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Characteristics of turf fungicides

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Most common turfgrass diseases are caused by fungi. Fungicides kill or inhibit the growth of fungi.

There are two general categories of fungicides:

  • contact/protectant
  • penetrant

Contact/protectant fungicides remain on the outside of the plant and protect the plant from new infection. They must be applied at comparatively short intervals that can range from 5 to 14 days, because the fungicides are degraded by ultraviolet light, washed from the leaf surface by irrigation or rain, or mowed away. These fungicides do not have curative activity and new growth is not protected. Thorough coverage of plant tissue is critical to successful protection. Examples of contact/protectant fungicides commonly used in turf include captan, chlorothalonil, chloroneb, etridiazole, fluazinam, fludioxonil, mancozeb, maneb, PCNB, and thiram. 


Penetrant fungicides are absorbed into plant tissue and may provide some curative action. The duration of control afforded by penetrant fungicides is often much longer than that offered by contact fungicides, and some redistribution into new tissue may occur as the plant grows. Application intervals vary, but often range from 14 to 21 days and longer. According to specific topical modes of action, penetrant/systemic fungicides can be further divided into three sub-categories:

  • Localized penetrants form a protective barrier on the plant surface and permeate into the leaf in the area where deposition occurred. These fungicides have some curative activity, but do not move upward or downward inside the plant. Examples include iprodione, polyoxin D zinc, trifloxystrobin, and vinclozolin.

  • Acropetal penetrants form a protective barrier on the plant, permeate into the plant, and move upward in the plant’s xylem. These fungicides have protective activity including new growth, and have good curative activity. Examples include azoxystrobin, fenarimol, mefenoxam, and triadimefon.

  • Systemic penetrants form a protective barrier on the plant, permeate into the plant, move upward in the plant’s xylem, and move downward in the plant’s phloem. These fungicides have protective activity including new growth, and have good curative activity. Of the currently available penetrant/systemic fungicides, only fosetyl-Al (Aliette Signature) is truly systemic and moves both upward and downward in the plant.

Refer to Table 20 for a list of available fungicide materials and their respective topical modes of action.

Fungicide resistance

Some fungicides are site specific in their mode-of-action. This means that it takes very little genetic change on the part of a fungus for resistance to occur. Resistance may result in poor disease control, meaning that higher application rates or shorter intervals are needed to maintain healthy turf, or complete control failure. Resistance may develop suddenly or gradually depending on the fungicide involved. Once resistance has developed in a fungal population, it may last for a long time or gradually disappear if the fungicide is no longer used, depending on the fungicide and site-specific factors. Resistance is common for some diseases, but not observed for others. Fungicide resistance has been documented for anthracnose, dollar spot, Microdochium patch, gray leaf spot, and Pythium blight. 


The best strategy is to try to prevent, or at least delay, resistance. All penetrant fungicides are at risk for resistance development due to their “single-site” mode-of-action. Contact/protectant fungicides are unlikely to result in resistance because most of them have “multi-site” modes-of-action with the exception of fludioxonil (Medallion) and a few others which have a “single-site” mode-of-action. There are multiple chemical groups with different biochemical modes-of-action for broad-spectrum disease control in turfgrass that are at risk for resistance. Fungicide resistance has already been reported in five of these groups (Benzimidazole, Dicarboximide, Demethylation Inhibitor (DMI), Strobilurin (QoI) and Phenylamide). 


Table 19. Turfgrass pathogens and chemical classes with documented fungicide resistance.

Turfgrass Disease (causal agent) Resistance to chemical classes (see Table 20)
Benzimidazole Dicarboximide DMI QoI Phenylamide
Anthracnose (Colletotrichum cereale) X   X X  
Dollar spot (Sclerotinia homoeocarpa) X X X    
Gray leaf spot (Pyricularia grisea)       X  
Microdochium patch/pink snow mold (Microdochium nivale)   X      
Pythium blight (Pythium aphanidermatum)         X

Mix or alternate between different site-specific chemical groups or with multi-site contact/protectant fungicides, indicated by different FRAC (Fungicide Resistance Action Committee) code numbers, to prevent or delay the development of resistance. Changing fungicides by brand or trade name will not prevent resistance if the active ingredient or chemical group is the same. Fungicide labels list the active ingredient(s) in smaller letters below the brand name. Be especially careful when using combination (pre-mixed) products, which may include fungicides subject to resistance prevention strategies. Tables 20-22 list fungicide materials along with their corresponding FRAC codes for ease of reference.

Guidelines to prevent or delay resistance to turf fungicides 


Minimize disease conditions

  • Employ good cultural practices.
  • Choose resistant turfgrass cultivars or species.

Make proper fungicide choices

  • Be sure of the problem.
  • Decide if it warrants treatment.
  • Read the label, calibrate, and apply properly.

Know the material

  • Read the label to determine the active ingredient.
  • Is repeated use likely to lead to resistance (i.e. does it have a single-site mode-of-action)?
  • Determine the fungicide group to which it belongs.
  • Mix or alternate between fungicide groups with single-site mode-of-action or with contact/protectant fungicides. Do not use fungicides with the same FRAC (Fungicide Resistance Action Committee) code number in combination or rotation.
  • Make sure all pesticides being applied in tank-mixtures are compatible prior to mixing.

Table 20. Chemical classes, trade names and topical modes of action of fungicides registered for use on turf.

Common Name FRAC 1 Group Name Trade Name(s) Topical mode of action 2

azoxystrobin

11

Strobilurin (QoI)

Heritage (50WG, TL, G)

Acropetal Penetrant

boscalid

7

Succinate Dehydrogenase Inhibitor

Emerald 70EG

Acropetal Penetrant

captan

M4

Phthamlimides

Captan (50W, 50WP, 4L), Captec 4L

Contact

chloroneb

14

Aromatic Hydrocarbon

Terraneb SP, Teremec SP, Andersons Fungicide V, Proturf Fungicide V

Contact

chlorothalonil 3

M5

Chloronitrile

Andersons 5% Daconil 5G, ArmorTech (825 DF, CLT 720), Concorde SST 6F, Daconil (5G, 2787, Zn, Ultrex, WeatherStik), Echo 720F, Ensign 720, Equus 500ZN, Manicure (6FL, Ultra), Lebanon Daconil 5G, Legend, Pegasus (6L, DFX, HPX)

Contact

cyazofamid

21

Quinone inside Inhibitors (QiI)

Segway

Localized Penetrant

etridiazol (ethazole)

14

Aromatic Hydrocarbon

Koban, Terrazole 35WP, Truban

Contact

fluazinam

29

Uncoupler of oxidative phosphorylation

Secure

Contact

fludioxonil

12

Phenylpyrrole

Medallion (WDG, WP)

Contact

fluoxastrobin

11

Strobilurin (QoI)

Fame 480SC

Acropetal Penetrant

flutolanil

7

Succinate Dehydrogenase Inhibitor

ProStar 70WP, Moncut 70-DF

Acropetal Penetrant

fluxapyroxad

7

Succinate Dehydrogenase Inhibitor

Xzemplar

Acropetal Penetrant

fosetyl-Al (Aluminum tris)

33

Phosphonate

Autograph, Chipco Aliette, Chipco Signature, Chipco Signature Xtra, Lesco Prodigy Signature, Viceroy 70DF

Systemic Penetrant

iprodione

2

Dicarboximide

Andersons Fungicide X, ArmorTech IP 233, Chipco 26 GT, Chipco 26019, Iprodione Pro, Lesco 18 Plus, Proturf Fungicide X, Raven

Localized Penetrant

isofetamid

7

Succinate Dehydrogenase Inhibitor

Kabuto

Acropetal Penetrant

mancozeb

M3

Dithiocarbamate

Dithane 75DF, Fore Rainshield 80WP, Junction, Lesco Mancozeb DG, Lesco 4 Flowable Mancozeb, Manzate Pro-Stick 200, Protect DF, WingMan (4L, DF)

Contact

mandestrobin

11

Strobilurin (QoI)

Pinpoint

Acropetal Penetrant

maneb

M3

Dithiocarbamate

Maneb 80WP, Maneb 75DF, Pentathalon (LF, DF)

Contact

mefenoxam

4

Phenylamide

Andersons Pythium Control, Mefanoxam, Subdue MAXX

Acropetal Penetrant

metalaxyl

4

Phenylamide

Subdue 2E, Subdue GR, Subdue WSP, Apron (seed treatment), Vireo MEC

Acropetal Penetrant

metconazole

3

Demethylation Inhibitor

Tourney

Acropetal Penetrant

myclobutanil

3

Demethylation Inhibitor

Andersons Golden Eagle, Eagle 20EW, Siskin

Acropetal Penetrant

PCNB (pentachloronitrobenzene or quintozene)

14

Aromatic Hydrocarbon

Andersons FFII 15.4G, Defend 4F, Engage 75W, Fluid Fungicide II, Lesco Revere 4000 4F (10G), Parflo 4F, PCNB 12.5G, Penstar 75WP, Terraclor 400F (75WP), Turfcide 400F (10G)

Contact

penthiopyrad

7

Succinate Dehydrogenase Inhibitor

Velista

Acropetal Penetrant

phosphite (salts)

33

Phosphonate

Appear, Alude 5.2F, Biophos, Fiata Stessguard, Fosphite, Jetphiter, Magellan, Phostrol, Reliant, ReSyst 5F, Vital 4L

Systemic Penetrant

polyoxin D zinc salt

19

Polyoxin

Endorse 2.5WP, Affirm 11.3WDG

Localized Penetrant

propamocarb

28

Carbamate

Banol 6S

Localized Penetrant

propiconazole

3

Demethylation Inhibitor

ArmorTech PPZ 143, Banner GL, Banner MAXX II, Kestrel, Lesco Spectator, Procon-Z, ProPensity, Propiconazole Pro 1.3MEC, PropiMax, Strider

Acropetal Penetrant

pyraclostrobin

11

Strobilurin (QoI)

Insignia Intrinsic SC, Insignia

Localized Penetrant

tebuconazole

3

Demethylation Inhibitor

Clearscape, Mirage Stressguard, Tebuconazole 3.6F, Torque, Skylark,

Acropetal Penetrant

thiophanate-methyl

1

Benzimidazole

Allban, Andersons Systemic Fungicide 2.3G, ArmorTech TM 462, Cleary's 3336 (F, WP, DG lite, G, GC, Pro-Pak, Plus), Fungo (Flo, 50WSB), Lesco T-Storm 2G, Systec, T-Bird (4.5L, WDG), Tee-Off 4.5F, T-Methyl SPC 50 WSB, TM (4, SF, 85WDG)

Acropetal Penetrant

thiram

M3

Dithiocarbamate

Defiant 75WDG, Thiram, Spotrete F

Contact

triadimefon

3

Demethylation Inhibitor

Accost 1G, Bayleton (50WSP, Flo), Andersons Fungicide VII 0.59G, Andersons 1% Bayleton 1G, Lebanon Bayleton 1G

Acropetal Penetrant

trifloxystrobin

11

Strobilurin (QoI)

Compass 50WDG

Localized Penetrant

triticonazole 5

3

Demethylation Inhibitor

Trinity, Chipco Triton (70WDG, Flo)

Acropetal Penetrant

vinclozolin

2

Dicarboximide

Curalan 4F, Touché EG

Localized Penetrant

1 Fungicide Resistance Action Committee (FRAC) Code: fungicides with the same FRAC code have the same mode of action. M-codes indicate multi-site chemicals with low risk of resistance development. It is recommended to rotate applications by FRAC code and not to make sequential applications of fungicides with the same FRAC code.

2 See above text for information on topical mode of action.
3 Use of chlorothalonil is regulated in Massachusetts under the Public Drinking Water Supply protection regulations, see the Pesticide Regulations section of this guide for details.
Phosphite (salts) is also commonly referred to as phosphorus acid or phosphonate.
5 Use of triticonazole is regulated in Massachusetts under the Public Drinking Water Supply protection regulations, see the Pesticide Regulations section of this guide for details.

Updated October 2017

Table 21. Pre-mixed fungicide products registered for use on turf.

Pre-mixed Products (Common Name) FRAC 1 Trade Name(s)

azoxystrobin + chlorothalonil 2

11 + M5

Renown

azoxystrobin + difenconazole

11 + 3

Briskway

azoxystrobin + propiconazole

11 + 3

Headway, Headway G, Contend B

Benzovindulflupyr + difenconazole

3 + 7

Contend A

chlorothalonil 2 + acibenzolar-S-methyl

M5 + P1

Daconil Action

chlorothalonil 2 + propiconazole

M5 + 3

Concert II, Echo Propiconazole Turf Fungicide

chlorothalonil 2 + tebuconazole

M5 + 3

E-Scape ETQ

chlorothalonil 2+ thiophanate-methyl

M5 + 1

Broadside, ConSyst, Peregrine, TM/C WDG, Spectro

chlorothalonil 2 + fludioxonil + propiconazole

M5 + 12 + 3

Instrata

chlorothalonil 2 + iprodione + tebuconazole + thiophanate-methyl

M5 + 3 + 3 + 1

Enclave

fluoxastrobin + chlorothalonil 2

11 + M5

Fame C

fluoxastrobin + tebuconazole

11 + 3

Fame T

fluopyram + trifloxystrobin

7 +11

Exteris

iprodione + trifloxystrobin

2 + 11

Interface Stressguard

mancozeb + copper hydroxide

M3 + M1

Junction

mancozeb + myclobutanil

M3 + 3

MANhandle

propamocarb + fluopicolide

28 + 43

Stellar

pyraclostrobin + boscalid

11 + 7

Honor

pyraclostrobin + fluxapyroxad

11 + 7

Lexicon

pyraclostrobin + triticonazole 3

11 + 3

Pillar G Intrinsic

thiophanate-methyl + chloroneb

1 + 14

Proturf Fungicide IX

thiophanate-methyl + flutolanil

1 + 7

SysStar

thiophanate-methyl + iprodione

1 + 2

ArmorTech TMI 20/20, 26/36 Fungicide, Dovetail, Lesco Twosome, Proturf Fluid Fungicide

thiophanate-methyl + mancozeb

1 + M3

Duosan (WP, WSB)

triadimefon + flutolanil

3 + 7

Prostar Plus

triadimefon + trifloxystrobin

3 + 11

Armada

triadimefon + trifloxystrobin + stress guard

3 + 11

Tartan Stressguard

1 Fungicide Resistance Action Committee (FRAC) Code: fungicides with the same FRAC code have the same mode of action. M-codes indicate multi-site chemicals with low risk of resistance development. It is recommended to rotate applications by FRAC code and not to make sequential applications of fungicides with the same FRAC code.

2 Use of chlorothalonil is regulated in Massachusetts under the Public Drinking Water Supply protection regulation, see the Pesticide Regulations section of this guide for details.

3 Use of triticonazole is regulated in Massachusetts under the Public Drinking Water Supply protection regulations, see the Pesticide Regulations section of this guide for details.

Updated October 2017