Composition, Activity and Persistence
of
Crop Protection Chemicals
and
Biological Agents
Graeme Cross, CAFRE
Why are Pesticides Necessary?
It is estimated that, even today, more than 40% of global
food production is lost to pest and disease attack
Most major losses affect the staple crops e.g.
• Rice
• Wheat
• Maize
• Cassava
• Beans/Pulses
What is a Pesticide (Plant Protection Product)?
Herbicide
Weed killer
Fungicide
Fungal (disease) controller
Bactericide
Bacteria (disease) controller
Insecticide
Insect (pest) killer
Acaricide
Mite/spider (pest) killer
Rodenticide
Rat / Mouse killer
Plant Growth Regulator
Growth habit alteration
What makes a substance dangerous (hazardous)?
• Caustic / Corrosive / Reactive
• Flammable
• Explosive
• Poisonous
• Irritating (to skin/ eyes/ respiration)
FACT: Some early pesticides contained heavy (toxic) metals e.g. As, Hg, Pb.
Q: Why were these products withdrawn (also why are they still very effective)?
Toxic metals are poisonous in low doses, accumulate readily in animal
tissues (fat, brain) and cannot be metabolised into harmless compounds
easily. They often attack a range of different life functions and remain
toxic in almost every form that they exist.
What are Pesticides (PPPs) made up of ?
Active Ingredient [chemical molecule(s)]
+
Solvent (sometimes acts as stabiliser)
+
=
Activators or other Adjuvants [Additives]
+
Carrier Substance [clay minerals or inert liquid(s)]
F
O
R
M
U
L
A
T
I
O
N
What is a pesticide FORMULATION?
The formulation is made up of
What does the FORMULATION achieve?
active ingredient +
carrier +
Keeps the AI in a storable and useable form
additives (adjuvants)
Eases the dilution / mixing
Maximises the effectiveness of application
Maintains stability of the product before during and after use
Why might different FORMULATIONS be used for the same A.I.?
Crop type (which part of the plant or tissue being treated)
Growing conditions
Environmental considerations
Application method (water availability?)
SOME COMMON ADJUVANT TYPES AND THEIR ACTIVITY
WHAT IS AN ADJUVANT?
A substance other than water which is not in itself a pesticide
but which enhances or is intended to enhance the effectiveness
of the pesticide with which it is used".
TYPES OF ADJUVANTS
Wetters, Stickers, Spreaders, Penetrants, Extenders (drift retardants)
CURRENT SIGNIFICANCE TO CROP PROTECTION
Surfactant usage in agrochemicals is estimated at no more than 4%
of total world consumption.
What other applications would you envisage?
Types of product FORMULATION – Quick Quiz
DP
Dustable Powder
EC
Emulsifiable Concentrate
SC
Suspension Concentrate
RB
Ready to Use Bait
SP
Soluble Powder
WG
Water Soluble Granule
WB
Water Soluble Bag
Which are the most dangerous formulations
in use?
(Discuss briefly)
Persistence – a Good or a Bad Thing?

In the Crop


In the ‘Target’


In the Immediate Environment


In the Wider Environment

What Governs the Persistence of a PPP?
Dosage rate – how much to start with?
Environmental Conditions:
Temperature
Light levels
Moisture
Humidity
Chemical Stability (‘half life’)
Soil Type / Growing Medium
(adsorption & immobilisation)
Growth Stage of Crop (dilution in vivo)
Formulation
Microbial Activity (biosphere)
DELTAMETHRIN
A synthetic pyrethroid insecticide /
acaricide (cf. pyrethrin)
Nerve agent
Fast knockdown and highly lipophilic
Degrades rapidly in water, air and light
Broad spectrum activity
Repellent effect
[Other pyrethroids = cypermethrin, cyfluthrin,
flumethrin, lambda-cyalothrin, permethrin]
DIFLUBENZURON
A benzoyl urea (benzamide) insecticide
Inhibits chitin synthesis (exoskeleton formation)
Selective action best targeting soft bodied insects
Stable in acidic solutions, soil and dry leaf (half-life
between 4 days and 4 months)
Persistent activity (H.I. 14 days +)
Pest feeding inhibited after contact
[Other benzoylurea insecticides include chlorfluazuron,
flufenoxuron, hexaflumuron, and lufenuron - ‘Frontline’]
PROCHLORAZ
A imidazole, dimethylation-inhibiting (DMi) fungicide
Site specific action in fungal membrane disruption
Prochloraz-manganese complex used for WP formulations
Harvest Interval = 4 days
‘Cobweb’ strains exist with reduced susceptibility (Ireland?)
Max Individual Dose = 120g/100m2 area
Max number of treatments = 2 x M.I.D. or 3 x reduced dose
rate of 60g/100m2
[Other triazole fungicides include imidazole,
fenbuconazole, penconazole, tebuconazole]
The Role of Biological Agents
A critical component of Integrated Pest Management (IPM)
“A living organism used to control or modify the behaviour of a
pest, or to compete with a disease organism”
Mushroom examples:
•Steinernema feltiae (‘Entonem’) nematode against Sciarid Fly
•Metarhizium anisopliae fungus (‘Met52’) against fly pests
Biological Agents – Pros and Cons
• A non-chemical option:
• Cost
- Operator safety (handling + use)
- No residues
• Co-ordination/forward planning
needed
- Order as required (no storage)
• Require the ‘host’ to be present
• They target the specific problem
• Narrow range of optimal conditions
• They have a ‘green’ perception
• Lag time before benefit shows
• They may last through the
production cycle
• Lifespan of product is often limited
Pesticide Use – Some Practical Implications
• Operator Competence:
- Training and CPD points
- The Voluntary Initiative
• Application Criteria and Compliances:
- Maximum Treatment Numbers
- Maximum Individual Doses
- Harvest Intervals
- Maximum Residue Levels (pesticide residue testing)
• H&S, Worker Welfare, Food Standards, QA, Environmental Protection
= DUTY OF CARE!
The Issue of Resistance
“Where an active ingredient (chemical) becomes less effective, due to an
increased ability of the pest or disease to tolerate exposure.”
Arises due to:
Inappropriate application rates or dosages used
Over-reliance on a single A.I. (or a limited range) for
control
Application
of
Crop Protection Chemicals
(with examples taken from
Production of Mushrooms)
Graeme Cross, CAFRE
What Does the Law Say?
A great deal, but almost exclusively relating to:
Commercial practice
Professional usage
Farming
Horticulture
Contractors
Employers and Employees
i.e. ‘domestic’ garden operations are not subject to these same laws
(apart from consumer protection aspects and ‘wilful pollution’ incidents)
Major Legislation Relevant to Use of PPPs
• Health and Safety at Work Order (NI) 1978
- overarching employer obligation to ensure worker welfare
• Food and Environment Protection Act 1985 [FEPA]
- food, human health and environmental protection
- safe, reasonable pest control methods
• Control of Pesticides Regulations (NI) 1987 (as amended) [COPR]
- added under FEPA, specific to PPPs e.g. MAPP register
- 1991 & 2005 PPP Regulations for EU standardisation
Major Relevant Legislation (cont.)
• Control of Substances Hazardous to Health Regulations (NI) 2003
- legal obligation to assess risk and implement adequate controls
- not confined to PPPs
• Personal Protective Equipment at Work Regulations (NI) 1993
- reinforces the provision of correct (fit) PPE in all professions
- clarifies the obligations and responsibilities for all parties
• Groundwater Regulations (NI) 2009
- from EC Directive 2006/118/EC on protection of (drinking) water
supplies against pollution and deterioration (originally 2000/60/EC)
- serious implications on field use of persistent materials e.g. IPU
Pesticide Use – Some Practical Implications
• Operator Competence:
- Training and CPD points [COPR]
- The Voluntary Initiative [not law yet!]
• Application Criteria and Compliances: [FEPA, COPR, PPPR, etc.]
- Maximum Treatment Numbers
- Maximum Individual Doses
- Harvest Intervals
- Maximum Residue Levels (pesticide residue testing)
• H&S, Worker Welfare, Food Standards, QA, Environmental Protection
= DUTY OF CARE! [e.g. COSHH]
Operator Competence – More Detail
• National Proficiency Test Council (NPTC) coordinates:
- Pesticide Application (PA) Certificates for anyone involved in
handling, distributing, storing, measuring and/or applying PPPs
- PA1 is the foundation module for all those responsible for
handling PPPs as part of their professional duty
- PA2a is the technical unit for operating a boom sprayer
- PA3a relates to operating an orchard (air-assisted) vertical sprayer
- PA4 relates to operating a granule or pellet applicator
- PA6 relates to operating a knapsack sprayer
• In NI, DARD (CAFRE) has responsibility for delivery of training and
assessment in these units (NB. Sustainable Use Directive, November 2015)
The Voluntary Initiative (V.I.)
•
•
UK Launch in 2001
Proactive industry (primary producer) response to
- threat of further legislation and
- increased taxation on PPPs
• 3 main tenets (pillars):
(i)
National Register of Sprayer Operators (NRoSO)
(ii)
National Sprayer Testing Scheme (NSTS)
(iii)
Crop Protection Management Plan (CPMP) on farm
• Additional measure through BASIS:
- Biodiversity and Environmental Training for Advisors
(BETA)
How Effective is the V.I.?
In 2011 (10th anniversary):
• 20 359 NRoSO members (£17 annual fee payable)
• 14 200 NSTS sprayer tests conducted (c. £100 fee per test)
• NSTS compliant sprayers represent approx. 86% of total
sprayed agricultural area
• 1.35 million Ha covered by a CPMP (free of charge)
• Target for CPMP inclusive area was 1.5 m Ha
Professional Agronomy Advice
Where should you seek guidance?
• Always read the product label! (information on approved
uses, recommended rates and limits, tank mixes/
compatibilities, correct PPE to wear, harvest intervals for
crops, minimum buffer zones, etc.)
• Your agronomist, agrochemical merchant and/or DARD
adviser should be BASIS qualified (certificated and up-todate in CPD points)
• Manufacturers have technical support resources through
websites and contact numbers
Hierarchies of Risk Control (H&S)
1. Eliminate the hazard at source
A. PROCEDURAL
2. Reduce or Substitute the hazard at
source
(planning ahead)
3. Remove (Separate) the operator
from the hazard
B. TECHNICAL
4. Contain (Enclose) the hazard
(engineering)
5. Limit operator exposure
6. Use P.P.E.
C. BEHAVIOURAL
(the human factor)
COSHH Assessments
These relate only to substances (but not just PPPs) in the
workplace
All employers (inc. self-employed) should carry out COSHH
assessment
All businesses of > 5 employees must have them recorded
and available
COSHH assessments should be kept up-to-date
A particular COSHH should be revised when any operational
or material change occurs
How to undertake a COSHH Assessment
1. List the tasks in your workplace that use (or generate) hazardous
substances
2. For each task, identify the (type) of substance involved e.g.
dust/powder, gas/vapour/smoke, liquid, filings, foam, spore.
3. Determine the hazard (if any) associated with each substance
identified
4. Consider the reasonable precautions and control measures that you
can implement during the operation, to minimise risk and to control
exposure
5. Decide what will be put in place, record this action plan and keep on
file for all operators’ information and training
What PPPs might be applied in mushroom prodn?
Type of product
An insecticide
Formulation(s)
Emulsifiable Concentrate or Oil in Water Emulsion
A fungicide
A biological control agent
A rodenticide
A herbicide e.g. glyphosate
Wettable Powder
Granule or Dispersible Concentrate
Ready to Use Bait
e.g. SL
Application Equipment & NPTC PA Tests
Relevant to mushroom production:
Hand held applicator with hydraulic nozzle / rotary atomiser
(knapsack)
= PA6d
Hand held applicator with minimum calibration
= PA6a
Fogging misting and smoke applicators
= PA9
The Principle of Hand-Held Application
Spray liquid (at correct concentration)
ejected under pressure through a narrow
aperture i.e. a nozzle of known
characteristics
What sort of spray quality
can you expect?
Factors Affecting Spray Application (Quality)
• The effect of output pressure
• The relationship between droplet size and coverage
(4/3 Π r3)
• The type of nozzle (single) and arrangement (multiple):
e.g. flat fan, even flat fan, hollow cone, solid cone
• The nature of the spray liquid e.g. a.i., solvent, adjuvants
Nozzles
Calibration of Equipment – Why?
To ensure uniform, consistent, predictable, measured applications
How?
For a predetermined test area:
(i).
(ii).
(iii).
(iv.)
Measure the nozzle output at a set pressure reading
(the maximum?)
Measure forward speed (or work rate) using water only
Calculate apparatus output / square metre
Check against product recommendations
(and adjust if necessary!)
How Much Active Ingredient?
A dilute spray solution of prochloraz (‘Sporgon 50WP’) fungicide
is needed to treat a mushroom crop.
Q1. Give brief, practical reminder points on the correct way to
make up this solution.
The ‘Sporgon 50WP’ solution has been made up using 120g
of product in 240 litres water.
Q2. What is the concentration of active ingredient in the spray solution?
The grower wishes to treat the crop at the reduced dose rate of
60g product per 100m2 production area.
Q3. What volume of spray solution should be applied per square metre?
Q4. Minimum product quantity for 240 litre solution, to comply with label?
What Should Application Records Include?
Location (site/field/tunnel.) ____________
Crop Type _________________
Initials /
signature
Operator ID
Dose Rate/
Qty/litre AI
Environmental
Conditions
Harvest Interval
Application
Method
Reason for Use
Active
Ingredient
Product Name
Date
Assessing Wind Speed (The Beaufort Scale)
F0 = no wind, F1 = 1-3 mph (avg), F2 = 4-7 mph, F3 = 8-12 mph
What Other Records / Reference Materials Should be Held?
• Emergency Action Plans (fire, spillage, pollution)
• Staff Health Audits, if appropriate
• Accident Record Sheets (not a book) – 10+ employees and
RIDDOR 1995 compliance
• PPP label copies, Safety Data Sheets & EAMU (SOLA) print-outs, as
needed
• PPP stock records/inventory – up-to-date!
• Residue tests if available or protocol records for traceability
Spray Application Recording Exercise:
• Transfer the relevant information from the paragraph below to
your spray application record sheet:
Last Saturday (6th December 2014) you decided to treat the 4 Ha
‘Meadow Field’ with 1 litre/ha of azoxystrobin fungicide (Brand
Name “Amistar”), to control the development of Sclerotinia Stem
Rot fungus.
You started this job at 10.00 a.m. and it took 90 minutes in total.
The weather conditions were dry, overcast and mild (with a light
breeze).
The pump of the boom sprayer you used was set at an operating
pressure of 6 bar (c. 87 psi) and it delivers 250 litres/ha of spray
solution (at your usual forward drive speed).