Weed control in lawns and other turf

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Title:
Weed control in lawns and other turf
Series Title:
Home and garden bulletin ;
Physical Description:
41 p. : ill. ; 22 cm.
Language:
English
Creator:
United States -- Agricultural Research Service
United States -- Extension Service
Publisher:
U.S. Dept. of Agriculture :
For sale by the Supt. of Docs., U.S. G.P.O.
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Weeds -- Control   ( lcsh )
Herbicides   ( lcsh )
Turfgrasses   ( lcsh )
Turf management   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
prepared by Agricultural Research Service and Extension Service.
General Note:
"May 1984"--P. 3.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 001285070
oclc - 10852061
notis - AGD5733
System ID:
AA00009148:00001


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Full Text
I I -7
A,77:


Weed Control in

Lawns and Other Turf


JUN 4


United States
Department of
Agriculture


PREPARED BY
Agricultural
Research
Service and
Extension
Service


Home and
Garden Bulletin
Number 239







Common, Chemical Names of Herbicides and Some Trademark
Names


Common Name
amitrole


asulam
atrazine

benefit

bensulide


bentazon

bromoxynil
2,4-D
dalapon
DCPA
dicamba
dichlorprop
(2,4-DP)

DSMA, MSMA,
MAMA, CMA

glyphosate
mecoprop
(MCPP)
metham
methyl bromide
oxadiazon


pronamide

siduron


Chemical Name
3-amino-s-triazole


methyl sulfanilylcarbamate
2-chloro-4-(ethylamino)-6-(isopropyl-
amino)-s-triazine
N-butyl-N-ethyl-a .a,a-trifluoro-2-6-
dinitro-p-toluidine
0,0-diisopropyl phosphorodithioate
S-ester with N-(2-mercaptoethyl)
benzenesulfonamide
3-isopropyl-1 H-2,1,3-benzothiadizain-
4(3H)-one 2,2-dioxide
3,5-dibromo-4-hydroxybenzonitrile
(2,4-dichlorophenoxy)acetic acid
2,2-dichloropropionic acid
dimethyl tetrachloroterephthalate
3,6-dichloro-o-anisic acid
2-(2,4-dichlorophenoxy)propionic
acid

methanearsonates


N- (phosphonomethyl)glycine
2-1(4-chloro- o-tolyl)oxylpropionic
acid
sodium methyldithiocarbamate
bromomethane
2-(ert-butyl-4-(2,4-dichloro-5-
isopropoxyphenyl)-A 2-1,3,4-
oxadiazolin-5-one
3,5-dichloro-N-(1,1-dimetyl-2-
propynyl)benzamide
1-(2-methylcyclohexyl)-3-phenylurea


Trademark name(s)1
AMINO TRIAZOLE WEED
KILLER, AMITROL-T,
CYTROL, WEEDAZOL
ASULOX
AATREX G

BALAN

BETSAN, PRESAN,
LESCOSAN, BETAMEC

BASAGRAN

BROMINAL, BUCTRIL
Too numerous to list
DOWPON, RADAPON
DACTHAL
BANVEL
WEEDONE DP (also
contains 2,4-D),
WEEDONE 20
DACONATE, DSMA Liquid,
WEED-E-RAD, CRAB-E-RAD,
WEED-HOE
KLEENUP, ROUNDUP
ISO-CORNOX 64; CHIPCO
TURF MCPP; MECOPEX
VAPAM, VPM
Too numerous to list
CHIPCO RONSTAR G


KERB

TUPERSAN


'List may be incomplete. Inclusion of trademarked names
is for information only and no recommendation to the ex-
clusion of others is intended.




r. w' r ;
Contents

Names of herbicides .................................................... 2
Cultural practices to control weeds.......................................... 4
fertilizing
liming
watering
mowing *
timing of cultural operations
Selective w eed control ......................................................... 6
buying herbicides
herbicide application
Herbicide treatments and weed types ...................................... 8
control of weed grasses
control of broadleaf weeds
Tillage and new seedlings or plantings........ .. ......... 12
tillage and turf establishment //<
control of weeds
soil fumigation /C
JUN 4 1984
Turf renovation and spot treatments...... .l ......................... .
herbicides for renovation
spot infestations
Equivalents ............................... ..............E S 15
Response of lawn weeds to herbicides .................................... 16
Drawings of common lawn weeds .................................... 18-40

This Home and Garden bulletin supersedes
Lawn Weed Control With Herbicides,
Home and Garden Bulletin No. 123,
revised April 1971.

May 1984
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402










3






Weed Control in Lawns and Other Turf'


The best defense against weeds is dense, vigorously growing turf-
grass. Weeds have difficulty in gaining a foothold in such a lawn. To
produce this kind of turf, you must select the best varieties of adapt-
ed grass species; grow them in good soil; maintain the correct soil
acidity; use the proper fertilizer for your growing conditions; water
the turf properly; use the correct growing procedure; and control
weeds, insects, diseases, and nematodes. In spite of these efforts,
weeds often become problems. Weeds may appear if the turf is
mechanically disturbed; if the turf is worn by excessive use; and if
diseases, insects, or droughts partially reduce the stand. Furthermore,
some weed species are particularly strong competitors.
When weeds occur in lawns there are many methods of control,
including use of cultural practices and herbicides. Herbicides are avail-
able for control of most of the weeds found in lawns and turf. If they
are used according to directions on the label, the recommended her-
bicides will not damage plants and the hazard is low to the user, oth-
er persons, pets, birds, and wildlife in the area. Always read the direc-
tions and precautions on the label of herbicides before use. If improp-
er cultural practices are the cause of thin, weedy turf, correct these
basic causes as the first step in weed control.

Cultural Practices to Control Weeds

Fertilizing The nutrient most often lacking in turf is nitrogen. It and
the two other more common fertilizer elements, phosphorus and po-
tassium, should be in good supply when turf species are making most
rapid growth. Several States recommend ratios of high nitrogen, low
phosphorus, and medium potassium for repeat use on turf. Consult lo-
cal experts about practices to be followed.
In the northern temperate climate, cool-season grasses should be
fertilized more heavily in the fall, with a lighter application or none at


'Dayton L. Klingman (retired), Agricultural Research Service
(ARS), USDA, Beltsville, Md.; E. 0. Burt (retired), Univ. of
Florida, Ft. Lauderdale; W. H. Daniel, Purdue Univ.,
W. Lafayette, Ind,; C. L. Elmore, Univ. of i alairnia Davis;
J. A. lawchitz, Univ. of Rhode Island, Kin,'ton and
J. I. Murray, AW USDA, Beltsville, Md.




It -7


all in early spring. Use of nitrogen in summer is less common. Annual
rates of nitrogen range from 2 to 6 lb/1,000 square feet. Nitrogen lev-
els in the soil should be declining in cool-season grass turf before
periods of expected hot or dry weather.
Fertilize warm-season grasses such as bermudagrass, zoysia, and
St. Augustinegrass with nitrogen during the spring, early summer, and
early fall months at an annual rate of 5 to 10 lb/1,000 sq. ft.

Liming A pH in the range of 6.0 to 7.0 is considered best for turfgrass
growth because it provides for more favorable nutrient availability and
microbial activity. Ground agricultural limestone is frequently needed
in acidic soils in the Eastern United States. Need for lime can be deter-
mined by soil test. As a generalization in higher rainfall regions, acid
sandy soils usually require light applications (about 100 lb/1,000 sq. ft.)
of ground or pulverized limestone every 2 or 3 years and clay soils re-
quire heavier applications (about 200 lb/1,000 sq. ft.) every 5 to 6
years. Lime can be applied at any season; however, late fall or-winter
is the best time.

Watering Sandy soils, because of their low moisture-retaining capaci-
ty, require frequent watering. Clay soils require less frequent watering
but larger amounts of water. Do not water the lawn until grass shows
signs of wilt. Then apply enough water, usually about an inch, to wet
the soil 6 inches deep or more. Do not apply water faster than it can
be taken in by the soil. Avoid watering lightly at frequent intervals;
this is wasteful and causes shallow growth of grass roots and stimu-
lates germination and growth of weeds. For instance, light, frequent ir-
rigation encourages the invasion of annual bluegrass and crabgrass.

Mowing Mow lawns of most cool-season grasses at least weekly to a
height of 2 to 2-1/2 inches. Close mowing, especially in hot weather,
weakens cool-season turfgrasses and invites weed invasion. Crabgrass,
in particular, can be reduced by the shading effects of the taller,
denser growth of permanent grasses on the crabgrass seedlings. Inva-
sion of spotted spurge, another warm-season weed, can be reduced
by high mowing.
Warm-season grasses, particularly bermudagrass, require closer
mowing than most cool-season grasses. Bermudagrass should be cut
frequently to a height of 5/8 inch or less. Others such as zoysia, cen-
tipedegrass, and carpetgrass should be mowed to a height of about 1
inch. St. Augustinegrass and bahiagrass should be cut at 2-1/2 to 3-
1/2 inches.






Mow lawns frequently. Keep the mower blades sharp. Unless
growth is excessive and there are weeds setting seed in the lawn,
leave the clippings on the grass. A mower with a mulching blade in-
creases rate of decomposition of the clippings. Do not let grass grow
unusually high. No more than one-third the length of the grass leaf
should be removed at a clipping. If a lawn is to be mowed at 2
inches, the grass should be mowed before it exceeds 3 inches in
height.

Timing of Cultural Operations In some turf areas, cultural operations
require aerating, verticutting, or dethatching to enhance growing
conditions. When planning these operations they should be timed to
be performed when the turf will regenerate quickly. At the same time
these operations should not uncover the soil or leave it bare at the
time of year when seeds of crabgrass, annual bluegrass, or goosegrass
germinate. These weeds invade rapidly into open areas.
These management operations should not be performed follow-
ing preemergence herbicide applications or the weeds will not be
controlled. If the preemergence herbicide bensulide or benefin is ap-
plied immediately after verticutting or dethatching, the grass regrowth
may be suppressed.

Selective Weed Control

Selective herbicides are chemicals that will control most weeds
without injuring the turfgrass. Use herbicides only when necessary and
as part of a complete lawn management program. Always read and
follow the directions on the label. An excess dosage of almost any
herbicide will damage lawn grasses, and a herbicide may kill one weed
and not affect others. To control some weeds you may need to use
herbicides that will temporarily or even permanently injure lawn
grasses.

Buying Herbicides Herbicides are sold in liquid, powder, and granu-
lar form. Most of them have common names that are assigned specifi-
cally to their chemical names. On the inside front cover of this publi-
cation, herbicides used for turf weed problems are listed. Because of
the great number of trade names under which these herbicides are
sold, the common names are used in the text of this publication.
The strength of liquid forms of herbicides may be stated on labels
as pounds-per-gallon acid equivalent and percent of active in-
gredients. The weed-killing strength of other herbicides is stated on
the label as percent of active ingredient. Labels on granular herbicides






state the percent of active ingredient and may give the size of lawn
area to be treated with the package contents.

Herbicide Application Granular herbicides are ready to use as pur-
chased. Granular herbicide particles are usually relatively large and
drift less than liquid sprays. Granular materials are best applied with ei-
ther the drop- or spinner-type spreader. Use the spreader setting
recommended by the manufacturer or that listed on the herbicide la-
bel.
Extra precautions should be taken in applying fertilizer-herbicide
mixtures. Do not overtreat by making a second or third trip around
trees and shrubs to give them an extra feeding of fertilizer. Such extra
trips can apply too much herbicide and cause injury or death to the
trees and shrubs. Do not use the fertilizer-herbicide mixture each time
the grass needs fertilizer.
Add liquid and wettable powder formulations to water and apply
as a spray. Use a sprayer that can be adjusted to make a coarse spray
at low pressure (less than 35 psi). On very small areas you may use a
garden sprinkling can. Care must be taken in handling sprays, especial-
ly herbicides such as 2,4-D, dichlorprop, mecoprop, and dicamba.
Drift of even small amounts of these can damage trees, shrubs,
flowers, and vegetables. Make treatments only when there is little or
no wind. Usually 1 to 5 gallons of spray mixture per 1,000 sq. ft. of
lawn are used. Within these limits the volume of spray used is not im-
portant. It is extremely important, however, to use the proper dosage
of herbicide per 1,000 sq. ft.
The most convenient equipment for applying sprays to small
areas is the pressure or knapsack sprayer of 1- to 3-gallon capacity.
This type of sprayer provides a fairly consistent volume of spray at
low pressure and allows you good control in limiting spray to the tar-
get area. Constant container agitation is necessary when using the
wettable powder or emulsifiable formulations or they will settle out.
One method of treating small patches or individual weeds is to
use a small paint brush or sponge nailed or wired to a broomstick or
dowel. Mix a small amount of herbicide in a container that has a large
enough opening so that the sponge or brush can be easily dipped.
After dipping, squeeze out the excess by pressing the brush or sponge
against the inside of the container. Simply "paint" or dab the weed.
Also, such commercial devices are available on the market. When us-
ing this method, dilute the herbicide as if it were to be sprayed. Do
not use full strength chemicals or turf injury will result.





7
j





Do not spray other plants such as flowers or vegetables with
equipment that has been used for herbicides. There may be enough
herbicide spray residue left in the sprayer to cause injury to these
plants.

Herbicide Treatments and Weed Types

Most lawn weeds are classed either as grasses or as broadleaf
types. The annual grass type includes crabgrass, foxtails, and barnyard
grass. Examples of broadleaf types include dandelions, plantains,
and chickweed. A narrow-leaf weed that is not a grass is nutsedge.
Each type requires different herbicides for effective control.
Herbicides used for crabgrass are usually effective on most other
annual grasses. The herbicides effective for controlling dandelion, plan-
tain, and chickweed are usually effective on most of the other
broadleaf weeds (see table and drawings at the back).
There are three types of weed control treatment:
* Preplanting a herbicide applied before seeding or sodding turf.
* Preemergence treatment the herbicide applied before weed
seeds germinate.
* Postemergence treatment the herbicide applied after weeds e-
merge. Sometimes, a sequence of treatment at definite intervals or
repeated treatments are required to kill weeds without excessive
injury to the turf.
Always read instructions on the label and pay particular attention
to limitations on use.

Control of Weed Grasses Crabgrasses and other annual summer
grasses may be a problem in lawns in most areas of the United States.
You can achieve best control from one of the preemergence herbi-
cides applied before seed germination. A good index as to best time
for application is when Forsythia is flowering or when lilacs are about
to bloom. Another useful index is when soil temperature reaches
50F. In most warm- and cool-season turfgrasses DCPA, benefin, ben-
sulide, siduron, and oxadiazon applied before weed seed germinates,
and according to directions, provide control. Only siduron can be
used on newly seeded turf areas. Other materials have a specified
waiting period (2 months or more) before overseeding is recommend-
ed. If no rainfall is received within 3 or 4 days after treatment, sprinkle
irrigation is recommended.
DCPA may injure red fescue and dichondra. Benefin may injure
bentgrass and dichondra. Bensulide may be used on most turf species.
Oxadiazon should not be used on bentgrass, centipedegrass, dichon-






dra, or zoysia; in some areas it will injure perennial ryegrass. Siduron is
not recommended for use on bermudagrass and some varieties of
bentgrass.
Some of the other weedy annual summer grasses that may be
controlled with these herbicides include barnyardgrass, fall panicum,
foxtails, and goosegrass. Goosegrass is usually the most difficult to
control.
For control of such weeds as crabgrass, Paspalum sp., spotted
spurge, and most other annual broadleaf weeds in centipede, St. Au-
gustine, and zoysia grasses, apply the granular formulation of atrazine
in January, February, or March before weeds germinate. Treat soon
after planting newly sprigged lawns to reduce competition from
weeds. Do not apply to root zone areas of trees and shrubs.
Postemergence use of methanearsonate herbicides (DSMA,
MSMA, CMA, and MAMA), in two to three treatments of 5- to 10-day
intervals, provides some control of seedling and juvenile plants of
crabgrasses, foxtails, sandbur, and other annual summer grasses. To be
effective and to minimize turf injury, soils should have enough mois-
ture to support active growth. Also, treatments should be made on
days when temperatures will not exceed 85F. Even so, some tem-
porary discoloration of turf is common. Generally, preemergence her-
bicides are more reliable for controlling crabgrass.
Asulam is used for postemergnce control of annual grasses and
certain broadleaf weeds in St. Augustinegrass only. Atrazine will also
control certain broadleaf and grass weeds when applied either pre-
emergence or postemergence in St. Augustinegrass.
Goosegrass tends to be a problem where soils are compacted
and turf is thin. It is an annual whose seeds germinate later than
crabgrass in spring and during the summer. Herbicide treatments used
for crabgrass control should be reinforced by a second application of
one-third to one-half the initial rate 4 to 5 weeks after the first appli-
cation to provide better goosegrass control. Most of the herbicides
give variable results. Oxadiazon tends to provide more reliable results
than the others. It may be best to correct the causes of the problem,
and reseed or sod in the fall to allow time for dense turf to develop
before the next spring.
Annual bluegrass tends to be a major problem in closely mowed
turf (such as putting greens) and in thin stands or along turf borders. It
is a cool-season species whose seeds can germinate throughout the
year except in the Deep South. Most preemergence herbicides used in
cool-season turfgrasses give only partial control. In some areas bensu-
lide is the preferred herbicide. Good turf management practices (infre-
quent irrigation and high mowing height) may limit infestation.






Annual bluegrass can be well controlled in bermudagrass in the
Southeastern States by pronamide either as a preemergence or post-
emergence treatment. Do not overseed treated areas for 90 days
after application of pronamide, unless finely ground charcoal is applied
before seeding.
Bermudagrass, quackgrass, zoysiagrass, kikuyugrass, nimblewill,
and other perennial grasses that spread by horizontal stems, either
below or above ground, are often weeds in cool-season turfgrass and
can be controlled by methods to be discussed under turf renovation.
Glyphosate is advantageous for spot treatments. Such spreading
perennial grasses often have dormant buds at the joints of the spread-
ing stems that may not be killed by a single treatment of herbicide.
When practical, a second application with 1 to 2 months between
treatments increases the chance of eradicating these species. Continue
to search for any live plants for many months or years after treatment.
Because glyphosate is effective only when applied to leaves, an abun-
dance of foliage on the weed grasses at the time of application is
necessary for control. Treated spots can be seeded, sprigged, or sod-
ded soon after treatment as discussed under "Renovation," page 13.
Any reinfestation should be spot-treated as soon as observed.
Tall fescue, timothy, orchardgrass, and other such perennial
bunch grasses, when in fine turf, give a clumpy appearance because
of their more rapid growth. If only a few clumps occur they can be
removed by cutting under them shallowly with a spade. The bunch
grasses can be spot sprayed. The bare spots can be resodded or filled
with topsoil and seeded. See renovation treatments.
Dallisgrass and some other Paspalum species are controlled by re-
peated applications of postemergence sprays with DSMA and other
methanearsonate herbicides at the highest rate recommended on the la-
bel. Some slight discoloration of turf may result temporarily. Do not use
on St. Augustine, bahiagrass, carpetgrass, or centipedegrass turf.

Control of Broadleaf Weeds Broadleaf weed control herbicides are
usually applied directly to foliage and stems of actively growing
weeds (postemergence treatments). Most should be applied in early
fall (to allow grass to fill spaces left by dead weeds) or in the spring.
Most broadleaf weeds are controlled by using one of the com-
mercially available products containing 2,4-D in combination with one
or more of the following: Dicamba, mecoprop, and dichlorprop.






There are only a few broadleaf weeds that will not be con-
trolled by these combinations. In newly seeded turf bromoxynil will
control many seedling broadleaf weeds. For weeds not controlled by
these herbicides, you may consult your local County Extension agent
or garden center representative for specific recommendations.
Responses of some common weeds to herbicides are given in the
table on pages 16 and 17. Do not mow or water lawn for at least 2
days after treatment.
If you use a granular material, be sure to follow instructions on
the label. It is generally recommended that such formulations be ap-
plied when plant leaves are moist by dew in early morning or just
after watering the lawn. Herbicide granules retained in water droplets
on the leaves are readily absorbed by the leaves.
A high percentage of lawn weeds are controlled by 2,4-D. How-
ever, several common weeds are not controlled by it. Included in this
group are a number of weeds that are well controlled by dicamba
(knotweeds, red sorrel, white clover, henbit, chickweeds, and many
others).
Take special care not to exceed recommended rates with dicam-
ba because it may be absorbed from the soil by plant roots of orna-
mentals in amounts injurious to shrubs and some trees. For safety, do
not treat within the "drip line" of shrubs and trees.
Speedwells and prostrate spurge are not well controlled with
2,4-D and herbicides commonly sold in mixtures with it except where
plants are quite young. These weeds can be suppressed by sprays of
DCPA applied at about the same time they should be applied for
crabgrass control. Bromoxynil applied postemergence on young spurge
will further reduce populations.
Yellow nutsedge is a perennial that reproduces mainly by nutlets
underground that may persist in the dormant stage. If you have only a
few plants, persistently pull the plants before each mowing date to
control them. Heavier stands are controlled with difficulty and often
incompletely. Two or three treatments with bentazon, DSMA, or other
methanearsonates in late June and July, with 7- to 14-day intervals
between treatments, will reduce stands of yellow nutsedge. Repeated
heavy treatments with 2,4-D will also reduce stands of yellow
nutsedge. Temporary slight discloration of lawn may result.
Wild garlic produces hardshell bulbs that may lie dormant under-
ground and may continue to produce plants for about 3 years. There-






fore, to control this species use three annual treatments with 2,4-D
made in late winter or very early spring at the highest rates recom-
mended on the label. Low volatile ester formulations are more effec-
tive than amine salts.


Tillage and New Seedlings or Plantings

Tillage and Turf Establishment Existing turf can be removed by a sod
cutter, or in small areas, with a flat shovel. Also, the areas can be cul-
tivated with rotary-tillage equipment. Many weeds are easily killed by
cultivating and drying. If time is available, fallowing the soil with cul-
tivation intervals of 3 to 5 weeks will control many of the weeds aris-
ing from seeds and vegetative parts present in the soil. However, til-
lage is seldom adequate to control such pernicious perennial species
as quackgrass, bermudagrass, zoysia, and nutsedge. Use one of the
herbicides, discussed under "Renovation," that has little or no residual
toxicity in the soil before tillage when renovating such areas; or use a
soil fumigant after tillage. Finally, add needed lime and fertilizer and
plant seed in a smooth, firm seedbed. High-quality seed of an adapt-
ed turf variety may be broadcast on the surface and raked in or seed
may be shallow drilled. It may be advantageous to cover the surface
lightly with a straw mulch, peat, or compost. If you broadcast seed on
the soil surface, wet the seed and soil (sprinkle irrigate) daily for 7 to
14 days until seedling plants are visible. Then water less frequently.

Control of Weeds Some weeds in new seedings can be partially con-
trolled by a proper balance of mowing, irrigation, and fertilization. If
seedling broadleaf weeds threaten to shade out turfgrass seedlings,
even after one or two mowings, they may be controlled by herbi-
cides. A mixture of 2,4-D with other herbicides can be used advan-
tageously on cool-season grass seedlings of such species as Kentucky
bluegrass, red fescue, and tall fescue if applied at one-quarter to one-
third the rate used in established turf. Such treatments should be de-
layed 5 weeks or more after seeding. Also, bromoxynil alone or in
combination with dicamba has effectively controlled many annual
broadleaf weeds in new seedings without any delay in use needed
after seeding.
In spring or early summer seedings, crabgrass, foxtail, or bermu-
dagrass plants can be controlled by an application of siduron made on
cool-season turf species at seeding time.






Soil Fumigation Soil fumigation before seeding or planting the turf
species is a very effective method of controlling persistent weeds if
used on moist, tilled soil.
0 Metham is a soil fumigant used to kill germinating seeds, rhizomes,
tubers, roots, and stems of weeds in soil.
The soil should be cultivated and kept moist for a week before
applying metham. Then treat with 1 to 2 pints of commercial formula-
tion in a sprinkling can to each 100 sq. ft. of soil using 2 to 5 gallons
of water. Immediately sprinkle .the treated area with water until soil is
wet as deep as control is desired. To increase effectiveness, an airtight
cover may be spread over treated area (cover edges with soil) to sub-
stitute for the water seal. This greatly increases the effectiveness of
the fumigant as a herbicide. You may seed 14 to 21 days after treat-
ment.
* Methyl bromide is a restricted fumigant herbicide that is very
poisonous and may be used only by a certified applicator. It is par-
ticularly effective for control of pernicious weed species with
nutlets, bulbs, corms, and lateral underground stems. It also kills
most seeds and disease organisms in the soil. It does not control
hard seeds of clover, dichondra, or field bindweed. Methyl
bromide must be applied when soil temperature is above 60F and
under a well-sealed airtight cover. Because of the poisonous char-
acter of the gas, it can be safely used only if strict precautions are
followed. You can remove the cover 2 days after treatment and
seed 2 days later.

Turf Renovation and Spot Treatments

Sometimes an existing lawn that has weeds and mixed grass
species needs to be changed into a turf of superior quality. For exam-
ple, a Kentucky bluegrass turf may have been invaded by bentgrass,
bermudagrass, zoysia, or quackgrass. These unwanted grass species
cannot be controlled selectively in Kentucky bluegrass. Therefore, they
must be killed before a new lawn is established. Renovation involves
killing or removing the existing vegetation and establishing new turf.
Select the time of renovation that will favor establishment of the
desired turf species (when you expect adequate rainfall to germinate
seeds, especially if irrigation is not available, and when competing
weeds will be least troublesome). You may need to seek local advice
because conditions differ greatly among regions and for turfgrass
species. Varieties of turf species should be those best adapted in the
region. Under some situations, or with some turf species, sodding or





sprigging is preferable to seeding. Check with your County Extension
agent for up-to-date information, especially about grass establishment
techniques.

Herbicides for Renovation A number of herbicides will kill established
vegetation and weeds. Some herbicides require no waiting period
after treatment before seeding while others leave toxic residues re-
quiring waiting periods of 20 to 50 days before seeding.
No seedbed tillage preparation is required when vegetation is
killed by herbicides provided the seed of turf varieties are placed in
contact with the mineral soil. The latter is important. A disk-seeder
machine will accomplish this task in one pass. If excessive thatch is
present, till, verticut, or thoroughly rake it with a thatch rake. Other
information under "Tillage," page 12, also applies here. Because ger-
minating weed seeds may present severe weed problems where limit-
ed tillage is practiced, supplemental weed control is often required.
* Glyphosate is used as a foliage spray and effectively controls
grasses and broadleaf weeds. Plants should have well-developed
foliage and be growing actively when sprayed. Glyphosate is
translocated throughout the plant and the vegetation should not
be mowed, verticut, or cultivated until 3 or more days after treat-
ment. Glyphosate is water soluble and is partially washed off
plants by rainfall or sprinkle irrigation within 6 hours of treatment.
Most cool-season grasses and annual grasses are killed by treat-
ment with 1 pound acid equivalent per acre of glyphosate. Almost all
plants of such strongly spreading grasses as bermudagrass are killed
with a single spraying with glyphosate at 4 lb/acre under favorable
conditions. In the Middle Atlantic States, two treatments, 1 to 2
months apart, at 1-1/2 to 2 Ib/acre are slightly more effective on ber-
mudagrass and zoysia. Moisture should be adequate to cause
development of dormant buds between treatments. Also, to increase
control in some areas, the turf can be verticut or cultivated 7 days
after treatment and the area can be completely dried out to kill any
remaining dormant buds.
You can seed turfgrasses soon after treatment with glyphosate
because it leaves no residues in the soil toxic to germinating grass
seeds. Glyphosate does not move laterally in runoff water from the
treated area. Prevent sprays or drift from contacting foliage of desir-
able plants or injury will result.
Use control methods described earlier for weeds that may be-
come a problem in the new seeding.
* Amitrole is a foliage-applied, translocated herbicide that will con-
trol most annual species and some perennial grass species. Best





control is achieved if weeds are growing vigorously in moist soil If
it does not rain within 5 to 7 days after treatment, apply heavy ir-
rigation. Ten to fourteen days after treatment (when grass or
weeds are white or brown) the area should be cultivated. This can
be done by digging, rototilling, or otherwise loosening and drying
treated areas-verticutting, aerating, or raking the area is not
enough. If rain or watering occurs within 12 hours after treatment,
reduced control will result. If bermudagrass regrows, it should be 2
to 3 inches high before retreating. Rototill the area again in 10
days and then seed.
* Dalapon is used for turf renovation in Arizona and California only.
Mow any dead vegetation present, irrigate, and wait 2 weeks for
new grass growth, then spray with 0.37 oz active ingredient per
1,000 sq. ft. (1 lb/acre). After 2 to 3 weeks, water at least 15
min/day for 1 week. Wait 4 to 6 weeks, then seed, plug, or sprig
new lawn.
Verticutting or rototilling, followed by drying of soil, will increase
control of bermudagrass and other perennial grasses.
Runoff water can carry dalapon to adjoining turf areas and cause
injury.

Spot Infestations Often a spot(s) of coarse grass such as tall fescue in
Kentucky bluegrass or pernicous perennials such as bermudagrass,
bentgrass, quackgrass, nimblewill, and others will occur in otherwise
high-quality turf. These cannot be killed selectively. Methods dis-
cussed under "Renovation," particularly glyphosate, can be used to kill
these spots so that they can be reseeded, sodded, plugged, or
sprigged. Be particularly careful to confine the spray to the spot in-
tended to be sprayed. For such weed species as bermudagrass, the
sprayed area should extend at least 12 inches beyond the last ob-
served bermudagrass plants because of their strong rhizome habit that
grows outwardly. Do not use dalapon for spot treatments because
runoff water carries the herbicide outside the treated spots to adjoin-
ing turf and kills more grass than intended.

Equivalents
1 quart = 2 pints = 4 cups = 32 fluid ounces = 946 milliliters
1 cup = 8 fluid ounces = 16 tablespoons = 237 milliliters
1 fluid ounce = 2 tablespoons = 29.6 milliliters
1 pound = 16 ounces = 454 grams
1 acre = 43,560 square feet = 0.405 hectare (ha)
1 hectare = 2.47 acres






Response of Lawn Weeds to Herbicides1


(Symbols: E = excellent, VG = very good, G = good, F

Type of
Weed plant
2,4-D MCPA

Bindweed, field Perennial G F
Convolvulus arvensis
Buttercup, creeping Perennial G E
Ranunculus repens
Chickweed, common Annual G F
Stellaria media
Chickweed, mouseear Perennial F F
Cerastium vulgatum
Cinquefoil, Canada Perennial VG G
Potentilla canadensis
Cinquefoil, sulphur Perennial VG G
P. recta
Clover, White Perennial P P
Trifolium repens
Clover, bur Annual F F
Medicago polymorpha
Daisy, English Perennial P P
Bellis perennis
Dandelion Perennial E E
Taraxacum officinale
Dock, curly Perennial VG G
Rumex crispus
Garlic, wild Perennial G F
Allium vineale
Ground ivy Perennial G F
Glecoma hederacea
Henbit Annual F F
Lamium amplexicaule
Ivy, English Perennial P P
Hedera helix
Knawel, annual Annual P P
Scleranthus annuus
Knotweed Annual F F
Polygonum aviculare
Medic, black Annual G G
Medicago lupulina
Moneywort Perennial E -
Lysimachia nummularia
Nutsedge, purple Perennial F P
Cyperus rotundus


= fair, and P = poor)

Control1

dicamba mecc

F




G
E

E (

E

E

E V

E I

E I

F I

VC I

F

G

E

F I

E

E I

C (




P I


>prop






E
-j




ji






Response of Lawn Weeds to Herbicides1 -continued


(Symbols: E = excellent, VG = very good, G = good, F = fair, and P = poor)

Type of Control'
Weed plant
2,4-D MCPA dicamba mecoprop


Nutsedge, yellow
C. esculentus
Pennywort, lawn
Hydrocotyle rotundifolia
Plantain, broadleaf
Plantago major
Plantain, buckhorn
P. lanceolata
Plantain, rugel
P. regelii
Posion Ivy
Toxicodendron radicans
Posion Oak
T. diversiloba
Puncturevine
Tribulus terrestris
Sorrel, red
Rumex acetosella
Speedwell, corn
Veronica arvensis
Speedwell, purslane
V. peregrina
Spurge, spotted
Euphorbia maculata
Strawberry, wild
Fragaria
Thistle, Canada
Cirsium arvense
Violet
Viola
Woodsorrel, yellow
Oxalis stricta
Woodsorrel, creeping
0. corniculata


Perennial F

Perennial VG

Perennial E

Perennial E

Perennial E


Woody G G


Woody G

Annual VG


Perennial P P


Annual

Annual

Annual


Perennial F


Perennial G C


Perennial F

Perennial F

Perennial P


1The effectiveness evaluations are given as general susceptibility of the weed to a her-
bicide. For further information consult individual labels and local authorities. Further
research may result in change in some of the current effectiveness ratings. A dash indi-
cates effectiveness is not known.

17






Large Crabgrass


Large crabgrass, an annual, reproduces by seed. The stems
are stout and vigorous; those that are prostrate root at the
joints. Stems are not hairy. The leaf blade and the lower
part of the leaf (sheath), which encloses the stem, are
hairy on large crabgrass; leaves and sheaths on smooth
crabgrass are hairless. Most leaf blades of large crabgrass
are 1/4 to 17/3 inch wide. Smooth crabgrass is not as coarse
and tall as large crabgrass. Seeds are borne on 3 to 10
branches that radiate from the top of upright stems. The
two rows of seed are on opposite sides of the branch.




I
Smooth Crabgrass

-1..






Bermudagrass


Bermudagrass is an aggressive perennial grass that forms a
dense, heavy sod. It reproduces by prostrate stems (both
above and below ground) that root at the joints, and by
seed. Below-ground stems are hard, scaly, and sharp point-
ed. Above-ground stems are gray green and most of their
surface is hairless. There are long hairs at the edges just
above the junction of the leaf blade and the sheath (the
part of the leaf that encloses the stem). Bermudagrass
often has two sheaths attached to a single joint. Seeds are
borne on three to five branches that radiate from the end
of a flattened stem; the two rows of seeds on each branch
are pressed closely against one side of the branch.







Goosegrass


Goosegrass is an annual that reproduces by seed. In gen-
eral appearance, it has some resemblance to crabgrass.
Stems are prostrate and without hairs, like those of
smooth crabgrass. Crabgrass stems root at the joints;
goosegrass stems do not. The pale-green leaf blades usual-
ly are without hairs and are 3 to 12 inches long; they may
be folded. Seeds are borne on 2 to 10 branches that radi-
ate from near the top of the stem. There are two rows of
seeds, both of which are on one side of,the branch.







Dallisgrass


Dallisgrass is a perennial with short rhizomes that gives a
clumped appearance in sparse stands. Stems are 18 to 60
inches tall and without hairs except at the ligules and on
the crowded spikelets that are on one side of the rachis.
Seeds are borne in 3 to 9 racemes per stem that are loose-
ly ascending or spreading. It is found in the Atlantic Coast
States, southward from New Jtlry and Missouri, and
across the southern border States.







Quackgrass


Quackgrass is a perennial noxious weed that reproduces
by seed and spreading underground stems. New shoots
and roots arise from joints on the underground stems.
Aboveground stems, 18 to 36 inches tall, are smooth with
three to six joints. Leaves have auricles, ligule 17/32 inch
long, hairy lower sheath and upper sheaths without hair or
nearly so. Leaf blades are soft, flat, with crowded fine ribs.
Seeds are borne in a single spike per stem, with three to
seven short-awned florets per spikelet. It is a noxious
weed found throughout the United States except the
southern area.


/
-I,






Nimblewill


Nimblewill, a perennial, reproduces by seed and by stems
that root at the lower joints. Growth that develops from
rooting stems forms dense patches 10 inches or more in
diameter. The lower part of the stem is semiprostrate;
upper parts curve upwards. The slender, hra,, hin, stems
are not hairy. Leaf blades are short, flat and hairless. The
stems that bear the seeds are branching and 2 to 6 inches
long Seeds are very in,,, and borne r,,I.






Barnyardgrass


Barnyardgrass is a summer annual that reproduces by seed
and is a problem in new seedings. Stems are stout, erect
to semiprostrate, often branching from the base, seldom
more than 3 feet in height. It has no ligule or auricle. Leaf
blades are hairless, elongate, and light green. The head is
branched, erect to nodding, green to purplish tinged, and
4 to 8 inches long. It tolerates wet sites and is found
throughout the Unted States except the extreme
southeastern area.






Annual Foxtail Grasses


The Foxtails shown are summer annual grasses. They
reproduce only by seed. Yellow foxtail (A) is the species
most often found in newer lawns. In mowed lawns, yellow
foxtail produces a mat of foliage and seed heads. The stem
bases usually are flattened and reddish. The stems are usu-
ally 6 to 12 inches high. The leaves are flat but may have a
spiral twist; they have long hairs where the leaf joins the
leaf sheath enclosing the stem. The growing season is
similar to that of crabgrass and control methods are the
same for both weeds. Green foxtail (B) has round stems
that branch at the base and are 10 to 20 inches high.
Heads are erect to slightly nodding, densely flowered, usu-
ally green to purple colored, and tapers slightly toward the
summit. Giant foxtail (C) is similar in many ways to green
foxtail, except it is taller, the stem weaker and often
lodged, the head is more lax and nodding, and the leaf
blades often are softly hairy beneath. It is seldom a weed
in lawns.






Field Sandbur


Field sandbur is a summer annual grass that reproduces by
seed that are borne in burs in terminal spikes. It is trou-
blesome in lawns, gardens, crops, and waste places mainly
because the spiny burs cause discomfort to persons and
animals. Stems are erect and often spreading and mat-like,
6 to 24 inches long. It is found mostly in sandy soils
along the South Atlantic Coastal Plain from Virginia to
Texas and westward from Arkansas to California.







Yellow Woodsorrel


Yellow woodsorrel, a perennial, reproduces by seed. It is a
low-growing plant, 4 to 12 inches tall. The weak stems
branch at the base and may root at the joints. Leaves are
divided into three folded, heart-shaped leaflets that radiate
from the end of a long, slender leaf stalk. Leaves are sour
tasting. The yellow flowers have five petals and occur in
clusters.






Yellow Nutsedge


Yellow nutsedge, incorrectly called nutgrass, is a grass-like
perennial weed. It reproduces by seed and tubers on the
underground lateral stems. Mature plants have nut-like
tubers at the tips of the lateral stems. Above-ground stems
grow erect and are triangular in cross section and
yellowish-green in color. Looking down on the plant, the
leaves appear in three ranks corresponding to the triangu-
lar stem rather than two ranks as in grasses. Nutsedge is
found in lawns in low, wet areas and in lawns that are
watered excessively in the summer.






Wild Garlic


Wild garlic is a perennial bulbous herb. It reproduces by
bulbs, bulblets, and seed. The stem is stiff, erect, leafy to
near the middle, and 12 to 50 inches tall. Leaves are 2-
ranked, with sheathing bases, the leaf blades circular and
hollow in cross section, striped, the younger ones easily
flattened and slenderly tapering. Plants form four types of
bulbs: aerial bulblets at end of upright stem, underground
hard shell bulbs (dormant) that have a single bladeless
storage leaf that contains a growing point at its base, cen-
tral bulbs, and soft offset bulbs.


'r 'ri 1






Prostrate Knotweed


Prostrate knotweed is a summer annual weed that repro-
duces by seed. Stems are 4 to 40 inches long, prostrate or
loosely ascending, the main stem corrugated, much-
branched, and mostly forming mats from thin taproots.
Leaves are alternate, sharp-pointed to rounded at the end,
narrowed at the base, blue-green, lanceolate, linear to ob-
long, 3/16 to 1 inch long and from 1/16 to 5/16 inch wide.
It is found throughout the United States.

31






Spotted Spurge


Spotted spurge, also known as prostrate spurge, is a sum-
mer annual reproduced by seed. Stems are slender, pros-
trate or ascending, branching from near the base, forming
mats 4 to 36 inches in diameter, soft, hairy, and often red-
dish, and have a milky juice. Leaves are opposite, 3/16 to
5/8 inch long, ovate to oblong in shape, and often
purple-mottled in appearance. It is distributed throughout
the Eastern and Central States, the Pax ifi Coast, and a few
areas in Idaho and Arizona.






Common Chickweed


Mouseear Chickweed


Common chickweed and mouseear chickweed are similar
in habit growth. Common chickweed is a low-spreading
plant, and mouseear chickweed is partly spreading to
erect. Leaves on both plants are small, single, and opposite
each other on the stems. Flowers on both are small; the
petals are white and fine. But there are distinct differences:
(1) Leaves of common chickweed are broadly oval, point-
ed at the tip, not hairy, and are borne on short leaf stalks;
leaves of mouseear chickweed are very hairy, more
elongated than round, and attached directly to the stem.
(2) Flower petals are slightly notched on mouseear
chickweed, and deeply notched on common chickweed.
Common chickweed is an annual or winter annual that
reproduces by seed and by creeping stems that root at the
joints. Mouseear chickweed is a perennial that normally
reproduces by seed; occasionally, it reproduces by root
development on lower branches.






Ground Ivy


\ \












\ !.
^.*,.
^ \( .^-,


Ground ivy, a perennial, reproduces by seed and by creep-
ing stems. Stems that are prostrate root at the joints;
those that are upright give rise to long leaf stalks. Stems
have four sides. The bright 'reen leaves are almost round
with round-toothed edges, and V2 to 1/2 inches in diame-
ter. Flowers are small, bluish purple, funnel shaped, and
borne in small clusters in the axils of the leaves.






Henbit


Henbit is a winter annual that reproduces by seed and,
occasionally, by rooting at the joints where stems touch
the ground. Stems are 4 to 6 inches tall, slender, hairless,
and four-sided. Leaves are oppostie each other on the
stems, and are hairy with rounded teeth. Lower leaves are
borne on leaf stalks; upper leaves are attached directly to
the stem and clasp the stem. Flowers are pinkish to pur-
ple.






Purslane Speedwell


~f2

I. /


Purslane speedwell is a winter annual that reproduces by
seed. Its root system is quite fibrous. The small, white
flowers are located in the axils of the upper leaves. The
seed pod is flat, heart shaped, and about 1/8 inch wide.
The weed is noticed especially in early spring when
bluegrass is just starting to grow well.






Common or Corn Speedwell


Common or corn speedwell is a winter annual that repro-
duces by seed. Its leaves are more oval than those of
purslane speedwell and are notched on the margins. The
flower petals are blue, and the whole plant is covered
with tiny hairs. The heart-shaped seed capsule may be 1/4
inch wide. Like purslane speedwell, this weed is found
growing in lawns in early spring when bluegrass is making
vigorous growth.






Plantains


Buckhorn, broadleaf, and blackseed plantains commonly
found in lawns are perennial plants that reproduce only by
seed. All have erect, leafless stems that terminate with a
flower spike. (A) Buckhorn plantain leaves are all basal in a
rosette, the blades are slender, lanceolate, with 3 to 5
prominent veins tapering into the petiole. This weed is
found throughout the United States with heaviest concen-
trations in the Middle Eastern States eastward from Nebras-
ka and Kansas. (B) Broadleaf plantain has broadly ovate
leaves, about 2 to 12 inches long, that form a rosette. The
blades are thick, rough on one or both sides when dry,
with minute hairs. The petioles are broad, usually green
(no purple tinge), and hairy at the base. It is found
throughout the United States. (C) Blackseed plantain has
broadly elliptic to oval leaves, about 2 to 8 inches long,
that form a basal rosette. The blade is simple, thin, pale,
hairless to slightly hairy, usually wavy-edged, petiole is
margined, at base usually hairless and tinged with purple.
It is found in the eastern half of the United States.






Red Sorrell


Red sorrell is a perennial that reproduces by creeping
rootstocks and seed. It gets its name from the reddish
appearance of the seed head. The rootstocks are shallow.
The leaves are 1 to 2 inches long, thick with smooth sur-
face, and sour tasting. The weed is seen mostly in the
spring and fall when it is cooler. It persists in areas of poor
drainage and acid soil conditions.






Dandelion


.. f -i .. ...<,,>- -. -, .


sp ol s n t _u Flowe ,-







many-branched crowns, with milky juice, and it repro-'












heads are golden-yellow, I to 2 inches in diameter in
Nli er, solitary at the end of a naked hollow stalk 2 to 30
inches long. It is found throughout most of the United
States.






Use of Pesticides

This publication is intended for na-
tionwide distribution. Pesticides are
registered by the Environmental Pro-
tection Agency (EPA) for country-
wide use unless otherwise indicated
on the label.

The use of pesticides is governed by
the provisions of the Federal Insecti-
cide, Fungicide, and Rodenticide Act,
as amended. This act is administered
by EPA. According to the provisions
of the act, "It shall be unlawful for
any person to use any registered
pesticides in a manner inconsistent
with its labeling." (Section 12(a) (2)
G))

The optimum use of pesticides, both
as to rate and frequency, may vary
in different sections of the country.
Users of this publication may also
wish to consult their Cooperative Ex-
tension Service, State agricultural ex-
periment stations, or county exten-
sion agents for information applica-
ble to their localities.

The pesticides mentioned in this
publication are available in several
different formulations that contain
varying amounts of active ingredient.
Because of these differences, the
rates given in this publication refer
to the amount of active ingredient,
unless otherwise indicated. Users are
reminded to convert the rate in the
publication to the strength of the
pesticide actually being used. For ex-
ample, 1 pound of active ingredient
equals 2 pounds of a 50-percent for-
mulation.


The user is cautioned to read and
follow all directions and precautions
given on the label of the pesticide
formulation being used.

Federal and State regulations require
registration numbers. Use only pesti-
cides that carry one of these regis-
tration numbers.

Federal and State regulations require
registration numbers. Use only pesti-
cides that carry one of these regis-
tration numbers.

USDA publications that contain
suggestions for the use of pesticides
are normally revised at 2-year inter-
vals. If your copy is more than 2
years old, contact your Cooperative
Extension Service to determine the
latest pesticide recommendations.

The pesticides mentioned in this
publication were federally registered
for the use indicated as of the issue
of this publication. The user is cau-
tioned to determine the directions
on the label or labeling prior to use
of the pesticide.


Follow

Pesticides
Label Exactly


*U.8. GOVERNMENT PRINTING OFFICE: 198 4 42 1 22 7 10 0 16










WI Ii
UNIVERSITY OF FLORIDA
I 1111 i i II II III I l l i I ll Ii111 21
3 1262 08584 2887
1:




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