Fungicide Resistance
Gary W. Moorman, Professor of Plant Pathology
A fungicide disrupts either energy producing reactions or a chemical building (synthesis) reaction within the target fungus. The way it kills the fungus is termed the fungicide's 'mode of action.' Certain fungicides, usually systemics, have very specific modes of action and are said to be 'at risk' to the development of resistance. An 'at risk' fungicide may bind to a very specific chemical within the fungus or disrupt one specific step required for the reaction. If the fungus has an alternate pathway to complete the reaction, can break down the fungicide or prevents the chemical from acting in the fungus, then the fungus is resistant to that fungicide. It is generally accepted that there is a great deal of variation within populations of fungi and a few individuals in the population naturally are resistant to certain types of chemicals. When the chemical is used, it kills almost all of the sensitive individuals in the population but the survivors are those few individuals resistant to the action of the chemical. The survivors give rise to the next generation and most of that generation is resistant to the chemical.
It is recommended that high risk (1 = low risk; 3 = high risk) chemicals be used sparingly, used in rotation with, or mixed with chemicals with different modes of actions. Fungicide Resistance Action Committees (FRAC) developed a numbering system in which chemicals that have the same mode of action have the same FRAC group number ( http://www.frac.info/frac/index.htm ). When selecting chemicals for rotation or mixing, select ones with different FRAC Group numbers (see below) because then you are using ones with different modes of action.
Listed below are some of the commonly used fungicides. Not all fungicides are listed. Chemical, trade names, and availability change frequently. This is not a complete list. It may not be up to date because items change daily.
| FRAC Group |
Class | Active ingredient |
REI Restricted Entry Interval |
Trade names (EPA reg. no.) |
|---|---|---|---|---|
| 1 | Benzimidazole | thiophanate methyl | 12 | 3336 (1001-69) OHP 6672 (51036-329-59807) Fungo Flo (51036-329-59807) Systec 1998 (48234-12) |
| debacarb | Fungisol (7946-14) |
|||
| 2 | Dicarboximide | iprodione | 12 | Chipco 26GT (100-1138) Chipco 26019 (264-481) Iprodione (51036-361) OHP 26 (432-888-59807) Sextant (51036-361-59807) |
| vinclozolin | 12 | Curalan (7969-62-58185) |
||
| 3 | Imidazole | triflumizole imazalil |
12 24 |
Terraguard (400-433) Fungaflor (499-508) |
| Pyrimidine | fenarimol | Rubigan (62719-134) |
||
| Piperazine | triforine | 12 | Triforine (241-355)fenamidone |
|
| fenamidone | 12 | FenStop (432-1389-59807) |
||
| Triazole | propicoonazole | 24 | Banner MAXX (100-741) Propiconazole (51036-403) Spectator (62719-346-10404) Kestrel (66222-41-81943) |
|
| triadimefon | 12 | Strike (3125-436) Bayleton (432-1360) |
||
| tebuconazole | Teuject (7946-24) |
|||
| myclobutanil | 24 | Systhane (707-253) Rally (62719-410) |
||
| 4 | Acylanine |
mefenoxam | 0 | Subdue MAXX (100-796) Fenox (70252-11-48234) |
| 5 | Piperidine | peperalin | 24 | Pipron (67690-1) |
| 7 | Anilide (carboxamide) |
flutolanil | 12 | Contrast (45639-208-58185) ProStar (432-1477) |
| 11 | Strobilurin | azoxystrobin | 4 | Heritage (10182-408) |
| kresoxim-methyl | 12 | Cygnus (7969-124) | ||
| pyraclostrobin | 12 | Insignia (7969-184) | ||
| trifloxystrobin |
12 | Compass (432-1371) | ||
| 12 | Phenylpyrol | fludioxonil | 12 | Medallion (100-769) |
| 14 | Aromatic hydrocarbon | PCNB | 12 |
Revere (400-407-10404) Blocker (5481-211) Terraclor (400-399) Defend (5481-444-1001) |
| Thiadiazole | etridiazole | 12 | Truban (58185-7) Terrazole (400-416) Banrot (58185-10) |
|
| 17 | Hydroxyanilide | fenhexamid | 4 | Decree (66330-35-67690) |
| 19 | Polyoxin | polyoxin | 4 | Veranda (66330-56-459807) Endorse (66330-41-1001) |
| 21 | Qil | cyazofamid | Segway (71512-13-279) | |
| 25 | Glucopyranosyl antibiotic | streptomycin | Streptomycin (66222-121) | |
| 28 | Carbamate | propamocarb | 12 | Banol (432-942) Previcur Flex |
| 40 | Cinnamic acid derivative | dimethomorph | 12 | Stature (241-419-67690) |
| 41 | Tetracycline antibiotic | oxytetracycline | Bacastat (74779-2) Mycoject (7946-18) |
|
| M |
Phthalimide | captan | 96 | Captan (66330-29) |
| Chloronitrile | chlorothalonil | 48 12 12 48 12 12 |
Daconil (50534-9) Echo (60063-7) PathGuard (60063-7-499) Exotherm Termil (70-223) Concorde (72167-24-1812) Pegasus (72167-24-1812) |
|
| Copper, complex | copper sulfate | 12 24 |
Camelot (1812-381) Phyton 27 (49538-3) |
|
| Copper, fixed | copper hydroxide | 48 | Kocide (352-656) | |
| cupric hydroxide | 48 | Champion (55146-1) | ||
| Dithiocarbamate | mancozeb | 24 | Dithane (707-180) FORE (707-87) Junction (1812-360) Pentathlon (1818-251) |
|
| manganese + zinc | 24 | Protect T/O (1001-65) | ||
| ferbam | 24 | Ferbam (45728-7) | ||
| ziram | 48 | Ziram (4581-140) | ||
| U | Phosphonate | fosetyl-Al | 12 | Aliette (432-890) |
| Phosphite | phosphorus acid salts | 4 | Alude (71962-1-1001) ArborFos (7946-26) |
|
| potassium phosphite | 4 | Vital (42519-24) | ||
| NC | potassium bicarbonate | 4 | Armicarb (5905-541-AA) Milstop (70870-1-68539) |
|
| Kaligreen (70231-1) Remedy (62719-70) Agricure (70870-1-1001) |
||||
| sodium hypochlorite | Clorox (5813-55) | |||
| hydrogen dioxide | ZeroTol (70299-1) TerraClean (70299-5) |
|||
| neem oil | 4 | Trilogy (70051-2) Triact (70051-2-59807) |
||
| paraffinic oil | 4 | JMS Stylet Oil 65564-1) Ultra-Fine Oil (862-23-499) |
||
| petroleum oil | PureSpray (69526-9) | |||
| potassium salts of fatty acids | 12 | M-Pede (62719-515) | ||
| sulfur | 24 | Kumulus (51036-352) | ||
| Combined products | ||||
| 4 + 12 |
mefenoxam + fludioxonil | 48 | Hurricane (100-951) | |
| 11 + 7 |
pyraclostrobin + boscalid | Pageant (7969-251) | ||
| M + M |
mancozeb + copper | Junction Fungicide (1812-360) | ||
| 1 + M |
thiophanate methyl + chlorothalonil | Spectro 90(1001-72) ConSyst (48234-7) |
||
| 1 + M |
thiophanate methyl + etridiazole | Banrot (58185-10) Zyban (58185-31 |
Group Mode of action
- Inhibits tubulin formation
- Inhibits RNA or DNA synthesis
- DMI (demethylation inhibitor), inhibits sterol synthesis
- Inhibits RNA synthesis
- Inhibits isomease in sterol synthesis
- Disrupts electron transport in mitochondria
- Disrupts beta-tubulin assembly
- Quinone outside inhibitors (QOI)
- Disrupts osmotic signal transduction
- Disrupts lipid peroxidation
- Disrupts cell wall synthesis
- Disrupts C4 demethylation in sterol biosynthesis
- Disrupts protein synthesis
- Affects membrane permeability
- Uncouples oxidative phosphorylation
- Disrupts phospholipids and cell wall deposition
- Protein synthesis attachment of tRNA to ribosomal receptor
- Disrupts proteins involved in stabilizing cell membranes during growth
M Multi-site activity
P Host plant defense induction
U Unknown mode of action
NC Not classified
DISCLAIMER
Notice: The user of this information assumes all risks for personal injury or property damage.
Warning! Pesticides are poisonous. Read and follow all directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams or ponds.
Issued in furtherance of Cooperative Extension work, Acts of Congress, May 8 and June 30, 1914, in cooperation with the U. S. Department of Penn State College of Agricultural Sciences research and extension programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
Visit Penn State Extension on the web at extension.psu.edu.
Where trade names appear, no discrimination is intended, and no endorsement by Penn State Cooperative Extension is implied.
This publication is available in alternative media on request.
The Pennsylvania State University is committed to the policy that all persons shall have equal access to programs, facilities, admission, and employment without regard to personal characteristics not related to ability, performance, or qualifications as determined by University policy or by state or federal authorities. It is the policy of the University to maintain an academic and work environment free of discrimination, including harassment. The Pennsylvania State University prohibits discrimination and harassment against any person because of age, ancestry, color, disability or handicap, national origin, race, religious creed, sex, sexual orientation, gender identity, or veteran status. Discrimination or harassment against faculty, staff, or students will not be tolerated at The Pennsylvania State University. Direct all inquiries regarding the nondiscrimination policy to the Affirmative Action Director, The Pennsylvania State University, 328 Boucke Building, University Park, PA 16802-5901; Tel 814-865-4700/V, 814-863-1150/TTY.
