Value Assessment

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Michael Downs
Section Head, Herbicides and Plant Growth Regulators Value
and Sustainability Assessment Directorate

Overview

• Supporting Documents
• Value:
  • Definition
  • Purpose of value assessment
  • Key requirements
  • Components of value assessment
  • Bridging data
  • Extrapolation
  • Case study
  • Tips and tricks

Supporting Documents

• DIR2003-04: Efficacy Guidelines for Plant Protection Products
• DIR99-06: Voluntary Pesticide Resistance-Management Labelling Based on Target Site / Mode of Action
• DIR93-17: Assessment of the Economic Benefits of Pesticides
• PRO2002-02: Guidelines for the Research and Registration of Pest Control Products Containing Pheromones and Other Semiochemicals
• DIR2001-02: Guidelines for the Registration of Microbial Pest Control Agents and Products

Value Defined

• The product's actual or potential contribution to pest management, taking into account its conditions or proposed conditions of registration, and includes the product's
  • Efficacy;
  • Effect on host organisms in connection with which it is intended to be used; and
  • Health, safety and environmental benefits and social and economic impact. (PCPA 2002)

Purpose of Value Assessment

• Evaluate product performance
• Prevent unnecessary exposure to workers, bystanders and the environment resulting from ineffective products or excessive dosages
• Provide a baseline for risk assessments and risk management decision making
  • Food residue exposure, occupational exposure, environmental exposure

Key Requirements

• Each pest control claim must be supported by data or a scientific rationale
• Data must be generated using sound scientific principles, experimental design and statistical analysis (GLP not required)
• Data must demonstrate a consistent, commercially acceptable level of control
  • Will vary with circumstances
• Data should demonstrate a benefit to the user, normally in relation to a registered commercial standard
• Trials should be conducted using the specific formulation and methods of application proposed for registration
• Trials must be conducted over a range of relevant climatic and geographical regions, typically over two seasons
• An adequate number of trials at proposed rates must be provided to demonstrate consistent performance at expected pest pressures
• Data should demonstrate that the lowest effective rate (LER) is proposed for registration
• Bridging arguments and data waiver requests must be fully documented and based on scientific rationales

Components of Value Assessment

• Efficacy
  • Level of control, duration, consistency
  • Lowest effective rate
• Non-safety adverse effects
  • Primarily herbicides; varietal differences (e.g. sweet corn)
• Damage to rotational crops
  • Primarily herbicides, in particular soil-applied
• Sustainability
  • Compatibility and contribution to sustainable production practices and integrated pest management
  • Comparison with alternative products and practices, contribution to risk reduction
  • Contribution to resistance management
• Economics
• Social impacts

Bridging Data

• Data from a set of trials directly comparing a proposed new use to either a registered use, or a proposed use that is supported by a full data set
• Trials should evaluate representative pests and most challenging label claims
• Side by side comparisons

Bridging Opportunities

• Resolved isomer
• New formulation, guarantee
• Coformulation
• Change in adjuvant, carrier
• Fertilizer impregnation
• Change in application method

Extrapolation

• A situation where a full data set has been submitted for established or proposed pest claims and additional claims are then considered based primarily on scientific rationales and less frequently on additional data
• Extrapolation may be possible based on groupings by crop or by pest
  • Note: Crop groupings in DIR98-02: Residue Chemistry Guidelines do not necessarily apply to value assessment.

Basis for Extrapolation

• Pest biology, ecology
• Pest/crop interaction
• Crop biology, ecology
• Crop competitiveness
• Crop production practices/agronomics
• Pest taxonomy
• Active ingredient mode of action
• Host specificity

Extrapolation Principles -Herbicides

• Efficacy extrapolation among crops:
  • Application timing relative to the weeds
  • Crop competitiveness
    • e.g. extrapolation of control of lamb's quarters in tomato to corn
• Efficacy extrapolation among weeds:
  • Biological similarity among proposed weeds
  • Weed response to the herbicide in question
    • e.g. control of perennial sow-thistle to annual sow-thistle
    • e.g. control of redroot, green and smooth pigweed to prostrate pigweed

Extrapolation Principles -Insecticides

• Foliar applied chemical insecticides:
  • Similarity of pest distribution and feeding damage
  • Similarity of dosage based on spray volume, plant structure and foliar volume
  • Similarity of application timing with respect to biotic and abiotic factors
  • Similarity in susceptibility of populations among regions

Extrapolation Principles -Fungicides

• Food crops:
  • Disease caused by the same pathogen (e.g. not powdery mildew on greenhouse vegetables)
  • Pest biology similar on both crops
    • Timing of appearance
    • Anatomical plant parts
  • Crop biology similar among crops
    • Seasonal pattern of growth and development
    • Physical shape and structure, canopy size
    • Target site of infection

Case Study: Proposed Uses

• Forbid 240 SC Insecticide/Miticide (spiromesifen)
  • Foliar-applied, contact/ingestion activity, coverage issue
• Proposed hosts and rates:
  • Greenhouse vegetables: 30-50 ml/100L
  • Ornamentals: greenhouse and outdoor: 15-30 ml/100L
  • Cucurbit vegetables (CG9): 500-600 ml/ha
  • Fruiting vegetables (CG8): 500-600 ml/ha
  • Leafy vegetables - leafy greens (CG4A): 500-600 ml/ha
  • Brassica leafy vegetables (CG5): 500-600 ml/ha
  • Tuberous and corm vegetables (CG1C): 580-1160 ml/ha
  • Field corn: 400-600 ml/ha, strawberry: 880-1160 ml/ha
• Proposed pests:
  • Whiteflies (sweet potato, silverleaf, potato)
  • Mites (11 species)
  • Potato psyllids
• Proposed application methods:
  • Ground equipment
  • Aerial
  • Chemigation
• Data submitted: 55 efficacy trials (U.S. and Europe)

Case Study: Value Assessment Approach

• Pool efficacy data and apply to multiple crops
  • Brassicas (CG5), leafy greens (CG4A), cucurbits (CG9), fruiting vegetables (CG8), tuberous and corm vegetables (CG1C) pooled
  • GH vegetables, GH ornamentals, outdoor ornamentals pooled
  • Strawberry and field corn addressed individually
• Rationale:
  • Active ingredient acts through contact and ingestion
  • Similarity among use patterns, crop architecture, foliage density, management practices

Case Study: Outcome

• Supported hosts and rates: all hosts
  • Greenhouse vegetables: 30-50 ml/100L
  • Ornamentals: greenhouse and outdoor: 30 ml/100L - no data to support lower rate
  • Cucurbit vegetables (CG9): 500-600 ml/ha
  • Fruiting vegetables (CG8): 500-600 ml/ha
  • Leafy vegetables - leafy greens (CG4A): 500-600 ml/ha
  • Brassica leafy vegetables (CG5): 500-600 ml/ha
  • Tuberous and corm vegetables (CG1C): 500-600 ml/ha -withdrew psyllids
  • Field corn: 400-600 ml/ha, strawberry: 880-1160 ml/ha
• Supported pests:
  • Two-spotted spider mite, banks grass mite, broad mite (3 of 11 mites)
  • Whitefly (sweet potato, silverleaf, greenhouse)
• Unsupported (withdrawn) pests:
  • Remaining mites (8 of 11 mites) - no data
  • Potato psyllid - no data
• Supported application methods:
  • Ground equipment
  • Aerial: only one trial submitted, coverage concern, but...
    • Precedent miticide with aerial application registered: same rate for ground and aerial application
    • Precedent product also has contact and ingestion activity
    • Precedent product also requires thorough coverage
• Unsupported (withdrawn) application methods:
  • Chemigation - insufficient data (1 trial)
• A note on geography:
  • Efficacy data largely from southern U.S.
  • What would be the response under Canadian conditions?
    • Rationale:
    • U.S. data presents worst case due to high pest populations under hot and dry conditions
    • Several studies conducted in spring or fall-similar to Canadian summer
• Phytotoxicity:
  • Generally none reported, but...
  • Variable response in greenhouse cucumber and rose
  • Data not available for all hosts in all crop groups
  • Solution: accept all proposed hosts and include warning on product label for ornamentals
    • Recommend test on small scale first
  • Specific warnings where concerns are known

Tips and Tricks

• Clearly define the proposed use
• Ensure all key requirements are addressed
• Anticipate questions and proactively provide responses
• Provide explanations for any unusual data
• Use and submit a spreadsheet to organize your data
• Group trials by pest pressure
• Define the assessment parameters
• Answer the basic questions:
  • Was the proposed use pattern evaluated in the trials?
  • Is it effective? Does it work?
  • Is there a rate effect or dose response?
  • What is the duration of control?
• Address resistance management
  • HRAC, IRAC, FRAC guidelines
• Summary tables:
  • DIR2003-04 Appendix I and II
  • Fill in all the required data columns
  • Efficacy-one table per crop/pest use
  • Crop tolerance-one table per crop
  • Note differences by discipline
  • Pivot Tables are your best friends

Pivot Table

• Parameter: % control
• Dat Range: All
• Crop: All
• Crop: All
• Herbecide Treatment
• Application rate
• Data
  • Count
  • Min
  • Max
  • Mean
• Frequency Range
  • 100-90%
  • 89-80%
  • 79-60%
  • <60%