Chlorothalonil

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Reference 1

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

Study period:

14 May 1992 to 28 May 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 122-1 (Terrestrial Plant Toxicity Tier I (seedling emergence))

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Remarks:

acetone

Details on preparation and application of test substrate:

PETRI DISH BIOASSAY
Calculations used as a basis for preparation of the test dosing solution were adjusted for 97.9% purity of the technical grade active ingredient test material. On May 19, 1992, to prepare the test dosing solution, the calculated amount of the test material, 1.95 grams, was dissolved in 400 milliliters of acetone, only. This concentration, when dispensed over the 2 area of the Petri dish, yields an actual application rate of 0.18 mg/cm , which is equivalent to a field rate of 15.0 pounds of active ingredient per acre.

SOIL BIOASSAY
Calculations used as a basis for preparation of the test dosing solution were adjusted for 97.9% purity of the technical grade active ingredient test material. On May 14, 1992, to prepare the test dosing solution, the calculated amount of the test material, 10.45 grams, was dissolved in 637.5 mL acetone to achieve the maximum formulated product label use rate of 16 pounds of active ingredient per acre (16 lb a.i./A). This concentration is 10.45 grams whole product/637.5 mL or 2.09 grams whole product/ 127.5 mL per rep; when dispensed over the area sprayed (12.3 ft2), this concentration yields an application rate of 0.18 mg whole product/cm2. The volume applied per rep was 127.5 ml, which is equivalent to a field rate of 119.2 gallons per acre.

WATER SOURCE
Water used to prepare the untreated control test solutions was chlorinated, of potable quality, and supplied by the municipal water company. In addition, it was filtered through a four-stage deionizing Milli-Q Reagent Water System

Species:

other: Fagopyrum esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Buckwheat
- Family: Polygonaceae

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Corn
- Family: Gramineae

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cucumber
- Family: Cucurbitaceae

Species:

other: Brassica kaber

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Mustard
- Family: Cruciferae

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Oat
- Family: Gramineae

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Family: Amaryllidaceae

Species:

Raphanus sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Radish
- Family: Cruciferae

Species:

Sorghum bicolor

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Sorghum
- Family: Gramineae

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Family: Leguminosae

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Family: Solanaceae

Test type:

seedling emergence toxicity test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

74.9°F to 83.9°F (corresponding to 23.8 to 28.8 °C)

pH:

Not specified

Moisture:

Not specified

Details on test conditions:

GERMINATION IN PETRI DISH BIOASSAY PROCEDURE
Two filter papers (Whatman No. 1, 8.26 cm diameter) were placed inside the bottom section of each glass Petri dish. The bottom section was then placed into the top section. A volume of 2.0 mL of the treatment solution was pipetted and evenly distributed onto the filter papers in each of the Petri dishes. A volume of 2.0 mL of blank acetone was applied to the solvent control Petri dish filter papers. No treatment was applied to the untreated control Petri dishes at this time. After drying, Milli-Q water was pipetted and evenly distributed onto all of the filter papers in volumes predetermined to be optimal for each species. Ten seeds of each of the designated species were then placed on the treated filter papers in each Petri dish, one test species per dish, four Petri dishes per species per dose. After the seeds were carefully placed in the Petri dishes, the dishes were covered and sealed with strips of Parafilm. Each Petri dish cover was labeled with the study number, the date, the species name, the dose, the rep number, and the randomization number. The Petri dishes, including the controls, were randomly assigned to the treatments. The experimental design used for this test was a randomized complete block design. Each treatment in the definitive study included four replicates per test species per dosage. There were four replicates of the solvent control as well as four replicates of the untreated (Milli-Q water, only) control. The Petri dishes were arranged in the plastic racks according to randomization number, to insure uniform handling. The racks holding the Petri dishes were placed in a reach-in incubator. The racks were then inclined at an approximate 20 angle. The test was held in darkness at 24° ± 3 C for 7 days. On May 26, 1992, at the conclusion of the Petri dish phase of the study, the dishes were removed from the incubator and percent germination was recorded. Germination was defined as any seed exhibiting a radicle length in excess of five millimetres.

SEEDLING EMERGENCE IN SOIL BIOASSAY PROCEDURE
The growth medium was steam-pasteurized natural soil amended with 50% silica sand and supplemental nutrients to insure plant growth. Planting containers were disposable fiber pans measuring 25.4 cm x 20.3 cm x 7.6 cm. The depth of soil in the pan approximately 7.0 cm. Soil was placed in the planting container, the upper surface of the soil 1.5 cm below the top edge of the flat. Ten seeds per species per replicate were planted, evenly Each species was planted at an empirically-determined optimal depth for germination and emergence. After planting, the seedbed was lightly tamped. A small volume of screened soil was then placed over the seed bed and carefully leveled off. Four replicates were run per dosage. There were four replicates of the untreated control. Each replicate was labeled with the study number, date, dose, rep number, and randomization number. Before treatment, the containers were randomly assigned to the control or treatment group. The experimental design was a randomized complete block design. On May 14, 1992, the test treatment was soil-surface applied with a moving sprayer equipped with a TeeJet nozzle number 8002E, the spray pattern uniformly covering the surface of the soil. This method insured a uniform distribution of the test material.

PLANT MAINTENANCE
After application of the test solution to the plants, the test containers were arranged according to randomization number in greenhouse 2, one of four ridge-and-furrow glass greenhouses attached to the testing facility building. Bach 2000 square foot greenhouse is separated by a glass curtain wall; all environmental controls and monitoring equipment are programmed individually. After treatment, the test flats were placed in the greenhouse on capillary mats and bottom-watered. Additional water was applied to the surface of the soil to facilitate contact of the test material with the seed; the volume applied was insufficient to cause test material leaching. A 2 gallons per minute nozzle was used for this purpose. Initially, this nozzle was used to water the test flats. After emergence of most of the species, a standard water-breaker nozzle was used for overhead-watering.
- Temperature: Recorded temperature data indicate a mean low temperature of 74.9°F and a mean high temperature of 83.9°F, with a mean temperature of 79.4°F for the two-week period during which the test was held in the greenhouse.
- Humidity: Recorded relative humidity data indicate a mean low humidity of 45.7% and a mean high humidity of 58.9%, with a mean relative humidity of 52.3% for the two-week period during which the test was held in the greenhouse.
- Lighting: Photoperiod setting was 14 hour light/10 hour dark cycle, with supplemental light operated by electronic controls and an electric eye. General Electric lamps (Number MV1000/C) were used for greenhouse illumination. Manufacturer's technical data for these lamps specifies an initial spectral energy distribution wavelength range of approximately 350 to 700 nanometers. Depending upon weather conditions and cloud cover, available incident light for the test period ranged from 1000 to 8000 foot candles.

EFFECT PARAMETERS MEASURED
Non-quantified visual observations were performed twice per week. Any unusual growth, as compared with the untreated controls, was noted. No phytotoxicity symptoms were observed throughout the course of the test. Plants were consistently observed to be healthy and vigorous. Emergence percents were recorded and fresh weights of the above-ground portions of the plants were taken and recorded on May 28, 1992, 14 days after treatment with the test material, at the time of the experiment termination.

Nominal and measured concentrations:

- Nominal concentration petri dish bioassay: 0 (Blank control), 0 (Solvent control) and and 4900 ppm
- Nominal concentration soil seedling emergence bioassay: 0 (Blank control), 0 (Solvent control) and 16392 ppm

Reference substance (positive control):

no

Key result

Species:

other: All plant species

Duration:

14 d

Dose descriptor:

other: NOER

Effect conc.:

18 kg/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Remarks on result:

other: As represent in original report

Remarks:

The effect value is equivalent to 24 mg/kg soil dw

Details on results:

The results are tabulated in 'Any other information on results incl. tables'.

PETRI DISH BIOASSAY RESULTS
- Seed germination: Results of the Petri dish bioassay indicated that the test chemical had no effect on seed germination. When compared with the untreated, solvent, and pooled controls nine species exhibited percent effects equal to or greater than 100.0%; only cucumber germination appeared slightly reduced (91.67%).

SEEDLING EMERGENCE IN SOIL BIOASSAY RESULTS
- Seedling emergence: In the seedling emergence in soil bioassay, the test chemical appeared to elicit no effect on seedling emergence. When compared with the untreated, solvent, and pooled controls, all species exhibited percent effects equal to or greater than 97.37%.
- Fresh weight: Treated fresh weights were compared with untreated fresh weights in the seedling emergence bioassay. Results ranged from 74.29% (onion) to 127.85% (cucumber). Buckwheat, mustard, oats, and onion exhibited percent effects below 90%. When these species were compared with the solvent controls, however, all effects except oats (84.81%) were greater than 90.0%, indicating a solvent effect. It is appropriate to compare treated mean fresh weight with solvent control mean fresh weight, due to the effect of the acetone solvent control. When compared with the solvent control, all treated fresh weight effects were greater than or equal to 84.81%.

Fresh weights were compared with untreated fresh weights in the seedling emergence bioassay. Results ranged from 74.29% (onion) to 127.85% (cucumber). Buckwheat, mustard, oats, and onion exhibited percent effects
below 90%. When these species were compared with the solvent controls, however, all effects except oats (84.81%) were greater than 90.0%, indicating a solvent effect. It is appropriate to compare treated mean fresh weight with solvent control mean fresh weight, due to the effect of the acetone solvent control. When compared with the solvent control, all treated fresh weight effects were greater than or equal to 84.81%.

Reported statistics and error estimates:

Mean percent germination, mean percent emergence, and mean fresh weight were determined. All treatment means were compared with the untreated control means to determine inhibition of 25% or greater. Additionally, treatment means were also compared with the solvent control means, only, as well as the pooled means of the untreated and solvent controls.

Table 1: Percent germination effect of the test substance compared to untreated, solvent, and pooled controls

Crop	Treatment vs untreated control	Treatment vs solvent control	Treatment vs pooled controls
Buckwheat	110.00	100.00	104.76
Corn	100.00	100.00	100.00
Cucumber	91.67	91.67	91.67
Mustard	102.56	105.26	103.90
Oats	100.00	105.26	102.56
Onion	121.21	102.56	111.11
Radish	105.26	108.11	106.67
Sorghum	100.00	108.33	104.00
Soybean	105.56	115.15	110.14
Tomato	100.00	109.09	104.35

 

Table 2: Percent emergence effect of the test substance compared to untreated, solvent, and pooled controls

Crop	Treatment vs untreated control	Treatment vs solvent control	Treatment vs pooled controls
Buckwheat	105.56	100.00	102.70
Corn	100.00	102.56	101.27
Cucumber	113.33	103.03	107.94
Mustard	100.00	97.50	98.73
Oats	100.00	102.63	101.30
Onion	100.00	126.92	111.86
Radish	102.56	100.00	101.27
Sorghum	108.82	105.71	107.25
Soybean	102.78	97.37	100.00
Tomato	103.23	110.34	106.67

 

Table 3: Percent fresh weight effect of the test substance compared to untreated, solvent, and pooled controls

Crop	Treatment vs untreated control	Treatment vs solvent control	Treatment vs pooled controls
Buckwheat	89.52	98.20	93.66
Corn	95.54	92.97	94.23
Cucumber	127.85	102.44	113.74
Mustard	84.52	90.98	87.63
Oats	77.92	84.81	81.22
Onion	74.29	113.04	89.66
Radish	92.54	97.50	94.95
Sorghum	120.75	116.67	118.68
Soybean	108.88	100.86	104.72
Tomato	109.80	91.80	100.00

Validity criteria fulfilled:

not specified

Conclusions:

The 14-d NOER was determined to be ≥18 kg/ha (equivalent to 24 mg/kg soil dw) in non-target plants.

Executive summary:

Under the data requirements of Subdivision J: Section 122-1, United States Environmental Protection Agency and in compliance with GLP, a study was performed to determine the effects of the test substance on ten non-target species of crop plants (buckwheat, com, cucumber, mustard, oats, onion, radish, sorghum, soybean, tomato). This test was designed to ascertain detrimental effects on seed germination and seedling emergence when administered as a single dose to seeds in Petri dishes and seeds planted in field soil. The concentration applied in the Petri dish bioassay was 4900 ppm whole product. When dispensed over the area of the Petri dish (53.59 cm2), this concentration yields an actual application rate of 0.18 mg whole product/cm , which is equivalent to a field rate of 16.0 pounds of active ingredient per acre, the highest labelled use rate of this material. The concentration applied in the seedling emergence in soil bioassay wag 16,392 ppm whole product. When dispensed over the area sprayed (12.3 ft ), this concentration yields an actual application rate of 0.18 mg whole product/cm2 which is equivalent to a field rate of 16.0 pounds of active ingredient per acre, the highest labelled use rate of this material. There were four reps of the treatment and four reps each of the untreated and solvent controls.

 

At the conclusion of the Petri dish phase of the study, seven days after the application of the test material to the seeds, percent germination was recorded. At the conclusion of the seedling emergence in soil phase of the study, fourteen days after the application of the test material, percent emergence was recorded and all above-ground parts of the plants were then harvested and fresh weights were taken. Observations made immediately prior to the harvest of the seedling emergence in soil test fourteen days after treatment indicated that all species were healthy and vigorous. Mean percent germination, mean percent emergence, and mean fresh weight were determined. All treatment means were compared with the untreated control means to determine inhibition of 25% or greater. Additionally, treatment means were also compared with the solvent control means, only, as well as the pooled means of the untreated and solvent controls.

 

Results of the Petri dish bioassay indicated that the test chemical had no effect on seed germination. When compared with the untreated, solvent, and pooled controls nine species exhibited percent effects equal to or greater than 100.0%; only cucumber germination appeared slightly reduced (91.67%). Similarly, in the seedling emergence in soil bioassay, the test chemical appeared to elicit no effect on seedling emergence. When compared with the untreated, solvent, and pooled controls, all species exhibited percent effects equal to or greater than 97.37%. Treated fresh weights were compared with untreated fresh weights in the seedling emergence bioassay. Results ranged from 74.29% (onion) to 127.85% (cucumber). Buckwheat, mustard, oats, and onion exhibited percent effects below 90%. When these species were compared with the solvent controls, however, all effects except oats (84.81%) were greater than 90.0%, indicating a solvent effect. It is appropriate to compare treated mean fresh weight with solvent control mean fresh weight, due to the effect of the acetone solvent control. When compared with the solvent control, all treated fresh weight effects were greater than or equal to 84.81%. Based on these findings, the NOER was determined to be 0.18mg/cm2, corresponding to 18 kg/ha (= 24 mg/kg soil dw).

Reference 2

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

Study period:

14 May 1992 to 28 May 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 122-1 (Terrestrial Plant Toxicity Tier I (vegetative vigor))

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Remarks:

acetone

Details on preparation and application of test substrate:

Calculations used as a basis for preparation of the test dosing solution were adjusted for 97.9% purity of the technical grade active ingredient test material. On May 14, 1992, to prepare the test dosing solution, the calculated amount of the test material, 10.45 grams, was dissolved in 637.5 mL acetone to achieve the maximum formulated product label use rate of 16 pounds of active ingredient per acre (16 lb a.i./A). This concentration is 10.45 grams whole product/637.5 mL or 2.09 grams whole product/127.5 mL per rep; when dispensed over the area sprayed (12.3 ft2), this concentration yields an application rate of 0.18 mg whole product/cm2. The volume applied per rep was 127.5 mL, which is equivalent to a field rate of 119.2 gallons per acre.

WATER SOURCE
Water used to prepare the untreated control test solutions was chlorinated, of potable quality, and supplied by the municipal water company. In addition, it was filtered through a four-stage deionizing Milli-Q Reagent Water System

Species:

other: Fagopyrum esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Buckwheat
- Family: Polygonaceae

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Corn
- Family: Gramineae

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cucumber
- Family: Cucurbitaceae

Species:

other: Brassica kaber

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Mustard
- Family: Cruciferae

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Oat
- Family: Gramineae

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Family: Amaryllidaceae

Species:

Raphanus sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Radish
- Family: Cruciferae

Species:

Sorghum bicolor

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Sorghum
- Family: Gramineae

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Family: Leguminosae

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Family: Solanaceae

Test type:

vegetative vigour test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

74.9°F to 83.9°F (corresponding to 23.8 to 28.8 °C)

pH:

Not specified

Moisture:

Not specified

Details on test conditions:

VEGETATIVE VIGOR TEST PROCEDURE
The premium-quality soilless commercial growing medium Terra-Lite Redi-Earth peat-lite mix, with a balance of primary and secondary nutrients, adequate moisture-holding capabilities, and sufficient pore space was used as the growth medium. All plants were planted in disposable plastic 9 cm square pots. Prior to the application of the test treatment solutions, all plants for each replicate were placed in an individual flat. Each treatment included four replicates. Each replicate contained five (5) pots of com, cucumber, soybean, and tomato. Each of these five pots contained one plant. Each replicate also included one pot each of a representative population of buckwheat, mustard, oats, onion, radish, and sorghum. There were four untreated (water only) control replicates and four solvent (acetone, only) control replicates. Corn, cucumber, soybean, and tomato - Several seeds per pot per species were planted. Depth of planting was approximately 1.0 cm to 1.5 cm, depending upon the size of the seed. After seedlings emerged, thinning to one plant per pot was performed. Buckwheat, mustard, oats, onion, radish, and sorghum - A measured volume of seed was sprinkled on the medium surface in the pot and covered with 0.5 to 1.0 an of additional medium. Test material application occurred on a uniform population, thinned at seedling emergence, if necessary, to avoid crowding. More plants than needed for this test were planted, so as to make certain that a uniform set of plants was available. Pot B of each species were selected for uniformity of plant populations. The plants tested were grown according to an empirically-derived schedule that insured all plants were growing vigorously at the time of the test material application. Plant species were within seven to fourteen days from planting when the test material was applied.

Each treatment in this study included four replicates. Each replicate consisted of five pots of corn, cucumber, soybean, and tomato. Each of these five pots contained one plant. Each replicate consisted of one pot each of a representative population of buckwheat, mustard, oats, onion, radish, and sorghum. Each replicate was labeled with the study number, date, dose, rep number, and randomization number. Before treatment, the containers were randomly assigned to the control or treatment group. The experimental design was a randomized complete block design. Prior to the application of the test material, the containers were overhead-watered. After the test material was applied, the flats were bottom-watered or soil-watered only. On May 14, 1992, the test treatment was foliarly-applied with a moving sprayer equipped with a TeeJet nozzle number 8002E, the spray pattern uniformly covering the plant foliage.

PLANT MAINTENANCE
After application of the test solution to the plants, the test containers were arranged according to randomization number in greenhouse 2, one of four ridge-and-furrow glass greenhouses attached to the Life Sciences building. Bach 2000 square foot greenhouse is separated by a glass curtain wall; all environmental controls and monitoring equipment are programmed individually. After treatment, the test flats were placed in the greenhouse on capillary mats and bottom-watered. Additional water was applied to the surface of the soil to facilitate contact of the test material with the seed; the volume applied was insufficient to cause test material leaching. A 2 gallons per minute nozzle was used for this purpose. Initially, this nozzle was used to water the test flats. After emergence of most of the species, a standard water-breaker nozzle was used for overhead-watering.
- Temperature: Recorded temperature data indicate a mean low temperature of 74.9°F and a mean high temperature of 83.9°F, with a mean temperature of 79.4°F for the
two-week period during which the test was held in the greenhouse.
- Humidity: Recorded relative humidity data indicate a mean low humidity of 45.7% and a mean high humidity of 58.9%, with a mean relative humidity of 52.3% for the two-week period during which the test was held in the greenhouse.
- Lighting: Photoperiod setting was 14 hour light/10 hour dark cycle, with supplemental light operated by electronic controls and an electric eye. General Electric lamps were used for greenhouse illumination. Manufacturer's technical data for these lamps specifies an initial spectral energy distribution wavelength range of approximately 350 to 700 nanometers. Depending upon weather conditions and cloud cover, available incident light for the test period ranged from 1000 to 8000 foot candles.

EFFECT PARAMETERS MEASURED
Non-quantified visual observations were performed twice per week. Any unusual growth, as compared with the untreated controls, was noted. The only phytotoxicity noted at any time occurred on May 18, 1992, four days after treatment. At that time, growing points in the solvent control and the treated cucumber plants appeared to be necrotic. This symptom was not observed at any of the subsequent dates of observation, May 21, 26, and 28, 1992 (7, 12, and 14 days after treatment, respectively). No other phytotoxicity symptoms were observed throughout the course of the test. Plants were consistently observed to be healthy and vigorous. Fresh weights of the above-ground portions of the plants were taken and
recorded on May 28, 1992, 14 days after treatment with the test material, at the time of the experiment termination.

Nominal and measured concentrations:

- Nominal concentration soil seedling emergence bioassay: 0 (Blank control), 0 (Solvent control) and 16392 ppm

Reference substance (positive control):

no

Key result

Species:

other: All plant species

Duration:

14 d

Dose descriptor:

other: NOER

Effect conc.:

18 kg/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

Results of this study yielded no 25% detrimental effect level for any species. The results are tabulated in 'Any other information on results incl. tables'.

- Fresh weights: Mean fresh weight for each species was compared with the mean fresh weight for the untreated, the solvent and the pooled controls, when compared with the untreated control, only cucumber appeared to exhibit an effect (74.3%); this was believed to be solvent-related. Treated cucumber was 106.24% that of the solvent control and 87.44% that of the pooled controls. Other species exhibited treatment effects ranging from 87.29% to 123.02% those of the untreated control effects.

Reported statistics and error estimates:

Mean fresh weight was determined. All treatment means were compared with the untreated control means to determine inhibition of 25% or greater. Additionally, treatment means were also compared with the solvent control means, only, as well as the pooled means of the untreated and solvent controls.

Table 1: Percent effect of the test substance compared to the untreated, solvent and pooled controls

Crop	Treatment vs untreated control	Treatment vs solvent control	Treatment vs pooled controls
Buckwheat	117.48	112.82	120.09
Corn	99.02	97.48	98.25
Cucumber	74.30	106.24	87.44
Mustard	100.48	99.05	99.76
Oats	95.15	114.27	103.83
Onion	98.51	135.94	114.23
Radish	87.29	101.85	94.01
Sorghum	100.67	96.07	98.32
Soybean	89.02	93.11	91.02
Tomato	123.02	124.62	123.81

Validity criteria fulfilled:

not specified

Conclusions:

The 14-d NOER was determined to be ≥18 kg/ha in non-target plants.

Executive summary:

Under the data requirements of Subdivision J: Section 122-1, United States Environmental Protection Agency, a GLP-compliant study was performed to determine the effects of the test substance on ten non-target species of crop plants (buckwheat, com, cucumber, mustard, oats, onion, radish, sorghum, soybean, tomato). This test was designed to ascertain detrimental effects on the vegetative vigor of plants when administered as a single dose to plant foliage. The concentration applied, 16,392 ppm whole product, when dispensed over the area sprayed (12.3 ft), yields an actual application rate of 0.18 mg whole product/cm (18 kg/ha) which is equivalent to a field rate of 16.0 pounds of active ingredient per acre, the highest labelled use rate of this material. There were four reps of the treatment and four reps each of the untreated and solvent controls. The plants used for this study were from 1 to 2 weeks from planting at the time of the test material application. After the plants were sprayed with the test material, they were held in the greenhouse.

At the conclusion of the study, fourteen days after the application of the test material, all above-ground parts of the plants were harvested, and fresh weights were taken. Final observations made immediately prior to the harvest of the test at fourteen days after treatment indicated that all plants of every species were healthy and growing vigorously. The only phytotoxicity noted at any time occurred on May 18, 1992, four days after treatment. At that time, growing points in the solvent control and the treated cucumber plants, only, appeared to be necrotic. This symptom was not observed at any of the subsequent dates of observation, May 21, 26, and 28, 1992 (7, 12, and 14 days after treatment, respectively). No other phytotoxicity symptoms were observed throughout the course of the test. Plants were consistently observed to be healthy and vigorous. No phytotoxicity symptoms of any kind were observed on the date of the test completion. Mean fresh weight for each species was compared with the mean fresh weight for the untreated, the solvent and the pooled controls. When compared with the untreated control, only cucumber appeared to exhibit an effect (74.3%); this was believed to be solvent-related. Treated cucumber was 106.24% that of the solvent control and 87.44% that of the pooled controls. Other species exhibited treatment effects ranging from 87.29% to 123.02% those of the untreated control effects. Based on these findings, the 14-d NOER was determined to be ≥18 kg/ha in non-target plants.

Description of key information

14-d NOER ≥ 24 mg/kg soil dw, Seedling emergence/seed germination

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

24 mg/kg soil dw

Additional information

Seedling emergence/seed germination test

Under the data requirements of Subdivision J: Section 122-1, United States Environmental Protection Agency, a study was performed to determine the effects of the test substance on ten non-target species of crop plants (buckwheat, com, cucumber, mustard, oats, onion, radish, sorghum, soybean, tomato). This test was designed to ascertain detrimental effects on seed germination and seedling emergence when administered as a single dose to seeds in Petri dishes and seeds planted in field soil. The concentration applied in the Petri dish bioassay was 4900 ppm whole product. When dispensed over the area of the Petri dish (53.59 cm2), this concentration yields an actual application rate of 0.18 mg whole product/cm , which is equivalent to a field rate of 16.0 pounds of active ingredient per acre, the highest labelled use rate of this material. The concentration applied in the seedling emergence in soil bioassay wag 16,392 ppm whole product. When dispensed over the area sprayed (12.3 ft ), this concentration yields an actual application rate of 0.18 mg whole product/cm2 which is equivalent to a field rate of 16.0 pounds of active ingredient per acre, the highest labelled use rate of this material. There were four reps of the treatment and four reps each of the untreated and solvent controls.  

At the conclusion of the Petri dish phase of the study, seven days after the application of the test material to the seeds, percent germination was recorded. At the conclusion of the seedling emergence in soil phase of the study, fourteen days after the application of the test material, percent emergence was recorded and all above-ground parts of the plants were then harvested and fresh weights were taken. Observations made immediately prior to the harvest of the seedling emergence in soil test fourteen days after treatment indicated that all species were healthy and vigorous. Mean percent germination, mean percent emergence, and mean fresh weight were determined. All treatment means were compared with the untreated control means to determine inhibition of 25% or greater. Additionally, treatment means were also compared with the solvent control means, only, as well as the pooled means of the untreated and solvent controls. 

Results of the Petri dish bioassay indicated that the test chemical had no effect on seed germination. When compared with the untreated, solvent, and pooled controls nine species exhibited percent effects equal to or greater than 100.0%; only cucumber germination appeared slightly reduced (91.67%). Similarly, in the seedling emergence in soil bioassay, the test chemical appeared to elicit no effect on seedling emergence. When compared with the untreated, solvent, and pooled controls, all species exhibited percent effects equal to or greater than 97.37%. Treated fresh weights were compared with untreated fresh weights in the seedling emergence bioassay. Results ranged from 74.29% (onion) to 127.85% (cucumber). Buckwheat, mustard, oats, and onion exhibited percent effects below 90%. When these species were compared with the solvent controls, however, all effects except oats (84.81%) were greater than 90.0%, indicating a solvent effect. It is appropriate to compare treated mean fresh weight with solvent control mean fresh weight, due to the effect of the acetone solvent control. When compared with the solvent control, all treated fresh weight effects were greater than or equal to 84.81%. Based on these findings, the NOER was determined to be 0.18mg/cm2, corresponding to 18 kg/ha (= 24 mg/kg soil dw).

Vegetative vigour test

Under the data requirements of Subdivision J: Section 122-1, United States Environmental Protection Agency, a GLP-compliant study was performed to determine the effects of the test substance on ten non-target species of crop plants (buckwheat, com, cucumber, mustard, oats, onion, radish, sorghum, soybean, tomato). This test was designed to ascertain detrimental effects on the vegetative vigor of plants when administered as a single dose to plant foliage. The concentration applied, 16,392 ppm whole product, when dispensed over the area sprayed (12.3 ft), yields an actual application rate of 0.18 mg whole product/cm (18 kg/ha) which is equivalent to a field rate of 16.0 pounds of active ingredient per acre, the highest labelled use rate of this material. There were four reps of the treatment and four reps each of the untreated and solvent controls. The plants used for this study were from 1 to 2 weeks from planting at the time of the test material application. After the plants were sprayed with the test material, they were held in the greenhouse.

At the conclusion of the study, fourteen days after the application of the test material, all above-ground parts of the plants were harvested, and fresh weights were taken. Final observations made immediately prior to the harvest of the test at fourteen days after treatment indicated that all plants of every species were healthy and growing vigorously. The only phytotoxicity noted at any time occurred on May 18, 1992, four days after treatment. At that time, growing points in the solvent control and the treated cucumber plants, only, appeared to be necrotic. This symptom was not observed at any of the subsequent dates of observation, May 21, 26, and 28, 1992 (7, 12, and 14 days after treatment, respectively). No other phytotoxicity symptoms were observed throughout the course of the test. Plants were consistently observed to be healthy and vigorous. No phytotoxicity symptoms of any kind were observed on the date of the test completion. Mean fresh weight for each species was compared with the mean fresh weight for the untreated, the solvent and the pooled controls. When compared with the untreated control, only cucumber appeared to exhibit an effect (74.3%); this was believed to be solvent-related. Treated cucumber was 106.24% that of the solvent control and 87.44% that of the pooled controls. Other species exhibited treatment effects ranging from 87.29% to 123.02% those of the untreated control effects. Based on these findings, the 14-d NOER was determined to be ≥18 kg/ha in non-target plants.