Turf Pest Control - Category 3B Kansas State University Agricultural Experiment Station
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Turf Pest
Control
Kansas State University Agricultural Experiment Station
and Cooperative Extension Service
Category 3B
Turf Pest
Control
Kansas State University Agricultural Experiment Station
and Cooperative Extension Service
Category 3B
Introduction 6 Table of Contents
Turf Diseases 7
Disease Diagnosis ....................................................................................... 7
Specific Diseases ......................................................................................... 8
Environmental Stresses .............................................................................. 14
Turf Weeds 19
Weed Life Cycles.........................................................................................19
Common Weeds in KansasTurfgrass...........................................................20
Weed Control Methods ............................................................................. 24
Herbicide Formulations ............................................................................. 26
Liquid Application...................................................................................... 27
Proper Use of Herbicides.............................................................................28
Application Equipment................................................................................32
Turf Insects 36
Pest Management Steps ............................................................................. 36
Common Turfgrass-Damaging Insects ...................................................... 37
Calibration 48
Field Sprayers...............................................................................................48
Liquid Sprayers............................................................................................49
Granular Applicators....................................................................................51
Measurement Calculations.......................................................................... 52
Pesticide Safety .......................................................................................... 53
Vertebrate Pests 55
Skunks......................................................................................................... 55
Moles...........................................................................................................56
Pocket Gophers............................................................................................56
Environmental Considerations 60
Phytotoxicity................................................................................................60
Drift.................................................................................................. 60
Persistence.......................................................................................... 61
Pesticide Hazards................................................................................ 61
Directions for Using this Manual
This is a self-teaching manual. At the end of each major section is a list of
study questions to check your understanding of the subject matter. These
study questions represent the type that are on the certification examination.
By studying this manual and answering the study questions, you should be
able to gain sufficient knowledge to pass the Kansas Commercial Pesticide
Applicators’ Certification examination. Correct answers appear on page 64.
5
Introduction T he turfgrass industry in Kansas
includes home lawns, institu-
tional and industrial grounds, sod
of temperature, rainfall, humidity, sun
intensity, day length, and wind add
considerable stress. Ideal growing
production, golf courses, athletic fields conditions exist only a few months
and other recreational turf, parks, out of the year.
roadsides, airports, and cemeteries.
Geographically, Kansas is in the
Home lawns comprise by far the
transition zone between the northern
greatest amount of turfgrass acreage.
cool-season grass range and the
Turfgrass is maintained for beautifi- southern warm-season grass range.
cation, recreation, erosion control, and Both kinds of grasses are grown in
utility. In general, people appreciate Kansas, but neither is as well adapted
and take pride in maintaining attrac- to conditions as it would be farther
tive and quality turf. Proper care and north or south. Because both cool-
timely pest control are necessary for season grasses (bluegrass, tall fescue
good color and density and to keep and ryegrass) and warm-season
turf free of weeds, insects, and disease. grasses (bermudagrass, zoysiagrass
Turf management involves selecting and buffalograss) can be grown,
the right grass, proper mowing, turfgrass managers should be able
watering, fertilizing, and controlling to identify and manage the various
thatch. grasses. Management practices for
cool-season and warm-season grasses
Cultural practices are the key
are distinctly different, with each type
to maintaining turf quality and
presenting distinct problems. Many
preventing problems. Pesticides can
chemicals are available for use on
aid in management but are not a
warm-season or cool-season turf only.
substitute. Pesticides will not offset
the negative effects of improper Problems may arise from selection of
watering, fertilization, or mowing the turfgrass species or cultivar. The
practices, thatch accumulation, poor wrong grass for the wrong situation
soil, or choosing the wrong species. can result in continual problems that
Climate, soil, management, pest are difficult to combat, even with
control, and selection of adapted proper management and pesticides.
species and cultivars affect growth. Problems develop when turfgrass is
unable to withstand environmental
The harsh Kansas climate can make
stress or when good management
it difficult to grow quality turfgrass
cannot offset ill effects. In these cases,
consistently. Extreme temperature
pesticides can be a valuable aid.
variation from summer to winter
limits the kinds of grasses that will This manual provides detailed infor-
grow. Rainfall and soil pH also mation on diagnosis and management
vary widely from eastern to western of turfgrass diseases, insect pests, and
Kansas. Unpredictable combinations weeds.
6
T urfgrasses are susceptible to
numerous diseases and environ-
mental stresses. Most diseases are
appropriate time of year, which varies
between cool-season and warm-
season species.
Turf Diseases
caused by fungi. Like other plants,
Avoid compaction. Compacted soil
turfgrasses are more susceptible
decreases the oxygen supply to roots
to disease when stressed. Damage
and interferes with water movement,
from environmental factors such as
reducing plant health. Core-aerate
temperature, moisture, soil fertility,
compacted areas. Coring is a form of
soil structure, or shade can be misdi-
cultivation in which a machine with
agnosed as disease. Pesticide appli-
hollow tines is used to remove soil cores.
cators should be familiar with both
kinds of problems. Prevent excessive thatch. Overly
thick thatch is a common problem in
Numerous fungi species infect turf.
turf stands with symptoms that can be
This manual describes the most
confused with diseases. More details
common diseases in Kansas. Many
about thatch are provided in the
fungi produce spores for reproduction
section on environmental stresses.
and spread. Because they thrive in
wet conditions, water management Use appropriate mowing heights.
(both foliar and soil) is the key to Each species has a range of mowing
disease control. In general, watering heights. For example, for tall fescue
deeply and infrequently is better than or Kentucky bluegrass lawns, 2 to
watering lightly and frequently. Each 3 ½ inches is recommended compared
fungus thrives in certain temperature to 1 to 2 inches for zoysiagrass or
ranges. Some diseases are common bermudagrass lawns. Golf courses
in cool weather, others are more have unique mowing requirements.
common when it is hot. The most common problem is
mowing too low. Mowing too low
Like all plants, turfgrass requires
reduces green tissue, reducing the
appropriate light, moisture, and
plant’s ability to conduct photosyn-
fertility. The following practices will
thesis. This leads to reduced energy
help maintain overall turfgrass health
reserves in the plant, making it more
and prevent disease development.
prone to stress and disease. Mow grass
Select appropriate turfgrass species frequently so that no more than ¼ to
and varieties. Do not plant grasses 1/3 of the leaf area is removed at any
that are not adapted to your area or one time. Continue to mow the lawn
for the site’s intended use. In addition, throughout the fall until the grass
use quality seed and plant at recom- stops growing.
mended seeding rates.
Improve airflow and light avail-
Provide adequate drainage. Ensure ability. If a site is shaded or has
good surface and subsurface drainage poor air flow, thinning or removal of
when establishing new turfgrass from surrounding shrubs and trees allows
seed or sod. Be particularly careful sunlight to penetrate and increases air
with low spots where water may flow. This speeds drying of the grass
stand. Excessive moisture can damage and aids in disease prevention. Space
roots and affect overall plant health. landscape plants properly to allow
adequate air movement and to avoid
Provide appropriate fertility.
excessive shade.
Different turfgrass species and sites
have different fertility requirements.
Determine what is appropriate for Disease Diagnosis
the specific site. Consider submitting The first step in control of turf-
a soil sample to a testing laboratory. grass problems is accurate diagnosis.
Some diseases thrive when fertility Incorrect diagnosis leads to inap-
is too low, and some thrive when propriate management and may
fertility is too high. It is essential to compound the problem.
find a balance and to fertilize at the
7
Turf Diseases Diagnosis requires knowledge of
what healthy turfgrass, including
• Determine potential problems
with soil structure or fertility.
roots, looks like and the symptoms Look for evidence of shallow soil,
of abnormal or diseased plants. Some buried debris, compaction, soil
diseases such as powdery mildew layering, poor drainage or other
and rust are relatively easy to iden- physical properties of the soil that
tify. Others, including most root and may be contributing to turfgrass
crown rot diseases, are more difficult decline. Many turf problems are
to diagnose without considerable also associated with nutrient
experience. Always keep in mind that (nitrogen, iron, others) excesses or
many turfgrass problems are caused deficiencies. Consider submitting
by environmental stress, not diseases. a soil sample to a laboratory for
fertility testing.
To diagnose turfgrass problems follow
these steps. • Determine the history of cultural
Brown patch in perennial ryegrass practices at the site. Find out
• Determine the overall distribution
what fertility, irrigation, culti-
of the problem. Is the damage
vation, and other practices have
uniformly distributed across the
been conducted at the site, and
turfgrass or is it concentrated
when. Problems can occur when
in one area? Streaks, bands,
fertilization is applied at an inap-
straight lines or perfect circles
propriate rate or the wrong time
are more likely to be caused by
of year for the type of grass at the
environmental, non-living factors.
site. In addition, too much or too
Clumps, patches, or random
little irrigation can be problem-
patterns are more likely caused by
atic. Mowing at the wrong height
a disease or other living organism.
can stress turf.
• Identify the affected turfgrass
• Review pesticide management
species and cultivar (if possible).
Brown patch lesion on tall fescue practices. Get a complete record
Turfgrass species and even culti-
of any previous pesticide applica-
vars within a species may vary in
tions to the turfgrass. Check rates,
their susceptibility to turfgrass
application dates, application
diseases. Many turfgrass stands
methods, and any other chemical
contain more than one species.
use patterns that could indicate a
By understanding the type of
problem.
turfgrass affected, you can help
narrow the possible causes of the • Use reference materials. Match
problem. symptoms with those described
in reference books. If you are still
• Observe symptoms on individual
unable to identify the problem,
plants. Look for the presence, size
collect a sample of sod (at least
and color of leaf spots, crown or
4 inches in diameter and deep
root rotting. These help identify
enough to include roots) from
Rhizoctonia brown patch on tall fescue the disease. Also look for fungal
the margin of the damaged area
fruiting structures.
and submit it to a plant disease
• Determine weather conditions diagnostic laboratory. Work with
before and during disease devel- turfgrass extension specialists.
opment. Turfgrass diseases are
weather dependent. Some develop Specific Diseases
during cool weather; others will The following section lists common
only cause problems during hot, turfgrass diseases in Kansas, when
humid conditions. they occur, symptoms, and manage-
• Knowledge of weather conditions ment. For information on other
will help you select the right diseases contact your local extension
disease. Certain turfgrass prob- agent or plant disease diagnostic
lems may be associated with or laboratory.
Rhizoctonia brown patch on tall fescue caused by adverse weather (exces-
sive rain, drought, heat, cold, etc.)
8
Brown Patch
Pathogen and conditions: Brown patch,
to prevent outbreaks of brown patch
on golf course putting greens during Turf Diseases
caused by the fungus Rhizoctonia the summer months ( June through
solani, is the most common and August). Preventive applications may
important disease of tall fescue in also be needed on perennial ryegrass
Kansas. The disease also can be prob- fairways and certain high mainte-
lematic on creeping bentgrass and nance tall fescue lawns. In other cases,
perennial ryegrass. Brown patch is fungicide treatments may be applied
a summer disease. It is most likely at the first appearance of symptoms.
when nighttime temperatures remain
above 70°F, and during extended Dollar Spot
periods of high relative humidity Pathogen and conditions: Dollar spot,
and leaf wetness. Brown patch is also caused by the fungus Sclerotinia
more severe on turfgrasses under high homoeocarpa, occurs on all turfgrasses
nitrogen fertilization. Affected turf- grown in Kansas. It is most problem- Rhizoctonia brown patch on tall fescue
grass generally recovers when cooler atic on creeping bentgrass fairways
temperatures return in late summer/ and putting greens. Dollar spot is
early fall. most severe in late spring and early
Symptoms: Brown patch appears as fall, but it may appear throughout
irregularly shaped patches of blighted the summer. The disease may occur
turfgrass that range in size from a few regardless of management or soil
inches to several feet in diameter. The fertility, although damage usually
blighted turf initially is purple-green is most severe if there is a nitrogen
but quickly fades to light brown. deficiency.
When the grass is wet, the diseased Symptoms: Dollar spot results in the
patches frequently have dark, purplish formation of small, roughly circular,
margins (smoke rings). The patches bleached patches of turf. In lawn-
tend to be more diffuse and irregular, height turfgrass the patches are Dollar spot lesion
and the entire lawn may look as if it is usually 2 to 6 inches in diameter. On
under drought stress. Individual plants putting greens, the patches are usually
may exhibit irregularly-shaped tan to 1 to 2 inches in diameter. Affected
gray leaf spots bordered by a dark- plants within the spots wilt and even-
brown margin. tually turn tan or brown. On indi-
Management: Do not over fertilize. vidual infected plants, leaves develop
Apply a majority of the nitrogen light yellow to tan lesions with
fertilizer in the fall, the best time for reddish-brown borders. In the early
cool-season grasses. Do not fertilize morning when dew is still present on
when brown patch is active. When the turfgrass, small cottony strings
seeding new areas, avoid seeding of the fungus can sometimes be seen
rates greater than the recommended growing from the diseased leaf blades.
rate. High seeding rates result in an Management: Dollar spot is more
excess number of turfgrass plants and severe in nitrogen-deficient turf. Dollar spot on tall fescue
creates conditions favorable for the Therefore, maintain an adequate
brown patch fungus. Do not irrigate fertilization program. Avoid night
susceptible turfgrass in late afternoon watering or other irrigation practices
or evenings if possible. This extends that allow the leaves to remain wet for
the number of hours the leaves remain long periods. On golf courses, fungi-
wet and increases the likelihood of cides are generally applied to manage
brown patch. Promote good air circu- dollar spot on creeping bentgrass
lation by proper pruning of trees and putting greens and fairways. New
shrubs. None of the bentgrass or tall cultivars of creeping bentgrass with
fescue varieties are highly resistant to reduced susceptibility to dollar spot
brown patch, although certain culti- are available.
vars of the turf-type tall fescues tend
to be more seriously damaged by the
disease. A preventive fungicide appli- Dollar spot on creeping bentgrass
cation program is usually necessary
9
Turf Diseases Fairy Ring
Pathogen and conditions: Fairy rings
Large Patch of Zoysiagrass
Pathogen and conditions: Large patch
are caused by numerous species of of zoysiagrass, also called zoysia
fungi in the group Basidiomycetes, patch, is caused by a fungus called
and they can occur in all species of Rhizoctonia solani. It is related to, but
turf. The fungi grow in the soil and distinct from, the strain of Rhizoctonia
or thatch, consuming organic matter. solani, which causes brown patch on
They are not directly pathogenic on cool-season turfgrasses in hot weather.
the turfgrass plants but they do affect Large patch is most common in early
the turfgrass growth. After rains or spring and late fall as the zoysia-
heavy watering, fungal fruiting struc- grass is entering or breaking winter
tures (mushrooms or puffballs) may dormancy.
appear in the ring area. In addition,
Symptoms: The disease results in rela-
white, spongy fungal growth (myce-
tively large, roughly circular patches
Fairy ring, type 1 lium) may be visible in the thatch or
(2 to 20 feet in diameter) with slightly
soil underneath the ring.
matted areas of discolored turfgrass.
Symptoms: Fairy ring symptoms are Patch margins are often bright orange
grouped into three categories. Type 1 especially in wet conditions. Patches
fairy rings include turf death and are sometimes persist from one season
most common on sand-based putting to the next. Individual shoots within
greens. The damage to the turfgrass has the patch develop pinpoint, reddish-
been associated with high salt content brown to black lesions on basal leaf
and hydrophobic (water repellent) sheaths. In order to see the lesions,
conditions in the soil, caused by the you must dig up the plant near the
fungi. Type 2 fairy rings display a ring patch border and look at the crown
of lush, dark-green turf and may or area near its attachment to the stolon.
may not have fungal fruiting structures Zoysiagrass slowly refills the damaged
(mushrooms or puffballs). Type 3 fairy areas during the summer.
Fairy ring, type 2 rings develop a ring of fruiting bodies
Management: Avoid overwatering,
with no visible effect on the turfgrass.
especially in the fall or early spring.
Fairy rings may range in diameter
Poorly drained areas are very suscep-
from a few inches to 50 feet or more,
tible to injury from large patch. Core
and they can expand over time (several
aeration or verticutting in June or
inches to a few feet per year).
July helps reduce thatch accumulation
Management: In many cases, fairy and invigorates the turfgrass. The
rings do not actually damage turf- fungus may be spread on infected
grass, symptoms are temporary, and turf cores removed during aerifica-
no management is needed. In lawns tion if conducted when the disease
or landscapes, if type 2 fairy rings are is active. Several fungicides will help
considered unsightly, the green rings suppress large patch development, but
can be masked with light fertilizer the timing of application is critical
Fairy ring, type 3 applications, but make sure to stay to good disease control. Preventive
within overall fertility recommen- applications should be applied in
dations for the turf species and site. mid- to late-September before large
Mushrooms and puffballs can be patch symptoms develop and as the
destroyed by mowing. Certain fungi- turf begins to enter winter dormancy.
cides are labeled for suppression of A second fungicide application in
fairy rings but are primarily used on mid- to late April as the turf begins
golf course putting greens. In golf to break winter dormancy may further
course putting greens, fairy rings reduce disease development.
are more common when fertility is
low, so providing adequate fertility Leaf Spot and Melting Out
can prevent rings from occurring. In Pathogen and conditions: Leaf spot
addition, for golf courses, there are and melting out is caused by several
methods to help overcome the hydro- different fungi. The most common
Drechslera on tall fescue phobic soils by using spiking, wetting on Kentucky bluegrass and tall fescue
agents, etc. lawns in Kansas is Drechslera poae.
10This disease used to be highly prob-
lematic on Kentucky bluegrass but
korrae. It is primarily a problem of
Kentucky bluegrass, but may also Turf Diseases
newer cultivars have some resistance. be found on red fescue and annual
The disease is most common in bluegrass.
spring and fall.
Symptoms of necrotic ringspot
Symptoms: The fungus infects young usually appear in late spring or early
succulent leaf tissue and causes small fall, but they may continue into the
elliptical, purple spots. The spots summer months. The disease is worse
eventually turn light gray or tan but when wet weather is followed by hot,
remain bordered by a dark brown to dry conditions.
purple margin. The leaf spot phase of
Symptoms: Necrotic ringspot causes
the disease usually does not damage
numerous circular to arc-shaped
the plant significantly. However,
patches of dead or dying turfgrass
during continuous cool, wet condi-
roughly 6 inches to 2 feet in diam- Large patch of zoysiagrass
tions, the fungus invades and girdles
eter. The affected turf in the ring is
the leaf sheath. As daytime tempera-
slightly matted, whereas the turfgrass
tures increase, leaves on crown-in-
in the middle often remains healthy
fected plants begin to turn light green
and green. Affected plants exhibit
or yellow, similar to nitrogen-deficient
extensive root discoloration and rot.
turf. Eventually these plants die and
Necrotic ringspot symptoms may
turn brown or straw colored. This is
be confused with other diseases,
referred to as “melting-out.” Severe
including fairy ring and summer
melting-out can result in irregular
patch. Laboratory examination is
patches of dead turf. Damaged
usually necessary for confirmation.
turfgrass stands often appear thin
or uneven and tend to have weed Management: Several varieties of
problems. Kentucky bluegrass exhibit reduced
susceptibility to necrotic ringspot
Management: The most effective
and should be used in areas where Large patch l lesion on zoysia leaf sheath
means of controlling melting out is
the disease has been a problem.
to plant resistant cultivars. Several
Alternatively, use other species of
varieties of Kentucky bluegrass are
turfgrass (tall fescue) that are not
available with good resistance to this
susceptible to the disease. On estab-
disease. Use a blend of three or more
lished turf stands with a history of
resistant cultivars. In lawns where
necrotic ringspot, promote overall turf
susceptible varieties are present,
health and root growth with proper
consider an overseeding program
fertilization and irrigation. Avoid
with resistant cultivars. Avoid exces-
excessive fertilization, especially
sive nitrogen fertilization in spring
fast-release forms of nitrogen. Irrigate
which favors lush growth, but do not
deeply and infrequently. Core aerate
“starve” the lawn of nitrogen during
compacted soils and maintain turf at
the spring. A well-balanced fertiliza-
the proper mowing height. Preventive
tion program will reduce the severity Necrotic ring spot on Kentucky bluegrass
fungicide applications in fall or early
of the disease. Mow turf regularly at
spring may be effective in suppressing
appropriate heights. Thatch reduction
disease development. Because this is
will also help reduce disease severity.
a root disease, fungicides need to be
Fungicide applications may be useful
applied in enough water to reach the
on lawns with a history of leaf spot
root zone or appropriately irrigated.
starting in spring when symptoms
are first apparent, usually late March
through April. The disease is very Pink Snow Mold/
difficult to control once the melt- Microdochium Patch
ing-out phase has begun. Pathogen and conditions: Pink snow
mold or Microdochium patch, caused
Necrotic Ringspot by the fungus Microdochium nivale, is
Pathogen and conditions: Necrotic common on bentgrass putting greens,
ringspot is a root disease caused by newly established ryegrass fair-
ways and occasionally on Kentucky Pink snow mold on creeping bentgrass
the soilborne fungus Ophiosphaerella
11Turf Diseases bluegrass and tall fescue in home
lawns in Kansas. Pink snow mold can
Symptoms: A powdery-like fungal
growth develops on the leaf surface.
occur anytime during cool (below Infected leaves often turn yellow
60°F), wet weather in fall, winter or and wither. Bluegrass lawns heavily
spring. The disease does not require infected with the mildew fungus tend
a snow cover for development, but to be thin. New plantings may be
it may be enhanced by it. Warm, dry killed when mildew is severe.
weather stops disease development
Management: Selectively prune
and allows the turfgrass to recover.
trees and shrubs to allow for greater
Another type of snow mold called
sunlight penetration and improve air
gray snow mold, or Typhula blight,
movement. Avoid excess nitrogen.
requires long periods of snow cover
Mow frequently at the recommended
and does not typically occur in
height. Consider renovating to a more
Kansas.
shade tolerant variety.
Powdery mildew Symptoms: Pink snow mold causes
round, tan, gray or to reddish-brown Pythium Foliar Blight
patches that are usually less than 6 Pathogen and conditions: Pythium
to 8 inches in diameter. Occasionally, foliar blight, sometimes called cottony
spots may coalesce to blight larger blight, is one of the most destructive
areas. During wet, cool weather, the turfgrass diseases. It is distinct from
margins of the patches often have a Pythium root diseases which are not
pink tinge. covered here. Pythium foliar blight is
Management: Cultural practices caused by several species of Pythium.
can reduce pink snow mold. Avoid Turfgrasses most commonly affected
excessive use of fast-release nitrogen are perennial ryegrass and creeping
fertilizer applications in late fall, bentgrass. Tall fescue is occasionally
especially to fall-seeded turfgrasses. damaged, but injury to Kentucky
Use slow release forms of nitrogen bluegrass and warm-season turf-
Pythium blight mycelium
fertilizer and mow frequently until grasses is rare. Pythium blight is most
growth has stopped. In spring, rake active in humid, wet summer weather
or mow affected areas to loosen the when air temperatures are high, espe-
matted turf and promote drying. For cially when nighttime lows exceed
high maintenance turf, such as golf 68°F.
course putting greens, fungicides Symptoms: The disease first develops
may be beneficial, especially at sites as small, irregularly-shaped, water-
with a history of the disease or sites soaked, greasy patches up to 4 inches
with newly seeded turfgrass. In those in diameter. A cottony growth may
cases, apply a fungicide starting in the be present early in the morning when
late fall (November) when daytime dew or other moisture is present. The
temperatures remain below 60°F and patches may merge and form streaks
the weather is wet. Additional appli- since the pathogen is spread by water
Pythium blight cations may be needed during winter and by mowing operations. The
and spring when cool, wet weather disease is more likely to occur in wet
persists. areas or in drainage flows. The disease
may spread very rapidly, killing large
Powdery Mildew areas of turf in just a few days or even
Pathogen and conditions: Powdery overnight.
mildew, caused by the fungus
Management: Maintain a proper
Blumeria graminis, is primarily a
balance of nutrients, avoiding an
problem of Kentucky bluegrass in
excess of nitrogen that stimulates lush
Kansas. The disease is most common
growth. Do not overwater. Improve
in shaded areas of the lawn. The
surface and sub-surface soil drainage.
disease usually occurs in late spring
Promote air movement by proper
and early fall when the relative
spacing and pruning of trees and
humidity is high and temperatures
shrubs. Where feasible, delay seeding
are cool.
until weather is cool and dry. For high
maintenance turfgrass with a history
12of Pythium blight, preventative fungi-
cide applications may be beneficial.
herpotricha, O. korrae, and O.narmari.
It is the most common and destruc- Turf Diseases
tive disease of bermudagrass.
Rusts The disease also occurs occasion-
Pathogen and conditions: Rust occurs ally on buffalograss and zoysia-
to some extent on all turfgrasses grass. Spring dead spot may occur
grown in Kansas; however, this disease on bermudagrass stands of all ages,
is generally most severe on suscep- although it typically appears three
tible cultivars of Kentucky bluegrass, to four years after the turf has been
tall fescue, perennial ryegrass and established.
zoysiagrass.
Symptoms: The disease results in the
Rust fungi include several species in formation of circular or arc-shaped
the genus Puccinia species, and they patches of dead turf in early spring
are host specific; i.e., the rust that as bermudagrass breaks winter
occurs on zoysiagrass is different than Rust pustules
dormancy. The dead patches, which
the one occurring on Kentucky blue- are slightly depressed and straw-col-
grass. Rust can occur in spring or fall, ored, may range in size from several
but normally appears in late August inches to several feet in diameter and
to early September and continues normally are randomly distributed
through the fall months. Rust throughout the stand. Roots and
outbreaks are dependent on favor- stolons of affected plants are often
able weather conditions and disease dark brown to black and are severely
severity may vary widely from one rotted. It may be necessary to dig
year to another. up a piece of sod near the margin of
Symptoms: From a distance, rust-in- the dead area and wash it in water to
fected turf appears dull yellow or light observe this symptom. During the
brown. Individual plants may die and summer, weeds invade and colonize
the turf becomes noticeably thin. The the bare soil. Bermudagrass slowly Spring dead spot of bermudagrass
disease tends to be more severe in recolonizes affected areas, and by
partially shaded areas such as under late summer there may be little or no
trees or along fences. Diseased plants evidence of the disease. Unfortunately,
initially develop light yellow flecks enlarged dead patches reappear the
on the leaves. As the spots enlarge, following spring in the same loca-
the surfaces of the leaves rupture, tions. Over a number of years, the
exposing masses of powdery, brick-red patches can become quite large,
fungal spores. The powdery substance coalesce, and develop arc-like patterns
easily rubs off. Continuous heavy in the turf stand.
infection causes many grass blades to Management: Several cultural
turn yellow, wither and die. Severely methods can reduce the severity
rusted turf stands may winter kill. of spring dead spot. Bermudagrass
Management: Turfgrass provided with should be cultivated (core aeration
appropriate levels of fertilizer and and/or verticutting) when the bermu-
water are less likely to be damaged dagrass is actively growing to reduce
by rust. Irrigate early in the morning thatch and promote good rooting.
rather than at night, to reduce dura- The appropriate time to cultivate
tion of leaf wetness, and mow at bermudagrass (a warm-season turf )
appropriate intervals. Mow frequently is summer. Avoid excessive nitrogen
at appropriate mowing heights. Rust fertilization (more than 4 lbs of
rarely reaches damaging levels. When active nitrogen per 1,000 sq ft per
establishing new plantings select vari- season). Do not fertilize late in the
eties that are resistant to rust. growing season (after mid-August).
Bermudagrass cultivars vary mark-
Spring Dead Spot edly in susceptibility to spring dead
spot. Use cold-tolerant cultivars. In
Pathogen and conditions: Spring
fungicide tests in Kansas, applica-
dead spot is a root disease caused by
tions in late summer and early fall
three soilborne fungi Ophiosphaerella
sometimes have reduced severity of
13Turf Diseases spring dead spot, but results have been
inconsistent.
These patches may form elongate
streaks, crescents, or circles 2 feet or
more in diameter. Healthy grass may
Slime Molds occur within the centers of patches
Pathogen and conditions. Slime molds of dead grass, giving a characteristic
are actually not fungi and they are not “frogeye” pattern. Summer patch
pathogens of turfgrass. Slime molds symptoms can easily be confused with
utilize decaying organic material and insect damage (grubs, billbug), herbi-
other microorganisms in the soil as a cide injury, or drought stress. These
food source. In humid weather slime possible causes should be eliminated
molds grow out of the soil and thatch before summer patch is diagnosed.
onto whatever is available for support, Management: Summer patch is an
including turfgrass and mulch. extremely difficult disease to control.
Symptoms: Slime molds form gray, Certain Kentucky bluegrass cultivars
Slime mold purple, black, white or yellow powdery show some resistance to summer
structures, the fruiting stage of the patch and should be seeded or sodded
organism. When crushed between in new locations or areas where the
the fingers, they disintegrate into a disease has been a problem. Several
powdery mass that easily rubs free cultural practices will help suppress
from the grass blade. disease development. Turfgrass should
be maintained in a healthy, but not
Management: Slime molds frequently overstimulated, growing condition.
cause considerable alarm as they A balanced fertilization program is
suddenly appear in spring, summer or important. Avoid excessive nitrogen
fall following heavy rains or watering. fertilization during the summer
Although they are unsightly, they months. Acidifying fertilizers may
do not damage the grass and do not reduce disease. Maintain appropriate
require any specific management. mowing heights Reduce thatch by
Summer patch on Kentucky bluegrass They are easily removed by raking or yearly core aeration. Summer patch
hosing off the affected turfgrass. may develop even with optimal turf
care, and certain cultural modifica-
Summer Patch tions may be necessary to save the
Pathogen and conditions: Summer turf. Seriously diseased turf should be
patch is a root disease caused by the watered lightly daily in the early after-
soilborne fungus Magnaporthe poae. It noon to cool the plants and provide
can be serious on Kentucky bluegrass some moisture for the diseased roots.
and annual bluegrass, causing symp- Preventive fungicide applications may
toms during summer heat stress. be effective in suppressing symptoms
of summer patch. A general rule is to
Symptoms: Early stages of the disease initiate fungicide applications when
may be difficult to detect. Initially, soil temperatures at a 3-inch depth
small patches of turf, 2 to 6 inches in reach 65°F for several consecutive
diameter, turn dull green. Eventually, days, which often occurs from late
Summer patch of annual bluegrass on
foliage changes to a dull reddish April through mid-May in Kansas.
putting green (Note that the creeping
brown, then tan, and finally a light Follow with several additional appli-
bentgrass is unaffected.)
straw color. The crowns and roots cations. Applications after symptoms
of blighted plants may show a slight have developed are not effective.
greenish-brown to black discoloration.
To see the discoloration, gently pull
plants and wash away the soil. Small Environmental Stresses
fungal strands called runner hyphae Chemical Burn
may be seen on the roots with a 10× Pesticides, fertilizers, household prod-
hand lens. These runner hyphae do ucts, and other chemicals may injure
not necessarily indicate summer grass if improperly applied. Burned
patch. Certain other fungi also areas may occur in spots or streaks,
produce similar strands on roots. In or the entire lawn may be scorched.
the final stages of the disease, blighted Prevent injury by following the direc-
Iron chlorosis turf areas form throughout the lawn. tions printed on the package label.
14Apply fertilizers evenly in recom-
mended amounts using a calibrated
Moss
Like algae, moss occurs where turf-
Turf Diseases
applicator. grass has been thinned due to one or
more site or environmental factors.
Nutrient Deficiency Reduce soil compaction, improve
Areas or all of the turf may become drainage, provide appropriate water
yellowed and stunted. Chlorosis and nutrients, and conduct other good
(yellowing) is usually caused by turfgrass agronomic practices.
nitrogen deficiency or iron deficiency.
Iron chlorosis is common in sites with Animal Urine Injury
a high soil pH. Follow recommended Injury from dog or other animal urine
fertility practices for the turfgrass may resemble brown patch or dollar
species and site condition. Submit soil spot. Affected areas are often more or
for nutrient testing and follow direc- less round and commonly up to a foot
tions in the report. or more in diameter. These are usually Soil sterilant (herbicide) injury to tall fescue
bordered by a ring of lush, dark green
Buried Debris grass. Injured grass turns brown or
A thin layer of soil over buried rocks, straw-colored and usually dies. Heavy
lumber, bricks, plaster, or concrete watering to flush the salts helps spots
dries out rapidly in dry summer to recover.
weather and may resemble disease.
Wet the soil and probe with a long Thatch
screwdriver or other implement. If the Thatch is a tightly intermingled layer
object is small it may be possible to of decomposing stems and roots that
dig it up and remove it. develops between green vegetation
and the soil surface. Thatch is not
Compacted Areas caused by returning clippings to the
Thin turf or bare spots appear in turf stand. Too much thatch keeps
heavily used areas. Waterlogged and water from penetrating the soil, makes Dry algae crust
heavy-textured (clay) soils become some disease problems worse, and
compacted especially in areas with inhibits root growth. Tall fescue and
frequent foot or vehicle traffic. In perennial ryegrass are bunchgrasses,
compacted soil, pore spaces are filled, which are less likely to accumulate
which decreases oxygen flow to the excessive thatch than Kentucky blue-
roots and interferes with water move- grass, zoysiagrass, or bermudagrass.
ment. Reduce compaction by aerifying Control thatch by cultivating when a
the soil. Improve drainage. Reduce half inch or more of thatch has accu-
traffic by putting in designated walk- mulated. The best time to cultivate
ways, paths, fences, or shrub rows. cool-season grasses is in the fall. In
contrast, the best time to cultivate
Algae warm-season grasses is in the summer.
A green to blackish algae slime may Core aeration, vertical mowing, and Dog urine injury
form on bare soil or thinned turf in power raking are three options. Each
low, wet, shaded or heavily used and method has pros and cons, so do some
compacted areas. The slimy mass research ahead of time to determine
of algae dries to form a thin, black which method is best for your site and
crust that later cracks and peels. The the turf species.
presence of algae usually indicates
an underlying site problem, and the
best prevention is by maintaining
a thick stand of turfgrass. Reduce
soil compaction, improve drainage,
provide appropriate water and nutri-
ents, and conduct other good turfgrass
agronomic practices.
Excessive thatch
15Turf Diseases Study Questions
1. What is included in turfgrass 6. To diagnose turfgrass diseases, the
management? following is important:
a. proper grass selection a. review cultural and
chemical practices
b. mowing
b. determining the overall
c. thatch control
distribution of the disease
d. all of the above
c. observe symptoms on
individual plants
2. An example of a cool season
grass is: d. all the above
a. bluegrass 7. Leaf spot and melting-out disease
is caused by a:
b. bermudagrass
a. bacteria
c. zoysia
b. virus
d. buffalo grass
c. fungus
3. What causes most turfgrass
d. rodent
diseases in the Midwest?
a. insects 8. From a distance, rust-
infected turf appears:
b. bacteria
a. dark green
c. fungi
b. dull yellow
d. viruses
c. dark brown
4. The following practices can
d. brick red
help prevent the development of
disease:
9. Powdery mildew can be
a. improve airflow and light reduced by:
availability
a. frequent nitrogen
b. select appropriate turf applications
species
b. pruning trees and shrubs
c. provide appropriate fertility to increase sunlight
d. all of the above c. spraying a bactericide
weekly
5. The first step in the control of
d. spraying a herbicide
any turfgrass disease is:
a. accurate diagnosis
b. apply a fungicide
c. apply a bactericide
d. apply an inch of water
16Study Questions Turf Diseases
10. In order to manage large patch 15. Rhizoctonia brown
fungus, it is important to: patch is the most common
and important disease on
a. allow thatch buildup __________.
b. core aerate when patch a. tall fescue
symptoms are active
b. bermuda grass
c. fertilize when the
symptoms are active c. Kentucky bluegrass
d. avoid overwatering in fall d. zoysiagrass
and early spring
16. In the control of brown patch
11. Spring dead spot is the most __________ is important.
common and destructive a. proper fertilization
disease of:
b. proper irrigation
a. bermudagrass
c. proper air circulation
b. tall fescue
d. all the above
c. zoysiagrass
d. Kentucky bluegrass 17. Summer patch is:
a. controlled by high nitrogen
12. Fairy ring is caused by: application
a. insects b. extremely difficult to
b. bacteria control
c. viruses c. easily controlled by one
application of fungicide
d. fungi
d. easily controlled by proper
13. Necrotic ring spot symptoms may aeration
be confused with summer patch
and __________. 18. Slime molds are ________
parasitic on plants.
a. Rhizoctonia large patch
a. seldom
b. rust
b. not
c. fairy ring
c. always
d. powdery mildew
d. usually
14. In lawn height turf, dollar spot
causes these symptoms: 19. Chlorosis is when the turf
becomes __________ in color.
a. rotted roots
a. purplish
b. tan or bleached patches
2-6 inches in diameter b. brownish
c. tan or bleached patches less c. yellowish
than one inch in diameter d. reddish
d. orange pustules on foliage
17Turf Diseases Study Questions
20. Moss occurs in lawns with: 21. Which statement about
thatch is NOT true:
a. low fertility
a. thatch interferes with
b. poor drainage, compaction
water flow into the soil
c. thinned turf
b. thatch inhibits root
d. combinations of the above growth
c. thatch is caused by
returning clippings to the
turf stand
d. thatch is less likely to
build up in bunchgrasses
such as tall fescue
18A ny plant can be considered a
weed if it is growing where it is
not wanted. Bentgrass, for example,
Perennial Weeds
Perennials, both broadleaf and grasses,
occur widely as turfgrass weeds.
Turf Weeds
would be a weed in a bluegrass lawn. Examples:
To plan a good weed control program,
you must: Broadleaf Weeds Grass Weeds
dandelion bermudagrass
• identify the desirable turfgrass,
wild garlic bentgrass
• identify the existing weeds, and plantain quackgrass
• combine pest control with good mouse-ear chickweed nimblewill
management practices. curly dock windmill grass
Weed Life Cycles Control Strategies
Annual Weeds The presence of weeds in turfgrass
Annual weeds complete their life does not always require the use of
cycle in less than one year. Because herbicides. In areas that contain sensi-
climatic conditions influence the tive plants, it may be better to avoid
timing of the life cycle, the correct the use of herbicides than to risk
time for control varies from place injury. In some locations, any kind of
to place, year to year and from one plant cover may be better than dead
species to another. In established turf- plants or bare ground.
grass, the chemical control of summer
Granular formulations are effective
annual weeds after midsummer may
for preemergence herbicides. Sprays
not be necessary or desirable.
are better for postemergence control
Examples of summer annual weeds where foliar coverage is needed.
common to turfgrass:
Broadleaf Weeds—Several post
Broadleaf Weeds Grass Weeds emergence herbicides are used to
selectively control annual, biennial and
knotweed crabgrass
perennial broadleaf weeds in turfgrasses.
spurge goosegrass They can be used alone or as combina-
purslane barnyardgrass tions of more than one active ingredient.
foxtail Spring and fall a pplications of postemer-
gence herbicides normally give satisfac-
Winter annuals are common in new
tory control and reduce the possibility
turfgrass. After the first year, good
of damage to nontarget plants. Young
management and dense turfgrass usually
weeds are usually more susceptible to
provide satisfactory control. Examples:
herbicides. Spot treatments are best for
Broadleaf Weeds Grass Weeds scattered weed populations. Weather
conditions affect control results.
common chickweed downy brome
shepherd's purse annual bluegrass Grass Weeds—Control of annual
grasses is best achieved with preemer-
henbit
gence herbicides for general infes-
tations and spot treatment with
Biennial Weeds postemergence herbicides for local-
Biennial weeds normally occur at ized infestations.
the same time as perennial broad-
leaf weeds. Controls are similar. Few herbicides are safe for use
Examples are: roundleaf mallow and on newly seeded turfgrass. Some
wild carrot. preemergence herbicides applied in
the spring may adversely affect germi-
nation of turfgrasses seeded in the
fall. Certain varieties of turfgrasses are
more prone to injury by herbicides.
Check labels for precautions.
19Turf Weeds Perennial grass weeds are the most
difficult to control. No herbicides
Common Weeds
are available which will control these
in Kansas Turfgrass
weeds without damaging cool-season Before selecting a control method,
turfgrass. Some will selectively control identify the weed.
them in warm-season turfgrass. Soil
fumigants and nonselective herbicides Barnyardgrass
are sometimes used. (Echinochloa crusgalli)
A coarse warm-season annual grass
Turfgrass Management with a flattened stem, especially near
The presence of weeds in turfgrass the base. Lower portion of the plant
does not always require the use of tends to be reddish purple. The seed
herbicides. Proper management can head branches into six to eight short
do much to encourage lawn grasses compact segments. Ligule and auricles
Barnyardgrass and discourage weeds. are absent.
Mowing at a height of 2 to 3 inches Bermudagrass (Cynodon dactylon)
shades the soil and protects cool-
Warm-season perennial that produces
season grass roots from damaging
both rhizomes and stolons that lie flat
effects of summer heat. High mowing
and creep across an area, rooting at
is an excellent deterrent to the germi-
the nodes. Flowering culms, flattened
nation and growth of many annual
erect or ascending 4 to 15 inches tall;
weed species. However, bermudagrass
ligule features a conspicuous ring of
and zoysiagrass perform best when
white hairs. A serious pest of cool-
mowed less than 2 inches.
season grasses.
Feeding programs that furnish lawn
grasses with necessary plant food Bindweed, field
elements throughout the growing (Convolvulus arvensis)
season tend to discourage weeds A deep-rooted perennial vine
Spreading bermudagrass through competition furnished by common throughout most of the
more vigorous turf. Fertilize cool- region. It is one of the more difficult
season grasses primarily in the fall, weeds to control. The spade-shaped
secondarily in the spring and only leaves have rounded tips and vary in
sparingly during the summer months. size. The funnel shaped flowers vary
Withhold spring fertilization of from white to light pink and are about
warm-season zoysia, buffalo, and the size of a nickel. The plants readily
Bermuda until mid-May; do not climb over shrubs and other orna-
fertilize them after mid-August. mentals. It spreads by both seed and
roots.
Watering will help grass survive
drought periods. Water as soon as Other common names: Creeping
the grass develops a blue-green cast. jenny; perennial morning glory.
Application of water before moisture
Field bindweed shortage symptoms appear is desir- Bluegrass, annual (Poa annua)
able. Soak the soil slightly deeper than A low-growing, compact, tufted
the depth of root penetration. Avoid winter annual. Some flattened stems
light, frequent sprinklings. may lie close to the ground. It does
Seed and sod free of weed seed and not have rhizomes. Leaves are soft,
off-type grasses is one of the first light-green and boat-shaped at the
steps in weed control. Many lawns tip. Starts growth from seed in early
contain undesirable coarse grasses fall and often grows throughout
and weeds because they were present winter. Can produce seed heads when
in the sod or seed. If you buy grass mowed at 3⁄16 inch. May die suddenly
seed, study the label to make certain during summer months.
undesirable weeds and grasses are not
present. Cultivated sod, inspected and
treated to reduce weeds, is becoming
Field bindweed more plentiful.
20Carpetweed (Mollugo verticillata)
A late-starting, rapidly growing
Dandelion
(Taraxacum off icinale spp.)
Turf Weeds
summer annual. The green, smooth Cool-season perennial common
stems branch from the root in all throughout the region. The yellow
directions, forming a flat circular flowers occur from early spring to late
mat on the soil surface. The light- fall. The thick fleshy taproot, often
green, smooth, tongue-like leaves are branched, can give rise to new shoots.
grouped five to six together forming Seedlings may appear throughout
whorls at each joint on the stem. the spring and summer and are often
Flowers are small, white, with several abundant in the fall.
at each joint.
Dock (Rumex spp.)
Chickweed, common The dock plant forms a large rosette
(Stellaria media) but rarely flowers when growing in
A hardy, low-growing annual or lawns. Curly dock (Rumex crispus) is Carpetweed
winter annual with creeping stems most common. The leaves have crin-
that root at the nodes. It has a deli- kled edges, often tinted red or purple.
cate appearance and is found in green Leaves of pale dock, also known as
form most of the year in milder tall dock (Rumex altissimus), tend to
climates. The small, opposite leaves be flatter and broader. Both species
are oval-shaped and smooth. The have flowering stalks that can grow up
small star-like flowers are white. to 3 feet tall.
Common chickweed is most often
found in the shade of trees and Fescue, tall (Festuca arundinacea)
shrubs, especially on the north side of A coarse, cool-season perennial bunch
buildings. grass. Scattered clumps are objec-
tionable in fine-textured turfgrasses.
Clover, white (Trifolium repens) Leaf veins are fibrous. When mowed,
A cool-season perennial legume that fibers show on the cut edge, especially White clover
spreads by underground and above if mowers are not well sharpened.
ground stems. May or may not be Mature leaf blades may be 1⁄2 inch
objectionable in lawns, depending wide, ribbed on top, and shiny smooth
on individual preference. Flowers are below. The lower portions of the
white, sometimes tinged with pink. stems are reddish purple, particularly
Seeds live for 20 years or more in the in the spring and fall.
soil.
A similar grass, meadow fescue,
Other common names: White Dutch (Festuca elatior) is also a frequent weed
clover. in bluegrass lawns.
Crabgrass (Digitaria spp.) Foxtail (Setaria spp.)
Crabgrass is one of the most common Foxtails are warm-season annuals.
warm-season annual grassy weeds. Yellow foxtail (Setaria glauca) has
The stems grow mostly prostrate, flattened stems, often reddish, on the Dandelion
branch freely and send down roots lower portion. Stems of green foxtail
where each joint comes into contact (Setaria viridis) are round. The seed
with the soil or moist grass. Seed of yellow foxtail is four times as large
head is divided into several finger-like as green foxtail. Giant foxtail (Setaria
segments. Two principal species are faberili) may be found in some lawns.
large crabgrass (Digitaria sanguinalis),
sometimes known as hairy crabgrass, Garlic, wild (Allium vineale)
and smooth crabgrass (Digitaria isch- The slender, smooth leaves are hollow
aemum). Smooth crabgrass tends to and attached to the lower portion of
be smaller and less hairy with purple the waxy stems. Both bulbs and bulb-
stems. lets are produced underground. Green
to purple flowers are often replaced
with bulblets. There is a characteristic
Curly dock
onion-garlic odor.
21Turf Weeds Wild onion is similar to wild garlic
but does not produce underground
Nutsedge, yellow
(Cyperus esculentus)
bulblets or have hollow leaves. Triangular stems of this warm-season
perennial produce three-ranked leaves
Goosegrass (Eleusine indica) from near the ground. Leaves are
A decidedly warm-season annual light yellow-green. Lower portion of
most often found growing where the plant is fibrous and brown. Roots
cool-season grass stands are thin. often terminate with small nutlets
Germinates later than crabgrass. about the size of a popcorn kernel.
The stems tend to be flattened and Seed heads resemble burs. Plants
white near the base. Flower heads grow rapidly in spring and early
are thicker and more robust than on summer. Several sedge species are
common crabgrass. The extensive common in this region, but this one is
fibrous root system makes it difficult most prevalent in lawns.
Wild garlic to pull.
Plantain, blackseed and broadleaf
Henbit (Lamium amplexicaule) Cool-season perennials that form
A winter annual that starts growing rosettes with prominently veined
in September. Characteristics include leaves. The leaves of blackseed
squarish stems on upright plants, (Plantago rugelii) are oval and 2 to
lavender to blue flowers, and opposite 3 inches across with purplish stalks.
leaves. A few plants may bloom in the Broadleaf plantain (Plantago major)
fall, but most blossom in early spring. has smaller leaves without purplish
coloration. Both species have rattail
Knotweed, prostrate seed heads several inches long.
(Polygonum aviculare)
An annual that germinates in early Plantain, buckhorn
spring and thrives into late fall. It (Plantago lanceolata)
Foxtail crabgrass grows flat from a long white taproot. Slender, narrow leaves of this peren-
Individual plants may spread two feet nial are about 1 inch across with three
or more. Stems are wiry and leafy to five prominent veins. The seed
with a thin, papery sheath at each leaf head is a short cylindrical spike.
node. Leaves often have a bluish cast.
Seeds are three-cornered, light-brown Poison Ivy (Rhus radicans)
early, and shiny black when mature. This woody perennial reproduces by
seed and root and is found mostly in
Mallow, purple poppy woods and shady places. Leaves are
(Callirhoa involucrata) divided into three oval leaflets. Seeds
Perennial that spreads by seed and are borne in white berries. All plant
underground root. Reddish-purple parts contain a toxic substance that
flowers are borne in clusters and have may be irritating to people. This plant
five petals. Leaves alternate. They is usually not a problem in turf, except
Goosegrass are 2 to 3 inches long, lobed, with in natural areas.
large oval stipules at the base. Lawns
started with pasture sod or soil may Puncturevine (Tribulus terrestris)
be infested. A prostrate, freely branching warm-
season annual that is slightly hairy.
Nimblewill Some stems may be 4 or 5 feet long.
(Muhlenbergia schreberi) It has a taproot, bright-green leaflets,
A warm-season perennial grass and yellow flowers. Seeds are angled,
with wiry fine stems that root at the with two stout spines that resemble a
nodes. Root system is shallow and Texas longhorn.
fibrous. It forms circular patches or
may be distributed throughout lawn.
Objectionable in cool-season lawns
because of delayed spring growth and
Henbit early dormancy in the fall.
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