Methyl (R)-2-(4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy)propionate

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: short-term (with study design considered suitable for long-term assessment)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants, Growth Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

EF-1400
Lot #: NA12150104
Active ingredient: 114 g Haloxyfop-R-methyl/L

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 156 g a.e./ha
- Sample storage conditions before analysis: Frozen

Vehicle:

yes

Remarks:

Tap water

Details on preparation and application of test substrate:

When application rates were > 26.0 g ae/ha aliquots of test substance were diluted in Letcombe tap water and made up to a final spray volume of 200 mL spray solution. When the application was < or equal to 26.0 g ae/ha a 10 mL stock solution was prepared, aliquots of the stock solution were then made up to a total volume of 200 mL using Letcombe mains tap water. Treatment solutions were freshly prepared on the day of application.

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Cultivated oat
- Plant family: Gramineae
- Variety: Dula
- Source of seed: Herbiseed, UK LTD

Species:

other: Cyperus esculentus

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Yellow nutsedge
- Plant family: Cyperaceae
- Source of seed: Herbiseed, UK LTD

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Plant family: Liliaceae
- Variety: Marco F1
- Source of seed: Nickerson - Zwaan Netherlands

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Plant family: Leguminosae
- Variety: Gemma
- Source of seed: Soybean Gar one crop

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Oilseed rape
- Plant family: Brassicaceae
- Variety: Apex
- Source of seed: Nickerson - Zwaan Netherlands

Species:

Beta vulgaris

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Sugar beet
- Plant family: Chenopodiaceae
- Variety: Saxon
- Source of seed: Hilleshog UK

Test type:

other: Toxicity to plants

Study type:

other: Glasshouse conditions

Substrate type:

natural soil

Limit test:

no

Remarks:

Single application

Post exposure observation period:

21 days

Test temperature:

13-32.65°C

pH:

7.15

Details on test conditions:

TEST SYSTEM
- Testing facility:
- Test container (type, material, size): 9 x 9 x 10 cm pot (except for Glycine max which is 11 x 11 x 12 cm pot)
- Amount of soil:
- Method of seeding:
- No. of seeds per container: 5 (A. sativa)
- No. of plants per container: 3 plants for C. esculentus, A. cepa, B. napus, B. vulgaris; 2 plants for G. max

PROPERTIES OF SUBSTRATE
- Soil texture: Sandy loam
- % sand: 74
- % silt: 14
- % clay: 12
- pH measured in CaCl2: 6.31
- Organic matter (%): 1.1
- CEC: 4.0 meq/100 g

GROWTH CONDITIONS
- Photoperiod: 14 hours lighting
- Light source: High pressure sodium vapour lamps
- Light intensity and quality: 140 µmole/m2/sec (PAR 400-700 nm)
- Day/night temperatures: 18/15°C
- Volume applied: 200 L/ha
- Method of application: Mardrive laboratory track sprayer (BDSPR02), TeeJet nozzle SS8003, reservoir pressure 2.1 BAR

Nominal and measured concentrations:

0, 0.81, 1.62, 3.25, 6.50, 13, 26, 39, 52, 104, 156 g a.e./ha

Species:

Avena sativa

Dose descriptor:

EC25

Effect conc.:

16 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: 20 day observation

Key result

Species:

Avena sativa

Dose descriptor:

EC50

Effect conc.:

19.8 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: 20 day observation

Species:

Allium cepa

Dose descriptor:

EC25

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Key result

Species:

Allium cepa

Dose descriptor:

EC50

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Species:

other: Cyperus esculentus

Dose descriptor:

EC25

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Key result

Species:

other: Cyperus esculentus

Dose descriptor:

EC50

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Species:

Brassica napus

Dose descriptor:

EC25

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Key result

Species:

Brassica napus

Dose descriptor:

EC50

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Species:

Glycine max (G. soja)

Dose descriptor:

EC25

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Key result

Species:

Glycine max (G. soja)

Dose descriptor:

EC50

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Species:

Beta vulgaris

Dose descriptor:

EC25

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Key result

Species:

Beta vulgaris

Dose descriptor:

EC50

Effect conc.:

> 156 g/ha

Nominal / measured:

acid equivalent

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

foliar fresh weight

Remarks on result:

other: highest dose tested

Conclusions:

EC50 (Allium cepa, Cyperus esculentus, Brassica napus, Glycine max, Beta vulgaris): > 156 g a.e./ha
EC50 (Avena sativa): 19.8 g a.e./ha

Executive summary:

This study was established to determine the EC25 and EC50 values (expressed in g a.e./ha) for test substance to a range of monocotyledons and dicotyledon species. The methodology is based on OCED guideline 208.

Applications were made post-emergence, in a total volume of 200 L/ha. Applications rates ranged from 0.81 to 156 g a.e./ha.

In total 3 monocotyledon and 3 dicotyledon species, from six different families were tested. The species evaluated represented members of the Gramineae, Liliaceae, Cyperaceae, Brassicaceae, Leguminosae and Chenopodiaceae. The growth stage at application ranged from BBCH 12-14 depending on the species. The plant species were raised, and the study was conducted under glasshouse conditions.

Visual injury was assessed on a 0-100 linear scale at approximately 7-day interval post application. At the final assessment timing (20 or 21 days depending on species) both visual injury and foliar fresh weight were recorded. EC25 and EC50 values were calculated for the foliar fresh weight using Minitab Statistical package 12.2.

The high tolerance of Allium cepa, Cyperus esculentus, Brassica napus, Glycine max and Beta vulgaris to the test substance resulted in minimal injury being observed on these species. Therefore, it was not possible to carry out regression analysis on the foliar fresh weight data and to predict the EC values. The EC25 and EC50 values were estimated to be >156 g a.e./ha.

Avena sativus was the only test species, which was sensitive to applications of the test substance at some of the higher rates tested. The EC25 and EC50 values calculated for foliar fresh weight data were 16.0 and 19.8 g a.e./ha respectively, the R Sq for the model used was 0.97.

Description of key information

EC50 19.8 g a.e./ha = 0.014 mg haloxyfop/kg soil dw exposed as a formulation (EF-1400). OECD 208; Reliability = 1

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

0.014 mg/kg soil dw

Additional information

The EC50 expressed as g a.e./ha was converted into mg a.s./kg soil dry weight using the below information nad assumptions:

EF-1400, 108 g a.s./L (10.49% w/w) (104 g a.e./L; acid equivalent factor: 0.963; density=1.03 g/mL)

Standard soil mass at 1 cm depth: 1.5 g/cm3 (1cm used since soil was sprayed on the surface rather than mixed into soil)