Dr. Andreas GoertzCrop Protection ResearchDisease Control Monheim
Uptake & Systemicity ofFungicidesDanish Advisor Course - Aarhus – September 2012
Uptake & Systemicity of fungicides
• Background
• Benzophenones
• SDHIs
• Strobilurins
• Triazoles
• Q&A session
Agenda
Page 2 • Danish Advisor Course – September 2012
Page 3 • Danish Advisor Course – September 2012
What is Uptake?
Definition:
Uptake is the process by which a substance crosses an absorption barrier and is absorbed into the body.
Agrochemicals are taken up and distributed in the p lant generally in a passive way along concentration gradients and according to their phys ico-chemical properties
The absorption barrier in plants is the cuticle
(similar to polymer membrane)
Page 4 • Danish Advisor Course – September 2012
What is Systemicity?
Definition:
Systemicity is the uptake of a compound into the plant (root or leaf) leading to a
translocation (in xylem -or- phloem -or- both) and activity away from the site of application.
ApplicationActivity
Application
UPTAKE
TRANSLOCATION
� ACTIVITY
Uptake into the plant is a requirement for systemic ity.A limited number of compounds is distributed in the canopy via the vapour phase.
Activity
Activity
Vapour pressure (mPa): the pressure at which a liquid is in equilibrium with its vapour at 25°C. It is a measure of the tendency of a material to vapourise. The higher the vapour pressure the greater the potential.
Physico-chemical parameters of commercial fungicides
TFS
TFS
TFS
TFS
UTC
UTCUTC
UTC
low
high
Distribution of 14C-labelled Trifloxystrobin in
soybeans 7 days after spray application
Page 5 • Danish Advisor Course – September 2012
Factors determining the vapour phase distribution o f a fungicide are its physico-chemical characteristics, the environmental conditions and t he canopy strutcure
There are four basic types ofsystemicity …
Local systemicityAbsorption to the leaf surface and limited uptake with some diffusion around the site of application (no long distance transport)
Trans-laminar systemicityA compound applied to one surface of the plant leaf and acts on the other side of the leaf after penetration (not necessarily connected with long distance transport)
Xylem systemicityA compound which is translocated over long distance only in direction of the xylem stream; movement is upwards the growing point of the plant (acropetal, apoplastic)
Phloem systemicityA compound which is translocated over long distance also in direction of the phloem stream; movement is downwards from the shoots to the roots (basipetal, symplastic)
Incr
easi
ngde
gree
ofsy
stem
icity
Page 6 • Danish Advisor Course – September 2012
Spray application ofcompound on upper
leaf surface
spray droplet on upper leaf surface xylem
phloem
compoundtaken up
There are four basic types ofsystemicity …
Local systemicityAbsorption to the leaf surface and limited uptake with some diffusion around the site of application (no long distance transport)
Trans-laminar systemicityA compound applied to one surface of the plant leaf and acts on the other side of the leaf after penetration (not necessarily connected with long distance transport)
Xylem systemicityA compound which is translocated over long distance only in direction of the xylem stream; movement is upwards the growing point of the plant (acropetal, apoplastic)
Phloem systemicityA compound which is translocated over long distance also in direction of the phloem stream; movement is downwards from the shoots to the roots (basipetal, symplastic)
Incr
easi
ngde
gree
ofsy
stem
icity
Page 7 • Danish Advisor Course – September 2012
Spray application ofcompound on upper
leaf surface
spray droplet on upper leaf surface xylem
phloem
compoundtaken up
There are four basic types ofsystemicity …
Local systemicityAbsorption to the leaf surface and limited uptake with some diffusion around the site of application (no long distance transport)
Trans-laminar systemicityA compound applied to one surface of the plant leaf and acts on the other side of the leaf after penetration (not necessarily connected with long distance transport)
Xylem systemicityA compound which is translocated over long distance only in direction of the xylem stream; movement is upwards the growing point of the plant (acropetal, apoplastic)
Phloem systemicityA compound which is translocated over long distance also in direction of the phloem stream; movement is downwards from the shoots to the roots (basipetal, symplastic)
Incr
easi
ngde
gree
ofsy
stem
icity
Page 8 • Danish Advisor Course – September 2012
Page 9 • Danish Advisor Course – September 2012
Xylem SystemicityA compound which is translocated over long distance only in direction of the
xylem stream (acropetal)
activityactivity
root stem leafapplicationapplication
There are four basic types ofsystemicity …
Local systemicityAbsorption to the leaf surface and limited uptake with some diffusion around the site of application (no long distance transport)
Trans-laminar systemicityA compound applied to one surface of the plant leaf and acts on the other side of the leaf after penetration (not necessarily connected with long distance transport)
Xylem systemicityA compound which is translocated over long distance only in direction of the xylem stream; movement is upwards the growing point of the plant (acropetal)
Phloem systemicityA compound which is translocated over long distance also in direction of the phloem stream; movement is downwards from the shoots to the roots (basipetal)
Incr
easi
ngde
gree
ofsy
stem
icity
Page 10 • Danish Advisor Course – September 2012
Additonal systemicity terms exist….
Page 11 • Danish Advisor Course – September 2012
Episystemicity
Leaf surface distribution in waxy layers via vapour phase. If the vapour pressure of theactive substance is sufficiently high, migration can begin from its deposition on the leafsurface, via vaporization and gas-phase transportation
Mesostemie
Episystemicity + translaminar systemicity; the active substance is absorbed by waxy layers; superficial chemical vapour movement and re-deposition on plant surfaces; the active substance also penetrates into plant tissue, ensuring protection to both leaf surfaces. There is little or no transport within the vascular system of plants.
Additonal systemicity terms exist….
Page 12 • Danish Advisor Course – September 2012
Episystemicity
Leaf surface distribution in waxy layers via vapour phase. If the vapour pressure of theactive substance is sufficiently high, migration can begin from its deposition on the leafsurface, via vaporization and gas-phase transportation
Mesostemie
Episystemicity + translaminar systemicity; the active substance is absorbed by waxy layers; superficial chemical vapour movement and re-deposition on plant surfaces; the active substance also penetrates into plant tissue, ensuring protection to both leaf surfaces. There is little or no transport within the vascular system of plants.
step 1
Spraydropletformation
Tank
step 3Spray deposit properties
The fungicide transfer to the target consist of sev eral steps arranged in series:step 2Retention
Leaf
PCF F F
F : step affected by formulation PC : step affected by physico-chemical properties of the fungicide
Important factors affecting fungicide activity
step 4Penetration
step 5Redistribution/translocation- long distance translocation
(in xylem or in both , xylemand phloem)
step 6Binding at target site
PC
PC
PCF Quelle: Pontzen, Baur
Physico-chemical properties affect fungicides activ ity at several steps; physico-chemical properties of a compound and formulation can have a strong impact on fungicide activity
Page 13 • Danish Advisor Course – September 2012
WettingSpreading
Apple = > 90 % Oilseed rape = 20-40 % Barley = < 5 %
Typical water retention
Page 14 • Danish Advisor Course – September 2012
The surface characteristics influence the retention /wettability of the spray solution on the leaf surface
Barley is extremelycovered with epicuticular
waxes
Smooth surface consistingof a layer of amorphous
waxes
Important factors affecting fungicide activity
step 2Retention
LeafF
WettingSpreading
Page 15 • Danish Advisor Course – September 2012
Important factors affecting fungicide activity
step 2Retention
LeafF
WettingSpreading
• When a spray droplet lands on a leaf or other plant surfaces it may be retained on the plant surface or bounce off the surface and ultimately land on some other plant parts or the soil.
• Droplets with a high dynamic surface tension like aqueous fungicide spray dropsfrequently bounce off or run off leaf and stem surfaces.
• In contrast, droplets with a low dynamic surface tension are more likely to beretained on plant surfaces.
Source: W.B. McCloskey
Page 16 • Danish Advisor Course – September 2012
Important factors affecting fungicide activity
step 2Retention
LeafF
WettingSpreading
• The addition of surfactants or wetting agents reduces the dynamic surface tensionof water droplets.
• Reducing dynamic surface tension allows spray droplets to spread out upon impact and increase the area of contact with the plant surface.
• Reduced dynamic surface tension and increased area of contact reduces thepropensity for spray droplets to bounce or roll off plant surfaces.
Source: W.B. McCloskey
100
80
60
40
20
0
Ret
entio
n (%
)
Optimized formulation
Smooth leaf surface Rough leaf surfacedue to crystalline waxes
Water or SC-formulation
OptimizedSpray Retention
Important factors affecting fungicide activity
step 2Retention
Leaf
F
WettingSpreading
Page 18 • Danish Advisor Course – September 2012
Important factors affecting fungicide activity
step 2Retention
LeafF
Horizontally positioned barley leaves were sprayed with an Air
Injection nozzle at 200 l/ha
Prosaro
Standard
An optimization of the product formulation can clea rly improve the retention and spreading of spray droplets on plant surfaces
WettingSpreading
Page 19 • Danish Advisor Course – September 2012
Important factors affecting fungicide activity
step 3Spray deposit properties
PCF
Spray deposit properties most important for fungici de performance. Deposit properties are decisive for the next step – release of the active f or penetration into the leaf
• Leaf surface characteristics
• Formulation type (spreading, solvents, humectants, etc.)
• Physical state of the active in the deposit (amorphous or cristallin)
• Physico-chemical properties of the active substance (solubility, melting point)
Page 20 • Danish Advisor Course – September 2012
step 3Spray deposit properties
PCF
Important factors affecting fungicide activity
• Surfactants or wetting agents can improve the absorption by reducing the rate ofspray droplet drying and crystallization of active ingredient
Greater fungicide absorption occurs from amorphous spray deposits compared to crystalline deposits.
Source: W.B. McCloskey
Melting point (°C) is the temperature at which the given active substance changes its physical state from solid to liquid.
Physico-chemical parameters of commercial fungicides
Page 21 • Danish Advisor Course – September 2012
uptake
50 100 150 200
mp [°C]
Importance of formulation
The higher the melting point the lower is the bioavailability out of deposit (very roughly correlation!). The higher the melting point the higher is the importance of formulation - for cuticle uptake..
Propiconazole = -23 °C
Source: PPNB – Pesticide Properties Data Base
• Lipophilicity
• Solubility
• Molecular Volume
� Well understood
� Well describable
� Prediction possible
Physico-chemical propertiesPhysico-chemical properties
• Temperature
• Humidity
• Wind
• Plant species
� Some understood and describable
� Prediction difficult due to influence of formulation
Environment & PlantEnvironment & Plant
• Retention
• Solubility
• Permeability
• Spreading
� In principle understood
� Describable
� Not predictable
FormulationFormulation
The penetration of a fungicide through the cuticule is a very complex interplay of different factors – clear predictions are difficult
Penetration of a compound through the cuticule
Important factors affecting fungicide activity
step 4Penetration
F PC
Page 22 • Danish Advisor Course – September 2012
leaf: cross-section
Spray deposit
cuticle
cell wall
epidermal cell
Cuticular waxes
1-2
µm
Source: Braune, W. et. al. (1983), Pflanzenanatomisches Praktikum
Barrier for leaf uptake of fungicides: the cuticule
lipophil / solid
hydrophil / liquid
Jeffree, C.E. (1996), Structure and ontogeny of pla nt cuticles
The cuticle is the intial contact point between an a grochemical and the plant and, where uptake into plant tissues is required for biological activ ity, it is the main absorption barrier to penetrati on
Important factors affecting fungicide activity
step 4Penetration
PCF
Page 24 • Danish Advisor Course – September 2012
Surface wax
Cutin + wax
Polysaccharides+ cutin
Pectin(negatively charged)
Lipophilic/solid
Hydrophilic / liquid
100 -300 nm
• Structural features of the cuticule
CW: cell wallP: pectin lamellaCL: cuticular layerCP: cuticle proper
Important factors affecting fungicide activity
step 4Penetration
PCF
Leaf uptake and subsequent redistribution strongly dependent on the partition behaviour of the fungicide between lipophilic compartments and hydro philic compartments
Cell wall ishydrophilic and is
hydrated
Lipophilicity of a compound is usually expressed as logP OW , which is the log of the partition coefficient (KOW) of a compound between octanol and water .
KOW = CO / CW (= distribution between the two phases)
W
O CO = 1000 mg / l
CW = 1 mg / lKOW = 1000 / 1
= 1000log POW = +3
Example with a lipophilic compound:
.
………….………….………….………….………….………….………….………….………….………….………….………….………….………….………….………….
………….………….………….………….………….………….………….………….………….………….………….………….………….………….
.
…………. …………. …………. …………. …………. …………. …………. …………. …………. …………. …………. …………. …………. …………. …………. ………….
More lipophilic(“organic” loving)and hydrophobic(“water” hating)
More hydrophilic(“water” loving)and lipophobic
(“organic” hating)log Pow = - 3
A contrastingexample
Physico-chemical parameters of commercial fungicides
Page 25 • Danish Advisor Course – September 2012
Lipophilicity of a compound is usually expressed as logP OW , which is the log of the partition coefficient (KOW) of a compound between octanol and water .
Physico-chemical parameters of commercial fungicides
0
20
40
60
80
Num
ber
ofco
mpo
unds
logP (pH 7)
< 0 0-1 1-2 2-3 3-4 4-5 > 5
Large range of variation in lipophilicity; clear pr eferred range: logP 2.5-4.5
Page 26 • Danish Advisor Course – September 2012
Page 27 • Danish Advisor Course – September 2012
Cuticule penetration of fungicides with molar volume > ca. 400 very limited. However, adjuvants can compensate limited mobility up to 100 -fold
Important factors affecting fungicide activity
step 4Penetration
F PC
Molecular weight The relative molecular mass (molecular weight) of a chemical is the mass of a molecule
of the chemical relative to the mass of a carbon atom taken as exactly 12.
The mean molecular weight of fungicides shows a ste ady increase over time. This leads A) to increasing limitations by reduced bioavailablity and B) the need for adjuvanted formulations
Page 28 • Danish Advisor Course – September 2012
Physico-chemical parameters of commercial fungicides
Page 29 • Danish Advisor Course – September 2012
0
20
40
60
80
0 6 12 18 24 30
EW 250 SC 430 & adjuvant, 1g/L SC 430
Pen
etra
tion
(%)
Time (h)
Cuticle penetration of tebuconazole
Droplet application to isolated aple leaf cuticles
Important factors affecting fungicide activity
step 4Penetration
F PC
Page 30 • Danish Advisor Course – September 2012
Important factors affecting fungicide activity
step 4Penetration
F PC
���� Improved availability of active out of the deposit by- better solubility of a.i. in deposit- avoidance of a.i. precipitation- precipitation of a.i. in the amorphous state- long lasting resolubilisation by high humidity/dew (humectants)- better coverage/spreading
� Improved/reduced cuticle uptake
���� Improved penetration of active by changing the barrier of the cuticle(swelling agents)
Formulation type and adjuvants (in-can or tankmixed ) can be of major importance for the penetration of agrochemicals and can in parts compe nsate unfavourable phys-chem properties of the active
Penetration: Effects of Adjuvants and Solvents
Page 31 • Danish Advisor Course – September 2012
Long distance translocation of fungicides is always passive and solely dependent on physico-chemical properties
step 5Redistribution/translocation- long distance translocation
(in xylem or in both , xylemand phloem)
PC
Important factors affecting fungicide activity
Log P < 2.5 3.2 ± 0.5 > 4.0
step 5Redistribution/translocation-- long distance translocation
(in xylem or in both , xylemand phloem)
PC
Important factors affecting fungicide activity
Page 32 • Danish Advisor Course – September 2012
Fast movementto leaf margins
Retention plus movement Strong
retention
Larger logP = stronger retention in leaf = less move ment
Xylem movementafter penetration
Page 33 • Danish Advisor Course – September 2012
Long distance translocation of fungicides is always passive and solely dependent on physico-chemical properties
step 5Redistribution/translocation- long distance translocation
(in xylem or in both , xylemand phloem)
PC
Important factors affecting fungicide activity
Mobility in plant tissue
2.5 3.0 3.5 4.0
Lipophilicity [logP]
0
20
40
60
80
A: Lipophilie
Anz
ahl d
er
Ver
bind
unge
n
logP (pH 7)
< 0 0-1 1-2 2-3 3-4 4-5 > 5
Page 34 • Danish Advisor Course – September 2012
Physico-chemical parameters of commercial fungicides
Source: PPNB – Pesticide Properties Data Base
Page 35 • Bayer-Fachsymposium 2011 – Dr. Andreas Goertz
• protective dropletapplication of fungicide tothe leaf base
Unbehandelt SDHI + SBI
step 5Redistribution/translocation- long distance translocation
(in xylem or in both , xylemand phloem)
PC
Important factors affecting fungicide activity
SDHI + SBI
The systemic translocation enables the control of f ungal growth not directly covered by fungicide application
Water solubility (mg/L) the mass of an active substance that can dissolve in a given volume of water. Value reported is at 20°C.
Physico-chemical parameters of commercial fungicides
0
20
40
60
80
< -1 -1-0 0-1 1-2 2-3 3-4 > 4
log 10 (solubility mg/L)
All protective fungicides: < 10 ppmMost prot. Fungicides: < 2 ppm
Large range of variation in water solubility; clear preferred range: 1-100 pm; low water solubility common property of protective fungicides
Page 36 • Danish Advisor Course – September 2012
fast transport to leaf margin good distribution
Compound remains in application area
application
good water solubility
> 3000 mg/l
medium water solubility
1 – 3000 mg/l
minor water solubility < 1 mg/l
e.g. Metalaxyle.g.
Prothioconazolee.g.
Trifloxystrobin
Physico-chemical parameters of commercial fungicides
Its just a momentum. The “stages” are fluent depend ing on solubility and water availability, etc.
Page 37 • Danish Advisor Course – September 2012
Page 38 • Danish Advisor Course – September 2012
Physico-chemical parameters of commercial fungicides
Bioavailability
Water solubility[g/L]
1000 100 10 1
Importance of formulation
The higher the solubility the higher the potential for bioavailability from the aequous phase. Water solubility is of lower importance within the plant and xylem mobility is stronger influenced by lipophilicityparameters.
Source: PPNB – Pesticide Properties Data Base
step 1
Spraydropletformation
Tank
step 3Spray deposit properties
The fungicide transfer to the target consist of sev eral steps arranged in series:step 2Retention
Leaf
PCF F F
F : step affected by formulation PC : step affected by physico-chemical properties of the fungicide
Important factors affecting fungicide activity
step 4Penetration
step 5Redistribution/translocation- long distance translocation(in xylem or in both , xylemand phloem)
step 6Binding at target site
PC
PC
PCF Quelle: Pontzen, Baur
Physico-chemical properties affect fungicides activ ity at several steps; physico-chemical properties of a compound and formulation can have a strong impact on fungicide activity
Page 39 • Danish Advisor Course – September 2012
WettingSpreading
Page 40 • Danish Advisor Course – September 2012
• Uptake and systemicity of fungicides is a complex interplay of various factors (incl. physico-chemical properties, formulation, environmental conditions, etc.)
• The optimum physical-chemical property requirements for compounds differ widelydepending on their applications.
• Formulation can (partly) compensate unfavourable physico-chemical properties
• An optimization of the product formulation can clearly improve the retention and spreading of spray droplets on plant surfaces
• Formulation type and adjuvants can be of major importance for spray deposit formationand cuticular penentration of fungicides
• The penetration of a fungicide through the cuticule is a very complex interplay of different factors – clear predictions are difficult
• Leaf uptake and subsequent redistribution strongly dependent on partition behaviour ofthe fungicides between lipophilic and hydrophilic compartments
• Systemic translocation of fungicides in the xylem solely dependent on the physico-chemical properties and is always passive
Summary of the theoretical background
Uptake & Systemicity of fungicides
• Background
• Triazoles
• Strobilurins
• Benzophenones
• SDHIs
• Q&A session
Agenda
Page 41 • Danish Advisor Course – September 2012
Page 42 • Danish Advisor Course – September 2012
Uptake & Systemicity of Fungicides
DISCLAIMER
The following theorectical conclusion in regard to the mode of transport of listedfungicides solely base on the physico-chemical properties of each active ingredientpublished on http://sitem.herts.ac.uk/aeru/footprint/index2.htm. Influences of formulation type and adjuvants potentially added to the spray solution, and environmental factors are NOT considered.
Therefore one has to be very cautious in generalizing conclusions. Any use of this information for further external purpose should only be done with additional involvement of experts.
Page 43 • Danish Advisor Course – September 2012
Uptake & Systemicity of Triazoles
• translaminar activity• acropetal translocation• no episystemicity
Theoretical conclusion
• reasonable water solubility= favourable for long distance translocation
• medium logP = favourable for acropetal translocation
• low vapour pressure = no vapour phase activity
Epoxiconazole
Physico-chemicalproperties of Triazoles
Molecularweight
Water solubility at 20 °C (mg/L)
MeltingPoint (°C)
LogPVapour
pressure at25 °C (mPa)
Epoxiconazole 329,8 7,1 136,7 3,3 0,01
Metconazole 319,8 30,4 104,2 3,85 0,000021
Prothioconazole 344,3 300 141,8 3,82 0,0004
Tebuconazole 307,8 36 105 3,7 0,0013
Source: PPNB – Pesticide Properties Data Base
Page 44 • Danish Advisor Course – September 2012
Uptake & Systemicity of Triazoles
• translaminar activity• acropetal translocation• no episystemicity
Theoretical conclusion
• reasonable water solubility= favourable for long distance translocation
• Medium/high logP = favourable for acropetal translocation
• low vapour pressure = no vapour phase activity
Metconazole
Physico-chemicalproperties of Triazoles
Molecularweight
Water solubility at 20 °C (mg/L)
MeltingPoint (°C)
LogPVapour
pressure at25 °C (mPa)
Epoxiconazole 329,8 7,1 136,7 3,3 0,01
Metconazole 319,8 30,4 104,2 3,85 0,000021
Prothioconazole 344,3 300 141,8 3,82 0,0004
Tebuconazole 307,8 36 105 3,7 0,0013
Source: PPNB – Pesticide Properties Data Base
Page 45 • Danish Advisor Course – September 2012
Uptake & Systemicity of Triazoles
Physico-chemicalproperties of Triazoles
Molecularweight
Water solubility at 20 °C (mg/L)
MeltingPoint (°C)
LogPVapour
pressure at25 °C (mPa)
Epoxiconazole 329,8 7,1 136,7 3,3 0,01
Metconazole 319,8 30,4 104,2 3,85 0,000021
Prothioconazole 344,3 300 141,8 3,82 0,0004
Tebuconazole 307,8 36 105 3,7 0,0013
Source: PPNB – Pesticide Properties Data Base
Theoretical conclusion
• good water solubility = favourable for long distance translocation
• medium/high logP = favourable for acropetal translocation
• low vapour pressure = no vapour phase activity
Prothioconazole
• translaminar activity• acropetal translocation• no episystemicity
Page 46 • Danish Advisor Course – September 2012
Uptake & Systemicity of Triazoles
Physico-chemicalproperties of Triazoles
Molecularweight
Water solubility at 20 °C (mg/L)
MeltingPoint (°C)
LogPVapour
pressure at25 °C (mPa)
Epoxiconazole 329,8 7,1 136,7 3,3 0,01
Metconazole 319,8 30,4 104,2 3,85 0,000021
Prothioconazole 344,3 300 141,8 3,82 0,0004
Tebuconazole 307,8 36 105 3,7 0,0013
Source: PPNB – Pesticide Properties Data Base
Theoretical conclusion
• reasonable water solubility = favourable for long distance translocation
• medium/high logP = favourable for acropetal translocation
• low vapour pressure = no vapour phase activity
Tebuconazole
• translaminar activity• acropetal translocation• no episystemicity
Uptake & Systemicity of fungicides
• Background
• Triazoles
• Strobilurins
• Benzophenones
• SDHIs
• Q&A session
Agenda
Page 47 • Danish Advisor Course – September 2012
Uptake & Systemicity of Strobilurins
Page 48 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Azoxystrobin 403,4 6,7 116 2,5 0,00000011
Picoxystrobin 367,3 3,1 75 3,6 0,0055
Pyraclostrobin 387,8 1,9 64,5 3,99 0,000026
Trifloxystrobin 408,4 0,61 72,9 4,5 0,0034
Physico-chemicalproperties ofStrobilurins
• Medium water solubility = favourable for long distance translocation
• relative low logP = favourable for acropetal translocation
• low vapour pressure = no vapour phase activity
Azoxystrobin
Uptake & Systemicity of Strobilurins
Page 49 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
Azoxystrobin
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Azoxystrobin 403,4 6,7 116 2,5 0,00000011
Picoxystrobin 367,3 3,1 75 3,6 0,0055
Pyraclostrobin 387,8 1,9 64,5 3,99 0,000026
Trifloxystrobin 408,4 0,61 72,9 4,5 0,0034
Physico-chemicalproperties ofStrobilurins
• Systemic xylem mobility• Translaminar activity
Theoretical conclusion
• Medium water solubility = favourable for long distance translocation
• relative low logP = favourable for acropetal translocation
• low vapour pressure = no vapour phase activity
Uptake & Systemicity of Strobilurins
Page 50 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Azoxystrobin 403,4 6,7 116 2,5 0,00000011
Picoxystrobin 367,3 3,1 75 3,6 0,0055
Pyraclostrobin 387,8 1,9 64,5 3,99 0,000026
Trifloxystrobin 408,4 0,61 72,9 4,5 0,0034
Physico-chemicalproperties ofStrobilurins
• Medium water solubility = favourable for long distance translocation
• Medium logP = favourable for acropetal translocation
• Low melting point = rapid foliar uptake
• high vapour pressure = vapour phase activity
Picoxystrobin
Uptake & Systemicity of Strobilurins
Page 51 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
Picoxystrobin
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Azoxystrobin 403,4 6,7 116 2,5 0,00000011
Picoxystrobin 367,3 3,1 75 3,6 0,0055
Pyraclostrobin 387,8 1,9 64,5 3,99 0,000026
Trifloxystrobin 408,4 0,61 72,9 4,5 0,0034
Physico-chemicalproperties ofStrobilurins
• Systemic xylem mobility• Translaminar activity• Episystemic distribution
Theoretical conclusion
• Medium water solubility = favourable for long distance translocation
• Medium logP = favourable for acropetal translocation
• Low melting point = rapid foliar uptake
• high vapour pressure = vapour phase activity
Uptake & Systemicity of Strobilurins
Page 52 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Azoxystrobin 403,4 6,7 116 2,5 0,00000011
Picoxystrobin 367,3 3,1 75 3,6 0,0055
Pyraclostrobin 387,8 1,9 64,5 3,99 0,000026
Trifloxystrobin 408,4 0,61 72,9 4,5 0,0034
Physico-chemicalproperties ofStrobilurins
• Relatively low water solubility = unfavourable for long distance translocation
• high logP = unfavourable for acropetal translocation
• Low melting point = rapid foliar uptake
• low vapour pressure = no vapour phase activity
Pyraclostrobin
Uptake & Systemicity of Strobilurins
Page 53 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Azoxystrobin 403,4 6,7 116 2,5 0,00000011
Picoxystrobin 367,3 3,1 75 3,6 0,0055
Pyraclostrobin 387,8 1,9 64,5 3,99 0,000026
Trifloxystrobin 408,4 0,61 72,9 4,5 0,0034
Physico-chemicalproperties ofStrobilurins
• Local-systemic• translaminar activity• limited acropetal translocation
Theoretical conclusion
• Relatively low water solubility = unfavourable for long distance translocation
• high logP = unfavourable for acropetal translocation
• Low melting point = rapid foliar uptake
• low vapour pressure = no vapour phase activity
Pyraclostrobin
Uptake & Systemicity of Strobilurins
The various strobilurin fungicides have very differe nt physio-chemical properties which consequently confer a wide range of biokinetic behav iours
Source: Bartlett et al. 2002
Page 54 • Danish Advisor Course – September 2012
Page 55 • Danish Advisor Course – September 2012
Trifloxystrobin(Mesostemic)
vapour phase activity and deposit
effect
Active on the surface of the plant
Absorbed through the cuticle
Penetration into plant tissue
Translaminar movement
Transport in the vascular system
low
high
Point of application
Uptake & Systemicity of Strobilurins
Distribution of 14C-labelled Trifloxystrobin in soybeans 7 days
after droplet application
The various strobilurin fungicides have very differe nt physio-chemical properties which consequently confer a wide range of biokinetic behav iours
Page 56 • Danish Advisor Course – September 2012
Uptake & Systemicity of Strobilurins
The various strobilurin fungicides have very differe nt physiocchemical properties which consequently confer a wide range of biokinetic behav iours
Source: Bartlett et al. 2002
Uptake & Systemicity of fungicides
• Background
• Triazoles
• Strobilurins
• Benzophenones
• SDHIs
• Q&A session
Agenda
Page 57 • Danish Advisor Course – September 2012
Uptake & Systemicity of Benzophenones
Page 58 • Danish Advisor Course – September 2012
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Metrafenone 409,3 0,492 100 4,3 0,153
Physico-chemical properties of Benzophenones
Source: PPNB – Pesticide Properties Data Base
• High molecular weight = low mobility in cuticule
Metrafenone
Uptake & Systemicity of Benzophenones
Page 59 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
• High molecular weight = low mobility in cuticule
• Low water solubility = unfavourable for translocation
Metrafenone
0
20
40
60
80
< -1 -1-0 0-1 1-2 2-3 3-4 > 4log 10 (solubility mg/L)
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Metrafenone 409,3 0,492 100 4,3 0,153
Physico-chemical properties of Benzophenones
Uptake & Systemicity of Benzophenones
Page 60 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
• High molecular weight = low mobility in cuticule
• Low water solubility = unfavourable for translocation
• High logP = limited xylem systemicity, but translaminar movement
Metrafenone
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Metrafenone 409,3 0,492 100 4,3 0,153
Physico-chemical properties of Benzophenones
Uptake & Systemicity of Benzophenones
Page 61 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
• High molecular weight = low mobility in cuticule
• Low water solubility = unfavourable for translocation
• High logP = limited xylem systemicity, but translaminar movement
• High vapour pressure = vapour phase distribution
Metrafenone
• absorbed in waxy cuticle• penetrates into the leaf• translaminar activity• local redistribution in the
canopy (episystemicity)• limited xylem translocation• local systemicity
Theoretical conclusion
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Metrafenone 409,3 0,492 100 4,3 0,153
Physico-chemical properties of Benzophenones
Uptake & Systemicity of fungicides
• Background
• Triazoles
• Strobilurins
• Benzophenones
• SDHIs
• Q&A session
Agenda
Page 62 • Danish Advisor Course – September 2012
Uptake & Systemicity of SDHIs
Page 63 • Danish Advisor Course – September 2012
• Medium water solubility = favourable for long distance translocation
• Low logP = favourable for acropetal translocation
• Low vapour pressure = no vapour phase activity
BoscalidSource: PPNB – Pesticide Properties Data Base
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Boscalid 343,2 4,6 143,3 2,96 0,00072
Fluopyram 396,8 15 117,5 3,3 0,0012
Physico-chemical properties of SDHIs
Uptake & Systemicity of SDHIs
Page 64 • Danish Advisor Course – September 2012
• Medium water solubility = favourable for long distance translocation
• Low logP = favourable for acropetal translocation
• Low vapour pressure = no vapour phase activity
Boscalid
• penetrates into the leaf• translaminar activity• translocation in the xylem
Theoretical conclusion
Source: PPNB – Pesticide Properties Data Base
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Boscalid 343,2 4,6 143,3 2,96 0,00072
Fluopyram 396,8 15 117,5 3,3 0,0012
Physico-chemical properties of SDHIs
Uptake & Systemicity of SDHIs
Page 65 • Danish Advisor Course – September 2012
Source: PPNB – Pesticide Properties Data Base
• Medium water solubility = favourable for long distance translocation
• Low logP = favourable for acropetal translocation
• Low vapour pressure = no vapour phase activity
Fluopyram
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Boscalid 343,2 4,6 143,3 2,96 0,00072
Fluopyram 396,8 15 117,5 3,3 0,0012
Physico-chemical properties of SDHIs
Uptake & Systemicity of SDHIs
Page 66 • Danish Advisor Course – September 2012
• Medium water solubility = favourable for long distance translocation
• Low logP = favourable for acropetal translocation
• Low vapour pressure = no vapour phase activity
Fluopyram
• penetrates into the leaf• translaminar activity• translocation in the xylem
Theoretical conclusion
Source: PPNB – Pesticide Properties Data Base
Molecularweight
Water solubility at 20 °C (mg/L)
Melting Point (°C)
LogPVapour
pressure at25 °C (mPa)
Boscalid 343,2 4,6 143,3 2,96 0,00072
Fluopyram 396,8 15 117,5 3,3 0,0012
Physico-chemical properties of SDHIs
Uptake & Systemicity of fungicides
• Background
• Benzophenones
• SDHIs
• Strobilurins
• Triazoles
• Q&A session
Agenda
Page 67 • Danish Advisor Course – September 2012
Page 68 • Danish Advisor Course – September 2012
Uptake & Systemicity of Fungicides
Answers to the questions raised in advance to the today‘s course
?
Page 69 • Danish Advisor Course – September 2012
Uptake & Systemicity of FungicidesQuestion: Is there a transport to new leaves emerged after treatment or only to the leaf tipson already developed leaves or is there a transport through the leaf sheaths?
Answer: Theoretically, fungicides with episystemic properties can redistribute around existingleaves and to newly emerging leaves in the vapour phase
Influencing factors:
• phys-chem properties,• environmental conditions• (humdity, temperature, wind), • formulation, • Crop & canopy structure
TFS
TFS
TFS
TFS
UTC
UTCUTC
UTC
low
high
The establishment of a vapour phase activity in far mers field is not predictable, clearly
Page 70 • Danish Advisor Course – September 2012
Uptake & Systemicity of Fungicides
Answer: Theoretically, xylem-systemic fungicides are capable of moving to newly expaningand newly emerging growth as the wheat or barley crop develops
• This movement occurs via translaminar mobility to consecutive leaf layers and subsequent xylem systemicity within them and/or by direct physical ‚pick-up‘ from the leaf axils by thenewly emerging foliar tissue as it passes through the axil ‚reservoir‘.
• Influencing factors: phys-chem. properties, environmental conditions (rainfall, dew), formulation, crop
The transport of xylem-systemic fungicides to new l eaf levels is theoretically possible, depends however on certain influencing factors
Question: Is there a transport to new leaves emerged after treatment or only to the leaf tipson already developed leaves or is there a transport through the leaf sheaths?
Page 71 • Danish Advisor Course – September 2012
low
highDistribution of 14C-labeled
Prothioconazole in soybeans
Dry plants Moistened plants
Uptake & Systemicity of FungicidesQuestion: Is there a transport to new leaves emerged after treatment or only to the leaf tipson already developed leaves or is there a transport through the leaf sheaths?
Moisture stimulates a redistribution of Prothiocona zole over the leaf as well as along the petiole and the stem. Consequently, the active can enter th e stem and is translocated to the apex.
Page 72 • Danish Advisor Course – September 2012
Uptake & Systemicity of Fungicides
Answer : NO, because of the complex interplay of various influencing factors
Influencing factors:
• Amount of a.i. bioavailable• disease pressure• occurring disease spectrum• epidemiology of fungal pathogens• environmental conditions (temparture, rainfall, dew, humidity)• variety (different canopy structure)• canopy size (area to be protected)• metabolic stability of compounds in plants• Distribution of compound in plant tissue
Biological tests under practical conditions are nee ded to have at least a basis for such a “guess”
Question: Can we use these information information to „guess“ how long time the effect of a spraying is lasting when we spray at different growth stages in cereals, grass seed andoilseed rape with different fungicides?
Page 73 • Danish Advisor Course – September 2012
Uptake & Systemicity of Fungicides
Answer :
Question: Why do we sometimes get scorch (phytotox) on leaves in cereals by use of triazoles
0
20
40
60
80
100
0 5 10 15 20 25
time (h)
pene
trat
ion
(%)
Influencing factors:
• environmental conditions• (heat, sunshine)• formulation (solvents, adjuvants)• application time• mixed application with other products
(liquid fertilizer, adjuvants, etc.) • variety
Penetration of the fungicide Tebuconazolethrough an isolated apple cuticle
10 °C
20 °C
30 °C
Thank you!Dr. Andreas Goertz