Publication 360, Fruit Production Recommendations: Resistance Management for Fungicides

Pub 360, Fruit Production Recommendations > Chapter 2, Pest Management > Resistance Management for Fungicides

Excerpt from Publication 360, Fruit Production Recommendations, 2010-11
Order this publication

1. Introduction
2. Resistance management strategies by fungicide group and disease for Ontario fruit crops
   • Table 2-11. Fungicide/Bactericide Groups Based on Sites of Action (PDF 77 kb)
3. Other information on Resistance Management
   • Introduction to Resistance
   • Assessing Resistance Risk
   • General Resistance Management Strategies
     • Table 2-10. Factors Favouring the Development of Resistance (PDF 65 kb)
   • Strategies for Managing Resistance to insecticides
4. Other topics in Pest Management
   • Integrated Pest Management - Monitoring
   • Thresholds
   • Pest Management Tools
   • Reduced Risk Pesticides
   • Using Mating Disruption in Fruit Crops
   • Pest Management for Organic Fruit Growers
   • Pest Resistance to Insecticides, Fungicides, Miticides
   • Resistance Management Strategies
5. Chapter 2 - Pest Management PDF 240 kb
6. Related Links

Strategies for managing resistance to fungicides

Introduction

• Rotate products from different chemical groups. Do not exceed the recommended number of applications per season or sequential applications of a pesticide or group of pesticides.
• Tank mix products from different families. This is an accepted resistance management strategy for fungicides. Use only registered tank mixes (specified on the label).
• Apply fungicides before disease occurs. Follow disease prediction models when possible. Applications of fungicides after the disease is established are more likely to select for resistant populations of the pathogen.

Know which fungicides are combinations of chemicals from more than one fungicide group (e.g. Pristine, Switch). It is important to rotate these fungicides with products from different groups.

Not all fungicides are prone to resistance. Most fungicides that affect a wide range of different metabolic processes in fungi are not prone to the development of resistance. These fungicides are known as multi-site inhibitors and are designated with an M in the group number (Table 2-11. Fungicide/Bactericide Groups Based on Sites of Action). These products can be applied to fungal pathogens repeatedlywithout rotation without significant risk of resistance development. Coppers and streptomycin are exceptions to this with respect to bacteria. For example, bacteria causing fire blight or blister spot can develop resistance to these products.

The strategy for preventing fungicide resistance depends on:

• the resistance risk of the pathogen to a particular fungicide group
• the availability of rotation options

Two components of a resistance management strategy for a fungicide group include:

• the number of consecutive applications before rotating to a different family group
• the maximum number of applications per season

In some cases, a single fungicide group can control more than one pathogen. In this case, the maximum number of consecutive and total applications per season should be based on the pathogen with the highest risk of developing resistance. For high-risk pathogens with fungicide options from many groups, rotation to a different group is recommended after a single application of a resistance-prone fungicide, although this is not necessarily required by the label. For pathogens controlled by few registered fungicide families, the recommendation is to use no more than two consecutive applications of a resistance-prone fungicide and then alternate to a different fungicide family. When a product contains active ingredients from more than one family, each application counts as a use for each family.

Resistance management strategies by fungicide group and disease for Ontario fruit crops

These strategies reduce the risk for resistance development, and may be more stringent than label guidelines. Solo products have one active ingredient. Combination products have more than one active ingredient and are indicated with an asterisk (*).

Group 3: Funginex, Indar, Nova, Nustar, Mission, Topas

• Apple scab resistance to Nova and Nustar has recently been confirmed in Ontario. Avoid using these products in orchards with resistance.
• For apple scab and powdery mildew in berries use no more than two consecutive applications then rotate to a different fungicide group; use fungicides from this group no more than four times per season.
• For powdery mildew in grape and brown rot in stone fruit, use once and then rotate to a different group; use fungicides from this group no more than twice per season.

Group 7: Lance, Pristine*

• For botrytis grey mould in berries, use no more than two consecutive applications then rotate to a different fungicide group. No more than 30% of total fungicides applied per season should include a solo or mixture product from this group. See Group 11 for recommendations for Pristine use.
• For powdery mildew in grape and brown rot in stone fruits use once and then rotate to a different group. Apply no more than twice per season as a solo or mixture product. See Group 11 for recommendations for Pristine use.
• Avoid using Pristine in apple orchards with documented resistance to Group 11 fungicides.
  

Group 9: Scala, Vangard, Switch*

• For apple and pear scab, use once then rotate to a different fungicide group. Use prebloom, no more than two applications per season.
• For botrytis grey mould in berries, use once then rotate to a different fungicide group. No more than 30% of total fungicides applied per season should include a solo or mixture product from this group.
• For botrytis bunch rot in grape and brown rot in stone fruit, use once then rotate to a different group. Use products from this group no more than twice per season.

Group 11: Flint, Sovran, Cabrio, Pristine*, Tanos*

• Apple scab resistance to Flint and Sovran has recently been confirmed in Ontario. Avoid using these products in orchards with resistance.
• For apple and pear scab, use no more than two consecutive applications then rotate to a different fungicide group. Use products from this group no more than three times per crop.
• For botrytis grey mould in berries use no more than two consecutive applications then rotate to a different fungicide group. No more than 30% of total fungicides applied per season should include a solo product from this group or no more than 50% of total fungicides applied per season if using combination products.
• For powdery mildew in grape, brown rot in stone fruit, use once and then rotate to a different group. Use fungicides from this group no more than twice per season as a solo or mixture product.

Group 17: Elevate

• For botrytis grey mould in berries, use no more than two consecutive applications then rotate to a different group. Do not use more than four times per season.
• For botrytis bunch rot in grapevine and brown rot in stone fruits, use once then rotate to a different group. Do not use more than twice per season.
  
  
  

  Table 2-11. Fungicide/Bactericide Groupings Based on Sites of Action* (PDF 78 kb)

  Group	Chemical family or group	Product Name	Active ingredient (* indicates the a.i. that puts it in this group)
  1	MBC	Mertec SC	thiabendazole
  		Senator 70 WP	thiophanate-methyl
  2	Dicarboximide	Rovral WP	iprodione
  3	DMI (this group is sometimes loosely known as sterol inhibitors)	Funginex SC Indar 75 WP Nova 40 W Nustar Mission 418 EC Topas 250 E	triforine fenbuconazole myclobutanil flusilazole propiconazole propiconazole
  4	Phenyl Amide (PA)	Ridomil Gold MZ Ridomil Gold 480 SL	metalaxyl* + mancozeb metalaxyl
  7	Anilide carboxamide	Lance WDG Pristine WG	boscalid boscalid* + pyraclostrobin
  9	Anilinopyrimidine	Scala SC Switch 62.5 WG Vangard 75 WG	pyrimethanil cyprodinil* + fludioxonil cyprodinil
  12	Phenylpyrroles	Scholar Switch 62.5 WG	fludioxonil cyprodinil + fludioxonil*
  11	QoI (stobilurins belong in this group, but not all QoI fungicides are strobilurins)	Cabrio EG Flint 50 WG Sovran Pristine WG Tanos 50 DF	pyraclostrobin trifloxystrobin kresoxim-methyl boscalid + pyraclostrobin* cymoxanil + famoxadone*
  17	Hydroxyaniline	Elevate 50 WDG	fenhexamid
  18	Antibiotic	Streptomycin 17	streptomycin
  22	Benzamides	Gavel 75 DF	mancozeb + zoxamide*
  27	Cyanoacetamide-oxime	Tanos 50 DF	cymoxanil* + famoxadone
  29		Allegro 500 F	fluazinam
  40	Carboxylic acid amide	Revus	mandipropamid
  44	Microbial	Serenade ASO Serenade MAX	Bacillus subtilis strain QST 713
  M	Inorganic	Copper 53 W Guardsman Copper Oxychloride Copper spray Kumulus DF Lime Sulphur Microscopic sulphur	tri-basic copper sulphate copper from copper oxychloride copper from copper oxychloride sulphur lime sulphur sulphur
  M	Dithiocarbamate	Dikar Dithane DG Dithane M45 Ferbam WDG Gavel 75 DF Penncozeb 75 DF Polyram DF Ridomil Gold MZ Thiram	mancozeb* + dinocap mancozeb mancozeb ferbam mancozeb* + zoxamide mancozeb metiram metalaxyl + mancozeb* thiram
  M	Phthalimide	Captan 80 WDG Folpan 80 WDG Maestro 80 DF	captan folpet captan
  M4	Chloronitrile	Bravo 500	chlorothalonil
  M6	Guanidines	Equal 65 WP	dodine
  NC	Biological	Actinovate SP	Streptomyces lydicus
  NC		MilStop	potassium bicarbonate
  U	Phosphonate	Aliette	fosetyl al

Note: Fungicides in Group M are multi-site inhibitors.
NC = not classified.