weed management in turf

8/3/2019 Weed Management in Turf

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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

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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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la ba

The grass leaf

Vernation

Ro fo

Ligules

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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.

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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.


Dithiopyr DimensionDSMA Methar 30Fenoxaprop-p-ethyl Acclaim ExtraMSMA MSMA Tur HerbicideQuinclorac Drive 75 DF Herbicide


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19

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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20

Table 3. Some broadleaf herbicides and herbicide combinations for use in cool-season turf.*


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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21

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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22

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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23

Table 4. Suggestions for selective control of turfgrass weeds in Pennsylvania, by weed species, continued.


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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24



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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25



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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26



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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27

Table 5. Suggestions for nonselective control of turfgrass weeds in Pennsylvania, by weed species.


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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28


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PreParedby Peter J. Landschoot, Professorofturfgrass

science

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weed management in turf

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