A Review of Fungicide Products Available for Major Diseases of the Northwest

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A Review of Fungicide Products Available for
Major Diseases of the Northwest

• Dr. Frank P. Wong
• Cooperative Extension Specialist
• University of California
• Wilbur-Ellis Professional
• Markets Technical Seminar
• January 24, 2008
• Coeur d Alene Golf and Spa Resort

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The Fungal Lifestyle
Fungi are extremely good at breaking down living
and dead organisms and and absorbing their
nutrients
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Waitea (Brown Ring) Patch on annual bluegrass,
Palos Verdes, CA
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What is a fungicide?

• Fungicides are pesticides that specifically kill
  fungi or inhibit fungal development
• About 40 different classes of fungicides used for
  plant protection
• Classes are based on target site and biochemical
  mode of action

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Multi-site
Site-specific
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Multi-site Inhibitors

• A very large class of fungicides that are
  generally older fungicides
• Affect multiple metabolic processes

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Multi-site Inhibitors

• Many work by breaking the molecular bonds that
  hold proteins together
• Others smother or otherwise physically damage the
  fungus

S
S
SH
SH
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Multi-site Inhibitors
Copper
EBDCs Chlorothalanil
Oil
Sulfur
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Single-site Inhibitors

• Affect a specific metabolic process
• Bind to proteins via lock and key process

F
NZ

F
NZ
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Single-site Inhibitors

• Lipid Biosynthesis
• Sub. Aromatic Hydrocarbons
• Dicarboxymides
• mRNA Synthesis
• Phenylamides
• Nuclear Division
• Benzimidazoles
• Respiration (MET complex II)
• Carboxins

• Amino Acid and Protein Synthesis
• Anilinopyrimidines
• Sterol Biosynthesis
• DMIs
• Respiration
• (MET complex III)
• QoIs
• Osmoregulation (unknown)
• Phenylpyrroles

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Systemicity
Non-systemic
Systemic

• Do not penetrate into plant
• Redistribute on plant surfaces
• Multi-site inhibitors
• Kills spores/inhibits germination
• Protectant only
• Broad spectrum

• Penetrate into plant
• Redistribute on within plants
• Single-site inhibitors
• Inhibits spore germination and or mycelial growth
• Protectant and curative
• Selective

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Non-systemics

• Mimimal redistribution from the point of
  deposition
• Works by contact with the fungus
• Adequate coverage is essential
• On the cuticle
• Redistributed washed off by water
• EBDCs, Chlorothalanil, etc.

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Systemics

• Local Systemic
• Local redistribution from the point of deposition
• On the cuticle
• Through the leaf (translaminar)
• Extent is variable

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Systemics

• Limited systemic (acropetal penetrant)
• Good movement from the point of application
• Through tissues
• Inside the vasculature
• Bulk movement
• DMIs, Phenylamides

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Systemics

• True Systemics (Basipetal penetrant)
• Only one fungcide
• Fosetyl-Al
• Moves through plant
• Down into roots
• Good against soil-borne oomycetes

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Single Site v. Multi-siteSystemic v. non-Systemic
Non-systemic/Multi-Site
Systemic/Single Site

• Protectant only
• Can wash off
• Shorter application intervals
• Broad spectrum
• Low Risk of Resistance

• Protectant and curative
• Less prone to washing off
• Longer application intervals
• Selective
• High Risk of Resistance

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How Does Resistance Occur?

• Resistant individuals occur naturally at low
  frequencies
• DNA replication
• Sexual recombination
• Natural mutagens
• Repeated fungicide use increases the frequency of
  resistant individuals
• When this frequency is high enough practical
  resistance occurs

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Cross-Resistance

• Once resistance develops to a fungicide all
  fungicides with the same biochemical mode of
  action are affected
• Cross-resistance class is defined as a class of
  fungicides that share the same biochemical mode
  of action and mechanism of resistance
• Example all DMI fungicides
• all affect sterol biosynthesis
• a change in the fungal enzyme affects all DMIs

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Fungicide Group MMulti-site fungicides
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Group M

• All contact fungicides with a non-specific mode
  of action are represented in this class
• Cholorothalonil
• Daconil Ultrex (Syngenta)
• Daconil Weatherstik (Syngenta)
• Mancozeb
• Fore (DowAgro)
• Dithane (DowAgro)
• Copper Hydroxide, Hydrogen Dioxide

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Group M Range of Activity
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Group M

• Pros
• Inexpensive
• Wide range of activity
• Algae control
• No resistance risk
• Cons
• Foliar diseases only
• Limited application intervals (7-14 days)
• Restrictions on chlorothalonil use

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Current Chlorothalonil Restrictions
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Group 14 FungicidesAromatic Hydrocarbons
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Group 14 Aromatic Hydrocarbons

• Pentachloronitobenzene (PCNB) is the major turf
  fungicide in this class
• Affects lipid (membrane) synthesis
• Non-systemic
• Highly stable in soil

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Group 14 Aromatic Hydrocarbons
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Group 14 Aromatic Hydrocarbons

• Pros
• Long term control of certain soil borne diseases
• No resistance for turf diseases
• Cons
• Phytotoxicity at high rates or high temperatures
• Possible use reductions or restrictions

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Group 3 FungicidesSterol Biosynthesis Inhibitors
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Group 3 SBI Fungicides

• Inhibit demethylation of ergosterol used in cell
  membranes
• Called SBI, SI or DMI fungicides
• Systemic, acropetal penetrant fungicides
• Fenarimol (Rubigan) - Gowan
• Myclobutanil (Eagle) - DowAgro
• Propiconazole (Banner MAXX) - Syngenta
• Triadimefon (Bayleton)- Bayer
• Triticonazole (Trinity) - BASF

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The sterol biosynthesis source of modes of
action
squalene-epoxidase
epoxisqualene-cyclase
DMIs (3)
C-14-demethylase
Amines (5)
ergosterol
?14-reductase
hydroxy- Anilides (17)
Amines (5)
C3-ketoreductase
?8 ?? 7 -isomerase
C3-ketoreductase
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Untreated
Treated
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Group 3 SBI Range of Activity
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Group 3 SBI Fungicides

• Pros
• Broad spectrum of activity vs ascomycete and
  basdiomycete fungi
• Systemic
• Lasting residual activity long application
  intervals
• Cons
• Some plant growth regulator effects at high rates
  or high temperatures
• Development of tolerance for some diseases

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Group 3 SBI Fungicides

• Resistance Issues
• Dollar Spot
• Anthracnose
• Tolerance present
• Most evident for fairway applications
• Low rates, long application intervals
• Increase rates or shorten intervals for increased
  control

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Group 11 FungicidesQo-Inhibitors
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Group 11 Qo-Inhibitors

• Derived from natural products
• Broad spectrum activity vs. all fungi
• Azoxystrobin (Heritage) Syngenta
• Fluoxastrobin (Disarm) - Arysta
• Pyraclostrobin (Insignia) - BASF
• Trifloxystrobin (Compass) Bayer

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Discovery and Synthesis from Natural Products
Myxococcus fulvus
Strobilurus tenacellus
Oudemansiella mucida
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Synthesis from Natural Products
Oudemansin A
Strobilurin A
Enol ether stilbene
Oxime Ether Group
Enol Ether Group
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QoI Mode of Action Mitochondrial Respiration
cristae
inner membrane space
matrix
outer membrane
inner membrane

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Biochemical Mode of Action
H
H
H
IV
I
II
Cyt b
Cyt c
UQ pool
ATP Synthase
Cyt c1
2e-
III
H
Succinate
1/2 O2
NADH
ADP
NAD
Fumarate
H2O
ATP
Inhibition of electron transport at the
hydroxyquinone-oxidation (outer) site in
cytochrome bc1 and uncoupling of oxidative
phosphoralation
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Physical Properties Wheat Leaf Movement Assay
Bartlett, et al., 2002, Pest Management Science
58649-662
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Physical Properties Wheat Leaf Movement Bioassay
vs. Blumeria graminis
Bartlett, et al., 2002, Pest Management Science
58649-662
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Group 11 QoI Range of Activity
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Group 11 QoIs

• Pros
• Broad spectrum of activity vs all fungal classes
• Systemic, local to acropetal penetrant activity
• Lasting residual activity long application
  intervals
• Cons
• Variable activity vs dollar spot
• Less systemic fungicides not very good for root
  infecting and soil fungi
• Development of resistance for some diseases

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Fungicide Resistance Issues
10 mg/L azoxystrobin
check
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Group 11 QoI Fungicides

• Resistance Issues
• Anthracnose
• Pink Snow Mold
• Resistance present
• Evident in locations with repeated applications
• Limit total use for these specific diseases

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Group 1 FungicidesBenzimidazoles
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Group 1 Benzimidazole Fungicides

• Inhibit nuclear division during cell replication
  by binidng to beta-tubulin
• Broad spectrum of activity vs most fungi
• Systemic, acropetal penetrant fungicides
• Thiophanate-methyl (3336) Clearys
• Benomyl (Benlate)- DuPont

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Group 1 Benzimidazole Range of Activity
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Group 1 Benzimidazoles

• Pros
• Broad spectrum of activity vs ascomycetes and
  basidiomycetes
• Systemic acropetal penetrant activity
• Lasting residual activity long application
  intervals
• Cons
• Not effective vs. some Rhizoctonia diseases
• Development of resistance for some diseases

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Group 1 Benzimidazole Fungicides

• Resistance Issues
• Anthracnose
• Dollar Spot
• Pink Snow Mold
• Resistance present
• Evident in locations with repeated applications
• Limit total use for these specific diseases

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Group 12 FungicidesPhenylpyrroles
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Group 12 Phenylpyrroles

• Function by inhibiting osmotic regulation
  pathways in fungi (os-1)
• Derived from a natural product derived from a
  soil Pseudomonad
• Local penetrant fungicide
• Good soil stability
• Fludioxonil (Medallion)- Syngenta

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Group 12 Phenylpyrrole Range of Activity
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Group 12 Phenylpyrroles

• Pros
• Strong vs anthracnose, Rhizoctonias and snow
  molds
• Good soil stability
• No resistance present
• Cons
• Local penetrant activity only
• Increased break down in sunlight
• Shorter intervals, higher rates for foliar
  diseases

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Group 19 FungicidesPolyoxins
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Group 19 Polyoxins

• Function by inhibiting cell wall (chitin)
  synthesis
• Developed originally as a Rhizoctonia fungicide
  from natural products derived from Streptomyces
  soil microbes
• Local penetrant fungicide
• Polyoxin-D (Endorse)- Clearys

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Group 19 Polyoxin Range of Activity
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Group 19 Polyoxins

• Pros
• Strong vs Rhizoctonias
• Good activity vs anthracnose and fairy ring
• Possible snow mold activity
• No resistance present
• Cons
• Local penetrant activity only
• Short application intervals, only one rate
  registered for Endorse

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Group 2 FungicidesDicarboximides
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Group 2 Dicarboximides

• Function by inhibiting osmotic regulation
  pathways in fungi (os-2)
• Local penetrant fungicides
• Iprodione (Chipco 26GT) Bayer
• Vinclozlin (Curlan) - BASF

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Group 2 Dicarboximides Range of Activity
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Group 2 Dicarboximides

• Pros
• Strong vs Rhizoctonias, leaf spots, snow molds
• Cons
• Local penetrant activity only
• Some tolerance present in pathogens

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Group 2 Dicarboximides

• Resistance Issues
• Dollar Spot
• Pink Snow Mold
• Tolerance present
• Most problematic in areas with repeated use,
  tends to decrease a few years after use is
  discontinued
• Low rates, long application intervals
• Increase rates or shorten intervals for increased
  control

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Group 7 FungicidesCarboximides
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Group 7 Carboximides

• Affect mitochondrial respiration by binding to
  succinate dehydrogenase in complex II
• Two very different fungicides in this group that
  share the same mode of action
• Flutolanil (ProStar) Bayer
• Boscalid (Emerald) - BASF

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Group 7 Carboximide Range of Activity
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Group 2 Dicarboximides

• Pros
• Flutolanil vs basidiomycetes
• Boscalid vs dollar spot
• No resistance present for either fungicide
• Cons
• Limited range of activity

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Group 4 and 33 FungicidesPhenylamides and
Phosphonates
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Group 4 and 33 Phenylamides and Phosphonates

• Both groups are Pythium-specific fungicides
• Mefenoxam (Subdue MAXX) Syngenta
• Inhibits RNA polymerase and protein synthesis
• Fosetyl-Al (Aliette, Signature) Bayer
• Unknown mechanism of activity

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Phenylamides and Phosphonates Range of Activity
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Group 4 and 33 Phenylamides and Phosphonates

• Pros
• Very effective vs Pythium and oomycete diseases
• Acropetal penetrant (mefenoxam)
• Basipetal penetrant (fosetyl-Al)
• Cons
• Limited range of activity
• Resistance for mefenoxam vs Pythium

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Links of Interest

• University of Kentucky Turf Fungicide
  Recommendations
• http//www.ca.uky.edu/agc/pubs/ppa/ppa1/ppa1.pdf
• Fungicide Resistance Action Committee
• www.frac.info

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Questions????

• Contact Info
• frank.wong_at_ucr.edu
• turfpathology.ucr.edu