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: October 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.
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Bibliographic ID: UF00066352
Volume ID: VID00117
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

Volume 33:10

North Florida Research and
Education Center in Quincy
showcased ditlerent exhibits
and fields, including this
pumpkin patch, at it annual
Fall Field Day last month.
Photo: Tyler Jones
IFAS Communications

October 2009



Scheduling Cotton Defoliation................................... .. Page 2


Poisonous Plant W atch ............................................................. Page 3
2009 Recommended Cultivars for Fall Forages................. Page 4


Peanut H harvest ................................................................................. Page 5


Soybean H arvest ............................................................................ Page 5

Weed Control

Controlling Wax Myrtle in Pastures ..........................................Page 6
Why Don't Pesticides Always Work? .................................. Page 7


Calendar................................. Page 2

Agronomy Notes

Cotton can be defoliated when at least 60% of the cotton is open (fiber showing) without yield loss. Defoliants
and boll openers work together to remove leaves and open all mature bolls within a two week period after
treatment. Picking ahead of this schedule may result in unopened bolls, leaves, and more trash in the seed cotton
resulting in discounts. Generally defoliants and boll openers work better under warmer conditions and with lower
rates than later in the season when temperatures are cooler.

It is normally expected that cotton that develops under hot conditions will have high micronaire (fiber thickness).
Lower micronaire fiber may be due to the extreme drought and heat that result in cotton bolls being set later in the
season and is more of a result of immature fibers and less cell wall thickening. Try defoliation about 2 weeks
before picking, because a wet fall and excess soil nitrogen can cause regrowth which would need to be defoliated
again or may result in staining of the lint. The pictures below show the same cotton variety with 2 nitrogen rates.
The plot on the left had a low rate of nitrogen and is ready to defoliate with more than 60% open bolls and the plot
on the right with a higher rate of nitrogen has mostly mature bolls but is a week away from defoliating.
Management can make a difference in many aspects of cotton growth and development; time to maturity and
harvest is one of them.

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

October 7 Advanced HACCP Training for the Food Industry, Gainesville
Best Western Gateway Grand

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

October 28th 2009 Florida Ag Expo, Gulf Coast REC, Balm
Growers will learn the most current information on: Production trends; Water
Management; Insect, Weed and Disease control strategies, and Food Safety.

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
Agronomy Noes
Calnda Co flnue onPae -:::

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

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

Poisonous Plant Watch

There are dozens of poisonous plants that infest pastures. Most of these species
-- are native to Florida and they are present for a majority of the grazing season.
However, late summer and early fall is one of the seasons when animal
poisoning most often occurs, the other being late winter and early spring when
cattle are hungry and there is no forage available yet.

S The most common poisonous plants in pastures in the fall are sicklepod, coffee
senna, and showy crotalaria. One reason for this is animals rarely browse these
species when grass is abundant and succulent. But in the fall, bahiagrass leaf
I,. c Crotalaria production has greatly slowed while seedhead production dominates. With the
Photos: B. Sellers decline in available forage, animals will begin to experiment on the other plants
present. Additionally, toxins most commonly accumulate in seeds with a much
lower concentration in the leaves and stems. It is possible that some animals
browse these poisonous plants all season with minimal ill effect. However, with
the days becoming shorter and seed production proliferating, casual browsing of
seed pods can quickly impact animal health.

As we draw nearer to frost, the presence of these poisonous plants becomes
even more important. The coffee weeds, for example, are much more tolerant to
frost than bahiagrass. A light frost can turn bahiagrass totally brown while these
plants remain unaffected. This rapid and dramatic reduction in available forage
can turn the attention of almost any animal onto poisonous plants.
If coffeeweeds, crotalarias, and other known poisonous species are present in
your pastures, develop a management plan for them now. This can
consist of spraying GrazonNext or simply mowing. If you suspect
animal poisoning, the most common signs are dark urine, listlessness,
and weight loss. If these signs are present, contact a veterinarian
without delay.

Dr. Jason Ferrell, Weed Specialist

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

Rye Recommended varieties: FL 401 (for early grazing or for use in blends), AGS 104, Wrens 96, Wrens
Abruzzi, Bates, Oklon, Wintergrazer 70, and Early Graze.

Oat Recommended varieties: Horizon 270, Horizon 201, Horizon 321, Horizon 474, SS76-40, RAM
LA99016, and TAMO 406.

Wheat Recommended varieties: SS8641, USG 3592, and Pioneer 26R61

Triticale- Triticale does not respond well to close grazing and therefore is only recommended for haylage or
silage. If used in grazing, consider blending with ryegrass to promote a longer growing season. Recommended
varieties for silage: Trical 2700, Trical 342, and Monarch

Ryegrass Recommended varieties: Attain, Big Boss, Bulldog/Grazer, Ed, Flying A, Jumbo, Maximus, Rio,
TAMTBO, Verdure.
Early: Attain, Big Boss, Bulldog/Grazer, Ed, Flying A, Oregro DH-3, Rio, TAMBO, and Verdure
Late: Attain, Big Boss, Jumbo, Marshall, ME94, Rio, TAMTBO, and Verdure. Season-long: Attain, Big Boss, Ed,
Jumbo, Rio, TAMTBO, and Verdure. These varieties were selected based on their recent three-year, multi-
location performance. Other ryegrass varieties, such as Prine, Florlina, Surrey II, Jackson, Big Daddy, TAM 90,
Passeral Plus, Brigadier, Fantastic, Graze-N-Gro, King, Beefbuilder III have also performed well in regional trials.
(Other new varieties may be suitable but have not been tested long enough in Florida.)

Tall Fescue In general, fescue should not be planted in Florida. Recommended varieties: Max Q endophyte
-friendly fescue where adapted.

White Clover Recommended varieties: Osceola (developed in Florida), Louisiana S-1, and Regal Ladino.
Durana and Patriot are also well adapted but have a prostrate growth habit and lower initial forage yields, but
persist well under grazing.
Red Clover Recommended varieties: Southern Belle, Cherokee (seed will be unavailable in 2009), Bulldog
Red, and Redland. Cherokee and Southern Belle were developed in Florida and both are non-dormant (earlier
forage production) types that produce greater total-season forage yields than dormant varieties.
Alfalfa Alfalfa is usually grown as a winter short-term perennial in Florida. Recommended varieties:
Florida 99 (seed will be unavailable in 2009), Bulldog 805, and Amerigraze 702.
Crimson Clover Recommended varieties: Dixie and AU-Robin. Flame, Chief, and Tibbee may be
available but commercial seed production for these cultivars will be limited in 2009.
Berseem Clover Recommended variety: Big bee.

Arrowleaf Clover Recommended varieties: Yuchi and Apache. Apache has improved virus resistance
compared to Yuchi.
Lupine Recommended varieties: Tifblue. Tifwhite and Frost are also recommended, however commercial
seed production of these lupine varieties has been limited and seed is currently unavailable.
Sweetclover Recommended varieties: None at present. New varieties should be commercially available

Austrian Winter Peas (Common). This annual legume is best suited to well-drained soils with high clay
content. Recommended varieties: Common

Vetch Recommended varieties: Hairy, Americus, AU-Early Cover, Cahaba White, and Nova II. Commercial
seed production of most vetch varieties will be limited in 2009.
Ball Clover -Recommended varieties: Segrest and common. Pre-inoculated seed is available in 2009

Dr. Yoana Newman Dr. Anne Blount Dr. J. Vendramini
Extension Forage Specialist Forage Breeding and Genetics Forage Specialist
Agronomy Notes Pa


Most of the peanut acreage will be harvested in October. There are many things that show up in peanuts
late in the season. Leaf spot can cause peanuts to defoliate and result in poor stem strength which may
result in yield loss. Be sure to maintain fungicide sprays late in the season in case late storms come in
and peanut harvest has to be delayed a few weeks. Other things that can cause yellow spots in peanut
fields are manganese deficiency and tomato spotted wilt virus. Manganese deficiency is often noted late
in the season on fields with a high pH. Both manganese deficiency and tomato spotted wilt symptoms
on peanuts are shown below. Note manganese symptoms showed up late in the season and that the older
leaves down in the canopy are still green.

Manganese deficiency on peanut
Tomato spotted wilt virus syrmptorlms

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

Soybean Harvest

It is important to harvest soybeans as quickly as possible to prevent loss in yield and quality. Moist
weather following dry down of soybeans can result in grain taking up moisture and fungal growth.
Several cycles of wetting and drying in the field after dry down can result in lower test weight and seed
quality resulting in discounts at the grain elevator. Likewise, soybeans tend to shatter after pods dry
down to harvest moisture resulting in further losses during the harvest operation if not harvested timely.
Soybeans should be harvested at 13% moisture or less but can be dried from 15-18% moisture if needed.
Soybeans are often harvested in October and if dry down is quick they seldom have to be dried. Moisture
should be around 11% if held in a grain bin for an extended period of time.

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

Agronomy Notes Pa

"Agronomy Notes" is prepared by: Maria Gallo, Interim Chair and Y. Newman, Extension Forage
Specialist (; A. Blount, Forage Breeding and Genetics (; J. Ferrell,
Extension Weed Specialist (; F.M. Fishel, Pesticide Coordinator (;
B. Sellers, Extension Weed Specialist (; J. Vendramini, Forage 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.

Wax myrtle (Myrica cerifera L.) is a native plant to the southeastern U.S. In most cases, it is scattered
throughout native ecosystems in Florida. However, it can be quite problematic in pastures if left
uncontrolled. It can become a dominant shrub in a pasture landscape reducing forage yield. In
rangeland, wax myrtle can be suppressed through burning. However, there is usually insufficient fuel to
carry a fire into a wax myrtle canopy in an improved pasture setting. Therefore, herbicides applications
are usually necessary in pastures.

l __ Control of wax myrtle can be challenging.
0 a Considering that this plant can reach heights
-4 VA of at least 20 feet tall, with canopy widths of

20 to 40 feet, control of this plant can be
extremely difficult.

I. recommendation for wax myrtle
-J, control is Remedy at 2 pt/acre.

S; However, there are some things that need to
be considered before applying Remedy to
.control wax myrtle.
Wax myrtle in a grazing pasture. First, the response of wax myrtle plants to
Photo: B. Sellers Remedy can be quite variable. This is
largely due to the size of the plant at
application. Research by Dr. Rob Kalmbacher, a retired professor at the Range Cattle REC, determined
that control of plants larger than 2.5 feet was erratic. He found that wax myrtle plants larger than 2.5 feet
should be mowed or chopped, followed by treatment of regrowth. It is recommended that wax myrtle be
chopped in the late fall or early spring and the regrowth treated the following fall. It has been my
experience that cutting the plants back (mowing, chopping, chipping, etc.) in late winter/early spring
allows for enough regrowth to treat the plants with herbicides by late summer/early fall.

Second, timing of the herbicide application does make a difference. Again, Dr. Kalmbacher found that
late summer/early fall applications of Remedy were quite effective. Why? This is the time that wax
myrtle plants are beginning to store energy to over-winter. Therefore, when the herbicide gets into the
plant, it is also transported to the root system with the energy reserves, resulting in more consistent
control of the plant.

Keys to controlling wax myrtle in Florida pastures

Plants should be no taller than 2.5 feet. If they are larger than this size, the plants should be
chopped or mowed at least 6 months before herbicide application.
Treat regrowth of wax myrtle plants in late summer (no earlier than August) or early fall (no
later than October) with 2 pt/acre Remedy.
Monitor the pasture the following growing season for escaped plants and retreat if necessary.
Dr. Jason Ferrell, Weed Specialist,

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

iV.~ci~ e
. V'W!
'PPP X~ .


Why Don't Pesticides Always Work?

Pesticides are valuable additions to the box of tools available to pest managers. However, they should be
considered as one part of the total integrated pest management (IPM) plan rather than the only solution. Pesticide
failure can occur for a variety of reasons:

Improper Pest Identification (incorrect pesticide selection)
Incorrect Pesticide Dosage
Improper Application Timing
Pesticide Does Not Reach Target Pest
Unfavorable Environmental Conditions
State of Poor Pesticide Condition
Pesticide Resistance

Improper Pest Identification Incorrect Pesticide Selection

Accurate pest identification is a cornerstone of any IPM program and should be considered a first step in the
program. Being able to accurately identify pests requires skill that is best acquired with much patience and
practice. Subtle differences among pest species may often lead to a false identity. For example, management for
the control of different species of grassy weeds can be very different. Although they may have common features,
such as parallel veins and round stems, crabgrass and bermudagrass control tactics are not always the same.

Crabgrass possesses an annual growth habit, while bermudagrass is a tougher-
to-control perennial with its vegetative rhizomes and stolons. Although some
postemergence herbicides may provide control of both species, preemergence
herbicides reliably control crabgrass, but are ineffective for control of

Regardless of the pest class, making an accurate identification is critical.
University of Florida/IFAS offers various services to help determine the cause
of plant problems and can provide pest identification.

Incorrect Pesticide Dosage
Crabgrass (above) has an annual growth
s ( ve) has an a g th Several reasons may account for this problem. Application equipment should
habit, while bermudagrass (below) is a
ait l ber be properly calibrated to deliver a known volume. Underdosing can be
Photos: F. Fishel expensive because retreatment may be necessary. On the other hand,
overdosing is a violation of the product's label wording. Because a rate listed
on a product label states that it will control a certain pest, don't assume that the
same rate will control other species.

Improper Application Timing

Apply the pesticide to the life stage of the pest that is most susceptible to the
effects of the pesticide. Generally, herbicides are most effective on small, early
stages of weed growth. Many insecticides are effective on insect larvae or
nymphs, but not on adults. Some pesticide labels will state their rates based
upon growth stage or size. Another potential problem involving timing is that
the application may take place following the infiltration or departure of a pest.
An application of a protectant fungicide will provide little, or no, control of a
plant pathogen that has already invaded its host plant. Many labels of products for plant disease control will state
to begin applications prior to the onset of infection.

Continued next page ...

Why Don't Pesticide Always Work?

Pesticide Does Not Reach Target Pest

Sometimes pesticide applications aren't effective because the pest is in a location that is difficult for the pesticide
to reach. Many insects are located on the underside of leaves, under bark or soil, or within stems and fruits. When
insects are on leaves' undersides, sprays must be directed to those areas to have an effect. Following their
application, some pesticides are required to be watered into the soil zone where underground insects are feeding,
either by rainfall or irrigation. Read the label for these and other special instructions for maximum product

Unfavorable Environmental Conditions

Most pesticides should not be applied just prior to or during rainfall. Although in a few instances, such as the
previous example, benefit is gained; however, most pesticides require a minimal amount of time to remain on the
treated surfaces. Rain washes pesticides off of foliage before they have time to take effect. High temperatures,
lack of moisture, and both acid and alkaline soil pH favor thicker cuticle formation on the surface of weeds. Thick
cuticles prevent uptake of herbicides, thus weed control is not maximized. Windy conditions favor drift, the loss
of a pesticide from its intended site by movement through air, and may cause injury to desirable plants Such
injury is subject to legal penalties.

State of Poor Pesticide Condition

Under some conditions, some pesticides can change into a form that is not effective. The age of the pesticide,
moisture, and temperature extremes are the primary factors responsible. Chemical reactions caused by such
conditions can alter the formulation's active ingredient, rendering them ineffective. Moisture is generally a
problem when dry products are stored in bags or containers that have not been adequately sealed. Statements on
the product's label often refer the user to not store the product in extreme heat. Heat may also cause volatilization
of some pesticides if their containers are not adequately sealed. Such statements are found in the "Storage and
Disposal" section of products' labels.

Pesticide Resistance

Pesticide resistance does not occur as often as some applicators of pesticides may think. Although there are
documented cases of more than 500 arthropod, and 200 fungi and weed species, this is not the most common
cause of pesticides to fail. Resistance often develops in pest populations that have been repeatedly treated with a
single pesticide. Development of resistance in pest populations may sometimes be averted or delayed by avoiding
the use of persistent pesticides, reducing the number of treatments and alternating pesticide modes of action.


There are many factors responsible for a pesticide's failure in controlling a pest. Although there are additional
reasons, most often some type of human error is involved in the problem. Some failures can be avoided by simply
following the product's label directions. Use common sense; read and follow all labels.

Dr. Fred Fishel
Pesticide Information Director

Agronomy Notes Pc

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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.

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