Crop Profile for Turfgrass in
North Carolina (2004)
Prepared:
February, 2004
Production Facts
- North
Carolina ranks eighth in the U. S. in total turfgrass acreage.
- There are
2,007,100 acres devoted to turfgrasses in North Carolina.
- Turfgrasses
are found in single-family dwellings, roadsides, parks, commercial
properties, churches, golf courses, schools, athletic fields, sod farms,
airports, institutions, and cemeteries.
- Over $833
million is spent annually to maintain these turf acres.
- The
equipment used to maintain the turf is valued at $3.5 billion.
- Single
family dwellings account for 61% of the turf area, 56% of expenditures,
and 84% of the value of turf related equipment.
- Single-family
dwellings, commercial properties, and golf courses comprise 69% of the
turf acreage, 87% of annual maintenance expenses, and 96% of the value of
turf equipment.
- Golf
courses represent 2.6% of the turf acreage, comprise 14% of maintenance
expenses, and 5% of the total value of turf equipment.
- North
Carolina ranks ninth in total turf acreage on golf courses with 51,700
acres on 531 golf courses.
- Twelve
turfgrass species are utilized in North Carolina. They are tall fescue,
fine fescue, bermudagrass, centipedegrass, Kentucky bluegrass, bahiagrass,
annual ryegrass, perennial ryegrass, zoysiagrass, St. Augustinegrass,
carpetgrass, and bentgrass.
Production Regions
Turfgrasses are grown in all
100 counties of North Carolina. Higher maintenance turf such as found in
single-family dwellings, golf courses, and commercial property is concentrated
in population centers of the state.
Production Practices
North Carolina is situated in
the transition zone, which means both cool-season and warm-season turf species
can be successfully grown. However, heat tolerance of cool-season species and
cold tolerance of warm-season species is an issue for turf managers in the
state. Because single-family dwellings comprise the largest percentage of the
turf acreage (61%) and tall fescue is the most common turf species in home
lawns, this turf species is grown on 37% (742,600 acres) of the turf acreage in
North Carolina. The second most common turf species is bermudagrass, which
represents 12.3% of the turf acreage in the state (247,873 acres). Labor is the
single biggest expense category totaling $374 million and accounting for 45 %
of the total. Equipment supplies and repairs, miscellaneous expenses, and
pesticides account for 30%, 21%, and 5% of turf maintenance expenses. On
pesticides, $41,973,000 was spent on turf maintenance in 1994. Single-family
dwellings accounted for 65%, or $27,158,000, of all pesticide expenditures.
Golf courses spent more in terms of dollars per acre on turf maintenance than
any other sector. Average turf maintenance expenses on golf courses was $2,243
per acre compared to cemeteries ($1,383), commercial properties ($1,287),
institutions ($621), schools ($590), churches ($415), airports ($233),
single-family dwellings ($386), roadsides ($83), and parks ($69).
Home Lawn and Commercial Turf
Care (includes church grounds, cemeteries and schools)
IRRIGATION
- Irrigation
is a critical component for maintaining high quality turfgrass and is most
common in commercial properties, but becoming increasingly popular in home
lawn settings. Few churches or schools will have irrigation on the
turfgrass areas. Many irrigation units are automated, "pop up"
types that require no worker activity on the turfgrass site unless there
is a maintenance problem with the irrigation unit.
- Irrigation
is commonly used during the spring, summer and fall and often occurs in
close association with pesticide applications. In some instances irrigation
may be used immediately after pesticide application to move the product
into the soil, enhance the pesticide's activity, or remove it from the
foliage and thatch and move it into the soil.
- Prolonged
reentry intervals (REIs) would impact irrigation only in situations that
require the installation of irrigation heads in the turfgrass areas or the
movement and placement of temporary irrigation units.
FERTILIZATION
- Fertilization
is a common practice in the maintenance of quality turfgrass in home and commercial
settings. The application of fertilizers is often done during the same
time of year that pesticides are applied. Some products (particularly
insecticides and herbicides) may be applied to a fertilizer carrier and
the worker applying the fertilizer is also the pesticide applicator.
MOWING
- Mowing must
be done on a frequent basis and is done at the same time of year as
pesticide applications. Mowing of commercial properties is often
accomplished with larger mowing units on which the worker rides, but other
properties (such as home lawn) may utilize walk behind units.
- Prolonged
REIs might influence mowing schedules, but applications could be timed to
avoid any problems. Mowing may occur as often as every five days during
optimal growing conditions, but few pesticides have REI longer than 24
hours in turfgrass.
AERIFICATION
- Aerification
is a cultural practice that occurs during periods of peak growth and is
temporally associated with pesticide application. This is a mechanical
process that typically involves riding on or walking behind the equipment.
On occasion cores are collected, usually by machine, but cleanup is often
by hand with shovels and rakes.
RESEEDING AND OVERSEEDING
- These
practices often take place in the spring and fall (often in conjunction
with aerification) and would more commonly be in association with
herbicide applications. Workers activities would be limited to walking
across the turfgrass or riding on equipment.
MOWING
- Essential
for maintenance of dense and uniform playing surface.
- Conducted
at frequencies ranging from 1 to 7 times per week, depending on site use.
- Mowing
involves little contact with treated turfgrass foliage, as most is
performed with riding mowers. Golf course tees and putting greens are
often mowed with walk-behind mowers, increasing the chance of exposure
through foot contact with treated surfaces.
- When leaf
clippings are removed during mowing, handling and emptying of clipping
baskets may expose workers to pesticide residues through skin contact.
IRRIGATION
- Essential
for maintenance of turfgrass stands during periods of inadequate rainfall.
- Conducted
at frequencies up to several times a day, depending on turfgrass species
and time of year.
- Most irrigation
is conducted using automatic sprinkler systems and involves no worker
contact with treated surfaces.
- Golf course
putting greens are often watered by hand, using a high-output hose and
nozzle. There is potential for worker exposure through foot contact with
treated surfaces and handling of hose which contacts treated surfaces.
FERTILIZATION
- Applications
of essential plant nutrients are performed as granular applications or
foliar sprays.
- Frequency
of fertilizer application ranges from annual to biweekly depending on
turfgrass species and site use. Most fertilization is performed with
riding tractors and involves no contact with treated surfaces. Granular
fertilizers are typically applied to golf course tees and putting greens
once or twice per year using a walk-behind spreader, creating the
possibility for exposure through foot contact with treated surfaces.
CULTIVATION
- Necessary
for relief of soil compaction and reduction of thatch accumulations
- Performed
one to five times per year, depending on turfgrass species and site use,
using a variety of implements.
- Aerification
plugs and debris are removed by machine, as a result, there is little
opportunity for worker exposure to pesticide residues on foliage or in
soil.
MOWING
- Essential for
maintenance of dense and uniform playing surface.
- Conducted
at frequencies ranging from 1 to 7 times per week, depending on site use.
- Mowing is
performed with riding mowers and involves little contact with treated
turfgrass foliage.
- When leaf
clippings are removed during mowing, handling and emptying of clipping
baskets may expose workers to pesticide residues through skin contact.
IRRIGATION
- Essential
for maintenance of turfgrass stands during periods of inadequate rainfall.
- Conducted
at frequencies up to several times a day, depending on turfgrass species
and time of year.
- Irrigation
is conducted using automatic sprinkler systems and involves no worker
contact with treated surfaces.
FERTILIZATION
- Applications
of essential plant nutrients are performed as granular applications or
foliar sprays. Frequency of fertilizer application ranges from annual to
biweekly depending on turfgrass species and site use. Most fertilization
is performed with riding tractors and involves no contact with treated surfaces.
CULTIVATION
- Necessary
for relief of soil compaction and reduction of thatch accumulations.
- Performed
one to five times per year, depending on turfgrass species and site use,
using a variety of implements.
- Aerification
plugs and debris are removed by machine, as a result, there is little
opportunity for worker exposure to pesticide residues on foliage or in
soil.
PLANTING
- Planting of
turfgrass on sod farms is typically done either by seed or by vegetative means
that would include sprigging, plugging, or sodding. Herbicides are often
used at planting.
- Irrigation
requirements are high during the early establishment phase on sod farms.
Therefore, farm workers will be in the fields working with irrigation soon
after planting of seed or vegetative means.
- Prolonged
REIs could impact irrigation where there is a problem with the irrigation
system. If no problems exist, the irrigation systems would work fine as
they are highly automated.
FERTILIZATION
- Turfgrasses
on sod farms are routinely fertilized by workers. However, all
fertilization is done by mechanical means, which includes tractors
equipped with high flotation tires with spreader equipment mounted on the
back.
- Fertilization
of turf on sod farms is almost always applied as a dry material that must
be watered to activate.
MOWING
- Turfgrasses
on sod farms are routinely mowed during and after establishment. Mowing is
always accomplished by tractor-mounted mowers and is never accomplished by
walk mowing. Therefore, worker contact with turfgrass tissue during the
mowing process is minimal.
HARVESTING SOD
- Harvesting
(or cutting) sod is very labor intensive. This requires that multiple
workers are placed on and around a mechanical sod harvester. As the sod is
mechanically cut, it is delivered via conveyor to palates where the sod is
physically placed to be loaded onto trucks. Workers physically handle both
turfgrass tissue as well as soil. If pesticides were present, the highest
amount of exposure would occur during this process.
Turfgrass pests include
disease pathogens, insects, and weeds. Some pests will always be present;
however, what can be considered an acceptable level of pest activity will vary
with each situation. For example, a light infestation of broadleaf weeds may be
tolerable in a park-like setting but would be unacceptable in a golf green.
Defining an acceptable level of pest activity, whether on roadsides, golf
courses, home lawns, athletic fields, or parks and grounds must be determined
by the individual most familiar with the situation. Measures available to the
turfgrass manager for the prevention and control of pest problems include the
wise use of pesticides along with management practices that promote a healthy, dense,
vigorous turf. Proper management practices can prevent or reduce pest
encroachment and development. Rising chemical costs, limited availability of
long-term residual pesticides, increased resistance to pesticides, and
environmental concerns have emphasized the importance of efficient turf
management and reduced dependency on pesticides. Research has shown that a
properly maintained lawn is better able to ward off certain diseases and weeds
and will tolerate a higher number of insects than a lawn, which is mismanaged.
In addition, turfgrass rate of recovery from injury, whether it be pest or
nonpest related, is usually faster when the turf has been managed properly.
Site Selection and Preparation
Proper site selection and
preparation can help prevent the development of future problems. Good soil and
surface drainage can help reduce disease and weed problems. Soil mixtures
developed specifically for certain types of turf areas can aid drainage, reduce
soil compaction, and provide an environment favorable for good growth.
Selective tree removal can limit shade and tree root competition as well as
reduce environmental conditions favorable to pest development. Certain diseases
such as Pythium blight are more likely to occur where air movement is impeded by
trees or dense undergrowth.
Soil amendments to improve drainage as well as fertilizer and lime are best
incorporated prior to seeding. The type and quantity of amendments should be
determined from chemical and physical soil tests. Soil test results are only as
good as the sample submitted; therefore, care should be taken to insure that
each sample is representative of each site. Amendments should be evenly spread
and thoroughly incorporated to be most effective and to eliminate a future
non-uniform appearance of the turf.
Turfgrass Selection
Turfgrass selection should be
based on the existing environment, intended use, and expected management
intensity. Check with a turfgrass specialist or extension agent to find out
which grasses perform best in a given area. Blends and mixtures should be used
whenever possible to insure good performance over a wide range of conditions.
Cool-season grasses (bentgrass, bluegrass, ryegrass, fescue) are best
established during the fall, whereas warm-season grasses (bermudagrass,
zoysiagrass, centipedegrass, St. Augustinegrass) are best planted in late
spring or early summer. Use of improved, adapted, turf-type grasses, free of
objectionable weeds, is one of the best means of preventing pest activity.
Numerous cultivars have been released with improved tolerance to certain
diseases such as leaf spot, rust, dollar spot, and others. Several cultivars
are also being marketed that claim resistance to certain insects. Insist on
certified seed to assure seed of high genetic purity. Uncertified seed
frequently produce plants of low quality that are very difficult to manage.
Also insist on seed that is free of weed and crop seed. (Crop seed consists of
objectionable and difficult to control perennial grasses.)
Nutrition
Fertilizer programs should
meet the nutritional needs of the turf without promoting excessive growth.
Specific nutrient needs can be determined with a soil test. (Remember: a soil
sample should accurately reflect the existing site.) Soils in intensively
managed areas should be sampled every year, and less intensively managed areas
should be sampled every 2 to 3 years. In addition to soil sampling, nutrient
analysis of tissue can be done as a more precise gauge of fertility
requirements on intensively managed turfgrass areas. Avoid fertilizing
cool-season grasses with high rates of nitrogen in late spring and summer to
prevent injury from environmental stress and pests. Such grasses are best
fertilized during the cooler portions of the year, especially the fall.
Fertilization of warm-season
grasses during late spring/early summer encourages healthy dense turf that can
withstand weed encroachment. A high rate of nitrogen applied in late summer or
fall can make warm-season grasses more susceptible to cold injury and pest
infestation. Warm-season grasses may benefit from potassium applied in late
summer to help improve winter hardiness. Care should be taken when using
quick-release sources of nitrogen to prevent turfgrass injury (leaf burn) and
promotion of lush, succulent growth. Use of slow-release nitrogen sources can
limit burn and excessive growth, but should be timed to precede the optimum
growth period of the grass species. Slow-release nitrogen sources are the best
choices for turf grown in sandy soils or near bodies of water.
Irrigation
When irrigating, water should
be applied infrequently but deeply. Foot printing, leaf curling, and
discoloration are indications that turf needs to be watered. Light, frequent
watering encourages a shallow root system, compaction from traffic, and
susceptibility to pests and environmental stresses. Deep, infrequent watering
encourages plants to develop an extensive root system. Irrigation schedules
should attempt to minimize the time during which foliage remains moist to
discourage disease. Early morning has proven to be the most effective and
efficient time to water. Localized dry spots on golf greens are best controlled
by coring and hand watering or by applications of wetting agents on the
isolated dry areas.
Mowing
Mowing frequency
and cutting height are important for maintaining quality turf and must be
adjusted to the time of year and growth rate of the grass. As a general rule,
no more than 30 to 40 percent of the leaf area should be removed in any one
clipping. Scalping and puffiness are often indications that the turf is not
being maintained at the proper height of cut. In general, raising the cutting
height helps grasses withstand environmental stress, provided an effective
cutting height is maintained. Some golf course superintendents, for example,
raise the cutting height of bentgrass slightly on greens to minimize the
effects of midsummer stress. Mowing grass when it is wet may prevent the
clippings from sifting back through the foliage and may spread disease pathogens.
Using a sharp blade will provide cleaner cuts of turfgrass leaves, which will
improve appearance of the turf and may reduce pathogen infection.
Turf Cultivation
Turfgrass areas may be
subjected to heavy traffic, which causes compaction and prevents water and
nutrients from entering the soil. Turfs grown in compacted soils are less
vigorous and more vulnerable to environmental stress. Wet soils are especially
prone to compaction. Turf managers should avoid watering playing fields a day
or two before a scheduled event. Turf cultivation selective tillage or coring),
practiced when weather conditions are suitable for active growth of a turf,
helps alleviate compaction, accelerates drying of persistently wet soils, and
improves turfgrass response to nutrients and certain pesticides. Cutting slits
(slicing) and punching holes (spiking) in some soils can improve water
infiltration and stimulate plant growth but will not be good substitutes for
coring.
Thatch
Thatch can be defined as a
layer of dead and living stems and roots situated above the soil surface.
Contrary to popular belief, grass clippings are not a component of thatch. In
fact, grass clippings, which are 75% to 85% water, decompose quickly and
release nutrients that help to fertilize turfgrass (grasscycling). Major causes
of thatch accumulation include (1) use of vigorous sod forming turfgrasses; (2)
high rates of nitrogen; and (3) frequent use of certain fungicides, herbicides,
and insecticides. Soil aeration (coring) combined with topdressing and verticutting
(power raking) has been shown to be an effective means of controlling thatch
buildup on intensively managed turfs by increasing the rate of decomposition. A
good topdressing mix (one that is compatible with the existing soil) should be
applied. Topdressing and vertical mowing are frequently used to reduce thatch
buildup on greens. On large or less intensively managed areas, reincorporation
of soil cores following aeration, using a drag mat, is an acceptable
alternative to topdressing. Light, repeated verticutting is preferred when
thatch is excessive. Turfs should be dethatched at a time when the turf can
quickly recover. However, overstimulation of plant growth should be avoided.
Slowrelease sources of nitrogen are less likely to leach and volatilize in
thatchy turf compared to a water-soluble source of nitrogen.
Integrated Pest Management (IPM)
An integrated pest management
(IPM) program is a multidisciplinary, ecologically based pest management system
that uses all available methods to keep pests at acceptable levels while
minimizing the effect on people, the environment, and turf. Pesticides are only
one of several options available to managers for controlling pests. Other
options include genetic, regulatory, physical, biological, and cultural solutions.
A sound IPM program is based on tolerating a level of pest damage, which does
not significantly reduce the acceptability of the turf. A sound IPM program
will include:
- A
knowledgeable manager.
Knowledge is the cornerstone of any successful IPM program. Managers
should know about the grasses being grown, the pests, which are likely to
be a problem, and the conditions that may impact the pests and grasses
being maintained.
- A
written plan.
This plan should include objectives for each turf area and the degree of
acceptable injury from pests. It will help define pest threshold levels.
Include in the plan specific management practices for nonchemical control.
- Definition
of pest threshold levels.
Determine what is acceptable for your turf, such as whether weeds should
be allowed or how many insects should be tolerated per square foot.
Recommendations are available regarding threshold levels for certain
insects.
- Implementation
of appropriate cultural practices.
Use of agronomically sound cultural practices results in a healthy, dense,
vigorous turf that is better able to ward off pests and pest injury.
- Monitoring
of pest activity.
Most pests are easy to manage when they are immature and few in number.
Frequent scouting can help determine the stage of pest activity or
injury.
- Maintenance
of accurate records.
Keeping accurate, up-to-date records of pest activity, actions taken, and
the results of those actions will assist in future planning.
Pesticides are sometimes
necessary to keep pests at tolerable levels. These chemicals will continue to
be an integral part of any IPM program. However, sole reliance on chemical
control can no longer be justified because of rising chemical costs, increased
resistance to pesticides, and environmental concerns. Some pesticides can also
enter surface or groundwater either from leaching or runoff. The selection of
pesticides to be used on the turf should be based on many criteria including
the pest to be controlled; the turfgrass species the pest is infesting; the
season and growth stage of the pest; the level of control desired; the
application method required for the pesticide; the duration of control from the
pesticide; the possibility of environmental contamination; and the need for
frequent rotation of pesticides of different modes of action for the target
organism to avoid pesticide-resistant plants, insects, and diseases. After all
factors are considered, there may be two or three possible choices of
pesticides for control of the pest.
Summary
Damage from turfgrass pests —
diseases, insects, and weeds — many times can be controlled at acceptable
levels with proper turfgrass management methods. Unacceptable levels of pest
damage often indicate a flaw in the current turfgrass management. Accurate
identification of the pest or other cause of the problem is necessary to
correct the flaw and prevent further damage. Integrated pest management
strategies dictate using the most safe, effective, and economical control
measures available. Pesticides should be considered as only one option among
available biological, cultural, chemical, manual, and mechanical pest control
tools. If pesticide use is warranted to maintain acceptable turfgrass quality,
the proper selection and use according to the pesticide label is required.
Insecticides and Nematicides
Home Lawns
Homeowners spend over $5
million on insect control in North Carolina, however this is only about 1% of
total maintenance costs. Newer products such as the pyrethroids, imidacloprid,
and halofenozide have entered the homeowner market and only in the past two to
three years has use been significant. This may be a reflection of the firm
grasp that chlorpyrifos, carbaryl, and diazinon had on the market place prior
to enactment of the FQPA. Perhaps most importantly, the newer products do not
have the broad range of use sites on the label, which allowed homeowners to use
these products virtually anywhere around the home. Chlorpyrifos, diazinon, and
carbaryl are broad spectrum products with maximum brand name recognition and
user familiarity. These products were preferred by homeowners, not only for the
above reasons, but also for the fact that they serve such a multitude of uses
around the home. Other products such as bendiocarb, trichlorfon and acephate receive
some use either as a product that a homeowner has been specifically directed to
purchase, in combination with a lawn care product (fertilizer), or as a product
of choice for a specific insect problem (e.g., acephate for mound treatment of
fire ants), but these are not major uses. Bendiocarb has been phased out and
few inventories remain.
Commercial
Insecticide use in the
commercial arena relies less upon broad spectrum approaches, but more on
addressing specific pest problems and use of the most cost effective product
for that need. Thus broad spectrum insecticides are less critical, however, the
broad spectrum products do allow commercial applicators to maintain a smaller
inventory of products to meet the needs of their operation. Only about 20 to 25%
of commercial properties (excluding golf courses) annually treat for insects.
Approximately 95% of all golf courses treat for insects each year.
Major pest problems in
commercial turfgrass include the white grubs. Recent introductions such as
imidacloprid, halofenozide and fipronil have dramatically changed the market
composition. Many commercial applicators have embraced these new products for
grub control and they now make up a very significant share of the white grub,
mole cricket, and fire ant markets. Both imidacloprid and halofenozide must be
used somewhat in a prophylactic or preventive mode to ensure product efficacy.
This is a challenge in North Carolina since our grub problems are not as
consistent as they are in the northeast U.S. A variety of other products are
used on the remaining acreage including carbaryl, trichlorfon, carbaryl, and
acephate. In general, these products are less expensive than the newer products
and are relatively efficacious. The market share for these products is split among
the various products with acephate holding a very small percentage of the grub
market. Trichlorfon is the product of choice as a rescue treatment for white
grub problems due to its high water solubility and rapid action (but short
residual activity). Carbaryl is used extensively for one grub species, the
green June beetle grub, since it has proven quite cost effective for that pest.
Diazinon is no longer labeled for use on turf (other than golf course) and has
been phased out due to actions of the FQPA. The other pests complexes such as
ants (including fire ants), chinch bugs, caterpillar pests, and mole crickets
all have a rather large array of products (including pyrethroids, imidacloprid,
halofenozide, and fipronil) available for their management and no one
particular product dominates the market (except fipronil is the product of
choice for mole crickets if budgets can afford that product).
Pyrethroids have become
increasingly popular for the control of many pests particularly the
caterpillars and chinch bugs due to the low use rates and the low mammalian
toxicity. Chlorpyrifos use is now restricted to golf courses and this has
eliminated the most efficacious product for southern chinch bugs and thus more
frequent treatments of pyrethroids are often required in the home lawn care
market. These include: deltamethrin, permethrin, cypermethrin, bifenthrin,
cyfluthrin, and lambda-cyhalothrin. Due to the widespread occurrence of these
pest across many crops and the sporadic nature of their pest status on turf
there does not appear to be a danger of resistance. Due to the nature of the
"crop", cultural practices play only a limited role in reducing
insect pest problems. Pest control for the white grubs, mole crickets, and fire
ants has been most dramatically as far as loss of the labeled products for
those pests due to FQPA.
Fenamiphos (an
organophosphate) and ethoprop are products registered for sting nematode
control in commercial turf. It is estimated that fenamiphos is used on 5% of
the commercial turf acreage and ethoprop is approximately 1%. While only 5% of
the acreage is treated with fenamiphos, this use is considered critical for the
management of otherwise uncontrollable sting nematodes. Numerous products are
under investigation for control of nematodes with turf with current state
labels in several southern states for Curfew (same as Telone II) from Dow
Agrosciences.
Herbicides
Weeds are the number one pest
problem for turfgrasses in North Carolina. Of all pest problems, weeds rank first
in all segments of the industry with golf courses being the lone exception
where weeds are second to diseases. Herbicides are heavily relied upon for weed
management in turf due to limited cultural control methods such as crop
rotation and cultivation. Preemergence herbicides for crabgrass and goosegrass
are the most commonly used products. These include dinitroanilines (DNAs) such
as pendimethalin (Pendulum, Pre M), prodiamine (Barricade), benefin +
trifluralin (Team Pro), oryzalin (Surflan). Two other commonly used
preemergence herbicides that are not DNAs are oxadiazon (Ronstar) and dithiopyr
(Dimension). As with insecticides, herbicides will be broken into two
categories: home lawn (homeowner use) and commercial (golf courses, commercial
properties, roadsides, and professional lawn care companies).
Home Lawns
Homeowners and tenants spent
$18.8 million on herbicides and weed control products in 1994. This represents
4% of total maintenance costs for lawn care but represents 69% of all costs
associated with pest control. Weeds rank as the number one turf management
problem in home lawns. Over 39% of turf management problems are weed problems.
Poor soil (20% of turf management problems) is the second most common turf
management problem. Insects and diseases are 2.9% and 0.6%, respectively.
Preemergence herbicides represent the majority (>80%) of weed control
products in home lawns. These include the DNAs for crabgrass and goosegrass
control and atrazine (various trade names) and imazaquin (Image) for preemergence/postemergence
broadleaf weed control and annual bluegrass control. In tall fescue, the DNAs
are essentially the only preemergence herbicides used whereas in warm-season
turf such as bermudagrass, centipedegrass, zoysia, and St. Augustinegrass, imazaquin
and atrazine are commonly used for miscellaneous broadleaf and annual bluegrass
control. The DNAs are also commonly used in warm-season turf for crabgrass and
goosegrass control. Postemergence herbicides are used for remedial weed control
in various turfgrass species utilized in home lawns. The only postemergence
herbicide available for crabgrass and goosegrass control is sethoxydim
(Vantage) for use in centipedegrass and fine fescue. There are many products
that are mixtures of herbicides and are mostly used for control of
miscellaneous broadleaf weeds. Common combination products include 2,4-D,
mecoprop, and dicamba in various concentrations and ratios. These products are
routinely available in garden centers.
Commercial
As with home lawns, weed problems
generally rank in the top 2 to 3 turfgrass management problems in commercial
turf. Because many more herbicides are available to turfgrass managers licensed
as commercial applicators, the spectrum of herbicides used in commercial turf
exceeds those used by homeowners. In some areas of commercial turf, herbicide
use makes up a vast majority of pesticide use.
Weed problems that result in
herbicide use include crabgrass and goosegrass which, as in home lawns, still
represents the vast majority of preemergence herbicide use. Preemergence
herbicides for crabgrass and goosegrass represent approximately 60% of all
herbicide use in commercial turf. These include the previously mentioned DNAs
(pendimethalin, oryzalin, trifluralin + benefin, benefin (alone)) and dithiopyr
and oxadiazon. Postemergence herbicides are also utilized for remedial
crabgrass and goosegrass control on approximately 10% of turfgrasses. These are
utilized when preemergence herbicide activity is inadequate. Products used for
postemergence control in bermudagrass include monosodium methanearsonate (MSMA)
and MSMA + metribuzin (Sencor). In cool-season turf, fenoxaprop (Acclaim Extra)
is utilized for postemergence crabgrass and goosegrass control. On some sites,
fenoxaprop is utilized as the primary means of crabgrass control but in most
cases it is still used when preemergence activity is lost. In many cases,
herbicides are used with both preemergence and postemergence activity. These
include ethofumesate (Prograss) for annual bluegrass control in cool-season
turf (2% of acreage), simazine for winter annual broadleaves and annual
bluegrass control (5% of acreage), atrazine for the same weeds (<1% of
acreage), imazaquin (5% of acreage), and pronamide (Kerb, 3% of acreage). In
industrial turf, particularly roadsides, herbicides make up 98% of all
pesticide use. Many industrial herbicides have both preemergence and
postemergence activity. Sulfometuron (Oust) is commonly used (90%) for
warm-season release on roadsides in North Carolina. Metsulfuron (Escort) also
has preemergence and postemergence activity and is used on approximately 15% of
industrial turf. Imazapic (Plateau or Imazapic Applicators Concentrate) is used
on approximately 5% of industrial turf. Many postemergence herbicides are used in
commercial turf. Combination products are also commonly used. These include
2,4-D, mecoprop, and dicamba (various trade names), 2,4-D, mecoprop, and
dichlorprop (various trade names), and triclopyr + clopyralid (Confront), and
combinations of these products. These postemergence herbicides are used on
approximately 25% of commercial turf in North Carolina for control of
miscellaneous broadleaf weeds. Glyphosate (Roundup Pro) and glufosinate
(Finale) are also used for turf renovation. Each year, approximately 4% of turf
acreage gets one of these herbicides.
Plant Growth Regulators
Plant growth regulators
(PGRs) are becoming increasingly popular turf managment tools in North
Carolina. Over 90% of PGRs are used either in industrial turf (seedhead
suppression) or highly maintained turf (golf courses). In industrial turf, all
PGRs are sublethal rates of herbicides. These include sulfometuron (Oust),
imazapic (Plateau or Imazapic Applicators Concentrate), or metsulfuron
(Escort). These products are used on 50% of industrial turf in North Carolina.
On golf courses, trinexapac-ethyl (Primo) is commonly used (55%) on golf course
fairways to reduce vegetative growth and to increase turfgrass quality. On
bentgrass putting greens, the predominant PGR used is paclobutrazol (60% of
bentgrass greens) for annual bluegrass control. Flurprimidol (Cutless) is also
used but less than 5% of bentgrass greens are treated with this PGR.
Fungicides
Diseases are an important
pest in all sectors of the turfgrass industry. In North Carolina, the most
severe disease problems occur on cool-season grasses (fescues, ryegrasses,
bluegrasses, and bentgrasses), which comprise 50% of the turfgrass acreage in
North Carolina. Approximately $8.4 million was spent on fungicides for
turfgrass disease control in 1999. In most landscape situations, diseases can
be managed effectively through selection of resistant varieties and use of
proper turfgrass management practices (mowing, fertilization, irrigation,
cultivation, etc.). Fungicide use is an essential component of disease
management programs in commercial turf because of limited flexibility in grass
selection and management practices.
Home Lawns
Homeowners and professional
lawn care companies spent $2.5 million on fungicides for disease control in 1999.
Approximately 90% of fungicide applications to landscape turf is made for
control of brown patch and large patch. Both diseases are caused by the fungus Rhizoctonia
solani; brown patch is specific to cool-season grasses and large patch is specific
to warm-season grasses. The DMI (myclobutanil, propiconazole, triadimefon) and
benzimidazole (thiophanate-methyl) classes of fungicides are used most
frequently for control of brown patch and large patch. Although these
fungicides are weak for Rhizoctonia control, they are readily available
to homeowners on store shelves. The DMIs and benzimidazoles also remain the
fungicides of choice for professional lawn care companies because of product
familiarity and relatively low cost per application. New classes of fungicides,
such as the QoIs (azoxystrobin, pyraclostrobin, and trifloxystrobin) and
benzamides (flutolanil) have not widely adopted in the lawn care sector,
primarily because they cost 50 to 100% more per application. However, these
products are highly effective for control of Rhizoctonia diseases, and
research is showing that reduced application rates or extended application
intervals provide excellent control in landscape situations. Use of the QoIs
and benzamides is expected to increase steadily over the next decade.
Commercial
In 1999, golf courses spent
$5.9 million on fungicides for turf disease control. Over 90% of fungicide
active ingredient is applied to putting greens, which comprise 3% of the
turfgrass acreage on a typical golf course. Fungicide use is critical for
putting green management because of regular mowing at 1/8" or less,
frequent traffic, and low tolerance for damage from disease. There is also a
limited selection of grasses that are adapted to this environment, and there
has been little progress in breeding these grasses for disease resistance.
There are many diseases that occur regular on putting green turf, including
dollar spot (Sclerotinia homoeocarpa), brown patch (Rhizoctonia
solani), Pythium blight (Pythium aphanidermatum), Pythium root rot (Pythium
spp.), anthracnose basal rot (Colletotrichum graminicola), yellow patch
(Rhizoctonia cerealis), pink snow mold (Microdochium nivale),
fairy ring (Basidiomycetes), algae (Cyanobacteria), take-all
patch (Gaeumannomyces graminis), and summer patch (Magnaporthe poae).
Because of the broad spectrum of pathogens that must be managed, golf course
superintendents must utilize all available classes of fungicides. The
availability of a large selection of fungicide classes is also important for
prevention of fungicide resistance, which is a common problem in populations of
Sclerotinia homoeocarpa, Pythium aphanidermatum, and Colletotrichum
graminicola.
Current Pesticide
Recommendations for Turfgrass in North Carolina
Current North Carolina
Cooperative Extension Service recommendations for pesticide use on turfgrass
are provided in the following tables in the North Carolina Agricultural
Chemicals Manual:
Many insects and small animals
live in or on turf. Some damage turfgrasses by feeding on or sucking sap from
the roots and leaves and, to a lesser extent, stems. Others damage turfgrasses
by making burrows in the soil that disturb roots. Insects may reduce stands by
killing plants, reduce turfgrass quality, or make plants more susceptible to
other pests. Some also transmit plant pathogens. If turfgrass areas have
stunted, distorted growth, browning or yellowing leaves, or dead areas, you
should confirm the presence of insects before an insecticide is applied.
Similar symptoms may be caused by diseases, nematodes, poor soil conditions, or
other factors. Potential insect damage to turf varies greatly due to many
factors such as fertility, irrigation, height of cut, age of turfgrass,
climate, food availability, plant response, natural enemies (parasites,
predators, and pathogens), and use of the area. Some turfgrasses are more
tolerant of insect attack than others and grow well in spite of insects. Others
may be severely damaged by the same number of insects. Fortunately, only a few
pests cause problems that require control measures in any given year.
Therefore, it is impossible to give a clear-cut guide to the number of insects
that must be present to cause damage for each situation. From experience we
know that certain insects must be controlled at the first sign of presence
because they will likely increase in numbers and cause considerable damage.
With other pests, pest buildup can be detected by frequent examination of the
turf and insecticides used only if the injury gets progressively worse. Heavy
infestations of cutworms, fall armyworms, or sod webworms may be tolerated on
fairways, industrial areas, home lawns, and parks with few ill effects, whereas
only a few in number severely damage golf greens.
Soil Insects
The major soil-inhabiting
insects in North Carolina are the grubs (larvae of many species of beetles such
as the Japanese beetle, green June beetle, Asiatic garden beetle, northern masked
chafer, southern masked chafer, and billbug), ants, mole crickets, and scale
insects such as ground pearls. Soil insects are difficult to detect and can
only be found by close examination of the roots, stems, and crowns of plants
along with soil from around the turfgrass. This usually requires a shovel or
spade to dig up the turf and soil. Moles, birds, and skunks feed on grubs and,
in the process, tear up the turf as they search for them, often causing
extensive damage.
Control: If an economic threshold of grubs exists, there are now
several alternatives to conventional insecticide use. The spores of Bacillus
popilliae, milky spore disease, for control of Japanese beetle larvae have
been around for years. Treatment with milky spore disease is expensive, very
slow, and should only be directed against Japanese beetle grubs. However, once
the spores are distributed, the treatment will provide some control for years.
Unfortunately, there are no data to support the effectiveness of milky spore,
and the availability of quality product has been sporadic in recent years. New
products such as various species of entomogenous nematodes that are currently
available and a new strain of Bacillus thuringiensis that is effective
against white grubs have provided and will provide future opportunities for
alternative management options. Timing and application techniques are critical
with these control options. Insecticides must be distributed evenly to obtain
good insect control. They may be applied as coarse sprays or granules. Because
effective control depends upon contact between the insect and the insecticide,
the treated area should be irrigated