Title: Agronomy Notes
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Permanent Link: http://ufdc.ufl.edu/UF00066352/00112
 Material Information
Title: Agronomy Notes
Physical Description: Serial
Creator: Agronomy Department
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: May 2009
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Bibliographic ID: UF00066352
Volume ID: VID00112
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: 000956365 - AlephBibNum


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IFAS Extension

A grass buffer zone protects this
waterway from pesticide invasion
(see article on Page 6.)
Photo: F. Fishel

Agronomy No tes

Volume 33:5 May 2009


Pearl Millet, A Summer Annual ..........................................Page 2
Plating Vegetative Material and Exposure Time ...... Page 3

Weed Control
Chaparral" A New Herbicide For Pastures..............Page 4
rl Broadcast Applications Of Arsenal PowerLine For
ran Cogongrass Control.............................................. Page 4
Protecting Water Resources From
Agricultural Pesticides ................. ....... .................. Page 6

Conservation Tillage Into Cover Crops .................. Page 2
Rotate Crops Even When Prices Are Low............... Page 2
Calendar, Field Day And Other Resources ......... Page 5

"Agronomy Notes" is prepared by: J.M. Bennett, Chairman and Yoana Newman, Extension
Forage Specialist ( i ., !1 cI..l ii J. Ferrell, Weed Specialist (li' c! i,, ii c.l ii F.M. Fishel,
Pesticide Coordinator (weeddr@ifas.ufl.edu); G. MacDonald, Weed Specialist
(pineacre@ufl.edu); B. Sellers Extension Weed Specialist (sellersb@ufl.edu); D. Wright,
Extension Agronomist (wright@ufl.edu). Designed by Cynthia Hight (chight@ufl.edu.) 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.

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.


Conservation Tillage Into Cover Crops

Conservation tillage has become a common practice for many row
crops farmers in Florida. Cover crops are a very important part of
conservation tillage and can be especially important without
irrigation. Some of our research has shown soil temperatures to be
25-30 degrees cooler with cover crops as compared to bare soil.
S This has a tremendous impact on plant stress; in most years,
research has shown from five to 10 % increase in yields with a
good cover crop. A close up view of a row stripped off for cotton
planting in an oat cover crop is shown in the picture below.

Dr. David Wright
Extension Crop Agronomist

,. to Dtug edu -
Good rotations often get thrown out when the price for one commodity is higher than the normal rotated crops. If no
crop appears profitable, use crops that will set the following crop up for higher yields the next year. Good rotations
are one of the keys to high yields, low pest pressure, reduced risks, and farm profitability. Rotations usually become
limited due to high prices for a commodity or ease of growing crops such as with Roundup Ready technology. We
have learned over the years that crop yields for legume crops like soybean and peanut decline rapidly if planted for
more than one year without rotation. Cotton and corn yields also decline without proper rotation but at a slower pace
than for the legume crops. Good rotations have always been a key to good production practices and will reduce pests
(diseases, insects, nematodes) if proper crops are used in the right sequence as well as legumes supplying nitrogen
for grass crops.

Dr. David Wright, Extension Crop Agronomist
North Florida REC
Quincy, wright@ufl.edu

Pearl Millet produces high quality forage for growing or lactating animals. It is adapted to well drained
soils with pH from 5.5 to 7.0. When to plant it? In May if you get a break from dry conditions and while
you have some moisture, or as soon as soil moisture conditions are right; the window for planting goes
from mid March to June, and the production season is June through September depending on when you
planted Seeding rates recommended are 12 to 15 lbs/acre if planted in rows, or 30 to 40 lbs/acre if
broadcasting the seed. Apply 30 lb N/A, 50% of the K20, and all of the P205 fertilizer recommended,
from the soil test recommendation, in a pre-plant or at-planting application. Apply 50 lb N/A and the
remaining K20 after the first grazing period. Apply an additional 50 lb N/A after each subsequent grazing
period. Graze when the forage is 14 to 24 inches tall, and stop when the stubble is at 6 to 8 inches.

Check with your county agent for assistance with soil test or how to locate the seed.

Dr. Yoana Newman, Forage Specialist
ycnew@ufl.edu I Agronomy Noes

Rhizoma peanut (also know as perennial peanut) and bermudagrasses are typically spread using
vegetative material. In the case of bermudagrasses, vegetative planting uses plant parts such as rhizomes
or sprigs (underground stems/roots), stolons (above ground runners), or tops (mature stems). Only
common, giant, and seed types (several brands) can be planted by "seeds." (We are currently evaluating
some seeded bermudagrasses throughout Florida, and preliminary information should be available at the
end of the season). Perennial peanut does not produce enough viable seed, therefore planting is done
using mainly plant parts.

Vegetative material can be used at different rates. If you want a fast stand, the more material (sprigs, for
rhizoma peanut; and sprigs, runners, or tops in the case ofbermudagrass) should be planted. The closer
the spacing between plant parts on the field, the faster the vegetative material will close in and cover the
planted area.

If still digging rhizomes for planting or when cutting tops, keep in mind that weathering of the material is
a major factor in the viability of the planting material, and one that is responsible for many failed
This chart shows the

No exposure 100
2 hours (9 a.m. 11 a.m.) 94
4 hours (9 a.m. 1 p.m.) 72
2 hours (12 noon 2 p.m.) 30
4 hours (12 noon 4 p.m.) 3
8 hours, shade and moist 100
(9 a.m. 5 p.m.)

I Plating Tops:

relationship of
exposure time to sun
and wind after digging
the planting material
and the effect on
viability due to
dissection of the
vegetative parts.

Tifton 85 and Jiggs are easier to root by tops than other hybrid bermudagrasses. Some tips for increasing
the chance of successful establishment are:

A Cut tops with a sickle bar mower, baling immediately, and plant before the bales becomes
hot enough to kill the grass. When planting in small areas, "forking or pitching" the newly
cut material or grass is adequate.

B Scatter and disk the tops into a prepared and moist seedbed before tops wilt. Keep in mind
that tops can die within minutes, even quicker than below ground material.

C With a roller, pack the soil to prevent moisture loss and help the needed soil/plant material

Dr. Yoana Newman
Forage Specialist

Agronomy Notes Pc

% Sprigs Alive at Planting

Exposure Time


Chaparral' A New Herbicide For Pastures

A new herbicide, ChaparralTM, was recently labeled in Florida. It is formulated as a dry flowable and contains both
aminopyralid (MilestoneTM) and metsulfuron (Cimarron/Escort/AllyTM). This product will be in short supply in
2009, but is expected to be in full supply in 2010. Application rates for Chaparral range from 1 to 3.3 oz/acre, but
most applications will likely go out in the 2 to 3 oz/acre range. An application of 2 oz/acre of Chaparral would be
equivalent to applying 4 fl oz/acre of Milestone and 0.3 oz/acre of Cimarron (See Table 1 for Milestone:Cimarron
ratios for allowable use rates of Chaparral).

Table 1. Ratios of Milestone and Cimarron in Chaparral

Chaparral rate Milestone rate Cimarron rate
oz/acre fl oz/acre oz/acre

1.0 2.1 0.17
1.5 3.1 0.24
2.0 4.2 0.31
2.5 5.3 0.41
3.0 6.3 0.48
3.3 7.0 0.53

Strengths : Chaparral will provide broad-
spectrum weed control of many weed species in
pastures including tropical soda apple when the
application rate is above 1.5 oz/acre. It will
suppress or severely injure common and
Pensacola bahiagrass in bermudagrass, stargrass,
and limpograss pastures. There will be little to no
volatility issues with this product and can be
applied in areas where 2,4-D and dicamba use is
limited due to the presence of sensitive crops.

Weaknesses: Chaparral will NOT kill dogfennel. It cannot be used for weed control in bahiagrass as it can
suppress the growth of Argentine bahiagrass and severely injure or kill Pensacola bahiagrass. When using this
product for bahiagrass suppression in bermudagrass, stargrass, or limpograss, tank mixing with 2,4-D or 2,4-D +
dicamba (WeedMaster, etc.) results in reduced bahiagrass control.

Where it fits: With the fact that Chaparral can cause some significant injury issues in bahiagrass, its use will
be limited to bermudagrass in North Florida and bermudagrass, stargrass, and limpograss in South Florida.

Dr. Brent Sellers, Extension Weed Specialist
Range Cattle REC, Ona, FL, sellersb@ufl.edu

Broadcast Applications of Arsenal PowerLine M

For Cogongrass Control

Cogongrass invasion is an ever-increasing problem in Florida pastures. This species is almost totally
refused by all grazing animals and will quickly exclude all other desirable forages. Research has been
conducted for many years to determine the most effective means of selectively controlling cogongrass in
pastures, but success has been limited.

Essentially, the only way to control cogongrass is to either use tillage or the non-selective
herbicides glyphosate or imazapyr to renovate the infested area.

Broadcast Applications Continued on Page 5...

Agronomy Notes Pa

Many experiments have compared the
effectiveness of glyphosate and imazapyr for
cogongrass control. From these trials we have determined that imazapyr is the most effective herbicide

There have been two imazapyr products labeled for use on pastures (ArsenalTM and StalkerTM), but the
label restricts applications to only 10% of the pasture per year. In areas where cogongrass covers
significant acreage, this restriction never allows for wide-scale cogongrass control or eradication. This
issue was recently addressed when BASF requested a label change for Arsenal PowerLineTM.

The new label (submitted as a 24C) is specific to Florida and allows broadcast applications of Arsenal
PowerLineTM at 48 oz/A, or as spot spray at a 1% solution.

If as pasture is treated with Arsenal PowerLine then animals should be either
1) Removed from the pasture for 30 days or
2) If they remain on the pasture they cannot be sold for slaughter for 30 days.

There is also a 30 day haying restriction after application.

For more information, you may access the 24C label at http://www.cdms.net/LDat/ld86K007.pdf

Dr. Jason Ferrell
Weed Specialist

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

Dr. Greg MacDonald
Weed Specialist

NIam (Saniiidai s) Scott's Slwinl2 Corn Fesi
Nloiinr Doi-a. FL

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lai 6-8

Cleanup of water contaminated with one or more pesticides is complicated, time-consuming, expensive
and usually not feasible. The best solution is prevention. The following management practices will help
to retain pesticides in target areas and keep them out of water resources.


Evaluate Location of Water Sources
Pesticide contamination of water frequently is associated with pesticide handling practices in the
vicinity of wells and other water sources. Pesticide spills near wells can move directly and quickly into
ground water. Wells should be properly cased, capped, and grouted. Avoid mixing, storing, or
disposing of pesticides within 100 feet of a well. Some pesticide labels may recommend specific
distances that pesticides should not be mixed and loaded within various surface water bodies, such as
intermittent streams and rivers, natural or impounded lakes, and reservoirs.

Consider Weather and Irrigation
Delay the pesticide application if heavy or sustained rain is anticipated. Pesticide runoff and leaching
are favored by rainfall soon after application. Do not apply pesticides before scheduled irrigations,
unless the product must be activated by moisture. Control the quantity of irrigation water to minimize
leaching and runoff

Use Integrated Pest Management (IPM)
The practice of IPM combines chemical, cultural, and biological control into one program to manage
pest populations. Fields must be scouted to identify pests, their population levels, and extent of
damage. Make pesticide applications only when necessary, using the lowest rate required for adequate
control. Reduction in the amount of pesticide use lowers potential movement to sources of water,
protects the environment and reduces costs. M

s Protecting Waute Resourc 7.Agn

Consider the Vulnerability of the Site
Determine the susceptibility of the soil to leaching. Soil texture, organic matter content, soil moisture
and permeability affect pesticide movement. Some pesticides readily move through soils that are well-
drained, sandy, or low in organic matter. For example, many of the common soils used for citrus
production in Florida have a content of well over 90%
permeability of the geologic layers between the soil surface and
the ground water. If sinkholes are present, surface water runoff
can quickly reach ground water with little natural soil filtering.
The slope of the field and the relative location of lakes, ponds,
streams, canals, or wetlands to the application site determine the
vulnerability of these surface water bodies to contamination
from pesticides.

Construct a berm or bank between the application site and
surface water bodies to prevent or reduce the amount of water
running off the field into the surface water following a heavy
rainfall. Develop a buffer zone, such as a grass border, between
the field or the mixing and loading site and surface water-
s buffer zone is between t his waterway and sensitive areas (see photo on left). Water should pass through a
S. .,. ,,, site and acts as afilter.
Photo: F. Fishel grass "filter" strip when draining off fields into canals or other
water conveyances.

IAgronomy Notes Pc


A gr

a Evaluate the Pesticide/Follow the Label
Select pesticides that are less likely to leach. Pesticides that
have the greatest potential to leach to ground water are highly water soluble, relatively persistent and do not adsorb
to soil. Some pesticides are classified as restricted use and have label statements because of concerns over water
contamination (see example below). Read the label before you purchase, use, or dispose of a pesticide. You are
required by law to follow label
RESTRICTED USE PESTICIDE directions. Be aware that there
For retail sale to and use only by certified applicators or persons under their direct supervision, and only for those l t p
uses covered by the certified applicator's certification. laws tat place limitations on
use of certain pesticides,
This product is a restricted use herbicide due to ground and surface water concerns. Users must read and follow .
all precautionary statements and instructions for use in order to minimize potential for atrazine to reach ground including aldicarb and
and surface water. bromacil. Label language will
alert users of such limitations.
Measure Pesticides Carefully
Accurately calculate the amount of pesticide needed to treat the site to assure you are staying within the label rate.
Careful calculations help eliminate disposal problems associated with excess spray mix.

Calibrate Sprayer
Calibrate application equipment frequently to assure the desired amount of pesticide is being applied (Figure 3).
Check the equipment for leaks and malfunctions.

Mix and Load Carefully
If possible, mix and load on a permanent or portable containment pad to avoid saturating the soil with pesticide. If
the water source (well, canal or pond) used for filling a spray tank is not protected by a
|, concrete pad, berm, or wall to prevent runoff into the source, fill the spray tank as far as
possible from the water source or fill the tank in the field from a nurse tank. Nurse tanks are
used to transport clean water for mixing and loading. Add the pesticide concentrate to the
sprayer in the field. Use a check valve (anti-siphon device) or an air gap between the end of
the water supply hose and the highest water level in the spray tank to prevent back-
siphoning from the spray tank into the water supply. Never place a hose into a tank while
filling (see photo on left); always leave an air gap to prevent back-siphoning.Anti-siphon
devices are required for chemigation equipment in Florida. Do not leave the spray tank
unattended when filling. Do not allow tanks to drain at mixing and loading sites. Close the
tank opening to prevent spills when transporting the sprayer to the field.

Store Pesticides Safely
Store pesticides in a facility with restricted access and away from all water resources. Use a facility with a concrete
floor that has been sealed to facilitate clean-up in the event of a spill or leak. Inspect containers regularly for leaks
and corrosion. Bulk pesticide storage tanks should be placed on concrete pads with dikes built around them to
prevent movement of pesticide should a spill or leak.

Dispose of Wastes Carefully
Follow the label when disposing of pesticides. Triple or pressure rinse empty pesticide containers and
add the rinse to the spray tank. Apply excess spray mix and rinse water from equipment cleaning to crops
or sites listed on the label. Don't drain it on the ground. Mount a tank of fresh water on the sprayer to
rinse the tank and sprayer. Where practical, excess spray mix or rinses can be held in a tank for use in a
later spray mix. Take empty, rinsed plastic pesticide containers to pesticide container recycling facilities
or to sanitary landfills. Excess pesticide concentrates can be given to another qualified user, safely stored
for hazardous waste collection days, or disposed of by a firm licensed to dispose of hazardous waste.

Dr. Fred Fishel, Pesticide Information Specialist
Agronomy Notes

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