Potassium phosphonates

Potassium phosphonates	Last updated: 30/05/2026
(Not known by any other names)

Hazard alerts

The following Pesticide Hazard Tricolour (PHT) alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement. The alerts for Highly Hazardous Pesticides (HHPs) are based on applying the FAO/WHO (Type 1) and the PAN (Type II) criteria to PPDB data. Further details on the HHP indicators are given in the tables below. Neither the PHT nor the HHP hazard alerts take account of usage patterns or exposure, thus they do not represent risk.

PHT: Environmental fate	PHT: Ecotoxicity	PHT: Human health	Highly Hazardous Pesticide
Environmental fate High alert: Persistent; GUS: High leachability	Ecotoxicity Moderate alert: Birds chronic ecotoxicity: Moderate	Human health Low alert	Highly Hazardous Pesticide (HHP) Type II alert

GENERAL INFORMATION

Description

A mixture of two (mono- and di-) inorganic potassium salts that has fungicidal properties and is used to control Pythium and Phytophthora on a variety of fruit and ornamental crops

Example pests/issues controlled

Root rot, damping-off, and stem rot caused by Pythium and Phytophthora species

Example applications

Fruit including avocados, apples, grapes; Ornamentals; Trees; Salad leaves and lettuce; Garlic and shallots; Sprouts and shoots

Efficacy & activity

Appearance and life cycle

Taxonomic classification

GB regulatory status

GB COPR regulatory status

Approved

Date COPR inclusion expires

31/01/31

GB LERAP status

Crop over 5m - See Authorisation for Crop LERAP Details

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

France

Date EC 1107/2009 inclusion expires

31/01/2026

EU Candidate for substitution (CfS)

Listed in EU database

Yes

Approved for use (✓) under EC 1107/2009 in the following EU Member States

ATAustria	BEBelgium	BGBulgaria	CYCyprus	CZCzech Republic	DEGermany	DKDenmark	EEEstonia	ELGreece
✓	✓	✓	✓	✓	✓	✓	✓	✓
ESSpain	FIFinland	FRFrance	HRCroatia	HUHungary	IEIreland	ITItaly	LTLithuania	LULuxembourg
✓	✓	✓	✓	✓	✓		✓	✓
LVLatvia	MTMalta	NLNetherlands	PLPoland	PTPortugal	RORomania	SESweden	SISlovenia	SKSlovakia
✓		✓	✓	✓	✓	✓	✓	✓

Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries

ISIceland	NONorway

Additional information

Also used in

Australia

Chemical structure

Isomerism

None

Chemical formula

KH₂PO₃ & K₂HPO₃

Canonical SMILES

Isomeric SMILES

International Chemical Identifier key (InChIKey)

International Chemical Identifier (InChI)

2D structure diagram/image available?

Yes

General status

Biopesticide type

Fungicide

Substance groups

Inorganic compound; Micro-organism derived

Minimum active substance purity

Known relevant impurities

Substance origin

Semi-synthetic

Mode of action

Mixed mode of application including direct toxicity to plant pathogens reducing populations and promotion of plants natural defences

Substance source

Many phosphonates occur naturally in protozoa, mollusks, coelenterates, and oomycete fungi

Uses

Crop protection

Farming system suitability

CAS RN

13977-65-6

EC number

CIPAC number

US EPA chemical code

076416

PubChem CID

CLP index number

756

Molecular mass (Da)

PIN (Preferred Identification Name)

Reaction mixture of Potassium hydrogen phosphonate and dipotassium phosphonate

IUPAC name

Reaction mixture of Potassium hydrogen phosphonate and dipotassium phosphonate

CAS name

Reaction mixture of Potassium hydrogen phosphonate and dipotassium phosphonate

Global Governance status: Listed (✓) under

UK Poisons List Order 1972	Rotterdam Convention	Montreal Protocol
XNo The Poisons List Order 1972	XNo Rotterdam Convention	XNo Montreal Protocol
Stockholm Convention	OSPAR	EU Water Framework Directive
XNo Stockholm Convention	XNo OSPAR	XNo EU Water Framework Directive

Relevant Environmental Water Quality Standards

Forever chemical

Highly Hazardous Pesticide (HHP)

Type I

Type II

Yes []

Other status information

Herbicide Resistance Class (HRAC MoA class)

Not applicable

Herbicide Resistance Class (WSSA MoA class)

Not applicable

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Examples of recorded resistance

Physical state

Deliquescent solids supplied in aqueous solution

Related substances & organisms

disodium phosphonate

dipotassium phosphonate

potassium hydrogen phosphonate

Commercial

Property

Value

Availability status

Current

Introduction & key dates

1997, introduced USA

Example manufacturers & suppliers of products using this active now or historically

Luxembourg Industries (Pamol) Ltd
UIM Agrochemicals (Australia)
BASF

Example products using this active

Formulation and application details

Usually supplied as an aqueous solution with a variety of application methods used including foliar sprays, soil drenches and root dips

Commercial production

Potassium phosphonates are commercially manufactured by neutralising phosphorous acid with potassium hydroxide in a controlled aqueous reaction. This process yields a mixture of mono- and di-potassium salts, primarily potassium phosphite which are collectively referred to as potassium phosphonates. The reaction is typically carried out under mild conditions to prevent decomposition of the phosphorous acid and to ensure complete neutralisation. Once the desired salt composition is achieved, the solution is filtered and concentrated, often forming a liquid formulation used directly in agricultural applications.

Impact on climate of production and use

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C at pH 7 (mg l⁻¹)

500000

High

Solubility - In organic solvents at 20 °C (mg l⁻¹)

Melting point (°C)

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

180

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

Log P

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data

Density (g ml⁻¹)

1.65

Dissociation constant pKa) at 25 °C

2.0

PKa(2) = 6.59

Vapour pressure at 20 °C (mPa)

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (Aerobic conditions)

DT₅₀ (typical)

142

Persistent

DT₅₀ (lab at 20 °C)

142

Persistent

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

381

Very persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU 2012 dossier: Lab studies DT₅₀ range 88-196 days, DT₉₀ range 319-442 days

Soil mineralisation

Aerobic (at 20 °C)

Anaerobic (at 20 °C)

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Note

Water-sediment DT₅₀ (days)

Water phase only DT₅₀ (days)

Sediment phase only DT₅₀ (days)

Air degradation

As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.

Decay in stored produce DT₅₀

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

10.7

Moderately mobile

K_oc (mL g⁻¹)

453.6

Notes and range

EU 2012 dossier: K_d range 3.1-18.96 mL g⁻¹, K_oc range 228-972 mL g⁻¹, Soils=5

Freundlich

K_f (mL g⁻¹)

K_foc (mL g⁻¹)

¹/_n

Notes and range

pH sensitivity

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

phosphoric acid

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

Rat

Low

Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)

1270

Rat 90-day

Low

Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)

> 400

Rat 2-yr

Low

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2250

Colinus virginianus as phosphonic acid

Low

Birds - Short term dietary LC₅₀ (mg kg⁻¹ bw d⁻¹)

> 1335

Colinus virginianus as phosphonic acid

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

149.04

Colinus virginianus NOEC

Moderate

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹ dw soil)

> 1000

Eisenia foetida as phosphonic acid

Low

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹ dw soil)

182.5

Eisenia foetida as phosphonic acid

Low

Soil micro-organisms

Nitrogen mineralisation: Minor transient effects
Carbon mineralisation: Minor transient effects

Dose: up to 26.99 mg posphonic acid/kg soil 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Vegetative vigour ER₅₀ (g ha⁻¹)

Seedling emergence ER₅₀ (g ha⁻¹)

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 145

as potassium phosphonates

Low

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic

Notes

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Mason bees (Osmia spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Other bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹, Std lab test

> 20200

Aphidius rhopalosiphi as phosphonic acid

Low

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹, Std lab test

> 8080

Typhlodromus pyri as phosphonic acid

Low

Beneficial insects (Ground beetles)

Beneficial insects (Butterflies)

Contact

Notes

Oral

Notes

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 118

Oncorhynchus mykiss as phosphonic acid

Low

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

100

Oncorhynchus mykiss as phosphonic acid

Low

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

> 118

Daphnia magna as phosphonic acid

Low

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

100

Chironomus riparius as phosphonic acid

Low

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

Aquatic Plants (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹)

Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)

Algae - Acute (growth rate, fresh; mg l⁻¹) (72 hr EbC50 (biomass), Static)

146.7

Desmodesmus subspicatus as phosphonic acid

Low

Algae - Chronic (growth rate, fresh; mg l⁻¹)

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves

Regulatory Threshold Levels (RTLs)

Note: These RTLs have been calculated using the regulatory approach used in the European Union and based on ecotoxocity values in the PPDB.

Species group

RTL

Notes

Mammals

Worst case of acute and chronic mammals

Birds

29.808

Worst case of acute and chronic birds

Soil organisms

36.5

Worst case of acute and chronic earthworms

Terrestrial plants

No data

No data for non-target plants vegetative vigour and seedling emergence

Pollinators

2.9

Worst case of contact and oral honeybees

Arthropods

4040

Worst case of parasitic wasps and predatory mites

Fish

1.18

Worst case of temperate acute and chronic fish

Aquatic invertebrates

1.18

Worst case of temperate acute and chronic aquatic invertebrates

Aquatic plants

14.67

Worst case of free-floating plants, rooted plants, acute and chronic algae

HUMAN HEALTH AND PROTECTION

General

Property

Value

Source; quality score; and other information

Interpretation

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

Rat

Low

Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)

1270

Rat 90-day

Low

Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)

> 400

Rat 2-yr

Low

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

> 4000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.05

Rat

Other Mammal toxicity endpoints

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

2.25

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

None allocated

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

5.0

Dermal penetration studies (%)

100

default

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risks identified for proposed uses

Occupational

Negligible risks identified for proposed uses

Mammalian dose elimination route and rate

Health issues

Specific human health issues (hazard-based)

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

No further information available

Handling issues

Property

Value and interpretation

General

Not oxisiding or explosive
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H302, H315, H320, H335

WHO Classification

Not listed

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

potassium phosphonates

French

German

Danish

Italian

Spanish

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	30/05/2026
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242

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