Group Title: Circular
Title: Weed control overview
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 Material Information
Title: Weed control overview
Series Title: Circular
Physical Description: 5 p. : ; 28 cm.
Language: English
Creator: McCarty, L. B ( Lambert Blanchard ), 1958-
Florida Cooperative Extension Service
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1993
Subject: Weeds -- Control -- Florida   ( lcsh )
Herbicides -- Florida   ( lcsh )
Golf courses -- Maintenance -- Florida   ( lcsh )
Turf management -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: L.B. McCarty.
General Note: Title from caption.
General Note: "July 1993."
 Record Information
Bibliographic ID: UF00008569
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA6833
ltuf - AJT2180
oclc - 29205751
alephbibnum - 001857786

Full Text



Florida Cooperative Extension Service

Weed Control Overview'

L. B. McCarty2

Choosing a complete and effective weed control
program involves many considerations before
initiation. Proper turf management in terms of
mowing height and frequency, watering, fertilization,
aerification, etc., must be adjusted and incorporated
to encourage proper and competitive turfgrass growth
and development. This will naturally suppress weeds.
If proper cultural practices are not followed, the turf
will weaken and allow weeds to become established.

The second step is to identify the weeds and their
approximate distribution on a golf course. Maps
outlining specific locations and identification of
specific weeds might allow the superintendent to spot
treat versus treating "wall-to-wall." This not only
saves time and money, it reduces the amount of
herbicide applied.

Next, the superintendent must decide what
specific herbicide(s) they can afford and which
herbicides will provide adequate control. This
publication, local or state Cooperative Extension
Service personnel, as well as experience from
colleagues, will help provide valuable information on
herbicides and their expected performance under local
conditions. Herbicide salespersons can also be an
excellent source of information of their respective
company's products. It is suggested that all of these
information sources be explored during the planning

Superintendents must decide if a pre- or post-
emergence herbicide, or a combination of both will be
necessary. Some superintendents prefer using

preemergence herbicides exclusively to avoid having
weeds visible to their members, or to avoid potential
turf phytotoxicity that can be associated with
postemergence herbicide use. However, others prefer
using only postemergence herbicides to minimize any
potential rooting inhibition associated with some
preemergence herbicides. Success, especially in the
initial weed management program, will probably
require a combination of both types of herbicides.

Pre-plant fumigation is highly recommended in
the initial construction of a golf course. The use of
methyl bromide is preferred followed by metham (or
metam-sodium). Non-selective pre-plant weed control
can be achieved by multiple (2 to 3) applications of
glyphosate. This, however, does not control
nongerminated seed or other pests located in the soil
and it requires a extended period of time to become
fully effective.


Preemergence control of newly sprigged or
sodded areas with minimum turf damage is best
achieved with products containing oxadiazon
(Ronstar). Oxadiazon provides good annual grass
weed control. Simazine also may be used at low rates
(0.5 to 1.0 lb ai/A) for broadleaf weed control in this
situation. If used, apply these materials immediately
following sprigging or sodding and irrigate with 1/4 to
1/2 inch of water. Members of the dinitroaniline
herbicide family (e.g., oryzalin, benefin, prodiamine,
or pendimethalin) should not be used until the
turfgrass is fully established.

1. This document is Circular 1113, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
Publication date: July 1993.
2. L. B. McCarty, Associate Professor, Environmental Horticulture Department; Cooperative Extension Service, Institute of Food and Agricultural
Sciences, University of Florida, Gainesville FL 32611.
The Institute of Food and Agricultural Sciences is an equal 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 Service office.
Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean

Circular 1113
July 1993

Weed Control Overview

A weed control schedule should be developed
once the turfgrass area is established. Again, this will
vary widely on the resources available to the
superintendent, weed species present, and overall
desires and goals of the individual golf club.

If weed pressure is heavy, then both pre- and
post-emergence herbicides will be needed. For
preemergence crabgrass control in established turf,
one of the dinitroaniline herbicides or dithiopyr
should be considered. These must be applied before
crabgrass germinates in early spring and repeated
every 90 to 120 days-depending on the specific
product used. Read the label directions for guidelines
on repeat application timing and any precautions
about overseeding timing. If broadleaf weeds are a
problem along with grass weeds, isoxaben (Gallery)
mixed with one of the dinitroaniline herbicides or
dithiopyr will broaden the window of weed species

If goosegrass is the predominate weed species
present, then oxadiazon should be the preemergence
herbicide chosen. The dinitroanilines also provide
goosegrass control but these are usually not as
consistent as oxadiazon. Oxadiazon should also be
the choice of materials used on heavy traffic areas
such as par-three tees, since it affects turfgrass rooting
less than the dinitroanilines. Preemergence
herbicides such as bensulide, dacthal, or napropamide
also provide good crabgrass control but like the
dinitroanilines, are not as consistent for goosegrass

Preemergence annual bluegrass control on
overseeded greens is provided in Florida either with
pronamide or fenarimol. Since each product has
specific strengths, weaknesses and restrictions, the
superintendent should research each product before
using it. Besides pronamide or fenarimol,
preemergence annual bluegrass control in overseeded
fairways is available with benefin or bensulide.
However, timing of this application in conjunction
with overseeding is important. The label should be
consulted for specific information before using any
herbicide. Selective postemergence annual bluegrass
control in an overseeded situation is not currently
available in Florida.

Preemergence annual bluegrass control in non-
overseeded areas is achieved with the same herbicides
used for preemergence crabgrass control. Isoxaben
can be added to this list to provide better winter
annual broadleaf weed control.

Preemergence and early postemergence annual
bluegrass control in non-overseeded bermudagrass
fairways is also provided by pronamide (Kerb) or
simazine (Princep T&O). Either material should be
applied in November and repeated in early January.
Besides annual bluegrass, simazine will also control
many winter broadleaf weeds. Do not use simazine
during bermudagrass spring transition or if temporary
yellowing to the bermudagrass can not be tolerated.

If nutsedge, specifically yellow nutsedge or annual
(water) sedge, is a problem in fairways, preemergence
control is available with metolachlor (Pennant).
Metolachlor also provides some annual grass and
broadleaf weed control but consult the label for
specific weed control activity.

Perennial ryegrass clump control involves
sanitation practices and herbicide use. Minimize seed
drift by seeding when winds are calm, clean shoes and
equipment before exiting seeded areas, and do not
water excessively as to wash seed. Apply a
preemergence herbicide such as pendimethalin,
oryzalin, dithiopyr, or prodiamine on surrounding
areas immediately before or after overseeding. A
repeat application may be necessary at one-half rate
in January for full season control.


If weed pressures are heavy or preemergence
herbicide applications are not timed properly, some
weed escapage can be expected. Cultural control
involves proper mowing to discourage weed seedhead
formation, thus preventing further sources of weeds
and the proper timing and use of postemergence

The phenoxy herbicides (2,4-D, 2,4-DP, MCPP,
MCPA) alone, or combined with the benzoic
herbicides (e.g., dicamba) have traditionally been used
to control broadleaf weeds. As weeds mature, repeat
applications every seven to fourteen days are required
for complete weed control, but often results in varying
degrees of turf phytotoxicity. The introduction of
much more active materials such as triclopyr or
metsulfuron reduce the number of applications
needed, thus reducing the potential of turf damage.

Postemergence grass weed control has
traditionally been attempted with single and
sequential applications of the arsenical herbicides
(MSMA and DSMA). Metribuzin (Sencor) is often
combined with these to reduce the number of

Page 2

Weed Control Overview

applications needed but is restricted to higher mowed
golf course areas such as fairways.

Diclofop-methyl (Hoelon or Illoxan) is also
available for postemergence goosegrass control with
minimum applications required. This provides
goosegrass control without the phytotoxicity often
associated with other grass herbicides.

Postemergence sedge control is confined to 2,4-D,
MSMA and most recently with bentazon and
imazaquin. Repeat applications will be needed as the
nutsedge plants mature.

In Florida, postemergence annual bluegrass and
ryegrass clumps are controlled best by pronamide or
simazine. Care must be taken not to treat desirable
ryegrass turf or areas up-slope to the ryegrass because
pronamide and simazine can move with water flow
onto these areas. Use these products early in winter
before seedhead formation begins, after which time,
control efficacy is reduced. Metsulfuron may also
control these clumps if treated early (before mid-

Selective control of perennial weeds such as
torpedograss is currently available only with spot-
treatment with glyphosate. Repeat applications of
glyphosate will usually be required for complete weed
eradication. Even if repeat applications are made,
subsequent weed seed germination or weed
introduction by man, animal, or the environment may
result in reinfestation.


When using any postemergence herbicide, certain
precautions should be followed to minimize any
problems. Treat the weeds when they are young (e.g.,
2 to 4 leaf stage). Larger weeds require repeat
applications. This will result in increased chance of

phytotoxicity and increased labor costs with added
wear and tear on equipment. Treat when the weeds
and preferably when the turf is actively growing and
good soil moisture is present. Treating when the
weed is actively growing results in better herbicide
uptake and translocation, thus better efficacy. If
weeds are treated after they begin to flower or
produce seedheads, herbicide activity will be reduced
and repeat applications will be necessary. If
seedheads or flowers are present, mow the weeds as
low as possible, wait several days until new regrowth
is evident, and then make the herbicide application.
Allowing weeds to produce seedheads may add to the
soil's weed seed reserve, therefore, mowing or
herbicide treatments should be in advance to
seedhead development.

An adjuvant in terms of a surfactant, wetting
agent, or crop oil concentrate is generally needed by
most postemergence herbicides. The label should be
consulted, however, as many postemergence
herbicides already contain them. A compatibility test
should be made of the proper ratio of the two
products to be tank mixed prior to their application.
This will ensure the products will stay in proper
suspension and not precipitate out.

All chemicals mentioned are for reference only.
Not all are available for turf use and may be
restricted by some state, provinces, or federal
agencies; thus, be sure to check the status of the
pesticide being considered for use. Always read and
follow the manufacturer's label as registered under
the Federal Insecticide, Fungicide, and Rodenticide
Act. Mention of a proprietary product does not
constitute a guarantee or warranty of the product by
the authors or the publishers and does not imply
approval to the exclusion of other products that also
may be suitable.

/01 *

L r ir..!

Page 3

Weed Control Overview

Table 1. Common and trade name examples of herbicides used on warm season turfgrasses

Common Name Manufacturer Trade Name(s)

Asulam Rhone-Poulenc Asulox 3.34 Ib/gal
Atrazine Ciba-Geigy + others AAtrex + others

Benefin Dow/Elanco Balan

Benefin + oryzalin Dow/Elanco XL 2G
Benefin + trifluralin Dow/Elanco Team 2G

Bensulide ICI Americas + others Betasan, Pre-San + others

Bensulide + oxadiazon 0. M. Scotts Goosegrass/Crabgrass Control

Bentazon BASF Basagran 4 Ib/gal, Basagran T/O
Bentazon + atrazine BASF Prompt (formerly Laddock)

Bromoxynil Rhone Poulenc Buctril 2 Ib/gal

Chlorsulfuron Lesco, DuPont Lesco TFC

Clopyralid DowElanco Confront
DCPA ISK Biotech + others Dacthal 75WP + others

Dicamba Sandoz + others Banvel 4 Ib/gal + others

Diclofop Hoechst-Roussel Illoxan and Hoelon 3EC

Dithiopyr Monsanto Dimension 1 Ib/gal, 1G

DSMA ISK Biotech + others DSMA Liquid + others

Ethofumesate Nor-Am Prograss 1.5 Ib/gal

Fenarimol DowElanco Rubigan 50W, 1 Ib/gal
Fenoxaprop Hoechst-Roussel Acclaim 1 Ib/gal, Horizon 1 Ib/gal

Halosulfuron Monsanto Manage 50WP

Hexazinone DuPont Velpar 2 Ib/gal

Imazaquin American Cyanamid Image 1.5 Ib/gal

Isoxaben Dow/Elanco Gallery 75DF
MCPA Rhone-Poulenc Weedar MCPA 4 Ib/gal + others

MCPP + 2,4-D + dicamba PBI/Gordon Trimec Southern
Lesco Three-Way Selective
Sierra Trex-San
Riverdale + others Triamine, Tri-Ester + others

Metribuzin Mobay Sencor

Metolachlor Ciba-Geigy Pennant 7.8 Ib/gal

Metsulfuron DuPont Escort 60 DF
O. M. Scott DMC Weed Control 60 DF

MSMA ISK Biotech + others Ansar; Arsonate; Bueno; Daconate +

Page 4

Weed Control Overview

Table 1. Common and trade name examples of herbicides used on warm season turfgrasses

Common Name Manufacturer Trade Name(s)

Napropamide ICI Americas Devrinol
Oryzalin DowElanco Surflan AS 4 Ib/gal

Pendimethalin American Cyanamid Pre-M 60 WDG
O. M. Scott Southern Weedgrass Control

Prodiamine Sandoz Barricade 65DF

Pronamide Rohm & Haas Kerb 50WP

Quinclorac BASF Drive 50WP, Facet, Impact

Sethoxydim BASF Vantage 1.0 Ib/gal

Siduron DuPont Tupersan 50 WP

Simazine Ciba Geigy + others Princep T & O 4 Ib/gal, 80WP +

Triclopyr + 2,4-D DowElanco Turflon

Page 5

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