Pesticide Management Fungicide Benefits Challenges Contribute to food

Pesticide Management Fungicide Benefits & Challenges: Contribute to food safety by controlling many of the fungi that produce mycotoxins. Meet increasing demand for more food and higher quality food. There are more than 125 active ingredients registered as fungicides worldwide. Growing demand by the public for crop protection agents with: low use rates, a benign environmental profile, and low toxicity to humans and wildlife.

Fungicide Classification 1. 2. 3. 4. 5. 6. Mobility in the plant Role in protection of the plant Breadth of metabolic activity Mode of Action Chemical group or class FRAC code Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification 1. Mobility in the plant Contact Fungicide Remains on the plant where it is applied, but is not absorbed into plant tissue; has no postinfection activity; repeated apps may be needed Systemic Fungicide Moves into plant tissue, may have postinfection activity; some move up plant in xylem tissue, some are locally systemic within treated portion of plant Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification 2. Role in protection of the plant Preventive (Protective) Activity Occurs when fungicide present on plant as a protective barrier before pathogen arrives or grows Early Infection (Curative) Activity Occurs when fungicide is absorbed by the plant and stops the pathogen in early development (24 -72 hrs) Antisporulant Activity Occurs when fungicide prevents spores from being produced; lesions may develop but less inoculum Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification 3. Breadth of metabolic activity Single-site Fungicide A fungicide that is active against only one point of function in one of the metabolic pathways of a fungus or against a single critical enzyme or protein needed by the fungus; may have systemic properties Multi-site Fungicide A fungicide that affects a number of different metabolic sites within the fungus Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification 4. Mode of action Is the means by which the fungicide kills or suppresses a target fungus or affects specific biochemical processes of the target fungus Examples Damaging cell membranes Inactivating critical enzymes or proteins Interfering with key processes (respiration, energy production) Mueller et al. – Fungicides for Field Crops, 2013

Pesticide Management Mode of Action: Fumigative - acts as vapor rather than a solid or liquid Protectant - protective barrier between plant & agent Systemic - taken up & distributed in the plant system Acropetal = upward movement Basipetal = downward movement Symplastic = movement in phloem tissue Ambimobile = movement in phloem & xylem

Fungicide Classification 5. Chemical group or class Is a set of chemicals that have a common biochemical mode of action; may or may not have a similar chemical structure 6. FRAC Code Fungicide Resistance Action Committee (FRAC) developed a code of numbers and letters that are used to distinguish fungicide groups based on their modes of action Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification Chemical Classes (Frac Code No. ) 1 – Benzimidazole Carbamate inhibit tubulin biosynthesis – mitosis in fungi 2 – Dicarboximide interfere with osmotic signal – germination, mycelium 3 – Demethylation Inhibitor (DMI) inhibit enzyme in sterol production – membrane & function 4 – Phenylamide inhibit RNA synthesis – mycelial growth, spore formation 7 – Succinate Dehydrogenase Inhibitor (SDHI) inhibit fungal respiration Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification Chemical Classes (Frac Code No. ) 9 – Anilino-Pyrimidine (AP) inhibit synthesis of amino acids – fungal penetration & growth 11 – Quinone Outside Inhibitor (Qol) inhibit respiration in mitochondria – spore germination & growth 12 – Phenylpyrrole (PP) interfere with osmotic signal – spore germination & growth 14 – Aromatic Hydrocarbon (AH) may interfere with lipid & membrane synthesis – mycelial growth 21 – Quinone Inside Inhibitor (Qil) inhibit fungal respiration & energy production Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification Chemical Classes (Frac Code No. ) 22 – Benzamide destroys microtubule assembly – fungal mitosis & cell division 27 – Cyanoacetamide-Oxime activity is unknown – is a preventive during early infection 28 – Carbamate interferes with synthesis of phospholipids and fatty acids 29 – Oxidative Phosphorylation Uncoupler inhibit energy production – germination & infection structures 30 – Organo Tin Compound inhibit fungal respiration Mueller et al. – Fungicides for Field Crops, 2013

Fungicide Classification Chemical Classes (Frac Code No. ) 32 – Heteroaromatic inhibit nucleic acid synthesis 33 – Phosphonate inhibit spore germination & mycelial development, SAR 40 – Carboxylic Acid Amide (CAA) affects formation of cell walls M – Multisite Activity are considered protectant or preventive fungicides; attack multiple biochemical sites within the pathogen Mueller et al. – Fungicides for Field Crops, 2013

Pesticide Management Fungicide Requirements: 1. Low lethal dosage to targeted organism 2. Noninjurious to the host 3. Nontoxic to man and animals 4. Imparts no undesirable flavor, odor, toxic properties 5. Compatible with other chemicals 6. Tenacious adherence to plant surface, resists weathering 7. Ease of preparation and application 8. Noncorrosive to containers, machinery, other objects 9. Low cost Maloy - Plant Disease Control, 1993

Pesticide Management Toxicity: Dose is expressed as the lethal dose required to kill a certain percentage of a test population (e. g. , 50 %) [ LD 50 of 30 means that 30 mg of chemical per kg body weight per test animal is lethal to 50 % of the animals ] Toxicity Groups: High LD 50 of < 50 Medium LD 50 of 50 - 500 Low LD 50 of > 500 (most fungicides) [ e. g. , thiram = 800, iprodione = 2000, captan = 9000 ] Maloy - Plant Disease Control, 1993

Pesticide Management Fungicide Formulations: Wettable Powder (WP) Dry Flowable (DF) Dust (D) Flowable (F) Emulsifiable Concentrate (EC) Liquid Concentrate (L, LC) Granule (G) Maloy - Plant Disease Control, 1993

Pesticide Management Fungicide Names: Chemical Name (active ingredient): methyl (E)-2 -{2 -[6 -(2 -cyanophenoxy) pyrimidin-4 -yloxy]phenyl}-3 -methoxyacrylate Class = Quinone inhibitor (Group 11) Common Name: Azoxystrobin Trade Name: Quadris

Pesticide Management Additional Information on Label: Restricted Entry Interval (REI): Minimum time between application of a pesticide to a field and when it is safe to reenter that field; usually 12 -24 hours for fungicides Pre-harvest Interval (PHI): Minimum amount of time that must pass between the last pesticide application and harvesting of the crop or grazing; usually 7 -30 days for fungicides Mueller et al. – Fungicides for Field Crops, 2013

Pesticide Management Fungicide Application: Determined by: - application equipment available - formulation - kind of crop Methods: Ground Duster Vaporizer Airplane Chemigation Unit Sprayer High Volume (HV) at 350 - 800 g/A Medium Volume (MV) at 100 - 350 g/A Low Volume (LV) at 10 - 100 g/A Ultra-low Volume (ULV) at < 0. 5 g/A

Pesticide Management Advantages of Seed Treatment: 1. 2. 3. 4. Easily applied when properly done Inexpensive compared to foliar sprays, soil drenches Effective since every plant (seed) is protected Supplement other control measures Most seed-treatment fungicides kill or inhibit pathogens on seed surfaces, but few kill pathogens embedded in the seed coat. Fewer fungicides eradicate pathogens beneath the seed coat. More recently developed materials are low in phytotoxicity, narrow in range of activity, and specific in mode of action. Maloy - Plant Disease Control, 1993

Pesticide Management Eradicants other than Seed Treatment: Dipping of transplants or seedlings Fumigation - methyl bromide Postharvest Disinfectants sulfur dioxide, nitrogen trichloride, formaldehyde, phenolic compounds, carbon dioxide, ozone Maloy - Plant Disease Control, 1993

Pesticide Management Factors Affecting Soil Fumigation: Soil Texture - range from sands ( > 85 % sand) to clays ( > 40 % clay) - coarse textured soils are generally easier to fumigate - the clay fraction absorbs large amounts of fumigant Soil Structure (Porosity) Soil Moisture Soil Temperature Organic Matter Plant Residues Maloy - Plant Disease Control, 1993

Pesticide Management Factors Affecting Soil Fumigation: Soil Texture Soil Structure (Porosity) - fumigants move through air passages and dissolve in the water film - too many or too large air channels allow fumigants to diffuse too rapidly to be effective Soil Moisture Soil Temperature Organic Matter Plant Residues Maloy - Plant Disease Control, 1993

Pesticide Management Factors Affecting Soil Fumigation: Soil Texture Soil Structure (Porosity) Soil Moisture - thickness of water film is important for retaining gas in soil since gas in soil air is in equilibrium with gas in the soil water; optimal amount of soil moisture (50 - 75 % of field capacity) provides both an adequate water film and large air passages Soil Temperature Organic Matter Plant Residues Maloy - Plant Disease Control, 1993

Pesticide Management Factors Affecting Soil Fumigation: Soil Texture Soil Structure (Porosity) Soil Moisture Soil Temperature - effectiveness increases with increasing temperatures, affects fumigant volatility, movement through soil, and postfumigant period before planting to reduce phytotoxicity - best results are obtained at 10 - 27 C Organic Matter Plant Residues Maloy - Plant Disease Control, 1993

Pesticide Management Effective Disease Control: Proper Timing Efficacy of the Fungicide Good Coverage (placement, exposure) Particle Size Adhesion Maloy - Plant Disease Control, 1993

ONION BACTERIAL DISEASES Disease Management Colorado State University, 1998/99 Kocide 2000 + Manex/Maneb: 10 x - Pre 6 - 9 x - Post ----- % Disease Reduction ----- % Increase [ Untreated check: disease intensity = ratings during August to September, yield estimate taken mid September; Xanthomonas Leaf Blight + Pantoea Blight ]

ONION BACTERIAL DISEASES Disease Management Notes: 1. max labeled rate of adjuvant in 18 gpa; 2. 1 g uv blue dye / 100 ml water; 3. % coverage = ave of 4 runs, 5 reps; 4. D. Gent & H. Schwartz, C S U - 2000

Pesticide Management Registration of Fungicides: FIFRA = Federal Insecticide, Fungicide and Rodenticide Act passed in 1947 for pesticide regulation FDA = Food and Drug Administration in 1954 established tolerances for food safety with the Miller Amendment EPA = Environmental Protection Agency was created in 1970 for registration, testing, tolerances for federal label Section 24 c = special local need (SLN) Section 18 = emergency crisis need Maloy - Plant Disease Control, 1993

Management Options - Fungicides • Section 18 – Soybean Labels for Soybean Rust – Quilt (axozystrobin + propiconazole) – Laredo (myclobutanil) – Tilt, Propimax, Bumper (propiconazole) – Stratego (propiconazole + trifloxystrobin) – Folicur, Orius (tebuconazole) – Headline SBR (tebuconazole + pyraclostrobin)

Management Options: IR-4 • Since 1963, the IR-4 Project has been the major resource for supplying pest management tools for specialty crop growers by developing research data to support new EPA tolerances and labeled product uses. • Major funding for IR-4 is provided from Special Research Grants from: * USDA-NIFA * USDA-ARS * USDA-FAS and * USDA-APHIS and is provided in cooperation with the State Agricultural Experiment Stations. These stations provide in-kind support valued at over $18 million annually.

Manage for Fungicide Resistance: • Use disease predictive models to effectively time fungicide applications • Scout fields frequently to monitor for early disease when conditions are conducive • Follow label recommendations – rate, interval, coverage, rotate fungicide groups • Integrated Pest Management Strategies http: //wiki. bugwood. org

Pesticide Management Fungicidal Resistance: Not a concern with older fungicides that are broad spectrum and non-site-specific Resistance is defined as a stable, inheritable adjustment by a fungus to a fungicide, resulting in less than normal sensitivity to that fungicide; is permanent Tolerance is acquired or adaptive resistance, which is not genetically transferable, and develops from exposure to increasing concentrations of a fungicide; is reversible Maloy - Plant Disease Control, 1993

Pesticide Management Fungicidal Resistance Mechanisms: Reduced Permeability or Exclusion of Toxicants from Cells Detoxification by Chemical Breakdown or Binding to Nontarget Sites Decreased Conversion into Toxicant Modification of Sensitive Sites [ some controlled by single genes, others by multiple alleles] Maloy - Plant Disease Control, 1993

Pesticide Management Fungicidal Resistance Development Affected by: Rate of Pathogen Sporulation and Dispersal Ability of Resistant Strains to Compete (Fitness) Threshold of Infection for Disease Development Nuclear Condition (haploidy, diploidy, polyploidy) and Nuclear Status (mono-, di-, or heterokaryosis) Maloy - Plant Disease Control, 1993

Pesticide Management Fungicidal Resistance Management: Integrate with nonchemical disease control measures Apply only when needed and at recommended dosages Select least specific fungicide that is available & effective Use mixtures of specific and broad-spectrum fungicides Mix application schedules (alternate fungicides) Maloy - Plant Disease Control, 1993

Pesticide Management Integration with Other Technologies: Implementation of IPM Systems Enhanced Diagnostic Techniques precision agriculture + targeted fungicide applications, diagnostic methods, forecasting models, remote sensing Use of Natural Fungal Antagonists (Biological Control) Crop Biotechnology - Enhancement of plant defenses by transgenic crop modification & other techniques Knight et al. - Ann. Rev. of Phytopath, 1997