie 4 NOTE TO PHYSICAN
considered adulterated unless applications can be
documented to be made in 2009 or earlier (Federal Register, May 15, 2009).

Note: This is interesting since EPA has revoked the tolerances for carbofuran but the registrations still exists.
When questioned why EPA did not suspend or cancel, EPA replied that EPA is required to "coordinate" action
under FIFRA and FFDCA "to the extent practicable and consistent with the review deadlines." EPA stated
neither FIFRA nor FFDCA required EPA to determine that a pesticide presents an "imminent hazard," as that
term is defined in FIFRA, prior to taking action to resolve dietary risks under FFDCA.

Dr. Fred Fishel, Pesticide Information Director

July 13-15 Short Course: Applications & Analyses of Mycorrhizal Associations
Information or registration call (352) 392-1951 email:

July 20-24 National Conference on Ecosystem Restoration (NCER)
Los Angeles, CA

July 22-23 Workshop: Breeding for Resistance to Whitefly-transmitted
Viruses, Orlando

August 1-2 Florida Small Farms & Alternative Enterprises Conference *
Kissimmee (Registration discount if received by June 1.)

September 15-18 International Citrus and Beverage Conference*, Clearwater Beach

September 22-24 Southwest Herbicide Applicator Conference*, Panama City Beach

October 20-22 Sunbelt Ag. Expo, Moultrie, GA

October 28th 2009 Florida Ag Expo
Gulf Coast REC, Balm

November 14 Florida 4-H Centennial Gala, Jacksonville

November 15-17 Energy Conference*, Orlando

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

Indicates events sponsored in part or fully by the University ofFlorida
Agronomy Notes P


UR E-Ahdi'- AE /*

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