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Fungicide Resistance Action Committee's (FRAC) Classification Scheme of Fungicides According to Mode of Action1
Frederick M. Fishel2This guide addresses resistance to pesticides and describes the Fungicide Resistance Action Committee's (FRAC) classification of fungicides and bactericides registered for use in Florida by their modes of action. A cross reference of active ingredient common names with corresponding examples of their trade names is also provided.
Fungicide-resistant plant pathogens are not new. Although the first fungicide resistance confirmation was in 1960, there were few subsequent incidences up until 1970. Since then, there have been more incidences, especially with the introduction of systemic fungicides. Also of concern has been the amount of time taken for resistance to emerge; sometimes within two years of a new commercial fungicide introduction. Fungicide resistance is not unique. Insecticide-resistant insects, herbicide-resistant weeds and antibiotic-resistant bacteria are well documented. These pests have two common traits: they have exceptionally large populations with a rapid rate of reproduction. Weeds were the last category of pests to show resistance because they only reproduce, at most, once per year. Insects reproduce with multiple generations in a single year; some bacteria and fungi reproduce several times in a single hour. Where large populations exist, great genetic diversity exists within the population. Within these populations, there will be several individuals that are tolerant of chemical control measures, perhaps only one in a million or billion. Pests typically become resistant when the same pesticide is used repeatedly within a single year or for several consecutive years. Some researchers believe selection pressure forces pests to mutate. However, there are more likely reasons for resistance:
- There were always a few of the resistant types present.
- When the pesticide is applied, the susceptible types are controlled, and then the smaller, resistant populations increase and re-infest the site.
Cross Resistance versus Multiple Resistance
More than 50 different fungicide active ingredients and many more trade products, including mixtures, are available to agricultural producers in Florida today. Many of these active ingredients work in the same way; in other words, they have the same mode of action. Although there are numerous trade products available at the current time, there are fewer than 20 growth mechanisms affected by these fungicides. When a certain plant pathogen is not controlled by fungicides affecting the same growth process, it is said to be cross-resistant. An example of a plant pathogen that has cross resistance is one that is resistant to fungicides in the chemical groups, triazoles and pyrimidines, both which are demethylation inhibitors which disrupt sterol synthesis. A more serious concern is multiple resistance. This is a phenomenon that occurs when a plant pathogen is not controlled by fungicides which affect different plant-growth processes. For example, a plant pathogen that is resistant to fungicides which inhibit both mitosis and protein synthesis, two differing fungal growth processes, would be labeled as a plant pathogen having multiple resistance.Fungicide Selection
Farmers and crop advisors need to know which fungicides are best suited to combat resistant plant pathogens. To support the use of fungicides suitable for resistance management, the FRAC numerical classification of fungicides in Table 1 is used on fungicide labeling by some manufacturers. The fungicides are classified according to their modes of action, collective and chemical group names, and active ingredient common names. Some examples of popular trade names are provided in Table 2 as a cross reference. The tables do not include all fungicides that are registered for use globally or in the U.S.; rather, those available only in Florida. Those which have an intrinsic "high risk" of resistance evolution are identified. "High risk" is determined by the following indicators:
The system is encouraged by FRAC for fungicide registrants to indicate the mode of action group in a uniform location on their product labels; some registrants currently identify the group on the front panel of their product labels. Similar systems have been proposed and encouraged for herbicides and insecticides. Because of the great variety of trade names and package mixtures of fungicides, it is difficult for agricultural producers to keep track of which modes of action they use.
- Cross resistance with existing fungicides;
- Laboratory studies have shown resistant mutants within the population;
- The active ingredient is known for the practice of repetitive use or sustained treatments;
- The active ingredient is known to have an extensive area of use; and,
- The target plant pathogens are known to have large populations with rapid multiplication.
Additional Information
Fungicide Resistance Action Committee (FRAC): http://www.frac.info/McCoy, C.W., M.E. Rogers, and L.W. Timmer. 2004. 2005 Florida citrus pest management guide: pesticide resistance and resistance management. UF/IFAS EDIS Document ENY-624. http://edis.ifas.ufl.edu/CG026 .
Tomlin, C.D.S., ed. 2003. The pesticide manual: a world compendium, 13th edition. The British Crop Protection Council. 1250 pp., ISBN 1 901396 13 4.
Tables
Table 1. FRAC's classification of fungicides registered for use in Florida by FRAC numerical code, mode of action, chemical group, and active ingredient common name with high risk indication.
FRAC code*
Mode of action
Group name
Chemical group
Common name
Resistance risk indication
1
Inhibition of mitosis and cell division
MBC fungicides
Benzimidazoles
Carbendazim Thiabendazole
HIGH RISK
Thiophanates
Thiophanate-methyl
2
Inhibition of lipids and membrane synthesis
Dicarboximides
Iprodione Vinclozolin
MEDIUM to HIGH RISK
3
Inhibition of sterol biosynthesis in membranes
Demethylation inhibitors (DMI fungicides)
Imidazoles
Imazalil
Piperazine
Triforine
Pyrimidines
Fenarimol
Triazoles
Difenoconazole Fenbuconazole
Myclobutanil
Propiconazole
Triadimefon
4
Inhibition of nucleic acid synthesis
Phenyl Amides
Acylalanines
Metalaxyl Metalaxyl-M
HIGH RISK
5
Inhibition of sterol biosynthesis in membranes
Amines (SBI: Class II)
Piperidines
Piperalin
6
Inhibition of lipids and membrane synthesis
Phosphoro-thiolates, dithiolanes
None registered for use in Florida
None registered for use in Florida
7
Inhibition of respiration
Carboxamides
Carboxin Flutolanil
Oxycarboxin
8
Inhibition of nucleic acid synthesis
Hydroxy-(2-amino) pyrimidines
None registered for use in Florida
None registered for use in Florida
9
Inhibition of amino acids and protein synthesis
Anilino-pyrimidines
Cyprodinil
10
Inhibition of mitosis and cell division
N-phenyl carbamates
None registered for use in Florida
None registered for use in Florida
11
Inhibition of respiration
Quinone outside inhibitors (QoI fungicides)
Methoxy-acrylates
Azoxystrobin
HIGH RISK
Methoxy-carbamates
Pyraclostrobin
Oximino acetates
Kresoxim methyl Trifloxystrobin
Oxazolidine-diones
Famoxadone
12
Inhibition of signal transduction
Phenyl Pyrroles (PP fungicides)
Fludioxonil
13
Inhibition of signal transduction
Quinolines
None registered for use in Florida
None registered for use in Florida
14
Inhibition of lipids and membrane synthesis
Aromatic hydrocarbons (AH fungicides)
Chloroneb Dicloran
PCNB
15
Inhibition of glucan and cell wall synthesis
Cinnamic acids
None registered for use in Florida
None registered for use in Florida
16.1
Inhibition of melanin synthesis in cell wall
Melanin biosynthesis inhibitors - reductase (MBI-R fungicides)
None registered for use in Florida
None registered for use in Florida
16.2
Inhibition of melanin synthesis in cell wall
Melanin biosynthesis inhibitors - dehydratase
None registered for use in Florida
None registered for use in Florida
17
Inhibition of sterol biosynthesis in membranes
Hydroxyanilides (SBI: Class III)
Fenhexamid
18
Inhibition of sterol biosynthesis in membranes
(SBI: Class IV)
None registered for use in Florida
None registered for use in Florida
19
Inhibition of glucan and cell wall synthesis
Polyoxins
Peptidyl pyrimidine nucleoside
Polyoxin
20
Inhibition of mitosis and cell division
Phenylureas
None registered for use in Florida
None registered for use in Florida
21
Inhibition of respiration
Quinone inside inhibitors (QiI fungicides)
Cyazofamid
MEDIUM to HIGH RISK
22
Inhibition of mitosis and cell division
Benzamides
Zoxamide
23
Inhibition of amino acids and protein synthesis
Enopyranuronic acid antibiotic
None registered for use in Florida
None registered for use in Florida
24
Inhibition of amino acids and protein synthesis
Hexopyranosyl antibiotic
None registered for use in Florida
None registered for use in Florida
25
Inhibition of amino acids and protein synthesis
Glucopyranosyl antibiotic
Streptomycin
HIGH RISK
26
Inhibition of glucan and cell wall synthesis
Glucopyranosyl antibiotic
None registered for use in Florida
None registered for use in Florida
27
Unknown
Cyanoacetamide-oximes
Cymoxanil
28
Inhibition of lipids and membrane synthesis
Carbamates
Propamocarb
29
Inhibition of respiration
2,6-dinitroanilines
Fluazinam
30
Inhibition of respiration
Organo tin compounds
Tri phenyl tin compounds
Fentin hydroxide
31
Inhibition of nucleic acid synthesis
Carboxylic acids
None registered for use in Florida
None registered for use in Florida
32
Inhibition of nucleic acid synthesis
Heteroaromatics
Isothiazolones
Octhilinone
33
Unknown
Phosphonates
Ethyl phosphonates
Fosetyl-Al Phosphorous acid
34
Unknown
Pthalamic acids
None registered for use in Florida
None registered for use in Florida
35
Unknown
Benzotriazines
None registered for use in Florida
None registered for use in Florida
36
Unknown
Benzene-sulfonamides
None registered for use in Florida
None registered for use in Florida
37
Unknown
Pyridazinones
None registered for use in Florida
None registered for use in Florida
38
ATP production (proposed)
Thiophene-carboxamides
None registered for use in Florida
39
Complex I of respiration (proposed)
Pyrimidinamides
None registered for use in Florida
40
Phospholipid biosynthesis and cell wall deposition (proposed)
CAA-fungicides (carboxylic acid amides)
None registered for use in Florida
None registered for use in Florida
41
Protein synthesis attachment of aminoacyl-tRNA to ribosomal acceptor (A) site
Tetracycline antibiotic
Oxytetracyline
HIGH RISK
42
Unknown
Thiocarbamate
None registered for use in Florida
None registered for use in Florida
P
Host plant defense induction
Salicylic acid pathway P1
Benzothiadazole (BTH)
Acibenzolar
M
Multi-site contact activity
M1
Inorganics
Copper (different salts)
M2
Inorganic
Sulfur
M3
Dithio-carbamates and relatives
Ferbam Mancozeb
Maneb
Metiram
Thiram
Ziram
M4
Phthalimides Captan Folpet
M5
Chloronitriles
Chlorothalonil
M6
Sulphamides
None registered for use in Florida
M7
Guanidines
Dodine
M8
Triazines
None registered for use in Florida
M9
Quinones (anthraquinones)
None registered for use in Florida
NC
Not classified
NC
Diverse
Oils Potassium bicarbonate
*Numbers and letters are used to distinguish the fungicide groups. The numbers were assigned primarily according to the time of product introduction to the market. The letters refer to P = host plant defense inducers, and M = multi-site inhibitors.
Table 2. Cross listing of active ingredient common names with trade products registered for use in Florida.
Common name
Trade products*®
Acibenzolar
Actigard
Azoxystrobin (HIGH RISK)
Abound, Amistar, Dynasty, Heritage, Protégé, Quadris, Quilt, Uniform
Captan
Agrox Premiere, Captan, Captec, Captivate, Fungitrol C, Kernel Guard, Maxima HB, Rescue One, SA-50, TCI, Vitavax PC
Carbendazim (HIGH RISK)
Mauget, Mergal, Polyphase, Rocima
Carboxin
Allerax, Kickstart, Prevail, Vitavax
Chloroneb
Catapult, Delta Coat, Teremec, Nu-Coat
Chlorothalonil
Applause, Banol C, Bravado, Bravo, Busan, Chloro Gold, Chloronil, Chlorosel, Chlorostar, Chlorothalonil, Concorde, Consyst, Daconil, Echo, Equus, Fungonil, Manicure, Maxcide, Nopcocide, Nucide, Pathguard, Pro Tech, Quadris, Quali-Pro, Ridomil Gold, SA-50, Spectro, Thor, Twosome
Copper (carbonate)
Captain, Nautique, Wolman E
Copper (chelates of copper citrate)
Algimycin, Bioguard, Bordeaux, Pool Time
Copper (ethanolamine complex)
Various swimming pool treatments
Copper (ethylenediamine complex)
Various aquatic herbicides
Copper (hydroxide)
Champ, Champion, Cobra Rod, Cu-Bor, Funguran OH, Junction, Kocide, Kop-Hydroxide, Mankocide, Neptune, Nu-Cop, Ridomil Gold Copper, Spin Out,
Copper (I oxide)
Various anti-fouling paints
Copper (II oxide)
Various wood preservatives
Copper (metallic)
Various algaecides and anti-fouling paints
Copper (naphthenate)
Various wood preservatives
Copper (oxychloride)
Agra Cop, Coc, Kop Oxy 85, Microsperse
Copper (salts of fatty and rosin acids)
Camelot, SA-50, Sunniland Coppercide, Tenn-Cop
Copper (sulfate pentahydrate)
Various swimming pool treatments
Copper (sulfate, anhydrous)
Copper-Z 4/4
Copper (triethanolamine complex)
Various algaecides and other water treatments
Cyazofamid (MEDIUM to HIGH RISK)
Ranman
Cymoxanil
Curzate, Tanos
Cyprodinil
Switch, Vangard
Dicloran
Botran
Difenoconazole
Dividend, Incentive
Dodine
Dodine, Elast, Syllit
Famoxadone (HIGH RISK)
Tanos
Fenarimol
Rubigan, Twosome
Fenbuconazole
Enable, Indar
Fenhexamid
Captevate, Decree, Elevate,
Fentin hydroxide
Agri Tin, Enable, Orbit, Super Tin
Ferbam
Ferbam
Fluazinam
Omega
Fludioxonil
Apron, Dynasty, Graduate, Maxim, Medallion, Scholar, Switch, Warden
Flutolanil
Artisan, Contrast, Moncoat, Moncut, Prostar, Sysstar
Folpet
Folpet, Fungitrol, several wood preservatives
Fosetyl-Al
Aliette, Prodigy, Signature
Imazalil
Clinafarm, Deccozil, Freshgard, Fungaflor, Magnate
Iodocarb
Many commercial preservative products available
Iprodione
Iprodione, Lesco 18 Plus, Rovral, Sextant
Kresoxim-methyl (HIGH RISK)
Cygnus, Sovran
Mancozeb
Acrobat MZ, Clean Crop Potato Seed, Cuprofix MZ, Dithane, Fore, Gavel, Junction, Mancozide, Manhandle, Manzate, Maxim, Moncoat, Nubark, Pentathlon, Penncozeb, Protect, Ridomil Gold MZ, Stature, Tops MZ Gaucho, Ziban
Maneb
Maneb, Manex, Pentathlon, Seed Treatment for Potatoes
Mefenoxam (HIGH RISK)
Agrox Premier, Allegiance, Allerax, Apron, Catapult, Delta Coat, Dividend, Dynasty, Flouronil, Incentive, Maxim, Mefenoxam, Meta-Mil, Prevail, Quell, Ridomil Gold, Subdue, System 3, Ultra Flourish, Uniform
Metiram
Polyram
Myclobutanil
Eagle, Immunox, Laredo, Manhandle, Nova, Systhane,
Octhilinone
Arch, Dobercide, Kathon, Mergal, Milbrex, Rocima, Skane, Tex-Stat, Thor
Oils
Biozide, Decident
Oxycarboxin
Plantivax, Provax
Oxytetracylince (HIGH RISK)
Flameout, OTC, Star Brite
Phosphorous acids
Magellan, Phostrol
Piperalin
Pipron
Polyoxin
Endorse
Potassium bicarbonate
Agricure, Armicarb, Kaligreen
Propamocarb
Banol, Previcur
Propiconazole
Alamo, Banner, Busan, Contend, Honor Guard, Infuse, Montero, Orbit, Premier, Propensity, Quilt, Spectator, Stratego, Tilt
Pyraclostrobin (HIGH RISK)
Cabrio, Headline, Insignia, Pristine
PCNB
Blocker, Defend, Parflo, Prevail, Revere, System 3, Terraclor, Turfcide, Vitavax
Streptomycin (HIGH RISK)
Agri Mycin, Bac-Master, Firewall, Seed Treatment for Potatoes, Streptrol
Sulfur
Many commercial products
Thiabendazole (HIGH RISK)
Add-2, Decco Salt, Di-All, Fresh Ban, Fresh Mark, Freshgard, Irgagard, Metasol, Post Harvest Lustr, Shield-Brite, Sta-Fresh, Stay-Clean, Super Mildex
Thiophanate-methyl (HIGH RISK)
Banrot, Cavalier, Fungo, Quali-Pro, Tee-Off, Topsin,
Thiram
Allerax, Bulb Saver, Defiant, Raxil, Spotrete, TCI Protector L, Thiram, Vitavax
Triadimefon
Armada, Bayleton, Fung Away, Fungisol, Fung-Onil, Strike
Trifloxystrobin (HIGH RISK)
Armada, Compass, Flint, Gem, Twist, Stratego
Triforine
Orthenex, Rosepride
Vinclozolin
Curalan, Touche
Ziram
Vancide, Ziram
Zoxamide
Gavel
*Trade product contains at least this sole active ingredient, but may be pre-mixed with additional active ingredients. Consult product label ingredient statements.
Footnotes
1. This document is PI-94, one of a series of the Pesticide Information Office, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date January 2006. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.2. Frederick M. Fishel, associate professor, Agronomy Department, and Director, Pesticide Information Office; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
Copyright Information
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