weed management in turf
TRANSCRIPT
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College of AgriCulturAl SCienCeS
AgriCulturAl reSeArCh And CooperAtive extenSion
weedManagement
inTURF
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Contents
Weed lie cycles .................................................................1
Weed identifcation ............................................................ 2
Growth habits o grasses ........................................... 2
Vegetative structures o grasses ................................. 3
Grass seedheads ........................................................ 4
Weed descriptions: Grasses and grasslike weeds ............. 5
Crabgrass .................................................................. 5
Goosegrass ................................................................ 5
Barnyardgrass............................................................ 6
Foxtail ....................................................................... 6
Annual bluegrass ....................................................... 7
Bentgrass ................................................................... 7
Orchardgrass ............................................................. 8
Nimblewill ................................................................. 8
Yellow nutsedge ......................................................... 9
Wild garlic ................................................................. 9
Weed descriptions: Broadlea weeds ............................... 10
Black medic ..............................................................10
Prostrate knotweed ...................................................10
Prostrate spurge ........................................................10
Purslane....................................................................11
Common chickweed .................................................11
Corn speedwell .........................................................11
Dog ennel ................................................................12
Henbit ......................................................................12
Mallow .....................................................................12
Yellow rocket ............................................................13Broadlea plantain ...................................................13
Buckhorn plantain ...................................................13
Creeping speedwell ..................................................14
Cinqueoil .................................................................14
Creeping buttercup ..................................................14
Dandelion ................................................................15
Ground ivy ...............................................................15
Heal-all.....................................................................15
Wild violet ................................................................16
White clover .............................................................16
Yellow woodsorrel ...................................................16
Yellow and orange hawkweed ...................................17
Cultural practices or improved weed management........ 17
Chemical weed control ....................................................17
Chemical control o grass and grasslike weeds .........18
Chemical control o broadlea weeds .......................19
Chemical control, by weed species ............................21
tables
Table 1. Some preemergence herbicides or the control o
summer annual grasses. ................................. 18
Table 2.Some postemergence herbicides or the control
o summer annual grasses. ............................. 18
Table 3. Some broadlea herbicides and herbicide combi-
nations or use in cool-season tur. ................ 20
Table 4.Suggestions or selective control o turgrass
weeds in Pennsylvania, by weed species.......... 22
Table 5. Suggestions or nonselective control o turgrass
weeds in Pennsylvania, by weed species.......... 27
Gru ckwdgm i md h sc
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Idifci Dic tur Wd.
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1
The simplest defnition o a weed
is a plant that grows where it is
not wanted. Creeping bentgrass,
a turgrass used on gol courses,
is oten considered a weed
because it is unwanted in
Kentucky bluegrass lawns. Weeds
are undesirable because they dis-
rupt tur uniormity and
compete with desirable grass spe-
cies or moisture, light, and nutri-
ents. Some weeds are harmul to
people because they attract bees,
cause skin irritation, or cause
poisoning i ingested.
An eective weed manage-
ment program depends on your
ability to identiy weeds and to
understand their lie cycles.
This inormation is essential
or developing a good cultural
weed management program. It
is also necessary or selectingherbicides and or determining
the proper time o year to
apply them.
Weed life cyclesTurgrass weeds can be grouped into one o three lie
cycles: annual, biennial, or perennial. Annuals are plants
that complete their lie cycle in one growing season.
Seeds o summer annuals germinate in spring, produce
vegetative growth in spring and summer, then produce
seed and die in the all. Winter annual seeds germinatein all; grow during all, winter, and early spring; then
produce seed and die in late spring. Examples o summer
annual weeds are crabgrass and prostrate knotweed. Two
winter annual weeds are annual bluegrass and common
chickweed.
Biennials require two growing seasons to complete
their lie cycles. They usually produce vegetative growth
the rst year, then fower and set seed during the second
year. Examples o biennial weeds are yellow rocket and
wild carrot.
Perennial weeds live or three or more years (al-
though leaves and aboveground stems oten die back at
the end o the growing season). Perennials produce newvegetative growth rom growing points at or below the
soil surace. Perennials also produce new plants rom
seed. Examples o perennial weeds are orchardgrass and
dandelion.
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Leaf arrangement
Ara Oo
B-
Rzomao
sooro
Bunch-type, rhizomatous, and
stoloniferous growth habits
Weed identificAtiOnTo identiy weeds you must rst distinguish between
broadlea weeds and grass weeds. Broadlea weeds usu-
ally have wider lea blades than grass weeds. Each lea
typically has a main vein that divides the lea in hal with
a network o smaller veins (originating rom the main
vein) orming a netlike pattern.Broadlea weeds have distinct lea shapes and surace
characteristics that can be used in identication. The
arrangement o leaves on stems can also be a useul
identication aid. Leaves either are alternately arranged
(when a lea grows rom a node on one side o the stem
and another is produced on the opposite side urther up
the stem) or arranged opposite one another.
Some broadlea weeds produce leaves in a circular
pattern (rosette) rom a central growing point located at
or beneath the soil surace. Others grow and spread by
means o creeping aboveground stems called stolons or
belowground stems called rhizomes. Broadlea weeds can
produce a brous root system or a root system domi-
nated by a large, feshy taproot.
Broadlea weeds oten bear colorul fowers o dier-ent sizes and shapes. At certain times o the year fowers
can be very useul identication aids.
Grass weeds have long, narrow leaves with veins run-
ning parallel to each other (they do not orm a netlike
pattern). Grasses do not have showy or colorul fowers,
and lea shapes are similar among species. The ability to
identiy grasses depends on recognizing growth habits,
certain vegetative eatures, and seedheads.
Growth habits of grasses
Growth habits o grasses can be divided into three dier-
ent categories: bunch-type, rhizomatous, and stolonier-
ous. In plants having a bunch-type growth habit, newstems are produced by tillering. A tiller is a stem that
arises rom a bud in the crown and grows vertically, re-
maining enclosed by the lea sheath. Although all grasses
produce tillers, only those that spread by tillering alone
are reerred to as bunch-type grasses.
In plants with the rhizomatous growth habit, lateral
growth occurs by horizontal creeping underground stems
called rhizomes. Rhizomes are produced rom buds in the
crown that break through the outer lea sheath. Rhi-
zomes produce nodes that can give rise to new tillers.
In plants having the stolonierous growth habit, lateral
growth occurs by horizontal creeping aboveground stems
called stolons. Stolons are produced rom buds in the
crown that break through the outer lea sheath. Stolons
produce nodes that can give rise to new tillers. Stolons are
usually green, whereas rhizomes are usually white.
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coar rgo
la a
la ba
The grass leaf
Vernation
Ro fo
Ligules
cawk Rmar Ab
Auricles
Leaf blade tips
B a targ o a ar oK a
Vegetative structures of grasses
Several vegetative eatures can be used to identiy grass
weeds. The most important are lea blade characteristics
and the structures associated with the collar.
Vernation is a term used to describe the arrangement o
the youngest lea in the bud shoot. Grasses with olded
vernation have leaves that are olded in a V-shape. Leaves
with rolled vernation are round with no olds. To deter-
mine i the grass has olded or rolled vernation, hold the
plant between your thumb and index nger and roll it.
I it rolls like a straw, it has rolled vernation, i it lies fat
and has edges, it is olded. You can also determine verna-
tion by cutting a cross-section o the stem just below the
lea blade.
Lea blades o grasses can vary in width and hairiness.
Some grasses have lea blades that are dominated by a
single prominent vein in the center o the lea. Others have
equal-sized veins running lengthwise over the entire width
o the blade. Lea blade tips may terminate in a sharp
point, a blunt tip, or keeled shape (boat-shaped tip).
The collar region is located between the lea blade and
lea sheath. It may or may not contain structures called
ligules and auricles. A ligule is the membranous or hairytissue located at the junction o the lea blade and lea
sheath. Ligules can vary considerably in size and shape
and may be membranous, a ringe o hairs, or absent.
Auricles are appendages that are considered an exten-
sion o the collar. They can be long or clawlike, small or
rudimentary, or absent.
Mmbrao frg o ar Ab
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Grass seedheads
Seedheads may be useul in distinguishing among grass
weeds. They can appear as open-panicle types, compact
spikes, and divided spikes.
O-a
a
d k-
a
coma, k
a
Grass seedheads
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Weed descRiptiOns: GRAsses And GRAssliKe Weeds
Crabgrass (Digitariaspp.)Two species o crabgrass, hairy and smooth, are com-
monly ound in Pennsylvania (smooth crabgrass pre-
dominates in turgrass stands). Both species are summer
annuals and have wide (1/4- to 1/2-inch), sparsely hairy,
pale-green leaves that taper to a sharp point. Leaves o
hairy crabgrass are hairier than smooth crabgrass. The
ligules o both species are long and membranous. Crab-
grass does not have auricles. Seedheads are divided spikes
that project like ngers rom the stem, producing thou-
sands o seeds in late summer. Seeds germinate in spring
when soil temperatures reach 55 to 58 F or several
consecutive days. Crabgrass plants die ater the rst rostin early all.
Goosegrass (Eleusine indica)
Goosegrass, also known as silver crabgrass, is common
in southern Pennsylvania. Leaves are darker green and
narrower than crabgrass (1/8 to 1/4 inch) and sheaths
have a silvery-green color (especially near the center o
the plant). The ligule o goosegrass is membranous and
divided in the center. The collar region is sparsely hairy
and has no auricles. Goosegrass has a divided spike-
type seedhead bearing seeds in straight rows on the seed
stalks. Goosegrass seeds germinate our to six weeks later
than crabgrass and germination continues throughout
the summer.
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Barnyardgrass (Echinochloa crusgalli)Barnyardgrass is a summer annual grass with wide
(greater than 1/2 inch) leaves and sheaths that lie close
to the ground. Barnyardgrass seeds germinate later than
crabgrass seeds, and plants do not tolerate low mow-
ing heights. This species has no ligule or auricles. The
seedhead is composed o compact spikes arising at
several locations on the main stalk. Barnyardgrass can be
a problem in newly established tur i seed is introduced
with the topsoil.
Foxtail (Setariaspp.)
Foxtail is a light-green, leay, summer annual grass weed
that reaches maturity in midsummer. It is oten conused
with crabgrass. As a weed in tur, oxtail is much less
common than crabgrass, but it can prolierate under low-
ertility conditions and high mowing heights as well as
in spring seedings. This weed can be distinguished rom
crabgrass by its hairy ligule and short, compact spike
seedhead.
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Annual bluegrass (Poa annua)Annual bluegrass is a light-green, small-statured, bunch-
type winter annual grass. Annual bluegrass is a highly
diverse species with some subspecies unctioning as
short-lived perennials. The ligule is long and membra-
nous and no auricles are present. Small but conspicuous
open-panicle seedheads are evident during most o the
growing season. Most seeds germinate in late summer or
early all. Although this species can persist throughout
the entire growing season on irrigated sites, it usually dies
during hot, dry conditions i not irrigated.
Bentgrass (Agrostisspp.)
Bentgrasses are desirable turgrass species when used on
gol course airways, putting greens, and croquet courts.
However, they are a common perennial grass weed
in many home lawns. Like other stolonierous weeds,
bentgrass creeps over desirable tur and orms large
light-green patches that usually turn brown in summer.
Bentgrass has rolled vernation; long membranous ligules;
no auricles; and narrow, fat lea blades that have equal-
sized veins across the entire width o the blade. The
seedhead is an open panicle but is rarely seen in lawns.
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Orchardgrass (Dactylis glomerata)Orchardgrass is a bunch-type perennial grass weed that
orms light green clumps in lawns. Leaves have olded
vernation and are wide (1/4 to 1/2 inch), light green,
and pointed at the tip. The sheaths o orchardgrass are
strongly compressed and fattened. Other eatures o
orchardgrass are the long, membranous ligule and the
open-panicle seedheads.
Nimblewill (Muhlenbergia schreberi)
Nimblewill is a blue-green perennial grass that is com-
mon in Pennsylvania lawns during summer. It spreads
over existing tur by stolons and orms dense patches.
Lea blades have a medium texture (about 1/4 inch wide)
and are short (1 1/2 to 2 inches) with lea tips taper-
ing to an abrupt point. The stems are long, slender, and
wiry with prominent nodes. Ligules are short, membra-
nous, and jagged. The lea blades have long hairs at the
margins but do not possess auricles. Seedheads are long,
slender, and inconspicuous. Nimblewill grows rapidly
during the warm summer months and turns brown or tanin winter.
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Yellow nutsedge (Cyperus esculentus)Yellow nutsedge is not a true grass but a member o the
sedge amily. Plants in this amily are characterized by
erect, triangular stems and a preerence or moist or wet
areas. Leaves and stems are yellow-green and shiny. Al-
though leaves and aboveground stems die in winter, new
growth occurs in spring and summer rom vigorous, scaly
rhizomes and nutlets that grow underground. Chestnut-
brown seedheads may be present on plants that are not
mowed.
Wild garlic (Allium vineale)
This species is a perennial weed that has a strong garlic
or onionlike odor when cut. It is one o the rst weeds to
emerge in early spring. Wild garlic produces long, slen-
der, mostly hollow leaves that are dark green and covered
by a waxy substance. Leaves emerge rom underground
bulblets that are covered by thin, papery scales. Flowers
may be present on uncut stems and can be white, pink, or
purple.
A closely related species, wild onion (Allium
canadense), looks very much like wild garlic. Wild garlic
is more common in Pennsylvania and has hollow leaves.Wild onion has fat (not hollow) leaves. Depending on
the growth stage and time o year, it may be dicult to
distinguish between these two species.
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Weed descRiptiOns: BROAdleAf Weeds
Black medic (Medicago lupulina)
Black medic is a low-growing, dark-green, summer an-
nual broadlea weed in tur. It can sometimes act as a
perennial during years when the winter is mild. Black
medic leaves have three leafets with the center leafet
extended on a short stalk. Stems may spread one or two
eet rom the original growing point but do not root at
nodes. Black medic has small, compact, yellow fowers
that orm in lea axils.
Prostrate knotweed (Polygonum aviculare)
Prostrate knotweed is a low-growing summer annual
that is well adapted to compacted, highly tracked areas
such as along sidewalks, in athletic elds, and in gol
course cart paths. The leaves are alternately arranged on
stems, small (1/2 to 1 inch long by 1/4 to 1/2 inch wide),
and blue green, and have margins that are not serrated
or lobed. Each lea is elliptical, tapering to a rounded
tip. Stems grow prostrate but do not root at nodes. One
distinct eature o knotweed is the papery sheath at thebase o each lea. Flowers are very small and white, and
grow in the lea axils.
Prostrate spurge (Euphorbia supina)
Prostrate spurge (sometimes called spotted spurge) is a
summer annual weed that spreads in a prostrate ashion
over the soil surace or over desirable grass species. Pros-
trate spurge can be recognized by its oppositely arranged,small (1/4- to 3/4-inch-long) leaves that have a reddish-
brown mark or enlarged spot on the upper surace. When
broken or cut, the stems exude a white, milky substance.
Flowers o spotted spurge are very small and pink or
white. This species is common in newly established
tur and requently occurs in mature tur that has been
thinned by insect attack.
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Purslane (Portulaca oleracea)
Purslane is a prostrate-growing, succulent (feshy) sum-
mer annual that grows in newly established tur or in thin
lawns. Stems are thick, sprawling, and red. Leaves are
thick and feshy, light green and wedge-shaped. Flowers
are small and yellow. Purslane is a prolic seed producer
and seeds may lie dormant in soil or many years beore
germinating.
Common chickweed (Stellaria media)
Common chickweed is most oten classied as a winter
annual, but it can grow and fower at any time during the
growing season. Leaves are small and elliptical (tapering
to a point), and occur opposite one another on square
stems that have a single row o hairs. Lea suraces are
smooth (not covered with hairs). Common chickweed
spreads in tur via branched, creeping, aboveground
stems that root at the nodes. Flowers are small and white,
and have ve petals. Common chickweed orms densepatches in high-cut tur and preers moist, shaded areas,
but it can grow in sunny areas and under very low mow-
ing heights (less than 1/4 inch).
Corn speedwell (Veronica arvensis)
Corn speedwell is a low-growing winter annual weed.
Upper leaves are small and taper to a point, whereas
lower leaves are rounded and lobed. Stems have an up-
right growth habit and do not spread more than an inchor two rom the crown. Plants are covered with sparse,
ne hairs. The plants most notable eatures are the small
blue fowers that grow in the lea axils and its heart-
shaped seed capsules. This weed grows in thin tur during
cool weather.
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Dog fennel (Anthemis cotula)
Dog ennel (also known as mayweed) is a winter annual.
It has nely divided leaves that give o an acrid odor
when crushed. The plant can grow up to six inches tall,
but it has the ability to escape damage by lawn mowers.
Dog ennel has a taproot and does not root at nodes. Per-
haps the plants most distinctive eature is the large fower
with white petals and a yellow center.
Henbit (Lamium amplexicaule)
Henbit is a winter annual weed that has oppositely ar-
ranged leaves with lobed margins. Stems are hairy and
square; they typically grow in an upright ashion but can
grow prostrate and occasionally root at nodes. Flowers
occur in the axils o upper leaves. They are pale purple,
long (up to 3/8 inch), and trumpet-shaped. Henbit is
ound in moist soils and can be especially troublesome in
tur during early spring.
Mallow (Malva rotundiolia)
Mallow is a biennial most oten ound in poorly main-
tained and underertilized tur. Leaves are large (greater
than 1 inch in diameter) and round with serrated mar-
gins. Mallow produces sprawling branches that ormnodes that do not root. Flowers are pink to lavender and
are produced in the axils o leaves and stems.
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Yellow rocket (Barbara vulgaris)
Yellow rocket unctions as a biennial, winter annual, or
perennial weed. It produces a rosette o leaves in tur.
Individual leaves are strongly lobed and terminate with a
large rounded lobe. In most cases, fowers do not develop
under low mowing heights, but bright yellow fowers
clustered at the tips o the uppermost branches can be
observed around ence posts or other structures that are
unmowed.
Broadleaf plantain (Plantago major)
Broadlea plantain is a large (3- to 6-inch diameter),
low-growing, perennial weed in Pennsylvania lawns.
Leaves grow in a rosette ashion and are spoon-shaped
with wavy margins. Prominent veins run lengthwise on
the lea surace. Seedheads are long (5 to 10 inches) and
are covered with seeds that adhere tightly to the stalk.
Broadlea plantain has a thick tap root that grows deep
into the soil.
Buckhorn plantain (Plantago lanceolata)
Buckhorn plantain is closely related to broadlea plan-
tain. It is a large perennial broadlea weed that grows in
a rosette ashion. Leaves are long and much more slender
than those o broadlea plantain. Individual leaves taperto a point and have prominent longitudinal veins and
smooth, wavy margins. Seed stalks are long and termi-
nate in small compact seedheads.
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Creeping speedwell (Veronica fliormis)Creeping speedwell, a perennial, is a small-statured plant
that can creep over desirable turgrasses and orm dense,
light-green patches several eet in diameter. Leaves are
oppositely arranged, very small (1/4 to 1/2 inch in diam-
eter), and rounded with scalloped margins. Stems grow
horizontally above ground and root at the nodes. Creep-
ing speedwell produces small blue and white fowers in
spring. Seed capsules are heart-shaped.
Cinquefoil(Potentillaspp.)Cinqueoil is a perennial weed that grows in low-ertility
soils and spreads by stolons. Depending on the species,
leaves have three to ve leafets with serrated margins.
Flowers o cinqueoil are small and bright yellow, and
have ve petals.
Creeping buttercup (Ranunculus repens)
Creeping buttercup spreads by extensive stolons that can
quickly take over large areas o thinned tur. Leaves are
dark green and divided into three segments. The fowers
are small, bright yellow, and cup-shaped.
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Dandelion (Taraxacum ofcinale)Dandelion is the best-known and perhaps the most com-
mon perennial turgrass weed in Pennsylvania. It orms a
rosette o long, narrow, and strongly lobed leaves. Dan-
delions produce thick taproots that can penetrate up to
several inches into the soil. Bright-yellow fowers (1 inch
in diameter) are produced on long stems in spring.
Ground ivy(Glecoma hederacea)
Ground ivy is a low-growing, creeping, perennial broa-
dlea weed. Leaves are oppositely arranged on stems
and are round or kidney-shaped with scalloped margins.
The upper lea surace has distinct veins and is sparsely
hairy. Stems are square, creeping, and long. Ground ivy
produces nodes that root at lea and stem axils and that
can orm new stolons. Flowers are blue or purple and
trumpet-shaped. This weed is most common in shaded
areas, but it can also grow in ull sun.
Heal-all (Prunella vulgaris)
Heal-all, a perennial weed, grows horizontally in tur
by means o creeping, aboveground stems that can root
at nodes. Leaves are oppositely arranged on stems and
broad at the base; they taper to a blunt tip. Veins areprominent on the upper lea surace, and margins are
smooth (not lobed or serrated). As with other members
o the mint amily, stems are square. Flowers are violet to
purple and are produced in dense clusters at the tips o
branches.
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Wild violet (Viola papilionacea)Wild violets are persistent perennial weeds that are di-
cult to control in tur. This species is an upright grower
that spreads by means o thick underground stems.
Leaves are heart-shaped and margins are serrated. The
lea surace is shiny owing to a thick waxy covering.
Flower petals are purple, and the center o the fower is
white or yellow.
White clover(Triolium repens)
Clover is a very common weed in nearly all tured areas.
Although some homeowners do not nd clover objec-
tionable, its creeping growth habit can overtake tur and
orm large dark-green patches. Clover leaves are com-
posed o three leafets, each with a small white mark in
the center. Stems grow above ground and root at nodes.
Clover produces white, compact fowers that are about
1/2 inch in diameter.
Yellow woodsorrel (Oxalis stricta)
Yellow woodsorrel (sometimes called oxalis) is a light-
green, upright perennial weed. Like clover and black
medic, each lea has three leafets. Leafets o yellow
woodsorrel can be distinguished rom other weeds bytheir distinct heart shape. Flowers are bright yellow with
ve petals. As fowers mature, they lose their petals and
orm banana-shaped seedpods that orcibly eject seeds.
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cultuRAl pRActices fOR iMpROved
Weed MAnAGeMentAny cultural practice that increases the density and vigor
o desirable turgrasses will discourage competition rom
weeds. Weeds can only exist i there is space or them.
Thus, cultural practices or weed control in tur are
aimed at shading and crowding the young weed seed-
lings by producing a dense sod. Eective cultural control
measures include the proper selection and establishmento turgrasses, adequate liming and ertilization, proper
mowing practices, judicious watering, and insect and
disease control.
Turgrasses that are not adapted to the environmen-
tal conditions and intended use o the tur may become
weak, resulting in a thin stand. When there are voids in
the tur, weeds have an opportunity to grow and compete
with the desirable species. The use o proper establish-
ment procedures helps to ensure that a dense tur will
compete with germinating weed seedlings.
Too high or too low a soil pH and inadequate ertil-
ization lessens the competitiveness o turgrasses, result-
ing in reduced density and subsequent weed invasion.Soil testing is the key to proper pH management and
ertilization. Soil test recommendations provide guide-
lines or ertilization and liming to establish and main-
tain turgrasses. Adequate nitrogen should be supplied
to avor the desirable species in the stand. Phosphorus
ertilization increases seedling vigor and is one actor
in reducing weed inestations in newly established tur.
Lime should be applied when the soil is too acid, and
acidiying materials can be used when the pH is too high.
Yellow and orange hawkweed(Hieraciumspp.)
Two types o hawkweed grow in Pennsylvania, yellow
and orange. Both species are perennials that produce a
rosette growth habit. Leaves are long and slender but not
lobed or serrated. Perhaps the most distinctive eature o
these species is the abundant, bristlelike hairs that cover
the lea surace. Flowers are produced on long stems andare bright yellow (yellow hawkweed) or orange (orange
hawkweed).
Improper mowing is one o the most common causes
o weed invasion. Mowing heights that are too short
result in weakened turgrasses and weed encroachment.
Most lawns should be cut at least 2 inches or higher.
Improper watering also contributes to weed inva-
sion. Frequent light watering encourages shallow rooting
and promotes weak tur, which becomes susceptible to
insect and disease attacks as well as damage rom trac.
Frequent light watering also encourages germination
and development o weeds at the expense o turgrasses.
Watering deeply (4 to 6 inches) beore turgrasses show
signs o wilting is a practical approach to a sound water-
ing program. A soil probe can be used to monitor soil
moisture levels.
Most weeds are opportunistic, lling in voids in tur
caused by diseases and insects. Diseases can be controlled
by cultural practices and with ungicides. Insect damage
can be reduced by maintaining a healthy tur, by using
insecticides, and by using biorational means o control,
such as endophyte-containing ryegrasses and escues,
which discourage lea and stem-eeding insects.
cheMicAl Weed cOntROlHerbicides are chemicals that kill or alter the normal
growth o weeds. They can be divided into two main
groups: selective and nonselective. Selective herbicides
are those that control the target weed(s) without damag-
ing desirable turgrass species. Nonselective herbicides
kill all vegetation (including turgrasses) and are used in
lawn renovation or on weeds not controlled by selective
herbicides.
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Herbicides can be urther divided into preemergence
and postemergence categories. Preemergence herbicides
are applied prior to germination and emergence o
weeds. These are typically used or controlling annual
weeds. Postemergence herbicides are used or control-
ling weeds that have already emerged rom the soil. They
are either contact or systemic in nature. Postemergence-
contact herbicides aect only those plant parts that they
contact and are not translocated to other portions othe plant. Postemergence-systemic herbicides are trans-
located throughout the plant; hence they are eective in
controlling perennial weeds that can generate new oliage
rom underground vegetative structures.
Herbicides can be applied to oliage or soil. Poste-
mergence herbicides are usually oliar applied, whereas
preemergence herbicides are soil applied. A oliar-applied
herbicide must contact and be absorbed by oliage, and is
less eective i washed o the lea surace by rainall or
irrigation. Soil-applied herbicides can be applied as either
liquids or granulars; they should be watered into the soil
during or ollowing application.
Chemical control of grass and grasslike weeds
Summer annual grasses
Summer annual grass weeds are usually controlled with
preemergence herbicides. These herbicides act by orming
a chemical barrier in the soil prior to seed germination
or emergence. The barrier prevents grass seedlings rom
emerging and developing normally.
Table 1. Some preemergence herbicides for the control ofsummer annual grasses.
Generic name Trade name
Benen Lebanon Balan 2.5GBenen + trifuralin TeamBensulide BensumecBensulide + oxadiazon Goosegrass/Crabgrass ControlDithiopyr DimensionOxadiazon RonstarPendimethalin Pre-M, Pendulum, HaltsProdiamine BarricadeSiduron Tupersan
You can use several preemergence herbicides to con-
trol summer annual grass weeds in Pennsylvania. Table1 lists the chemical (generic) and trade names o some
commonly used preemergence herbicides.
Several actors should be considered in choosing
a preemergence herbicide. The rst is the saety o the
chemical or turgrass species and cultivars. For example,
oxadiazon may injure ne escues, but it is generally sae
on Kentucky bluegrass, ryegrass, and tall escue. Most
preemergence herbicides have long residual activity in the
soil and may aect newly seeded turgrasses. Thus, seed-
ing o turgrasses should be postponed or the amount o
time specied on the manuacturers label. Siduron is the
only material that can be saely used during or immedi-
ately ollowing seeding.
For maximum eectiveness, preemergence herbicides
should be applied uniormly at the label recommended
rates. These herbicides are more ecient when watered-in
within two to three days o application.
The timing o preemergence herbicide applications
is the most critical component o an eective chemi-cal control program. As a general rule, the best time to
apply preemergence materials is approximately 10 to 14
days prior to the expected germination period in spring.
Crabgrass begins to germinate when soils are moist and
the temperature in the upper inch o soil reaches 55 to
58 F at daybreak or our to ve days. Forsythia fower
petal all is not a consistently reliable means o determin-
ing timing o crabgrass herbicide applications. Normally,
preemergence crabgrass treatment in Pennsylvania
should take place as ollows:
Southeastern Pennsylvania March 15 to April 15
Northern tier and high altitude counties April 20 to May 10Other Pennsylvania areas April 1 to May 1
Depending on the product, time o application, and
location, reapplication within 60 days may be required
or season-long control. Consult product labels to de-
termine i two applications are allowed or needed. Poor
weed control may occur with late applications. In these
cases, postemergence herbicides may be required.
Goosegrass germinates later than crabgrass. Preemer-
gence herbicide applications to control goosegrass should
take place three to our weeks ater the normal dates or
applying crabgrass control materials.
Postemergence control o crabgrass and some othersummer annual weeds involves the use o chemicals that
kill growing plants ater they have appeared in the tur.
Postemergence herbicides can be used to treat only those
areas where summer annual grass weeds have emerged.
Preemergence herbicides, on the other hand, are usually
applied over the entire tur area since the applicator does
not know where seeds are or i they are present.
For postemergence herbicides to be eective, crab-
grass must be uniormly covered. Thus, these compounds
should be applied only when crabgrass is visible in the
stand. Table 2 lists the chemical and trade names o some
commonly used postemergence herbicides or annual
grass control.
Table 2. Some postemergence herbicides for the controlof summer annual grasses.
Generic name Trade name
Dithiopyr DimensionDSMA Methar 30Fenoxaprop-p-ethyl Acclaim ExtraMSMA MSMA Tur HerbicideQuinclorac Drive 75 DF Herbicide
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The methanearsonates (MSMA and DSMA) act as
contact herbicides. The most commonly used methanear-
sonate, MSMA, may injure desirable species at high tem-
peratures (greater than 80 F), and repeat applications at
specied intervals are necessary or complete control (see
label). It is important not to water tur or 24 hours ater
application. MSMA is eective in controlling crabgrass
under both adequate and low soil moisture levels.
Fenoxaprop-p-ethyl is a postemergence herbicide thatis slowly translocated within the plant. It can eectively
control tillered crabgrass with a single application. It is
relatively sae on cool-season turgrasses but may injure
some Kentucky bluegrass cultivars, especially at high
temperatures early in the season. It should not be applied
i cool-season turs show signs o drought stress. Fenox-
aprop-p-ethyl is less eective when tank-mixed with
phenoxy-type herbicides such as 2,4-D and MCPP.
Dithiopyr acts as a preemergence and postemergence
herbicide. It provides postemergence control o crabgrass
only up to the one-tiller stage o development, but it can
be combined with enoxaprop-p-ethyl when two or more
tillers are present.
Quinclorac is a postemergence herbicide eective in
controlling crabgrass and some broadlea weeds. Optimum
control o crabgrass is achieved when quinclorac is applied
beore development o the second tiller or when crabgrass
plants have fve or more tillers. In some cases, quinclorac
does not provide complete control o crabgrass at the two-,
three-, and our-tiller stages o development. In these situ-
ations, a second application may be required or complete
control. Quinclorac can be mixed with other herbicides, in-
cluding pendimethalin and phenoxy herbicides, to improve
weed control. For best results, apply quinclorac in combi-
nation with a methylated seed oil according to directionson the label.
Postemergence herbicides can be combined with
preemergence herbicides to ensure that late-germinating
summer annual grasses will be controlled along with
weeds that have already emerged. Studies at Penn State
have demonstrated improved control o crabgrass with
postemergence-preemergence applications over postemer-
gence applications alone. Be sure to ollow label direc-
tions when considering combinations o herbicides.
Winter annual grasses
Annual bluegrass is a tenacious and dicult-to-control
winter annual grass weed in tur. The ollowing should beused only as a guide or determining which products and
methods are available or controlling this weed.
Beore attempting to manage this species, realize
that complete eradication is nearly impossible and that
acceptable control may take several years to achieve.
A chemical control program will usually be ineec-
tive without a well-designed cultural control program
that avors desirable tur species over annual bluegrass.
Chemical control o annual bluegrass can be attempted
with preemergence herbicides, herbicides that have both
preemergence and postemergence activity, and chemical
growth regulators.
Several commercial preemergence herbicides can be
used or annual bluegrass control. Application should
take place in September just prior to the peak period o
annual bluegrass germination. Since seeds o this species
germinate at dierent times o the year, complete control
with a single application o a preemergence herbicide
is unlikely. Although repeat applications will improvecontrol, newly developing roots and rhizomes o desir-
able turgrass species may be inhibited. Only the annual
subspecies o annual bluegrass can be controlled with
preemergence herbicides. Be sure to ollow label precau-
tions i overseeding with turgrasses.
Ethoumesate (Prograss) is a herbicide that has
both pre- and postemergence activity against annual
bluegrass. This herbicide can be applied to perennial
ryegrass and Kentucky bluegrass, and is labeled or use
on creeping bentgrass airways. At least two applica-
tions o ethoumesate are required or successul control.
Applications should be about 30 days apart beginning in
September and the last application should take place no
later than December 1 or ater soil temperatures all be-
low 40 F. Be sure to ollow label directions as rates vary
depending on the turgrass species present.
Reduction o annual bluegrass populations in
bentgrass airways can be achieved with applications
o the growth regulators paclobutrazol (Trimmit) or
furprimidol (Cutless). The best results occur with both
spring and all applications. Both products reduce growth
and cause yellowing o annual bluegrass or up to ve
weeks ater application. The use o growth regulators or
annual bluegrass control requires a great deal o care and
a undamental knowledge o gol course management.Perennial grass weeds
Most perennial grass weeds cannot be controlled with
selective herbicides in tur. Spot treatment with a nonse-
lective herbicide such as glyphosate (Roundup) is the
most reliable means o removing these weeds rom tur.
Glyphosate is an especially eective herbicide or peren-
nial grass weeds since it is translocated through stolons
and rhizomes and leaves no harmul soil residual. This
herbicide is most eective when applied to actively grow-
ing plants.
A common perennial grasslike weed, yellow nutsedge,
can be removed selectively rom tur with the herbicideshalosuluron (Sedgehammer) or bentazon (Basa-
gran). Be sure to ollow label directions and note
restrictions or nontolerant species.
Chemical control of broadleaf weeds
Broadlea weeds are usually controlled with selective
postemergence herbicides. The most common broadlea
herbicides used in tur include 2,4-D, 2,4-DP (dichlo-
rprop), MCPP (mecoprop), dicamba, clopyralid, and
triclopyr. There are many dierent commercial ormula-
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Table 3. Some broadleaf herbicides and herbicide combinations for use in cool-season turf.*
Generic name Trade name
2,4-D (amine) Solution Water Soluble, Weedestroy AM-40
Carentrazone-ethyl Quicksilver
Clopyralid (amine) Lontrel
Dicamba (amine) Banvel, K-O-G Weed Control
Fluroxypyr (amine) SpotlightMCPA (amine) MCPA-4 Amine
MCPA (ester) MCPA LV 4 Ester
MCPP (potassium salt) MCPP 4K Tur Herbicide
MCPP (amine) MCPP-p 4 Amine
Triclopyr (ester) Turfon Ester
2,4-D + 2,4-DP (ester) Tur Weed & Brush Control
2,4-D + 2,4-DP + MCPP (amine) Triamine, Triamine Jet Spray
2,4-D + clopyralid + dicamba (amine) Millenium Ultra
2,4-D + MCPP + dicamba (amine) Trimec Tur Herbicide, Trimec Bentgrass Formula, Triplet Selective, Triplet Hi-D,
Triplet SF, Three-Way Selective, Bentgrass Selective, Ortho Weed B Gon,
Spectracide, Weed Stop, Bayer Advanced Weed Killer or Lawns
2,4-D + MCPP + dicamba + carentrazone Speed Zone2,4-D, MCPP, dicamba + sulentrazone Surge
2,4-D + triclopyr (amine) Turfon II Amine, Chaser 2 Amine
2,4-D + triclopyr (butoxyethyl ester) Chaser Tur Herbicde
2,4-D + triclopyr + clopyralid (amine) Momentum
MCPA + 2,4-DP + MCPP (amine) Triamine II
MCPA + clopyralid + dicamba (amine) Trupower
MCPA + MCPP + dicamba (amine) Tripower Selective
MCPA + MCPP + dicamba + carentrazone Power Zone
MCPA + triclopyr + clopyralid (amine) Battleship
MCPA + triclopyr + dicamba (amine) Horsepower
MCPA + triclopyr + dicamba (ester) Cool Power, Three-Way Ester II
Triclopyr + clopyralid (amine) ConrontIsoxaben (preemergence herbicide) Gallery 75 DF
*Products containing clopyralid should not be used on residential lawns, but they can be used on institutional grounds, athletic felds, and gol
courses.
tions and mixtures o these compounds (see Table 3).
It is extremely important to identiy the weed(s) to be
controlled beore selecting one o these herbicides. All
have the potential to damage trees, shrubs, fowers, and
vegetables i they contact the oliage. Trees and shrubs
are particularly sensitive to dicamba since this herbicideis mobile in the soil and can be taken up by tree roots.
Liquid postemergence broadlea herbicides are avail-
able as salts and esters. The most popular salt ormula-
tion is the amine salt. The amine salt is soluble in water
and suitable or spray applications. Amine ormulations
are nonvolatile, but they can react with calcium and
magnesium ions (present in hard water and ertilizer
solutions) to orm insoluble salts.
Esters are insoluble in water but soluble in organic
solvents and oils; hence, they are ormulated as emulsi-
able concentrates. When added to water, ester ormula-
tions orm emulsions and do not react with calcium and
magnesium ions. Esters provide better penetration o
the thick waxy coating on leaves o some weeds when
compared with salts.
Esters can be classied as short- or long-chainmolecules. Short-chain esters are highly volatile and can
damage sensitive nontarget plants. Volatility increases
as temperatures increase and thereore esters are usually
used during cool weather. Volatility o long-chain ester
ormulations, such as butoxyethyls, is minor and gener-
ally presents no serious problems when used according to
environmental restraints listed on the label. Only long-
chain esters are used or tur weed control.
The most eective control o broadlea weeds is
obtained when postemergence herbicides are applied as
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sprays to oliage (and not washed o). Granular ormu-
lations o these products are sometimes used to control
broadlea weeds; however, granulars should be applied to
moist (dew-covered) oliage or optimum control.
Postemergence broadlea herbicides are most eec-
tive when weeds are actively growing (spring and all)
and when air temperatures are greater than 70 F. During
these periods, absorption and translocation o the her-
bicides by weeds are greatest, and desirable tur specieshave a chance to grow into the voids let ater the weeds
are killed. Consult herbicide product labels or optimum
environmental conditions and timing o application.
Some manuacturers have attempted to satisy the
demand or aster kill o broadlea weeds by adding the
ast-acting herbicide, carentrazone, to ormulations con-
taining slower-acting, systemic herbicides. Carentrazone
belongs to a class o herbicides called protox inhibitors
and acts on broadlea weeds by disrupting chlorophyll
synthesis, resulting in rapid yellowing and desiccation.
This herbicide does not translocate throughout the plant;
thus, it does not provide good broadlea weed control
by itsel. However, when it is combined with the systemic
broadlea herbicides 2,4-D, MCPA, MCPP, and dicam-
ba, the result is ast burndown and, eventually, complete
kill.
Clopyralid is a broad-spectrum broadlea herbicide
present in numerous herbicide ormulations and used
widely in cool-season tur. In 2003, labels o products
containing clopyralid were amended to eliminate use on
residential tur in the United States. This was done in
response to concerns about the potential or damage to
sensitive plants rom clopyralid-treated tur residues in
compost. The label change was based on several reports
o plant damage rom compost containing trace amountso clopyralid and not on human health concerns.
Clopyralid-containing products can still be used in non-
residential tur markets, such as institutional grounds,
athletic elds, and gol courses.A ew annual broadlea weeds are controlled with
preemergence herbicides. Spotted spurge, or example,
is controlled with prodiamine, a common annual grass
herbicide. One preemergence broadlea herbicide, isoxa-
ben (Gallery), controls a wide spectrum o annual
broadlea weeds; however, this material has no activity
on broadlea weeds when generated rom underground
vegetative structures.
Chemical control, by weed species
Herbicides or combinations o herbicides used to control
weeds are listed, by weed species, in Tables 4 and 5. For
convenience, additional inormation is provided on toler-
ant species, dates o application, and methods o applica-
tion. These suggestions are not a substitute or pesticide
labels. The label provides detailed inormation on saety
and proper use o the herbicide. Read the entire label
beore applying any pesticide.
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Table 4. Suggestions for selective control of turfgrass weeds in Pennsylvania, by weed species.*
Weed Material Apply Remarks
AnnuAl BlueGRAss
Poa annua bensulide Late summer Apply just prior to expected annual bluegrassgermination (late August or early September).Eectiveness o control varies. Only eective inreducing populations o the annual subspecies o
or annual bluegrass.
ethoumesate September and For use on established perennial ryegrass orOctober Kentucky bluegrass or when establishing perennial
ryegrass. Two applications are necessary. Do not mixwith liquid ertilizers or other pesticides. Also labeled
or or bentgrass airways.
paclobutrazol or See remarks Use or gradual conversion rom annual bluegrass tofurprimidol creeping bentgrass in gol course airways through
selective growth retardation. Follow label directionsor application timing and rates.
BlAcK Medic
Medicago lupulina Clopyralid, or furoxypyr, Spring or all Best control when weeds are actively growing.or dicamba, or quinclorac, Products containing carentrazone provide asteror combination o products burndown o black medic than those withoutcontaining clopyralid or carentrazone.dicamba, or 2,4-D + triclopyr
chicKWeed:
Common MCPP, or dicamba, or Spring or all Best control when weeds are actively growing.Stellaria media combination o productsMouse ear containing MCPP andCerastium vulgatum dicamba, or clopyralid +
triclopyr, or 2,4-D +
triclopyr
chicORy
Cichorium intybus 2,4-D, or combination o Spring Most eective on young weeds.products containing 2,4-Dor MCPA
cinquefOil
Potentillaspp. 2,4-D + MCPP + dicamba, Spring Dicult to kill. May require repeat applications.or 2,4-D + dicamba, or2,4-D + triclopyr
clOveR
Trioliumspp. Clopyralid, or furoxypyr, or Spring, summer, Best control when weeds are actively growing.
dicamba, or quinclorac, or or all Combinations o herbicides containingcombinations o herbicides carentrazone provide aster burndown o clovercontaining clopyralid or than those without carentrazone.dicamba, or 2,4-D + triclopyr
*Suggestions or specifc herbicides are based on product label inormation and perormance in a limited number o research trials. Because
herbicide eectiveness can vary with environmental conditions, location, and methods o application, suggestions listed in this table may not
completely conorm to the turgrass saety and weed control standards indicated by research trials.
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Table 4. Suggestions for selective control of turfgrass weeds in Pennsylvania, by weed species, continued.
Weed Material Apply Remarks
cORn chAMOMile
Anthemis arvensis
dOG fennel
Anthemis cotula
pineApple Weed 2,4-D + MCPP + dicamba, Spring, summer,Matricariaspp. or 2,4-D + dicamba or all Best control when weeds are actively growing.
cRABGRAss:
Small (smooth) Preemergence control: Early to mid-spring Best controlled i herbicides are applied aboutDigitaria ischaemum benen, or benen + trifuralin, 2 weeks prior to expected crabgrass germination.Large (hairy) or bensulide, or bensulide + Crabgrass normally germinates when soilDigitaria sanguinalis oxadiazon, or dithiopyr, or temperatures near the surace reach 5558F or
oxadiazon, or pendimethalin, several consecutive days. Herbicides are moreor prodiamine, or siduron eective when watered in ollowing application.
Check labels or nontolerant species and cultivars.Check labels or intervals until overseeding can takeplace. Seeding o desirable grasses may be made atthe time o or immediately beore the application o
siduron. Eectiveness o some herbicides onestablished tur may be enhanced by a secondapplication i the label species that a secondapplication is allowed.
Postemergence control: Early summer Apply postemergence products only when crabgrassFenoxaprop-p-ethyl, is visible in the stand. Apply enoxaprop-p-ethyl onlyor methanearsonates when soil moisture is adequate and crabgrass is(DSMA or MSMA), or actively growing. This herbicide may temporarilyquinclorac, or dithiopyr discolor some Kentucky bluegrass cultivars and is
less eective i tank-mixed with phenoxy herbicides.Methanearsonates may injure desirable turgrassspecies at high temperatures (greater than 80F).Apply quinclorac beore development o secondtiller or when crabgrass plants have ve or moretillers.In some cases, quinclorac does not providecomplete control o crabgrass at the two-, three-, andour-tiller stages o development. Quinclorac can bemixed with other herbicides, including phenoxys,to improve weed control. Dithiopyr controls crabgrasspostemergence only up to tiller initiation.
cReepinG ButteRcup
Ranunculus repens 2,4-D + dicamba, or 2,4-D + Spring or all Dicult to kill. May require repeat applications.triclopyr, triclopyr + clopyralid,or 2,4-D + MCPP + dicamba,
or 2,4-D + 2,4-DP + dicamba,or 2,4-D + 2,4-DP
cuRly dOcK
Rumex crispus 2,4-D + dicamba, or 2,4-D + Spring to early Mature plants dicult to kill.MCPP + dicamba, or 2,4-D + summertriclopyr
table continued
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Table 4. Suggestions for selective control of turfgrass weeds in Pennsylvania, by weed species, continued.
Weed Material Apply Remarks
dAndeliOn
Taraxacum ofcinale 2,4-D, or 2,4-D + MCPP + Spring or all May require spring and all applications.dicamba, or 2,4-D + 2,4-DP +dicamba, or 2,4-D + 2,4-DP,or 2,4-D + triclopyr
GOOseGRAss
(silver crabgrass) Preemergence control: Late spring to Herbicides are more eective when watered inEleusine indica bensulide + oxadiazon, or early summer ollowing application. Check labels or nontolerant
oxadiazon, or pendimethalin species and cultivars and or intervals untiloverseeding can take place.
Postemergence control:
Fenoxaprop-p-ethyl Early summer Fenoxaprop-p-ethyl should be applied only whenthere is adequate moisture and goosegrass isactively growing. This herbicide may temporarilydiscolor some Kentucky bluegrass cultivars and isless eective i tank-mixed with phenoxy-type
herbicides.
GROund ivy
Glechoma 2,4-D + MCPP + dicamba, Early spring or all. Extremely dicult to kill. Repeat applicationshederacea or triclopyr and clopyralid, Fall applications will reduce, but may not completely eliminate, this
or 2,4-D + triclopyr are most eective weed.i made ater rstrost.
hAWKWeed
Hieracium spp. 2,4-D + dicamba, or Early spring or all Repeat applications may be necessary. Control may2,4-D + MCPP + dicamba, be improved with a wetting agent (check herbicideor MCPA + MCPP + dicamba label to see i a wetting agent is allowed). Thoroughly
wet the plant. Accompany with adequate lime andertilizer treatment.
heAl-All
Prunella vulgaris 2,4-D + MCPP + dicamba Early spring or all Dicult to kill. Repeat applications may be needed.
henBit
Lamium 2,4-D + dicamba, or 2,4-D + Spring Dicult to control. Treat weeds when young; repeatamplexicaule 2,4-DP, or 2,4-D + MCPP + applications may be necessary.
dicamba, or triclopyr +clopyralid, or 2,4-D + triclopyr
KnOtWeed
Polygonum aviculare dicamba, or MCPP, or Spring to mid- Best control when weeds are actively growing.2,4-D + MCPP + dicamba summer
MAllOW
Malva spp. 2,4-D + MCPP + dicamba, or Spring Extremely dicult to kill. May require repeat2,4-D + triclopyr, or applications.2,4-D + 2,4-DP, or 2,4-D +2,4-DP + dicamba
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Table 4. Suggestions for selective control of turfgrass weeds in Pennsylvania, by weed species, continued.
Weed Material Apply Remarks
nutsedGe, yellOW
Cyperus esculentus Bentazon or halosuluron When weeds are Do not apply to newly seeded turgrass. Avoidactively growing in mowing 35 days beore and ater applyinglate spring or early bentazon and halosuluron. Bentazon may injuresummer ryegrasses.
plAntAins:
Broadlea 2,4-D, or 2,4-D + MCPP + Spring or all Best control when weeds are actively growing.Plantago major dicamba, or 2,4-D + 2,4-DP +Buckhorn dicamba, or 2,4-D + triclopyr,Plantago lanceolata or triclopyr + clopyralid, orRugels MCPA + MCPP + dicambaPlantago rugelii
puRslAne
Portulaca oleracea 2,4-D + MCPP + dicamba, When actively Dicult to kill; repeat applications may be needed.or 2,4-D + triclopyr growing
sheep sORRel
(red sorrel)Rumexacetosella 2,4-D + 2,4-DP + dicamba, Spring, summer, or Apply lime and ertilizer as needed.
or dicamba, or 2,4-D + early allMCPP + dicamba, ortriclopyr + clopyralid, orMCPA + MCPP + dicamba
shepheRds puRse
Capsella bursa- MCPP, or dicamba, or Spring or all Best control when weeds are actively growing.pastoris 2,4-D + MCPP + dicamba,
or triclopyr + clopyralid, orMCPA + MCPP + dicamba
pROstRAte spuRGeEuphorbiasupina Postemergence control: When weeds are Spurge is dicult to kill; may require repeat
dicamba, or 2,4-D + MCPP + actively growing applications.dicamba, or MCPA + MCPP +dicamba
Preemergence control: Early to mid-springpendimethalin, or benen +trifuralin, or prodiamine
speedWells:
Creeping 2,4-D + triclopyr, or Mid- to late May Extremely dicult to control; repeat applications mayVeronica fliormis quinclorac be necessary.
Corn or rock Postemergence control: Spring or summer Extremely dicult to control; repeat applications mayVeronica arvensis 2,4-D + MCPP + dicamba, be necessary. or 2,4-D + triclopyr
Preemergence control: Late summer Apply in August beore weeds germinate. Oxidiazon
Thyme-leaved 2,4-D + MCPP + dicamba Spring Extremely dicult to control; complete controlVeronica serpylliolia unlikely. Be sure lime and ertilizer needs are met.
Other speedwellsVeronicaspp. 2,4-D + MCPP + dicamba Spring or summer Dicult to control.
table continued
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Table 4. Suggestions for selective control of turfgrass weeds in Pennsylvania, by weed species, continued.
Weed Material Apply Remarks
viOlets
Violaspp. 2,4-D + 2,4-DP, or May Limited eectiveness; repeat applications usually2,4-D + 2,4-DP + dicamba, necessary.or triclopyr + clopyralid, or2,4-D + triclopyr
Wild cARROt
Daucus carota 2,4-D, or 2,4-D + dicamba, Early spring or all Apply to young plants or when plants are activelyor 2,4-D + MCPP + dicamba, growing.2,4-D + triclopyr
Wild GARlic
Allium vineale
Wild OniOn
Allium canadense 2,4-D, or 2,4-D + MCPP + Spring, when Requires treatment annually or several years. Usedicamba, or 2,4-D + 2,4-DP + garlic and onions ester ormulation, wet plants thoroughly.dicamba are actively growing
Wild GeRAniuM
(cranesbill)Geraniumspp. 2,4-D + MCPP + dicamba, or Spring Dicult to kill. May require repeat applications.
MCPA + MCPP + dicamba
WOOdsORRel, yellOW
Oxalisspp. 2,4-D + 2,4-DP, or 2,4-D + Summer or all Dicult to kill. May require repeat applications.2,4-DP + dicamba, or2,4-D + triclopyr, or triclopyr +clopyralid
yARROW
Achillea milleolium 2,4-D + dicamba, or 2,4-D + Spring Best control when weeds are actively growing.MCPP + dicamba, or
2,4-D + 2,4-DP + dicamba,or 2,4-D + MCPP + dicamba,or 2,4-D + triclopyr
yellOW ROcKet
(wintercress) 2,4-D, or 2,4-D + MCPP + Spring Best control when weeds are actively growing.Barbarea vulgaris dicamba
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Table 5. Suggestions for nonselective control of turfgrass weeds in Pennsylvania, by weed species.
Weed Material Apply Remarks
BentGRAss
Agrostisspp. glyphosate Any time air is warmer Kills all vegetation in the treated area. I there is nothan 50F and rain is not rain within 6 days ollowing rst treatment, applyexpected within 10 hours water to encourage sprouting and growth. I regrowthater treatment appears, apply second application at three-quarter
rate. Prepare seedbed when kill is complete; seedingmay begin when seedbed is ready.
niMBleWill
Muhlenbergia glyphosateschreberi
tAll fescue
Festuca glyphosatearundinacea
ORchARdGRAss
Dactylis glomerata glyphosate
quAcKGRAss
Agropyron repens
OtheR peRenniAl
cOOl-seAsOn GRAsses glyphosate
ZOysiAGRAss
Zoysiaspp. glyphosate When zoysiagrass is Zoysiagrass is extremely dicult to control. Repeatactively growing in applications are usually necessary. Make rstsummer. application in early summer, then wait a ew weeks
to see i new growth occurs. I it does, treat again.Continue until no regrowth occurs.
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PreParedby Peter J. Landschoot, Professorofturfgrass
science
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