Fungicide Resistance – Prairie Crop Protection

Pathogen Resistance (Insensitivity) Management

Any fungal pathogen population may contain strains naturally insensitive to a fungicide and other fungicides within the same Group. A gradual or total loss of disease control may occur over time if these fungicides are used repeatedly in the same

fields. Other resistance mechanisms that are not linked to site of action but specific for individual chemicals, such as enhanced metabolism, may also exist.

To delay fungicide resistance/insensitivity:

Where possible, rotate the use of a fungicide, (and others within the same Group) with different Groups that control the same pathogens.
Where possible, tank mix fungicides with a high risk of developing insensitivity with other fungicides from a different Group.
DO NOT apply more than the maximum number of applications listed on the label. Avoid consecutive sprays of a fungicide, or other fungicides in the same Group, in a season.
Fungicide use should be based on an integrated pest management (IPM) program that includes scouting and accurate recording related to pesticide use and crop rotation. An IPM program also considers cultural, biological and other chemical control practices.
Monitor treated fungal populations for signs of fungicide insensitivity. If disease continues to progress after treatment with a product, DO NOT increase the use rate. Discontinue use of the product and switch to another fungicide with a different target site of action.
Contact your local regional crops specialist or certified crop advisor for any additional pesticide management and/or IPM recommendations for specific crops and disease problems in your area.

Fungicide Modes of Action

Why are fungicides needed?

Control of disease during crop establishment.
Increase productivity of crop (photosynthesis) and/or reduce blemishes.
- Maintain yield and/or market value.
Improve storage life and quality of harvested plants / grain / produce.
- Prevent spoilage and/or production of mycotoxins.

How do fungicides work?

There are several ways to define ‘mode of action’:

Timing:
- Preventative: fungicide must be present on plant surface before the pathogen and repeated applications are required to protect new growth.
- Curative: pathogen may already be present (post- infection, pre-symptom kick-back activity).
- Eradicant: (post-symptomatic activity).
- Inhibitive: prevents spore germination or sporulation.
Placement:
- Contact (AKA protectant): immobile – must come in direct contact with the pathogen.
- Systemic (AKA penetrant): mobile – can move within plant.
Movement:
- Intra-plant Movement: within crop via vapour phase or redistribution by rain.
- Passive Absorption – by diffusion.
- Apoplastic Movement: xylem-mobile; move within free space and cell walls, upward through the transpiration stream (with water).
- Symplastic Movement: phloem-mobile (common characteristic of herbicides and insecticides but very few fungicides).
Spectrum:
- General, Non-specific, or Broad Spectrum: fungicide affects pathogen in multiple ways.
- Specific or Narrow Spectrum: fungicide targets a specific metabolic site in pathogen or against critical enzyme or protein. Genetic changes or naturally insensitive fungi have a greater chance to overcome the fungicidal effect (resistance/insensitivity).
Composition:
- Inorganic Fungicides: sulfur or metal ions such as copper.
- Organic Fungicides: contain carbon atoms.
- Biopesticides: suppressing pest populations using naturally occurring organisms or natural products derived from plants.
Biochemistry:
- Primary basis to classify fungicides, developed by Fungicide Resistance Action Committee (FRAC) using their general Mode of Action on fungi, and their chemistry.
  - All fungicides within a group share a common mode of action and resistance mechanism.
  - Fungicides within a group may have different chemical structures.
  - Resistance management strategies required wherever resistance is known or there is a risk of resistance development
  - See Table 1.

Table 1. Fungicide Groups Based on Biochemical Mode of Action (FRAC)

Mode of Action Target	Chemical Group & Chemical Name	Resistance Risk	Foliar Fungicide Products Registered in Saskatchewan/ Manitoba	Seed Treatment Products Registered in Saskatchewan/Manitoba
A. Nucleic Acid Synthesis	4. Phenyl Amides	High	Ridomil Gold/Bravo,* Ridomil Gold SL/Bravo,* Ridomil Gold 480EC, Ridomil Gold 480SL	Allegiance FL, Apron Advance,* Apron Maxx RTA,* Belmont 2.7FS, Cruiser Maxx Beans,* Cruiser Maxx Corn,* Cruiser Maxx Vibrance Beans,* Cruiser Maxx Vibrance Pulses, Cruiser Vibrance Quattro, EverGol Energy,* Helix Vibrance, Insure Cereal, Insure Cereal FX4,* Insure Pulse,* Maxim Quattro, Metlock CT, NipsIt SUITE Cereals OF Seed Protectant,* Prosper EverGol,* Rancona Pinnacle, Rancona* Trio,* Raxil MD,* Raxil PRO,* Raxil PRO Shield,* Trilex Component B, Trilex EverGol,* Trilex EverGol Shield, Vibrance Maxx RFC/RTA, Vibrance Maxx RFC with Intego Seed Treatment, Vibrance Quattro,* Visivio*
B. Cytoskeleton and motor proteins	1. Methyl Benzimidazole Carbamates	High	None	Apron Advance,* Cruiser Maxx Corn,* Maxim Quattro,* Mertect SC, Senator PSPT
B. Cytoskeleton and motor proteins	22. Benzamide	Low to Medium	Gavel 75DF*	Intego Solo Fungicide, Vibrance Maxx RFC with Intego Seed Treatment
C. Respiration	7. Carboxamides	Medium	Aprovia Top, Cantus WDG Fungicide, Cotegra, Dyax,* Elatus, Fontelis, Kenja 400SC,* Lance AG, Lance WDG Fungicide, Luna Tranquility, MIRAVIS Ace,* MIRAVIS Neo 300SE,* Nexicor, Priaxor, Propulse, Sercadis, Trivapro Vertisan*	Cruiser Maxx Vibrance Beans, Cruiser Maxx* Vibrance Pulses, Cruiser Vibrance Quattro, Emesto Silver, EverGol Energy, Gaucho CS FL, Helix* Vibrance, Insure Cereal FX4, Insure Pulse, Prosper* EverGol,* Rancona V RS, Rancona Trio,* Titan Emesto,* Trilex Component A, Trilex EverGol,* Trilex EverGol Shield,* Vibrance 500FS, Vibrance Maxx RFC/RTA,* Vibrance Maxx RFC with Intego Seed Treatment, Vibrance Quattro,* Vibrance Ultra Potato, Visivio, Vitaflo 280, Vitaflo* Fungicide, Vitaflo SP Fungicide
	11. Strobilurins	High	Acapela, Azoshy 250 SC, Cabrio Plus,* Delaro 325 SC, Dyax, Elatus, Evito 480, Fungtion SC, Headline EC, MPower Spade, Lance AG, Nexicor, Priaxor,* Quadris, Quadris Top,* Quilt,* Reason 500SC, Tanos,* TopNotch, Trivapro Twinline*	Cruiser Maxx Corn, Insure* Cereal,* Insure Cereal FX4, Insure Pulse, Maxim Quattro, Prosper EverGol, Stadium,* Trilex Component A, Trilex EverGol,* Trilex EverGol Shield*
	21. Cyano-imidazole	Medium to High	Ranman 400SC	None
	29. 2,6-Dinitroanilines	Low	Allegro 500F	None
	45. Triazolopyrimidyl- amine	Medium to High	Zampro*	None
D. Amino Acid & Protein Synthesis	9. Anilino-pyrimidine	Medium	Luna Tranquility, Scala SC*	None
E. Signal Transduction	2. Dicarboximides	Medium to High	Overall 240 SC, Prodex SC, Rovral Flo	None
E. Signal Transduction	12. Phenylpyrroles	Low to Medium	–	Apron Advance, Apron Maxx RTA, Cruiser Maxx Beans,Cruiser Maxx Corn, Cruiser Maxx Potato Extreme, Cruiser Maxx Vibrance Beans, Cruiser Maxx Vibrance Pulses, Cruiser Vibrance Quattro, Helix Vibrance, Maxim D, Maxim MZ PSP, Maxim PSP, Maxim Quattro, Stadium, Vibrance Maxx RFC/RTA, Vibrance Maxx RFC with Intego Seed Treatment, Vibrance Quattro, Visivio
F. Lipid / Membrane Synthesis & Cell Wall Degradation	44. Bacillus strain QST 713	Low	Serenade OPTI, Serenade Soil, Double Nickel LC, Double Nickel 55	None
F. Lipid / Membrane Synthesis & Cell Wall Degradation	49. Oxysterol binding protein homologue inhibitors (OSBPI)	Medium to High		Lumisena
G. Sterol Biosynthesis	3. Demethylation Inhibitors	Medium	Aprovia Top, Bumper 432 EC, Caramba, Co-Op Pivot, Cotegra, Delaro 325 SC, Fitness, Fullback 125SC, Fungtion SC, Hornet 432 F, Nexicor, Palliser, Pivot 418EC, Proline 480SC, Propel,* Nufarm Propiconazole Fungicide, Propi Super 25 EC, Propulse, Prosaro XTR, Quadris Top, Quash, Quilt, Tilt 250E, TopNotch, Trivapro, Twinline	Cruiser Maxx Potato Extreme, Cruiser Vibrance Quattro, Emesto Silver, EverGol Energy, Helix Vibrance, Insure Cereal, Insure Cereal FX4, Maxim D, Metlock CT, NipsIt SUITE Cereals OF Seed Protectant, Rancona Pinnacle, Rancona V RS, Rancona Trio, Raxil MD, Raxil PRO, Raxil PRO Shield, Stadium, Titan Emesto, Vibrance Quattro, Vibrance Ultra Potato, Visivio
H. Cell Wall Biosynthesis	40. Carboxylic Acid Amides (CAA)	Low to Medium	Forum, Revus, Zampro*	Vibrance Ultra Potato*
P. host plant defence induction	P 06 microbial	Not known	LifeGard WG	None
U. Unknown	27. Cyanoacetamide- oximes	Low to Medium	Curzate, Tanos*	None
	33. Phosphonates	Low	Confine Extra, OxiDate FC, Phostrol, Rampart	Confine Extra, Rampart
	NC. (Not classified) and diverse	Not known	Contans WG, Regalia Maxx	Heads Up Plant Protectant, StorOx
M. Multi-Site Contact Activity	M1. Inorganic copper	Low	Copper products, Cueva, Parasol WG	None
	M2. Inorganic sulphur		Cosavet DF Edge	None
	M3. Dithiocarbamates		Cabrio Plus, Dithane Rainshield, Elixir, Gavel 75DF,* Manzate Pro-Stick, Manzate Max, Penncozeb 75DF, Penncozeb 80WP, Polyram DF	Gaucho CS FL, Maxim MZ PSP, Penncozeb 80WP, Potato ST16, Solan MZ, Tuberseal, Vitaflo 280, Vitaflo Fungicide, Vitaflo SP Fungicide*
	M4. Phthalimides		None	Agrox FL
	M5. Chloronitriles		Bravo 500, Bravo Zn, Echo 720, Echo 90DF, Elixir, Ridomil Gold/Bravo, Ridomil Gold SL/Bravo*	None

*Products contain more than one active ingredient and appear in more than one group.