Lawn and Ornamental Part 1:

Turfgrass Disease Management

IFAS Publication: SSPLP14

Prepared by: M.L. Elliot and P.F. Harmon

Learning Objectives:

To better understand the nature of turfgrass diseases

To be able to make better decisions when selecting fungicides
for treating turfgrass disease
Publication #SSPLP14

Turfgrass Disease Management M. L. Elliott and P. F. Harmon

Introduction
Turfgrass diseases are often overlooked because the biological organisms (plant
pathogens) causing the problems are rarely observed and commonly mistaken for other
injuries or disorders. Use of proper cultural practices (i.e., water, mowing, and fertility)
will reduce the risk of grasses becoming diseased or severely damaged by turfgrass
pathogens. This publication discusses turfgrass diseases, their causal agents,
diagnosis, and management.

What Is a Disease?
A disease is an interaction between the plant and a pathogen that disrupts the normal
growth and appearance of the plant. While turfgrasses may be affected by diseases all
year, individual turf diseases are active for only a few months each year, usually
because of weather patterns and resulting environmental effects. However, any stress
(environmental or manmade) placed on the turf weakens it, making it more susceptible
to diseases.

Turfgrass diseases in Florida are caused by fungi (yeasts, molds, and mushrooms are
types of fungi). Most fungi living in lawns are completely harmless to plants. In fact, they
are beneficial because they decompose the grass clippings and old roots. A very small
number of fungi cause plant diseases.

The absence of turfgrass disease does not indicate that the turfgrass area is free of
fungal pathogens. The pathogens are likely surviving in the environment in a state of
dormancy or as a saprophyte (nonpathogenic phase), living off dead organic materials
in the thatch and soil layers.

Diseases are the exception and not the rule for lawns. Spots and patches of yellow
or brown turfgrass do not necessarily mean the lawn has a disease. Various injuries or
disorders may cause the turf to appear diseased. Turfgrass diseases can be difficult to
diagnose, so involvement of these other factors should first be ruled out. An injury to
turfgrass is a destructive physical occurrence, such as pesticide damage (Figure 1),
mowing the grass too short (Figure 2), or a fuel leak. A turfgrass disorder is associated
with imbalances of physical or chemical requirements for turfgrass growth. Examples
include nutritional deficiencies, cold temperatures, drought (Figure 3), and excessive
rainfall. Again, while these problems may appear to be diseases, there are no
pathogens involved. However, these injuries or disorders may weaken the turf so much
that a pathogen may attack the plants and cause a disease.

Figure 1. Damage from an excessive rate of herbicide. No disease.

Credit: M. L. Elliott
Figure 2. St. Augustinegrass mowed too short, resulting in scalped turfgrass. No disease.
Credit: M. L. Elliott
 Figure 3. Dry patches in St. Augustinegrass. No disease.
Credit: M. L. Elliott

Disease Process
There are many steps in the disease process, and all are dependent on environmental
conditions. The first step is inoculation, when the pathogen comes in contact with the
susceptible plant. This is always occurring with turfgrasses. The next steps determine if
a disease will develop. Infection is the second step, when the pathogen actually enters
the plant. Fungi can enter a plant via wounds (i.e., cut leaf blades), natural openings
(i.e., stomates), or direct penetration using a number of different mechanisms. A fungus
infecting a plant does not automatically imply disease. The pathogen must become
established inside the host for the host to exhibit disease. It is at this point that the
pathogen starts to disrupt the normal growth of the plant or affect the appearance of the
plant. Depending on the pathogen, it may then reproduce (i.e., produce spores). These
reproductive structures or other parts of a pathogen may then spread to other turfgrass
plants. A disease epidemic means that large populations of turfgrass plants are affected
by the pathogen.
Disease Symptoms
Unlike insects or weeds, it is not possible to monitor the number of turfgrass pathogens
present in a given area. Instead, disease symptoms (if already present), the weather,
and stress factors affecting the turfgrass are monitored. It is critical to document active
disease sites, as many disease outbreaks occur in the same location each year. It is
also important to determine if the active disease sites are associated with environmental
characteristics, such as excessive shade, fertilizer application timing, type of fertilizer,
soil type, or excessive irrigation. These records can be used to help predict disease
outbreaks and to design effective management strategies.

There are two common patterns of turfgrass disease symptoms. One is a circular patch
of turfgrass, either small or large, that is no longer uniformly green. The second is turf
that has spots on the leaves. If disease patches are present, examine the leaves and
roots in these patches for characteristic disease symptoms and signs (actual fungal
structures) of the pathogen. The best time to observe fungal mycelia is in the early
morning when dew is still present. Mycelia look similar to white cotton candy. Early
afternoon is a good time to look for localized patches of wilt or drought symptoms that
may indicate root or crown diseases. For turf with spots, note the color and shape of the
spots, but always keep in mind that there are several other conditions that are not
caused by disease that can produce similar symptoms.

Monitoring the weather helps with disease prediction and determining the necessity of
fungicide applications. If the disease-affected areas are small and the weather is not
conducive to an epidemic, then a fungicide may not be necessary, or only spot
applications may be required. However, if the long-term weather forecast is conducive
to development of a disease that routinely occurs in the area in specific landscapes,
then a fungicide may be useful in preventing an outbreak. Again, the location in the
landscape where the disease occurs is important and should be noted, especially if it
occurs more than once a year or recurs each year. The disease may be occurring in
areas affected by a microclimate created by man.

Disease Control Practices

Disease control is often not a simple process. Control recommendations are aimed at:
1) altering the environment so it is less favorable for disease development; 2)
suppressing pathogen growth; and 3) decreasing stress on turfgrass. An integrated
management program that includes cultural and chemical methods is the key to
preventing and controlling turfgrass diseases.

There are three steps to disease management. First, it is necessary to correctly identify
the disease. Next, the conditions that promote disease development should be
delineated. Then management techniques can be outlined to alter or eliminate the
conditions conducive to disease development. Disease samples can be sent to your
local UF/IFAS Extension Plant Diagnostic Center for diagnosis
(see http://edis.ifas.ufl.edu/sr007 for submission guidelines).
The primary obstacle that landscape maintenance companies and pest control
companies face is lack of control over all management practices. For example, the
homeowner may control the irrigation system but contract out the mowing and
application of fertilizer and pesticides with multiple companies. Coordination and clear
communication among all those involved with maintenance is required to ensure healthy
turfgrass.

Cultural Control Practices

Proper cultural practices can create an environment that does not promote disease
development. While not possible to change weather patterns (the overall environment),
it is possible to change localized environments. For example, limiting water-saturated
soils by reducing excessive irrigation is a way the local environmental condition can be
controlled by humans to reduce disease risk. Every maintenance practice, fertilizer
application, and chemical (especially herbicide) application has an impact on turfgrass
health.

If turfgrass becomes diseased, cultural practices should be implemented first or at the

same time that fungicides are applied. If a home lawn, recreational site, or commercial
landscape has a history of developing a particular disease at a certain time of year, then
it makes sense to implement cultural practices to prevent this yearly reoccurrence.

Landscape maintenance professionals can explain to the landscape owner the reasons
for altering a practice. Records indicating disease outbreaks, cost of fungicide
applications, and turf replacement can provide justification for changes in maintenance
practices. The landscape owner may be more accepting of these changes if they
understand the potential benefits of altering a maintenance practice in both economical
and ecological terms.

The cultural practices discussed below are designed to alter the turfgrass environment
to prevent diseases or, at least, lessen their severity.

Turfgrass Selection
The selection of turfgrass species (e.g., St. Augustinegrass, centipedegrass,
bahiagrass, etc.) and cultivars within that species (e.g., 'Floratam' vs. 'Raleigh' St.
Augustinegrass) should be based on location and how the turf will be used and
maintained. Selections that are not suited for a particular area are continually stressed
and more susceptible to diseases and pests, requiring increased maintenance costs in
terms of labor and pesticides. For example, St. Augustinegrass does not tolerate shade
conditions and requires supplemental irrigation, while Centipedegrass should be grown
in soils with low pH (i.e., less than 6.0). Check with your local UF/IFAS Extension office
for recommendations (http://solutionsforyourlife.ufl.edu/map/).
Mowing Practices
Mowing is the most common turfgrass maintenance practice and can be the most
damaging when done improperly. Mower blades must be sharp so they cut rather than
tear the turf leaves. Mowing should occur as frequently as necessary so that no more
than one-third of the leaf is removed at any one time. Turfgrasses that are cut below
their optimum height become stressed and more susceptible to diseases, especially
root rots. The actual recommended turf height depends on the turfgrass species being
grown. It is especially important not to mow St. Augustinegrass too low. Wet grass
should not be mowed due to the potential for spreading water-borne pathogens.

When any disease occurs, the cutting height should be raised. A low cutting height
reduces the leaf tissue necessary for photosynthesis, the process by which the plant
produces energy for growth. An active disease eventually reduces the leaf canopy, and
photosynthesis is reduced even further. Raising the cutting height increases the green
plant tissue available for photosynthesis, resulting in more energy for turfgrass growth
and subsequent recovery from the disease.

Mulching mowers do not increase diseases. However, if an area of the lawn has an
active leaf disease, this area should be mowed last to prevent the spread of the
disease. After mowing the diseased area, the mower should be washed with water to
remove diseased leaf clippings.

Water Management
Irrigation is essential to prevent drought damage during the dry season. Yet, the amount
and the timing of application can either prevent or facilitate disease development. This
balance exists because most fungal pathogens that cause leaf diseases require free
water (e.g., rainfall, irrigation, dew) on the leaf or very high humidity to initiate the
infection process.

Dew formation and the length of the dew period is dependent on temperature and
humidity. The length of the dew period is a critical factor for leaf disease development.
Irrigating in the evening before dew forms or in the morning after dew evaporates
extends the dew period. One strategy to reduce the risk of disease development is to
irrigate when dew is already present. Dew is usually present in the predawn hours,
between 2 and 8 a.m. This also dilutes or removes the guttation fluid (fluid being forced
out of the leaf tips by internal plant pressure) that can accumulate at the cut leaf tip and
may provide a food source for some pathogens.

Turfgrass should only be irrigated when drought stress is observed (as evidenced by
curled leaf blades). When irrigation is necessary, it should be applied as to only saturate
the root zone of the turfgrass. Irrigating every day for a few minutes can be detrimental
to the turfgrass because it does not provide enough water to the root zone, but it is
beneficial for the turfgrass pathogens. The irrigation system should apply the water
uniformly across the lawn.
Nutrition (Fertilizer) Management
Many diseases are also influenced by the nutritional status of the grass, especially
nitrogen (N). Both excessively high and excessively low nitrogen fertility contribute to
turfgrass diseases. For example, excessive nitrogen applications encourage brown
patch and gray leaf spot diseases, while very low nitrogen levels are conducive for the
development of dollar spot disease. The minimal amount of nitrogen required for the
particular species of turfgrass in the lawn should be applied because it is easy to add
nitrogen but impossible to remove it.

Potassium (K) is also an important component in the prevention of diseases, possibly

because it prevents plant stress. To maintain healthy turfgrass, the amount of elemental
potassium applied should be either the same or greater than the amount of nitrogen. It
is beneficial to increase the amount of potassium in an area prone to disease. The use
of both nitrogen and potassium from slow-release sources is highly encouraged
because both are readily leached from the soil. If it is not possible to obtain slow-release
potassium, apply smaller amounts of quick-release potassium more frequently. This is
especially critical during the rainy season. Damaged roots have a difficult time
absorbing nutrients from the soil. When turfgrass roots are damaged or not functioning
properlywhether from diseases, nematodes, or water-saturated soilsit is beneficial
to apply nutrients in a liquid solution sprayed on the leaf tissue. Frequent applications of
small amounts of nutrients to the leaves help keep the plant alive until new roots are
produced. Application frequency is dependent on the severity of the root problem but
could be as often as twice a month.

Thatch Management
Thatch is the tightly bound layer of living and dead stems and roots that develops
between the zone of green vegetation and the soil surface. It is a natural component of
turfgrass. Bacteria, fungi, earthworms, and other organisms that naturally live in the soil
decompose thatch. When excessive thatch accumulates, it means plant tissue is being
produced more quickly than it is being decomposed.

Excessive thatch often causes the mower to sink because the turfgrass is "spongy."
This produces a lower cutting height than desired and potential scalping of St.
Augustinegrass, which results in stressed turf. Physical removal is the best way to
eliminate excessive thatch. Review maintenance practices to prevent excessive thatch
from occurring again. The cause could be too much nitrogen being applied or too much
or too little water being used for irrigation. Correcting those practices that promoted
excess thatch development should prevent it from occurring again.

Soil Physical and Chemical Status

There are several soil conditions that can lead to a weakened plant, resulting in higher
disease susceptibility. Compacted soils prevent proper drainage, resulting in areas that
remain excessively wet. Once they dry out completely, they are often difficult to rewet.
Turfgrass in these areas may have root systems that are deprived of oxygen, creating
an ideal situation for root rots to develop. High soil pH can affect nutrient uptake, while
high salt concentrations also impact turfgrass health.

If areas in the lawn or landscape appear to dry out first or are the first to appear sick, a
metal rod can be used to be sure that there is nothing buried at that location. It is not
uncommon to find building materials buried in the landscape. If an area is waterlogged
for long periods, building that area up so that it is level with the rest of the lawn could
correct the problem.

Chemical Control Practices

What Is a Fungicide?
Fungicides are pesticides used to manage fungal diseases. Fungicides are effective
because they can: 1) suppress or slow down fungal growth; or 2) prevent the fungus
from reproducing. Most fungicides are active against a limited group of fungi. This is
why it is important to know what disease you need to control.

Fungicides do not promote the growth of the turfgrass. The only way healthy turfgrass
reappears is when new growth occurs. For example, a leaf spot will remain on the leaf
even after a fungicide is applied. This diseased leaf area will remain until it is removed
by mowing and a new leaf replaces it, or until the leaf dies and begins to decompose.
Since many turfgrass diseases occur when the grass is not actively growing, complete
recovery may be very slow. It may seem like the turfgrass is not responding to the
fungicide application, when in fact the fungicide has been effective against the fungal
target. It is simply that the turfgrass has not grown enough to replace the diseased
tissue.

When to Use a Fungicide

It is acceptable to use fungicides on a preventive basis (prior to disease development)
as long as it is understood which diseases/pathogens are likely to occur in a particular
location at any given time of the year. For example, it is not necessary to apply a
fungicide to protect against Pythium blight on St. Augustinegrass because this is an
extremely rare disease. Also, a fungicide to prevent take-all root rot is unwarranted
when this disease has never been observed on that particular lawn.

Fungicides should only be used when absolutely necessary. A lawn disease in one
location does not mean it will occur on adjacent landscapes/properties/lawns, as
management techniques or turfgrass cultivar may be different. The primary factor for
turfgrass disease development in Florida is the environmentnot just the overall
environment, but also the microenvironment created by building placement in the
landscape or by management practices. In fact, each side of a building may have its
own microenvironment influenced by factors such as trees, other buildings, bodies of
water, and soil type.

When using a fungicide, label directions must be read and followed. Labels are
important to determine the proper rates, amount of water needed to apply the product
effectively, irrigation requirements, and safety instructions for mixing, applying, and
storing the product. Almost all pesticide failures are due to misapplication, including
misidentification of the problem. Misuse of a product can waste money, become a
safety risk, and pollute the environment.

Other maintenance practices must be considered relative to fungicide applications.

Unless the clippings are returned to the turfgrass, mowing should be postponed for at
least 24 hours (preferably longer). The fungicide is probably on the leaf. If the clippings
are collected when the yard is mowed, the fungicide is also collected. Unless the
product is supposed to be irrigated into the soil, irrigation should also be postponed for
at least 24 hours after a fungicide application. Ideally, the turf area should be mowed
and irrigated prior to a fungicide application to allow a maximum time interval between
fungicide application and the next turfgrass maintenance operation.

Fungicide Categories
Turfgrass fungicides can be divided into four broad categories based on the location of
their activity: 1) contact fungicides; 2) systemic fungicides; 3) local-penetrant fungicides;
and 4) mesostemic fungicides. They can also be divided into very small groups based
on chemical properties.

Contact fungicides

Contact fungicides are generally applied to the leaf and stem surfaces of turfgrasses.
They are considered protective or preventive fungicides. They inhibit the fungi on the
plant surface so the fungus is not able to enter/infect the plant. These fungicides remain
on the plant surface and do not penetrate the plant. They remain active only as long as
the fungicide remains on the plant surface in sufficient concentration to inhibit fungal
growth, usually 714 days. Leaves that emerge after the fungicide has been applied
are not protected. Any fungus already in the plant will not be affected. To obtain
optimum protection, it is important that contact fungicides evenly coat the entire leaf
surface and are allowed to dry completely before irrigating or mowing.

Contact fungicides are normally used to control foliar diseases and not root diseases.
The exceptions are those used to control Pythium root rot (i.e., chloroneb and
etridiazole). Contact fungicides have a broad spectrum of disease control activity and
have been used extensively in the turf industry for a number of years. However, recent
changes in labeling have occurred, so always read the label prior to fungicide use.
Mancozeb can only be applied by a professional pesticide applicator. Chlorothalonil can
no longer be applied to the turfgrass in residential landscapes (i.e., single-family homes,
condominiums, and apartment complexes). It can be applied to the turfgrass of
commercial landscapes and to the ornamentals in a residential landscape.

Systemic Fungicides

Systemic fungicides are chemicals that penetrate plant surfaces and are then
translocated (moved) within the plant vascular system, usually limited to the xylem. The
exception is fosetyl-Al (Aliette), which is translocated in xylem and phloem (primarily
phloem) tissue.

In general, systemic fungicides have curative and protective properties with extended
residual activity. Because systemic fungicides are absorbed by the plants, they work
inside the plant to 1) control pathogenic fungi that have already entered the plant and
initiated a disease (curative action); and 2) inhibit fungi that enter the plant from initiating
a disease (preventive action). Their residual activity is also due to the fact that the plant
absorbs them. Once a systemic fungicide is inside the plant, it cannot be removed by
water or degraded by sunlight. Newly emerged plant tissue may contain sufficient
concentrations of the fungicide to protect it from fungal infection. Therefore, systemic
fungicides do not need to be applied as often as contact fungicides; usually 2130-day
intervals are adequate.

Systemic fungicides usually have a very specific mode of action and do not have as
broad a spectrum of disease control as contact fungicides. However, they control both
foliar and root pathogens. When attempting to control root diseases, systemic
fungicides may need to be watered into the root zone for maximum effectiveness. As
indicted above, the majority of systemic fungicides are xylem limited. If the fungicides
are only applied to the leaf tissue, the compounds may never reach their root target in
the amount needed for control.

Local-penetrant fungicides

Local-penetrant fungicides are capable of penetrating the plant surface, but they only
move very short distances within the plant. These fungicides do not enter the xylem or
phloem tissue, so the majority of the fungicide remains on or near the plant surface.
Included in this group of fungicides are iprodione and vinclozolin. These fungicides are
considered protective/preventive fungicides. The discussion on contact fungicides
applies to this group of fungicides also.

Mesostemic fungicides

Mesostemic fungicides are a new group of fungicides that includes trifloxystrobin (e.g.,
Compass). This fungicide is strongly attracted to the plant surface and is absorbed by
the waxy plant layers. It appears to continuously penetrate the leaf surface. However, it
is not translocated in the plant vascular system (xylem or phloem), and so is not truly
systemic. These fungicides redistribute on the plant surface via localized vapor
movement and surface moisture. This group of fungicides work best as a preventive
fungicide. Because the fungicide is not directly exposed to weathering factors,
reapplication intervals are 1421 days.

Chemical Names and Classes

Each fungicide has three different names. Each has one chemical name (a long
technical name based on its chemistry) and one common name (a simpler one-word
name), but the fungicide can have multiple trade or brand names (Table 1). Fungicides
are also divided into chemical groups based on their chemical properties and activities.
The UF/IFAS Extension EDIS website can be referenced for a homeowner's guide to
turfgrass fungicides (http://edis.ifas.ufl.edu/document_pp154).

To prevent fungicide resistance from developing in a pathogen population, it is

important to know which fungicides belong to the same chemical group. Fungicides in
the same chemical group have the same mode of action. Fungicides should be
periodically alternated or used in mixtures with fungicides belonging to different
chemical groups to prevent fungicide resistance. For example, alternating between
Bayleton (triadimefon) and Banner MAXX (propiconazole) is ineffective because
both fungicides belong to the same chemical group, demethylation inhibitors.

Instruction Labels
It is extremely important to read and follow the instructions on the label. Almost all
pesticide failures are due to either misidentification of the problem or misapplication of
the pesticide. Misuse of a product can waste money, become a safety risk, and pollute
the environment. These labels are considered legal documents that must be
followed as required by law.

Except for chemicals used to buffer the water pH, NO additives (e.g., surfactants)
should be added to a fungicide unless the label specifically states this is acceptable.
The majority of fungicides already have a surfactant as part of the fungicide formulation.
Fertilizer solutions should NEVER be mixed with fungicides, especially fungicides that
contain metals (e.g., mancozeb, fosetyl-Al, and chlorothalonil with zinc) without
determining compatibility. It has taken years of research to produce the fungicides
currently on the market. Reading the label and asking questions of university and
chemical company employees will allow one to take advantage of this knowledge.

Biological Control Practices

When naturally occurring microorganisms are allowed to flourish in the turfgrass
ecosystem, they can help reduce disease potential or disease damage. They
accomplish these tasks by: 1) competing with the pathogens for food sources; 2)
producing chemicals that inhibit the growth of the pathogens; or 3) physically excluding
the pathogens from the plant by occupying the space first. Therefore, it is just as critical
to keep the soil microbial population healthy as it is the turfgrass. Reducing pesticide
use is one way this may be accomplished. Although many products (e.g., sugars,
enzymes, carbohydrates, etc.) on the market claim to increase natural microbial
populations, there is no documentation that this occurs in home lawns or landscapes in
Florida.

Microorganisms not naturally present in the turfgrass environment can be introduced in

an attempt to control diseases. This can be done by applying organic materials that
have natural microbial populations (i.e., composts) or have had microbial populations
added to them (i.e., natural organic fertilizers with microbial supplements). However,
there is little documentation that these products consistently prevent diseases. For both
types of products, they must be applied prior to disease development because they
work preventively, not curatively. Natural organic fertilizers should be used for their
nutrient value (i.e., nitrogen and potassium) and not for any possible secondary effects.

There are many products composed of living organisms, primarily bacteria and fungi, on
the market that claim they increase turfgrass health. However, for any material to be
considered a biological fungicide or microbial biopesticide, the U.S. Environmental
Protection Agency (EPA) must register it. EPA registration indicates that the safety of
the product to humans, nonhumans (e.g., fish), and the environment has been
determined. Materials that have not been approved by the EPA should be used with
caution. Many naturally occurring bacteria and fungi are also secondary human
pathogens, especially for people with weak immune systems. As part of the natural
ecosystem, they cause few problems. However, caution should be exercised when
concentrated formulations of these organisms are applied through a pesticide sprayer to
create aerosols. Also, many of these products have not been evaluated using proper
experimental protocols.

Summary
A disease is an interaction between the plant and a pathogen that disrupts the
normal growth and appearance of the plant. Diseases are the exception and not the
rule for lawns.
The three steps to disease management include correctly identifying: 1) the disease;
2) the conditions promoting disease development, and 3) the management
techniques that can alter or eliminate these conducive conditions.
Management techniques should rely on cultural practices first, with fungicides
applied only when necessary.
Cultural practices include selecting the proper turfgrass, mowing at the correct
height, irrigating only as needed and at the correct time, balancing nitrogen and
potassium in quantity and source, avoiding or reducing excessive thatch
accumulation, and preventing or reducing compacted soils.
Every maintenance practice, fertilizer application, and chemical (especially
herbicide) application has an impact on turfgrass health.
 Tables

Table 1.Turfgrass fungicides listed by chemical group for use in Florida

Mode
ofaction
Common name (trade Location of
Chemical group Mode of action
name example) activity
FRAC
codes
Acylalanines Mefenoxam Systemic; upward Nucleic acid
4
(phenylamides) (Subdue Maxx) movement synthesis
Delocalization of
Systemic; upward
Acylpicolides Fluopicolide (Stellar) spectrin-like 43
movement
proteins
Chloroneb (Tersan)
Lipids and
Aromatic
Contact membrane 14
hydrocarbons Etridiazole (=ethazole)
synthesis
(Terrazole)
Lipids and
Systemic; upward
Carbamates Propamocarb (Banol) membrane 28
movement
synthesis
Boscalid (Emerald)
Systemic; upward Respiration
Carboxamides 7
movement (complex II)
Flutolanil (ProStar)
Multisite contact
Chloronitriles Chlorothalonil (Daconil) Contact M5
activity
Metconazole (Tourney)

Myclobutanil (Eagle)

Propiconazole
Demethylation Systemic; upward Sterol biosynthesis
(Banner MAXX) 3
inhibitors movement in membranes
Triadimefon (Bayleton)

Triticonazole (Trinity,
Chipco Triton)
Iprodione
(Chipco 26GT,
Dicarboximides Iprodione Pro) Local penetrant Signal transduction 2

Vinclozolin (Curalan)
Mancozeb (Dithane,
Multisite contact
Dithiocarbamates Fore) Contact M3
activity
 Thiram (Defiant)
Copper hydroxide Multisite contact
Inorganic metals Contact M1
(Kocide) activity
Fosetyl-Al (Chipco
AlietteSignature)
Systemic; upward
Phosphonates and downward Unknown 33
Phosphorous acid
movement
(Alude, Resyst,
Magellan)
Polyoxin D zinc salt Systemic; upward Glucan and cell wall
Polyoxins 19
(Endorse ) movement synthesis
PhenylPyrroles Fludioxonil (Medallion) Contact Signal transduction 12
Azoxystrobin (Heritage)

Fluoxastrobin (Disarm) Systemic; upward

QoI quinone outside movement Respiration
11
inhibitors Pyraclostrobin (Insignia) (complex III)
Mesostemic
Trifloxystrobin
(Compass)
QiI quinone inside Respiration
Cyazofamid (Segway) Limited systemic 21
inhibitor (complex III)
Thiophanates (MBC Thiophanate methyl Systemic; upward Mitosis and cell
1
fungicides) (3336) movement division
1Read all labels to determine the specific site where it is legal to use the products on turfgrass. For

example, some products can only be used on golf courses, whereas others can be used on all turf sites
except residential turfgrass.
2Specific products are listed for example only. Neither inclusion of products nor omission of similar
alternative products in this publication is meant to imply any endorsement or criticism.
3FRAC = Fungicide Resistance Action Committee. Codes indicate the biochemical target site. M1, M3,
and M5 indicate multisite inhibitor (broad mode of action) with no significant risk of resistance.
See http://www.frac.info for further information. When considering rotation and tank mixes, be sure to
use materials that do not have the same mode of action.