diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

Test conducted with formulated substance

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Version / remarks:

DRAFT

GLP compliance:

yes

Analytical monitoring:

yes

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Species:

Lolium perenne

Plant group:

Monocotyledonae (monocots)

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Species:

Pisum sativum

Plant group:

Dicotyledonae (dicots)

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Species:

Helianthus annuus

Plant group:

Dicotyledonae (dicots)

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Test type:

seedling emergence toxicity test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

14 d

Details on test conditions:

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
Soil type: Standard soil (silty loam) from Bayer CropScience GmbH,
Global Biology Herbicides, Horticulture, H 872, Industriepark
Hoechst, 65926 Frankfurt am Main. The soil was sieved to 2
mm. The soil was analysed separately without GLP in the
laboratory of Development Ecotoxicology, Bayer
CropScience AG, 40789 Monheim
Sterilisation: 120 degrees vapour for about 30 minutes.
Fertilization: 2.4 g Blaukorn per liter

further information see materials and methods

Nominal and measured concentrations:

The herbicide formulation, the safener formulation and the blank formulation were applied at 1200 mL/ha product equivalents.

Reference substance (positive control):

not specified

Species:

Zea mays

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Remarks:

, survival, biomass, phytotoxicity and growth.

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Remarks:

, survival, biomass, phytotoxicity and growth.

Species:

Lolium perenne

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Remarks:

, survival, biomass, phytotoxicity and growth.

Species:

other: Cucumber, oilseed rape, pea, soybean, sugar beet and tomato

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Remarks:

, survival, biomass, phytotoxicity and growth

Corn

No significant adverse effect of 1200 mL/ha mefenpyr-diethyl on the emergence, survival, biomass,

phytotoxicity or growth. There was a 16% reduction in biomass with the product formulation,

however this was not significant and was not associated with any other adverse effect apart from

26% phytotoxicity.

Oats

No significant adverse effect of 1200 ml_/ha mefenpyr-diethyl on the emergence, survival, biomass,

phytotoxicity or growth. There was a 6% reduction in biomass with the product formulation, however

this was not significant and was not associated with any other adverse effect.

Ryegrass

No significant adverse effect of 1200 mUha mefenpyr-diethyl on the emergence, survival, biomass,

phytotoxicity or growth. There was a 14% reduction in biomass with mefenpyr-diethyl, however this

was not significant and was a not a result of the test item as the blank formulation resulted in a 17%

reduction in biomass. The product formulation also resulted in a 19% reduction in biomass. These

effects on biomass were not associated with any other adverse effect.

Cucumber, oilseed rape, pea, soybean, sugar beet and tomato

No significant adverse effect of 1200 ml_/ha mefenpyr-diethyl on the emergence, survival, biomass,

phytotoxicity or growth on any dicotyledonous species. There were 13% and 12% reductions in

oilseed rape and tomato biomass with mefenpyr-diethyl, however these were not significant.

Dicotylenous species are not highly sensitive to fenoxaprop-P-ethyl and there were only minor nonsignificant

adverse effects with oilseed rape and tomato.

Findings

Analysis of the application solutions of the blank formulation, safener formulation and the product formulation

revealed values of 0%, 102.9% and 102.5% of nominal respectively.

No adverse effects on the emergence, survival or growth of any species were observed after treatment with the

formulated safener and the safener containing post emergence herbicide.

Conclusion

No biologically significant (> 30%) herbicidal potential of the safener mefenpyr-diethyl (AE F107892) was

noted in any of the nine plant species tested when applied at the 1200 mL / ha equivalent of the herbicide

fenoxaprop-P-ethyl (AE F046360). In particular, no effects were observed in the monocotyledonous species

being most sensitive to post emergence exposure with the herbicide fenoxaprop-P-ethyl.

Reference 2

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

Test conducted with formulated substance

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Version / remarks:

DRAFT

Deviations:

yes

Remarks:

Due to the proven graminicidal specifity of the herbicide a ratio of 1 (monocot) :1(dicot) species was used to improve the sensitivity of test system

GLP compliance:

yes

Species:

Hordeum vulgare

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Barley
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Corn
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Oats
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Lolium perenne

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Ryegrass
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cucumber
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: oilseed rape
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: soybean
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Helianthus annuus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Sunflower
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Source of seed: Seeds were supplied from commercial sources via Bayer CropScience GmbH,
Horticulture, H872, 65926 Frankfurt am Main.
- Historical germination of seed: Routine germination tests were carried out on
the seeds to ensure their viability
- Seed storage: in plastic boxes in the refrigerator.

Test type:

vegetative vigour test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

21 d

Test temperature:

Range: 16 - 25° C

pH:

7.4

Details on test conditions:

TEST SYSTEM
- Testing facility:
- Test container: Commercial plastic flower pots (10 -13 cm diameter)
- Amount of soil:
- Method of seeding: Seeds were introduced manually in the soil. They were covered by about the amount of soil with there one sice and top watered immediately to facilitate germination. To reach the 2-4 leaf stage at the start of testing, sowing was started 41 -12 days prior to testing. Tomato and sunflower seeds were pre-sown in trays and transplanted into the pots at least 7 days before application. For the other species seeds were introduced directly into the pots.
- No. of seeds per container: for tomato, cucumber and sunflower 10 pots with 4 plants were used, whereas the other species had 5 plants each per pot.
- No. of plants: In total 40 plants per treatment group were tested.
- No. of replicates per treatment group: 8-10 pots per treatment group, depending on the species.




SOURCE AND PROPERTIES OF SUBSTRATE
- Geographic location: Standard soil (silty loam) from Bayer CropScience GmbH, Global Biology Herbicides, Horticulture, H 872, Industriepark Hoechst, 65926 Frankfurt am Main.
- Pretreatment of soil: The soil was sieved to 2 mm. The soil was analysed separately without GLP in the laboratory of Ecotoxicology, Bayer CropScience AG, 40789 Monheim.
- Composition and particle size:
0.063 - 2.0 mm sand = 14.2%
0-0.002 mm clay =20.7%
0.002-0.063 mm silt =65.1%
- Organic carbon content: 1.19%
- pH: 7.4


GROWTH CONDITIONS
- Photoperiod: Regulated at 16 h light: 8 h dark.
- Light source: Natural daylight supplemented by artificial lighting to provide the required photoperiod
- Light intensity and quality: >15000 lux lamps turn off, >20000 lux
shading closes. Range: 7616 -17773 lux
- Day/night temperatures: Regulated at 23 ± 5°C day and 18 ± 5° C night; deviations up to 32°C occurred for short times but without effects on the plant growth. Range: 16 - 25° C
- Air - moisture: 50 - 100 %
- Watering regime and schedules: Following the initial top watering to facilitate germination of the seed, bottom watering was performed with saucers standing below each pot. Water was given and retained within the saucer according to the need of the plants in order to have an optimal water supply for plant growth.

EFFECT PARAMETERS MEASURED:
Mortality: Number of plants that died after application was recorded at days 7,14 and 21.
Growth Stages: Growth stages at the final assessment were reported according to BBCH-Monograph - Growth stages.
Plant biomass: The dry weight was determined at the final assessment. The plants of one pot represent one replicate.

- Phytotoxicity rating system: Phytotoxicity was recorded at each assessment time following a letter rating system.
0: no injury or effect
A: slight symptom(s) throughout the whole plant or more moderate symptom(s) on a small area, i.e. one leaf
B: moderate symptom(s) throughout the whole plant or severe symptom(s) on a limited area, i.e. one-two leaves
C: severe symptom(s) throughout the whole plant with younger or newly developed leaves growing normally
D: total plant symptom(s) with the plant showing poor vigour.
E: moribund or dead plant

Phytotoxitity Records: Visual phytotoxicity ratings from the living plants (e.g. chlorosis, necrosis, stunting, abnormal growth) at days 7, 14 and 21 according to EPPO Standard 135.

- Application Scheme:
- Control: 200 L/ha of deionized water for all species.
- Test items: 1200 mL product / ha in 200 L/ha of deionized water for each species.
(stock solution; blank formulation, stock solution; safener formulation, stock solution; product formulation)

Nominal and measured concentrations:

200 L/ha of deionized water for all species.
1200 mL product / ha in 200 L/ha of deionized water for each species.

Reference substance (positive control):

not specified

Species:

Hordeum vulgare

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL product/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

phytotoxicity

Remarks:

, survival, biomass and growth

Species:

Zea mays

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL product/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

phytotoxicity

Remarks:

, survival, biomass and growth

Species:

Avena sativa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL product/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

phytotoxicity

Remarks:

, survival, biomass and growth

Species:

Allium cepa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL product/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

phytotoxicity

Remarks:

, survival and growth

Remarks on result:

other: Mefenpyr-diethyl caused a small but significant reduction of 16% in biomass

Species:

Lolium perenne

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

phytotoxicity

Remarks:

, survival, biomass and growth

Species:

other: Cucumber, oilseed rape, soybean, sunflower and tomato

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 200 other: mL/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

phytotoxicity

Remarks:

, survival, biomass and growth

Barley

No significant adverse effect of 1200 mL/ha mefenpyr-diethyl on the survival, biomass,

phytotoxicity or growth. The lack of any adverse effect of the graminicidal fenoxaprop-P-ethyl

was due to the safening property of mefenpyr-diethyl in the product.

Corn

No significant adverse effect of 1200 mL/ha mefenpyr-diethyl on the survival, biomass,

phytotoxicity or growth. The product formulation at 1200 mL/ha resulted in complete

mortality.

Oats

No significant adverse effect of 1200 mL/ha mefenpyr-diethyl on the survival, biomass,

phytotoxicity or growth. The product formulation at 1200 mL/ha resulted in complete

mortality.

Onion

Mefenpyr-diethyl caused a small but significant reduction of 16% in biomass although no

effect was apparent on survival, phytotoxicity or growth. There was an 11% non significant

adverse effect on biomass with 1200 mL/ha product formulation, however there was no

impact on growth or any phytotoxicity.

Ryegrass

No significant adverse effect of 1200 mL/ha mefenpyr-diethyl on the survival, biomass,

phytotoxicity or growth. There was a 44% and 10% reductions in biomass and survival with

1200 mL/ha product formulation and also a chlorosis.

Cucumber, oilseed rape, soybean, sunflower and tomato

There were no significant effects of 1200 mL/ha mefenpyr-diethyl on any dicotyledonous

species. The only adverse effect with any of these species, regarded as insensitive to the

product formulation was a 17% reduction in biomass.

Findings

Analysis of the application solutions of the blank formulation, safener formulation and the product formulation

revealed values of 0%, 102.9% and 102.5% of nominal safener conc. respectively. There was no effect of either

the blank formulation or the safener formulation on the survival of any species. With the herbicide, 100%

mortality of corn and oats occurred and there were minor effects (10%) on the mortality of only ryegrass and

oilseed rape.

Conclusion

No biologically significant (> 30%) herbicidal potential of formulated AE F107892 was noted in any of the ten

plant species tested when applied at the 1200 mL/ha equivalent of the herbicide AE F046360 24 EW14 A719. In

particular, no effects were observed in the monocotyledonous species being most sensitive to exposure with the

herbicide AE F046360 24 EW14 A719. The safening activity by mefenpyr-diethyl of fenoxaprop-P-ethyl is seen

by the absence of any phytotoxicity with barley, which would be sensitive to the herbicide alone.

A minor reduction of the shoot dry weight (16 %) of onion, which attained statistical significance, was not

considered to be biologically relevant or indicative of a relevant herbicidal activity of AE F107892.

Additional information

The substance is not expected to pose a risk to terrestrial plants. There is no indication for high adsorption or high persistence of the substance in soil. The determined log Pow of the substance is 4 and the adsorption potential is low (Koc range 486 – 823). Available tests on the biodegradation of the substance in soil determined half-lives of 7-13 days. Thus a long-term exposure of terrestrial organisms to substance is not likely. The substance is not acutely very toxic to aquatic organisms. All available effect concentrations (EC/LC50) are > 1 mg/L . Furthermore the available acute toxicity test conducted with earthworms determined no toxic effects of the substance. The study was conducted according to OECD guideline 207 (1991) using artificial soil as substrate. Earthworms of the species Eisenia fetida were exposed to a limit concentration of 1000 mg/kg. The artificial soil, prepared from a mixture of dried sphagnum peat, kaolin clay and industrial sand, was mixed with the test substance. No mortalities or symptoms of intoxication were observed. The determined 14-day LC50 was > 1000 mg/kg soil dw was no death occurred at this limit dose. In the absence of any sublethal findings (intoxication symptoms, weight gain and intoxication symptoms) the NOEC (14 d) was 1000 mg/kg soil dw. The available studies ontoxicity of the substance to soil microorganisms determined no adverse effects. The studies were conducted according to OECD 217 ( Soil Microorganisms: Carbon Transformation Test, 2006a) and OECD 216 (Soil Microorganisms: Nitrogen Transformation Test, 2006b). The study was performed in a field soil at concentrations equivalent up to a field application rate of 525 g test item/ha. A NOEC (28 d) of 0.7 mg/kg soil dw (nominal) was determined for respiration rate and nitrate formation rate respectively.

According to Annex IX, column 2 of Regulation (EC) No 1907/2006, toxicity testing with terrestrial plants does not need to be conducted as the Chemical Safety Assessment does not indicate a need for further investigations. According to Annex XI, Section 3 of Regulation (EC) No 1907/2006 toxicity tests on soil macroorganisms are considered not necessary. The exposure concentrations for the terrestrial compartment during the lifecycle of the substance are low. The environmental exposure assessment for the substance indicates no risk for the terrestrial compartment (all RCR< 1; please refer to Chapter 9 and 10 of the Chemical Safety Report for detailed information).