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Ecotoxicological information

Toxicity to terrestrial plants

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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:
07 May 1990 to 06 Jul 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPP 123-1 (Seedling Emergence Tier II)
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
yes
Remarks:
Acetone
Details on preparation and application of test substrate:
On May 8, 1990, the test substance was applied, in a geometric progression of three, to all plant species at the rates of 0.0, 0.0185, 0.056, 0.167, 0.5, and 1.5 lb ai/A. The ten crops were planted on May 7, 1990. Because of poor or erratic seed emergence of carrot, cabbage, and onion, these crops were replanted and treated on June 12, 1990. Treatment application rates were calculated on the percent active ingredient of the technical material which was 92.0% ai. Each plot was sprayed at the equivalent of 50 gpa of water. The test spray concentration of 3.5952 gm ai/L (3595.2 ppm) was prepared by adding 586.2 mg of test substance in 142.5 mL of deionized water plus 7.5 mL of acetone. At the highest concentration, an oily residue was found on the flask and required vigorous agitation to prevent residue from forming on the glass.
Species:
Glycine max (G. soja)
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Soybean
Species:
Lactuca sativa
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Lettuce
Species:
Daucus carota
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Carrot
Species:
Lycopersicon esculentum
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Tomato
Species:
Cucumis sativus
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Cucumber
Species:
Brassica oleracea var. capitata
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Cabbage
Species:
Avena sativa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Oat
Species:
Lolium perenne
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Perennial ryegrass
Species:
Zea mays
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Corn
Species:
Allium cepa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Onion
Test type:
seedling emergence toxicity test
Study type:
laboratory study
Substrate type:
artificial soil
Limit test:
no
Total exposure duration:
21 d
Test temperature:
24 - 26 °C
pH:
Not reported
Moisture:
Not reported
Details on test conditions:
TEST SYSTEM
- Test containers: The seedling emergence study was conducted with seeds planted in plastic Corn-Pack (M1725, Black, 7.5 x 7.5 x 6.0 cm). Each pot was completely filled with soil.
- Method of seeding: Seeds selected for each crop were uniform in size and were assigned impartially to the test and control groups. A plexiglass template was used to create planting holes in the soil, thus allowing for uniform planting depth and distribution of the ten seeds planted per pot. Soybean, cucumber, oat, and corn were planted at a depth of 2.5 cm while the remaining six species were planted at a depth of 1.3 cm. Each treatment/crop combination was replicated three times.
- No. of seeds per container: 10
- No. of replicates per treatment group: 3
- No. of replicates per vehicle control: 3
- Water used in the test system: The water used as the compound solvent and for subsequent irrigation was from a well located at the test facility. The pH of the irrigation water was 7.4.
- Soil used in the test system: The seedling emergence study was conducted with steam-sterilized Hanford sandy loam soil.
- Soil preparation: Hanford sandy loam soil, obtained from the test facility, was sterilized for 48 hours in a soil sterilizer. Perlite was added to the sterilized soil to facilitate drainage. Soil used in this study was from batch 8, 9, 10, prepared according to standard SOPs.

TREATMENT APPLICATION
All applications of the test substance were performed indoors with a belt sprayer which is enclosed in a fume hood and is equipped with a single nozzle. A nozzle height of 12 inches was used to achieve a spray swath of 20 inches. The liquid was collected from the nozzle into a graduated cylinder and the nozzle pressure and belt speed were adjusted to obtain approximately 23.3 mL per plot. A nozzle pressure of 50 psi was used. Spraying with the test substance commenced immediately after compound dissolution, therefore, the test material was assumed to be stable under the conditions of administration.
After treatment, the pots were randomized within crops and among treatments, and placed in a greenhouse at the test facility. The pots were then watered to accelerate movement of the test substance into the seed zone. The greenhouse (42 x 30 x 12 ft) is positioned in a north to south direction. It is equipped with 1000 W lighting using General Electric R1000 Multi-Vapor to supplement light during periods of low sunlight intensity. It is also equipped with a cooling system, Groton Climate and Environmental Control.

IRRIGATION SCHEDULE
Pots were watered using nozzles placed 4.0 ft apart. The irrigation duration and intervals were five, nine, six, and ten minutes of irrigation at 9:00 a.m., 12:00 p.m., and 4:00 p.m. Duration of irrigation increased as
plants matured. The irrigation cycle was controlled. Calculations determined that a total of approximately 33 mL of water were used to irrigate each pot per day at 5 minutes, 46 mL at 9 minutes, 22 mL at 6 minutes, and 50 mL at 10 minutes.

LIGHT QUANTITY AND DURATION
The photoperiod was recorded as the time from sunrise to sunset. Periods of light and duration were recorded. Light quantity was determined in footcandles using a photometer. Measurements were taken at canopy height at approximately 10:00 a.m. and 2:00 p.m. on weekdays. The mean light intensities at 10:00 a.m. were 2484 and 2376 footcandles, respectively, and at 2:00 p.m. were 2805 and 2944, respectively

EFFECT PARAMETERS MEASURED
Seedling emergence was recorded at 10 and 14 days after treatment. Seedling survival and height were recorded at 21 days after treatment. Phytotoxicity ratings were recorded at 10, 14, and 21 days after treatment. Twenty-one days after treatment, the plants within treatment replicates were cut at soil level and dried in preweighed aluminum foil sheets. Plant material was dried at approximately 70°C for a minimum of 48 hours. The dry weight of the plant material was then recorded.
Nominal and measured concentrations:
- Nominal concentrations: 0.0, 0.0185, 0.056, 0.167, 0.5, and 1.5 lb ai/A

Reference substance (positive control):
no
Key result
Species:
other: Brassica oleracea var., capitata, Avena sativa and Zea mays
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.056 lbs/acre
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
Plant height (cabbage and oat) and dry weight (cabbage and corn)
Remarks on result:
other: as reported in the original report
Remarks:
effect value equivalent to 0.063 kg/ha or 0.084 mg a.i./kg soil dw
Key result
Species:
Brassica oleracea var. capitata
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
0.63 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
Plant dry weight
Remarks on result:
other: Equivalent to 0.84 mg a.i./kg
Species:
Allium cepa
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
0.69 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
Plant height
Remarks on result:
other: Equivalent to 0.92 mg a.i./kg
Details on results:
An overivew of all the results and the derived NOECs, EC25 and EC50 values are presented in 'Any other information on results incl. tables'.

EMERGENCE AND SURVIVAL
Through day 14, percent emergence for all rates for lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion did not differ significantly from the control. The no-effect concentration for percent emergence for the eight crops at the 14-day observation period was the maximum concentration of 1.5 lb ai/A. The no-effect concentration for soybean and cabbage was reached at 0.5 lb ai/A. Crops listed in order of increasing sensitivity to the test substance based on percent emergence no-effect concentration (lb ai/A) are: Lettuce = carrot = tomato = cucumber = oat = ryegrass = corn = onion (91.5) < soybean = cabbage (0.5).
Due to a lack of significant rate effects or a lack of a true dose response for seedling emergence, a probit analysis was not conducted, therefore, EC values could not be determined for soybean, lettuce, carrot, tomato, cucumber, oat ryegrass, corn, and onion. Cabbage demonstrated a dose response, therefore, a probit analysis was conducted and resulted in an EC50 value of 4.520 lb ai/A.
At the 21-day observation period, soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion showed no significant difference in the survival rate between the control and any rate of the test substance. Cabbage showed a reduction of 49% in percent survival at the highest concentration rate resulting in a significant difference between that rate and all others including the control, therefore, a no-effect concentration for cabbage was reached at 0.5 lb ai/A.
Crops listed in order of increasing sensitivity to the test substance based on percent survival no-effect concentration (lb ai/A) are: Soybean = lettuce = carrot = tomato = cucumber = oat = ryegrass = corn =onion (1.5) < cabbage (0.5).
Due to a lack of significant rate effects or a lack of a true dose response for seedling survival, a probit analysis was not conducted nor EC25 and EC50 values determined on soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion. Cabbage demonstrated a dose response, therefore, a probit analysis was conducted and resulted in an EC50 value of 2.536 lb ai/A.

PHYTOTOXICITY
At the 21-day observation period, carrot, oat, and corn showed no significant difference between the control and any of the five concentrations tested and a resultant no-effect concentration of 1.5 lb ai/A. Soybean, lettuce, tomato, cucumber, and onion all showed a significant difference between the control and the highest concentration of 1.5 lb ai/A, therefore, resulting in a no-effect concentration of 0.5 lb ai/A. The highest treatment rate (no-effect concentration) resulting in a phytotoxicity rating not statistically significant (p < 0.05) from the control at the 21-day observation period was 0.167 lb ai/A for cabbage and ryegrass. Crops listed in order of increasing sensitivity to the test substance based on phytotoxicity no-effect concentration (lb ai/A) at the 21-day observation period are: Carrot = oat = corn (1.5) < soybean = lettuce = tomato = cucumber = onion (0.5) < cabbage = ryegrass (0.167).

PLANT HEIGHT
The statistical analysis of the plant height data of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn, and onion showed significant difference between the control and the highest concentration of 1.5 lb ai/A. The highest treatment rate (no-effect concentration) not significantly different from the control was 0.5 lb ai/A for soybean, lettuce, carrot, and cucumber. The no-effect concentration, as defined by this study for plant height, for tomato, ryegrass, corn, and onion was 0.167 lb ai/A, and 0.056 lb ai/A for cabbage and oat at the 21-day observation period. Crops listed in order of increasing sensitivity to the test substance based on plant height no-effect concentration (lb ai/A) at the 21-day observation period are: Soybean = lettuce = carrot = cucumber (0.5) < tomato = ryegrass = corn = onion (0.167) < cabbage = oat (0.056). Lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn, and onion all demonstrated a plant height dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC values were determined. Soybean did not demonstrate a true dose response, therefore, the EC values were not determined. The EC50 value (lb ai/A) for each crop in order of increasing sensitivity (lb ai/A) is: Oat (58.760) < carrot (41.268) < corn (8.210) < lettuce (4.267) < tomato (3.921) < cucumber (1.564) < ryegrass (0.969) < cabbage (0.684) < onion (0.615).

PLANT DRY WEIGHT
Plant dry weight of all crops was evaluated at 21 days after treatment. Statistical analysis of the plant dry weight data showed that there was no significant difference in plant dry weight between the control and any other rates on lettuce, carrot, and cucumber resulting in a no-effect concentration of 1.5 lb ai/A. The no-effect concentration as defined by this study for soybean and oat was 0.5 lb ai/A. Tomato showed a 29% detrimental effect at the 0.5 lb ai/A concentration but was not statistically different from the control, however, it was considered biologically significant. The highest treatment rate (no effect concentration) not significantly different from the control was 0.167 lb ai/A for tomato, ryegrass and onion, and 0.056 lb ai/A for cabbage and corn. Crops listed in order of increasing sensitivity to the test substance based on plant dry weight no-effect concentration (lb ai/A) are: Lettuce = carrot = cucumber (1.5) < soybean = oat (0.5) < tomato = ryegrass = onion (0.167) < cabbage = corn (0.056). Due to a lack of significant rate effect or a lack of a true dose response, a probit analysis was not conducted nor EC values determined on lettuce, carrot, and cucumber. Soybean, tomato, cabbage, oat, ryegrass, corn, and onion all demonstrated a plant dry weight dose response, therefore, a probit analysis was conducted on the data for these crops. The EC50 value (lb ai/A) for each crop in order of increasing sensitivity to the test substance is: Oat (30.836) < corn (2.694) < tomato (2.071) < soybean (2.025) < ryegrass (1.253) < onion (1.226) < cabbage (0.562).
Results with reference substance (positive control):
No positive control was used.
Reported statistics and error estimates:
- Mean and Percent Effect Calculation: All of the data were entered into a Lotus 1-2-3 spreadsheet. The spreadsheet calculated replicate means, treatment means, standard deviations, and analysis of variance tables. Treatment means were used to calculate the percent effect resulting from the treatment.

- Analysis of Variance: An analysis of variance table was constructed using the Lotus 1-2-3 raw data spreadsheet. A one-way analysis of variance model for data with equal subsamples, as outlined in Steel and Torrie, was used to analyze the data (percent germination and radicle length). Treatment mean separation was achieved by using Lotus 1-2-3 spreadsheet. Means were separated by using Duncan’s New Multiple Range Test.

- Probit Analysis: The percent effect values were input into a SAS probit analysis program. The program ignores positive values and transforms the dose by natural logarithms. For seed germination, the probit is calculated using all data points; for all other parameters, the probit is calculated using replicate means

Table 1: Percentage of seedling emergence at 10 and 14 days, and percent survival at 21 days after treatment of the soil surface with the test substance.

Crop

Treatment rate (lb a.i./A)

Days after treatment

10

14

21

Percent Emergence

Percent Effect

Percent Emergence

Percent Effect

Percent Emergence

Percent Effect

Soybean

0.0

100

 

100

 

100

 

0.0185

93

-7

93

-7

97

-3

0.056

100

0

100

0

100

0

0.167

97

-3

97

-3

97

-3

0.5

93

-7

93

-7

93

-7

1.5

70

-30

83

-17

93

-7

Lettuce

0.0

97

 

97

 

97

 

0.0185

100

3

100

3

100

3

0.056

97

0

97

0

97

0

0.167

97

0

97

0

97

0

0.5

97

0

100

3

100

3

1.5

100

3

100

3

100

3

Carrot

0.0

83

 

83

 

83

 

0.0185

83

0

83

0

83

0

0.056

83

0

87

5

87

5

0.167

77

-7

83

0

83

0

0.5

60

-28

77

-7

80

-4

1.5

60

-16

77

-7

77

-7

Tomato

0.0

93

 

93

 

93

 

0.0185

93

0

93

0

93

0

0.056

93

0

93

0

93

0

0.167

97

4

97

4

97

4

0.5

90

-3

93

0

97

4

1.5

77

-17

73

-22

77

-17

Cucumber

0.0

100

 

100

 

100

 

0.0185

97

-3

97

-3

97

-3

0.056

100

0

100

0

100

0

0.167

100

0

100

0

100

0

0.5

100

0

100

0

100

0

1.5

83

-17

87

-13

90

-10

Cabbage

0.0

93

 

93

 

93

 

0.0185

90

-3

90

-3

90

-3

0.056

83

-11

83

-11

87

-6

0.167

77

-17

77

-17

77

-17

0.5

77

-17

77

-17

77

-17

1.5

47

-49

53

-43

47

-49

Oat

0.0

90

 

90

 

90

 

0.0185

97

8

97

8

97

8

0.056

90

0

90

0

90

0

0.167

100

11

100

11

100

11

0.5

80

-11

80

-11

80

-11

1.5

97

9

97

8

97

8

Ryegrass

0.0

100

 

100

 

100

 

0.0185

90

-10

90

-10

90

-10

0.056

97

-3

97

-3

97

-3

0.167

97

-3

97

-3

97

-3

0.5

80

-20

83

-17

90

-10

1.5

93

-7

93

-7

93

-7

Corn

0.0

100

 

100

 

100

 

0.0185

97

-3

97

-3

93

-7

0.056

100

0

100

0

100

0

0.167

100

0

100

0

100

0

0.5

100

0

100

0

100

0

1.5

100

0

100

0

100

0

Onion

0.0

77

 

73

 

77

 

0.0185

80

4

80

10

80

4

0.056

80

4

80

10

80

4

0.167

90

17

90

23

90

17

0.5

7

0

83

14

83

8

1.5

53

-31

70

-4

67

-13

 

 

Table 2: Mean phytotoxicity rating at 10, 14, and 21 days after treatment of the soil surface with the test substance.

 

Crop

Treatment rate (lb a.i./A)

Days after treatment

10

14

21

Soybean

0.0

0.1

0.0

0.0

0.0185

0.1

0.1

0.1

0.056

0.0

0.0

0.0

0.167

0.1

0.1

0.1

0.5

02

0.2

0.0

1.5

2.4

2.4

2.5

Lettuce

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.1

0.1

0.0

0.5

0.9

0.4

0.0

1.5

2.6

2.2

0.4

Carrot

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.2

0.0

0.167

0.0

0.2

0.0

0.5

0.1

0.3

0.2

1.5

0.1

0.2

0.1

Tomato

0.0

0.1

0.0

0.0

0.0185

0.1

0.0

0.0

0.056

0.1

0.1

0.0

0.167

0.1

0.0

0.0

0.5

0.5

0.3

0.2

1.5

2.6

2.1

2.0

Cucumber

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.1

0.1

0.0

0.167

0.1

0.1

0.1

0.5

0.1

0.1

0.0

1.5

1.9

1.7

1.7

Cabbage

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.1

0.167

0.6

0.3

0.1

0.5

1.9

1.4

1.3

1.5

2.9

2.9

2.6

Oat

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

0.0

0.0

0.0

1.5

0.0

0.0

0.0

Ryegrass

0.0

0.1

0.0

0.0

0.0185

0.1

0.0

0.0

0.056

0.0

0.2

0.0

0.167

0.0

0.3

0.0

0.5

0.4

1.8

0.8

1.5

1.9

2.9

2.5

Corn

0.0

0.1

0.1

0.1

0.0185

0.1

0.2

0.0

0.056

0.1

0.1

0.1

0.167

0.2

0.1

0.2

0.5

0.1

0.1

0.1

1.5

0.2

0.2

0.1

Onion

0.0

0.2

0.1

0.3

0.0185

0.1

0.1

0.1

0.056

0.1

0.0

0.0

0.167

0.1

0.2

0.2

0.5

0.4

1.0

0.6

1.5

2.0

2.9

2.9

Phytotoxicity ratings were based on a 0-4 scale with 0 = no effect, 1 = slight effect limited to one leaf, 2 = moderate effect on whole plant, 3 = severe effect on whole plant, and 4 = total effect or plant death.

 

Table 3: Height of seedlings emerging after 21 days treatment of the soil surface with the test substance.

 

Crop

Treatment rate (lb a.i./A)

Plant height after 21 days (mm)

Percent Effect

Soybean

0.0

349

 

0.0185

336

-4

0.056

340

-3

0.167

327

-6

0.5

313

-10

1.5

88

-75

Lettuce

0.0

86

 

0.0185

85

-1

0.056

88

2

0.167

90

5

0.5

81

-6

1.5

52

-40

Carrot

0.0

66

 

0.0185

67

2

0.056

68

3

0.167

69

5

0.5

58

-12

1.5

57

-14

Tomato

0.0

119

 

0.0185

104

-13

0.056

114

-4

0.167

104

-13

0.5

92

-23

1.5

60

-50

Cucumber

0.0

117

 

0.0185

127

9

0.056

128

9

0.167

126

8

0.5

123

5

1.5

72

-38

Cabbage

0.0

66

 

0.0185

67

2

0.056

61

-8

0.167

52

-21

0.5

39

-41

1.5

20

-70

Oat

0.0

330

 

0.0185

328

-1

0.056

323

-2

0.167

315

-5

0.5

296

-10

1.5

269

-18

Ryegrass

0.0

167

 

0.0185

179

7

0.056

164

-2

0.167

152

-9

0.5

109

-35

1.5

66

-60

Corn

0.0

317

 

0.0185

296

-6

0.056

279

-12

0.167

272

-14

0.5

233

-26

1.5

213

-33

Onion

0.0

142

 

0.0185

142

0

0.056

144

1

0.167

122

-14

0.5

92

-35

1.5

25

-82

Plants were extended to their maximum height and measured to the nearest millimeter.

 

Table 4: Mean dry weight of the plants after 21 days treatment of the soil surface with the test substance.

Crop

Treatment rate (lb a.i./A)

Plant height after 21 days (mm)

Percent Effect

Soybean

0.0

342

 

0.0185

332

-3

0.056

345

1

0.167

381

11

0.5

342

0

1.5

158

-54

Lettuce

0.0

54

 

0.0185

50

-7

0.056

53

-2

0.167

59

9

0.5

45

-17

1.5

52

-4

Carrot

0.0

9

 

0.0185

10

11

0.056

10

11

0.167

10

11

0.5

7

-22

1.5

7

-22

Tomato

0.0

51

 

0.0185

43

-16

0.056

52

2

0.167

45

-12

0.5

36

-29

1.5

22

-57

Cucumber

0.0

154

 

0.0185

179

16

0.056

168

9

0.167

196

27

0.5

198

29

1.5

137

-11

Cabbage

0.0

72

 

0.0185

68

-6

0.056

69

-4

0.167

54

-25

0.5

40

-44

1.5

18

-75

Oat

0.0

91

 

0.0185

95

4

0.056

90

-1

0.167

81

-11

0.5

81

-11

1.5

75

-18

Ryegrass

0.0

17

 

0.0185

17

0

0.056

15

-12

0.167

14

-18

0.5

11

-35

1.5

8

-53

Corn

0.0

129

 

0.0185

111

-14

0.056

99

-23

0.167

933

-28

0.5

72

-44

1.5

78

-40

Onion

0.0

12

 

0.0185

12

0

0.056

13

8

0.167

11

-8

0.5

8

-33

1.5

6

-50

Plants were cut at the soil level and placed in a pre-weighed paper bag. Plants were dried at 70°C for 48 hours. The total weight of the plants was divided by the number of plants collected to obtain the mean weight per plant.

 

 

Table 5: Statistical NOEC, EC25 and EC50 values in lb a.i./A.

Plant

Seedling emergence

Seedling survival

Phytotoxicity

Plant height

Plant dry weight

NOEC

EC25

EC50

NOEC

EC25

EC50

NOEC

Mean rating

NOEC

EC25

EC50

NOEC

EC25

EC50

Soybean

0.5

ND

ND

1.5

ND

ND

0.5

0.0

0.5

ND

nd

0.5

0.797

2.025

Lettuce

1.5

ND

ND

1.5

ND

ND

0.5

0.0

0.5

1.143

4.267

1.5

ND

ND

Carrot

1.5

ND

ND

1.5

ND

ND

1.5

0.1

0.5

5.051

41.268

1.5

ND

ND

Tomato

1.5

ND

ND

1.5

ND

ND

0.5

0.2

0.167

0.400

3.921

0.167

0.228

2.071

Cucumber

1.5

ND

ND

1.5

ND

ND

0.5

0.0

0.5

1.413

1.564

1.5

ND

ND

Cabbage

0.5

0.465

4.520

0.5

 

 

0.167

0.1

0.056

0.218

0.684

0.056

0.178

0.562

Oat

1.5

ND

ND

1.5

ND

ND

1.5

0.0

0.056

4.477

58.760

0.5

2.857

30.836

Ryegrass

1.5

ND

ND

1.5

ND

ND

0.167

0.0

0.167

0.381

0.969

0.167

0.227

1.253

Corn

1.5

ND

ND

1.5

ND

ND

1.5

0.1

0.167

0.548

8.210

0.056

0.094

2.694

Onion

1.5

ND

ND

1.5

ND

ND

0.5

0.6

0.167

0.280

0.615

0.167

0.445

1.226

 

Validity criteria fulfilled:
yes
Conclusions:
Plant dry weight and height were the most sensitive parameters with EC50 values of 0.562 (=0.63 kg/ha or 0.84 mg a.i./kg soil dw) (cabbage) and 0.615 lb/A (=0.69 kg/ha or 0.92 mg a.i./kg soil dw) (onion), respectively. The lowest NOEC value was determined to be 0.056 lb/A (= 0.063 kg/ha or 0.084 mg a.i./kg soil dw) for cabbage, oat and corn, based on plant growth.
Executive summary:

Tier 2 nontarget seedling emergence studies were conducted to determine the effect of the test substance on the seedling emergence of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn and onion. The study was conducted in accordance with EPA 123 -1 and in compliance with GLP. A plexiglass template was used to create planting holes in the soil, thus allowing for uniform planting depth and distribution of the seeds planted per pot. Soybean, cucumber, oat, and corn were planted at a depth of 2.5 cm while lettuce, carrot, tomato, cabbage, ryegrass, and onion were planted at a depth of 1.3 cm. The test substance was applied to the soil surface at the rates of 0.0, 0.0185, 0.056, 0.167, 0.5, and 1.5 lb ai/A.

 

Survival/emergence

Through day 14, percent emergence for all rates for lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion did not differ significantly from the control. The no-effect concentration for percent emergence for the eight crops at the 14-day observation period was the maximum concentration of 1.5 lb ai/A. The no-effect concentration for soybean and cabbage was reached at 0.5 lb ai/A. Crops listed in order of increasing sensitivity to the test substance based on percent emergence no-effect concentration (lb ai/A) are: Lettuce = carrot = tomato = cucumber = oat = ryegrass = corn = onion (1.5) < soybean = cabbage (0.5). Due to a lack of significant rate effects and a lack of a true dose response for seedling emergence, a probit analysis was not conducted, therefore, EC25 and EC50 values could not be determined for soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion. Cabbage demonstrated a dose response, therefore, a probit analysis was conducted and resulted in an EC50 value of 4.520 lb ai/A. At the 21-day observation period, soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion showed no significant difference in the survival rate between the control and any rate of the test substance. Cabbage showed a reduction of 49% in percent survival at the highest concentration rate resulting in a significant difference between that rate and all others including the control, therefore, a no-effect concentration for cabbage was reached at 0.5 lb ai/A. Crops listed in order of increasing sensitivity to the test substance based on percent survival no-effect concentration (lb ai/A) are: Soybean = lettuce = carrot = tomato = cucumber = oat = ryegrass = corn = onion (1.5) < cabbage (0.5). Due to a lack of significant rate effects or a lack of a time dose response for seedling survival, a probit analysis was not conducted nor EC25 or EC50 values determined on soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion. Cabbage demonstrated a dose response, therefore, a probit analysis was conducted and resulted in an EC50 value of 2.536 lb ai/A.

 

Phytotoxicity

At the 21-day observation period, carrot, oat, and corn showed no significant difference between the control and any of the five concentrations tested and a resultant no-effect concentration of 1.5 lb ai/A. Soybean, lettuce, tomato, cucumber, and onion all showed a significant difference between the control and the highest concentration of 1.5 lb ai/A, therefore, resulting in a no-effect concentration of 0.5 lb ai/A. The highest treatment rate (no-effect concentration) resulting in a phytotoxicity rating not statistically significant (p < 0.05) from the control at the 21-day observation period was 0.167 lb ai/A for cabbage and ryegrass. Crops listed in order of increasing sensitivity to the test substance based on phytotoxicity no-effect concentration (lb ai/A) at the 21-day observation period are: Carrot = oat = corn (1.5) < soybean = lettuce = tomato = cucumber = onion (0.5) < cabbage = ryegrass (0.167).

 

Plant height

The statistical analysis of the plant height data of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn, and onion showed significant difference between the control and the highest concentration of 1.5 lb ai/A. The highest treatment rate (no-effect concentration) not significantly different from the control was 0.5 lb ai/A for soybean, lettuce, carrot, and cucumber. The no-effect concentration, as defined by this study for plant height, for tomato, ryegrass, corn, and onion was 0.167 lb ai/A, and 0.056 lb ai/A for cabbage and oat at the 21-day observation period. Crops listed in order of increasing sensitivity to the test substance based on plant height no-effect concentration (lb ai/A) at the 21-day observation period are: Soybean = lettuce = carrot = cucumber (0.5) < tomato = ryegrass = corn (0.167) < cabbage = oat (0.056). Lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn, and onion all demonstrated a plant height dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EC50 values were determined. Soybean did not demonstrate a true dose response, therefore, the EC25 and EC50 values were not determined. The EC50 value (lb ai/A) for each crop in order of increasing sensitivity (lb ai/A) is: Oat (58.760) < carrot (41.268) < corn (8.210) < lettuce (4.267) < tomato (3.921) < cucumber (1.564) < ryegrass (0.969) < cabbage (0.684) < onion (0.615).

 

Plant dry weight

Plant dry weight of all crops was evaluated at 21 days after treatment. Statistical analysis of the plant dry weight data showed that there was no significant difference in plant dry weight between the control and any other rates on lettuce, carrot, and cucumber resulting in a no-effect concentration of 1.5 lb ai/A. The no-effect concentration as defined by this study for soybean and oat was 0.5 lb ai/A. Tomato showed a 29% detrimental effect at the 0.5 lb ai/A concentration but was not statistically different from the control, however, it was considered biologically significant. The highest treatment rate (no-effect concentration) not significantly different from the control was 0.167 lb ai/A for tomato, ryegrass and onion, and 0.056 lb ai/A for cabbage and corn. Crops listed in order of increasing sensitivity to the test substance based on plant dry weight no-effect concentration (lb ai/A) are: Lettuce = carrot = cucumber (1.5) < soybean = oat (0.5) < tomato = ryegrass = onion (0.167) < cabbage = corn (0.056). Due to a lack of significant rate effects or a lack of a true dose response, a probit analysis was not conducted nor EC25 and EC50 values determined on lettuce, carrot, and cucumber. Soybean, tomato, cabbage, oat, ryegrass, corn, and onion all demonstrated a plant dry weight dose response, therefore, a probit analysis was conducted on the data for these crops. The EC25 value (lb ai/A) for each crop in order of increasing sensitivity to the test substance is: Oat (30.836) < corn (2.694) < tomato (2.071) < soybean (2.025) < ryegrass (1.253) < onion (1.226) < cabbage (0.562).

Based on these findings, it was concluded that emergence, survival and condition of plants were not affected in any species at rates ≤0.56 kg ai/ha. Plant dry weight and height were the most sensitive parameters with EC50 values of 0. 562 (=0.63 kg/ha or 0.84 mg a.i./kg soil dw) (cabbage) and 0.615 lb/A (=0.69 kg/ha or 0.92 mg a.i./kg soil dw) (onion), respectively. The lowest NOEC value was determined to be 0.056 lb/A (= 0.063 kg/ha or 0.084 mg a.i./kg soil dw) for cabbage, oat and corn, based on plant growth.

Endpoint:
toxicity to terrestrial plants: short-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08 May 1990 to 18 Jun 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPP 123-1 (Vegetative Vigor Tier II)
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
yes
Remarks:
Acetone
Details on preparation and application of test substrate:
On May 24, 1990, the test substance was applied to all plant species at the rates of 0.0185, 0.056, 0.167, 0.5. and 1.5 lb ai/A. Treatment application rates were calculated on the percent active ingredient of the technical material which was 92.0% ai. Plants were sprayed at the equivalent of 50 gpa of water. The test spray concentration of 3.5952 gm ai/L (3595.2 ppm) was prepared by adding 586.2 mg of test substance in 136.5 L of deionized water plus 13.5 mL of acetone. An additional 4% (6 mL) of acetone was added to compound prior to addition of water to prevent oily residue noted in earlier work with this compound.
Species:
Glycine max (G. soja)
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Soybean
Species:
Lactuca sativa
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Lettuce
Species:
Daucus carota
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Carrot
Species:
Lycopersicon esculentum
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Tomato
Species:
Cucumis sativus
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Cucumber
Species:
Brassica oleracea var. capitata
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Cabbage
Species:
Avena sativa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Oat
Species:
Lolium perenne
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Perennial ryegrass
Species:
Zea mays
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Corn
Species:
Allium cepa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Onion
Test type:
vegetative vigour test
Study type:
laboratory study
Substrate type:
artificial soil
Limit test:
no
Total exposure duration:
21 d
Test temperature:
24 - 26 °C
pH:
Not reported
Moisture:
Not reported
Details on test conditions:
TEST SYSTEM

- Seed planting: Seeds selected for each crop were uniform in size and were assigned impartially to the test and control groups. A plexiglass template was used to create planting holes in the soil, thus allowing for uniform planting depth and seed distribution of the ten seeds planted per pot. Soybean, cucumber, oat, and corn were planted at a depth of 2.5 cm while the remaining six species were planted at a depth of 2.3 cm. Each treatment/crop combination was replicated three times.
- Plant selection: After planting, the pots were placed in a greenhouse and watered adequately for seedling emergence and growth. Seedlings were allowed to grow to the appropriate stage of growth (1-3 true leaves). Prior to treatment, each pot was thinned to five plants of uniform height and stage of growth.

- No. of seeds per container: 10
- No. of replicates per treatment group: 3
- No. of replicates per vehicle control: 3
- Soil preparation: Hanford sandy loam soil, obtained from the test facility, was sterilized for 48 hours in a sterilizer. Perlite was added to the sterilized soil to facilitate drainage.
- Water: The water used as the compound solvent and for subsequent irrigation was from a well located at the test facility. The pH of the irrigation water was 7.4.

TREATMENT APPLICATION
All applications of the test substance were performed indoors with a belt sprayer which is enclosed in a fume hood and is equipped with a single nozzle. A nozzle height of 12 inches was used to achieve a spray swath of 20 inches. The liquid was collected from the nozzle into a graduated cylinder and the nozzle pressure and belt speed were adjusted to obtain approximately 23 mL per plot. A nozzle pressure of 50 psi was used. Spraying with the test substance commenced immediately after compound dissolution, therefore, the test material was assumed to be stable under the conditions of administration. After treatment, the pots were placed in a greenhouse at he test facility. The greenhouse (42 x 30 x 12 ft) is positioned in a north to south direction. It is equipped with Spero Lighting 1000 W using General Electric R100 Multivapor to supplement light during periods of low sunlight intensity. It is also equipped with a cooling system, Groton Climate and Environmental Control. On May 25, 1990, the pots were randomized within crops and among treatments. Study plants were hand-watered for 48 hours to avoid chemical washoff.

EFFECT PARAMETERS MEASURED
Plant height was recorded prior to treatment and 21 days after treatment. Phytotoxicity ratings were recorded 7, 14, and 21 days after treatment in accordance with SOPs. Twenty-one days after treatment,
the plants within treatment replicates were cut at soil level and placed in preweighed aluminum foil sheets. Plant material was dried at approximately 70°C for a minimum of 48 hours. The dry weight of the plant material was then recorded.
Nominal and measured concentrations:
- Nominal concentrations: 0.0, 0.0185, 0.056, 0.167, 0.5, and 1.5 lb ai/A

Reference substance (positive control):
no
Species:
Brassica oleracea var. capitata
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
0.85 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
dry weight
Remarks on result:
other: Equivalent to 1.13 mg a.i./kg
Species:
Glycine max (G. soja)
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
0.87 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
plant height
Remarks on result:
other: Equivalent to 1.16 mg a.i./kg
Details on results:
An overivew of all the results and the derived NOECs, EC25 and EC50 values are presented in 'Any other information on results incl. tables'.

PHYTOTOXICITY
At the 21-day observation period, lettuce, tomato, oat, and corn showed no significant difference (p < 0.05) between the control and any of the rates tested, resulting in a no-effect concentration of 1.5 lb ai/A. Carrot showed a significant difference (p < 0.05) between the control and the 0.5 lb ai/A rate due to minor phytotoxicity on one plant in each replicate in that treatment group. However, there was no significance between the control and the maximum concentration for carrot at the 21-day observation period, resulting in a no-effect concentration of 1.5 lb ai/A. At the 7- and 14-day observation periods, lettuce and tomato showed a significant difference (p < 0.05) between the control and 0.5 lb ai/A concentration, however, both crops outgrew the effects by the 21-day observation period. The highest treatment rate (no-effect concentration) resulting in a phytotoxicity rating not significant (p < 0.05) from the control at the 21-day observation period, was 0.5 lb ai/A for onion, and 0.167 lb ai/A for soybean, cucumber, cabbage, and ryegrass. Crops listed in order of increasing sensitivity to the test substance based on phytotoxicity no-effect concentration (lb ai/A) at the 21- day observation period are: Lettuce = carrot = tomato = oat = corn (1.5) < onion (0.5) < soybean = cucumber = cabbage = ryegrass (0.167).

PLANT HEIGHT
Treatment of lettuce and carrot with the test substance did not result in a significant difference (p < 0.05) in plant height at the 21-day observation period between the control and any of the rates tested. The highest treatment rate (no-effect concentration) not significantly different from the control was 0.5 lb ai/A for oat. The no-effect concentration, as defined by this study for plant height, for tomato, cucumber, cabbage, and corn was 0.167 lb ai/A, 0.056 lb ai/A for soybean and onion, and 0.0185 lb ai/A for ryegrass at the 21-day observation period. With the exception of lettuce, carrot, oat, and corn, the test substance exceeded 25% reduction on plant growth at the two highest concentrations (0.5 lb ai/A and 1.5 lb ai/A) on soybean, tomato, cucumber, cabbage, ryegrass, and onion. Crops listed in order of increasing sensitivity to the test substance based on plant height no-effect concentration (lb ai/A) at the 21-day observation period are: Lettuce = carrot (1.5) < oat (0.5) < tomato = cucumber = cabbage = corn (0.167) < soybean = onion (0.056) < ryegrass (0.0185). Due to a lack of significant rate effects in plant height or a lack of a true dose response, a probit analysis was not conducted nor EC50 and EQ25, values determined on lettuce, carrot, tomato, and oat. Soybean, cucumber, cabbage, ryegrass, corn, and onion demonstrated a plant height dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EQ50 values were determined. The EQ50, value (lb ai/A) for each crop in order of increasing sensitivity is: Corn (6.604) < cucumber (5.547) < ryegrass (2.568) < cabbage (2.441) < onion (1.394) < soybean (0.755).

PLANT DRY WEIGHT
Statistical analysis of the plant dry weight data showed that there was no significant difference in plant dry weight between the control and any other rates on lettuce, cucumber, cabbage, oat, ryegrass, corn, and onion. Tomato produced some vigorous plants in the 0.167 lb ai/A treatment rate resulting in significance between that rate and all others including the control. The no-effect concentration, as defined by this study for plant dry weight for tomato, was 1.5 lb ai/A. An increase in plant dry weight of carrot from 16% to 39% resulted in significance between the control and 0.0185, 0.056, 0.167, and 1.5 lb ai/A treatment rates. This response was due to vigorous plants produced in those rates. Treatment of carrot with the test substance did not result in any detrimental effects in plant dry weight and a no-effect concentration was determined to be 1.5 lb ai/A. At 0.5 and 1.5 lb ai/A, cucumber showed a 32% and a 28% reduction in plant dry weight, respectively, but this was not statistically significant due to variability in plant dry weight in the lower rates. Cabbage showed a reduction in plant dry weight from 5% at 0.056 lb ai/A to 60% at 1.5 lb ai/A, but due to variability was not statistically significant. The non significance in cucumber can be attributed to an increase in plant height at the 0.0185 and 0.167 lb ai/A rates were as the non-significance in cabbage can be attributed to an increase in the plant height of replicate 2 of the 0.056 lb ai/A rate. Although not statistically significant, a no-effect concentration was determined to be 0.167 lb ai/A for cucumber, and 0.056 lb ai/A for cabbage based on biological significance. The highest treatment rate no-effect concentrate on was 0.056 lb ai/A for soybean. Crops listed in order of increasing sensitivity to the test substance based on plant dry weight no-effect concentration (lb ai/A) (Table 7) are: Lettuce = carrot = tomato = oat = ryegrass = corn = onion (1.5) < cucumber (0.167) < soybean = cabbage (0.056).

Due to the lack of significant differences in plant dry weight or a lack of a true dose response, a probit analysis was not conducted nor EC25 and EC50 values determined on lettuce, carrot, tomato, oat, ryegrass and corn. Soybean, cucumber, cabbage and onion demonstrated a plant dry weight dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EC50 values were determined. The EC50 value for each crop in increasing sensitivity is: Cucumber (4.984) < onion (3.850) < soybean (2.039) < cabbage (0.773).
Results with reference substance (positive control):
No positive control was used.
Reported statistics and error estimates:
- Mean and Percent Effect Calculation: All of the data were entered into a Lotus 1-2-3 spreadsheet. The spreadsheet calculated replicate means, treatment means, standard deviations, and analysis of variance tables. Treatment means were used to calculate the percent effect resulting from the treatment.

- Analysis of Variance: An analysis of variance table was constructed using the Lotus 1-2-3 raw data spreadsheet. A one-way analysis of variance model for data with equal subsamples, as outlined in Steel and Torrie, was used to analyze the data (percent germination and radicle length). Treatment mean separation was achieved by using Lotus 1-2-3 spreadsheet. Means were separated by using Duncan’s New Multiple Range Test.

- Probit Analysis: The percent effect values were input into a SAS probit analysis program. The program ignores positive values and transforms the dose by natural logarithms. For seed germination, the probit is calculated using all data points; for all other parameters, the probit is calculated using replicate means

Table 1: Mean phytotoxicity rating at 7, 14 and 21 days after treatment with the test substance.

Crop

Treatment rate (lb a.i./A)

Days after treatment

 

7

14

21

Soybean

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

2.0

1.9

1.2

1.5

2.0

2.0

2.9

Lettuce

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

0.3

0.4

0.0

1.5

2.0

1.6

0.1

Carrot

0.0

0.0

0.2

0.1

0.0185

0.1

0.2

0.1

0.056

0.0

0.1

0.0

0.167

0.0

0.0

0.0

0.5

0.4

0.5

0.3

1.5

0.0

0.1

0.0

Tomato

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

2.0

1.3

0.1

1.5

2.0

2.0

0.9

Cucumber

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

0.9

1.2

1.2

1.5

2.0

2.0

1.9

Cabbage

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.1

0.0

0.0

0.167

0.5

0.8

0.4

0.5

1.5

2.5

1.9

1.5

2.2

3.1

2.9

Oat

0.0

0.0

0.1

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

0.1

0.0

0.0

1.5

0.2

0.0

0.0

Ryegrass

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

0.0

1.1

2.0

1.5

0.0

1.6

2.0

Corn

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.0

0.0

0.167

0.0

0.0

0.0

0.5

0.0

0.0

0.0

1.5

0.0

0.1

0.1

Onion

0.0

0.0

0.0

0.0

0.0185

0.0

0.0

0.0

0.056

0.0

0.1

0.0

0.167

0.0

0.0

0.0

0.5

0.0

0.1

0.0

1.5

0.0

2.1

2.2

 

Table 2: Plant height and percent difference in height at 0 and 21 days after treatment with the test substance.

Crop

Treatment rate (lb a.i./A)

Days after treatment

Percent increase in plant height

Percent effect on plant growth

0

21

Plant height (mm)

Percent difference

Plant height (mm)

Percent difference

Soybean

0.0

33

 

358

 

985

 

0.0185

35

6

356

-1

917

-7

0.056

34

3

332

-7

876

-11

0.167

32

-3

297

-20

797

-19

0.5

34

3

214

-40

529

-46

1.5

32

-3

124

-54

288

-71

Lettuce

0.0

47

 

78

 

66

 

0.0185

49

4

77

-1

47

-14

0.056

50

6

77

-1

54

-22

0.167

50

6

81

4

62

-6

0.5

46

-2

77

-1

67

2

1.5

48

2

76

-3

58

-12

Carrot

0.0

33

 

81

 

145

 

0.0185

34

3

90

11

165

14

0.056

41

24

90

11

120

-21

0.167

36

9

86

6

139

-4

0.5

35

6

80

-1

129

-11

1.5

38

15

95

17

150

3

Tomato

0.0

72

 

156

 

117

 

0.0185

68

-6

144

-8

112

-4

0.056

70

-3

146

-6

109

-7

0.167

78

8

157

1

105

-10

0.5

69

-4

127

-19

84

-28

1.5

71

-1

116

-26

63

-46

Cucumber

0.0

42

 

112

 

167

 

0.0185

42

0

123

10

193

16

0.056

42

0

113

1

169

1

0.167

42

2

117

4

172

3

0.5

42

0

88

-27

110

-34

1.5

42

0

84

-25

100

-40

Cabbage

0.0

35

 

78

 

136

 

0.0185

32

-3

78

0

144

6

0.056

30

-9

71

-9

137

1

0.167

32

-3

60

-23

88

-35

0.5

31

-6

51

-35

65

-52

1.5

31

-6

47

-40

52

-62

Oat

0.0

36

 

319

 

786

 

0.0185

30

-17

347

9

1057

34

0.056

38

6

325

2

755

-4

0.167

36

0

347

9

864

10

0.5

40

11

306

-4

665

-15

1.5

37

3

259

-19

600

-24

Ryegrass

0.0

67

 

207

 

209

 

0.0185

69

3

212

2

207

-1

0.056

56

-16

181

-13

223

7

0.167

66

-1

165

-20

150

-28

0.5

69

3

142

-31

106

-49

1.5

69

3

124

-40

80

-62

Corn

0.0

36

 

325

 

803

 

0.0185

32

-11

351

8

997

24

0.056

37

3

333

2

800

0

0.167

38

6

321

-1

744

-8

0.5

34

-6

265

-18

679

-15

1.5

56

0

219

-33

508

-37

Onion

0.0

65

 

166

 

155

 

0.0185

69

6

179

8

159

3

0.056

67

3

158

-5

136

-12

0.167

63

-3

135

-19

114

-26

0.5

64

-2

129

-24

97

-37

1.5

65

0

75

-55

15

-90

 

Table 3: Plant height and percent difference in height at 0 and 21 days after treatment with the test substance.

Crop

Treatment rate (lb a.i./A)

Dry weight

Percent effect

Soybean

0.0

571

 

0.0185

610

7

0.056

562

-12

0.167

501

-2

0.5

465

-20

1.5

314

-45

Lettuce

0.0

118

 

0.0185

119

1

0.056

113

-4

0.167

109

-8

0.5

117

-1

1.5

110

-7

Carrot

0.0

31

 

0.0185

38

23

0.056

43

39

0.167

36

16

0.5

31

0

1.5

42

35

Tomato

0.0

117

 

0.0185

103

-12

0.056

122

4

0.167

161

38

0.5

112

-4

1.5

93

-21

Cucumber

0.0

355

 

0.0185

442

25

0.056

344

-3

0.167

402

13

0.5

241

-32

1.5

255

-28

Cabbage

0.0

171

 

0.0185

122

-29

0.056

162

-5

0.167

106

-38

0.5

96

-44

1.5

68

-60

Oat

0.0

182

 

0.0185

196

8

0.056

203

78

0.167

213

17

0.5

187

3

1.5

162

-11

Ryegrass

0.0

45

 

0.0185

62

38

0.056

50

11

0.167

47

4

0.5

47

4

1.5

38

-16

Corn

0.0

177

 

0.0185

208

18

0.056

178

1

0.167

198

12

0.5

176

-1

1.5

162

-8

Onion

0.0

29

 

0.0185

37

28

0.056

31

7

0.167

28

-3

0.5

26

-10

1.5

22

-24

 

Table 4: Statistical NOEC, EC25 and EC50 values expressed in lb a.i./A.

Crop

Phytotoxicity

Plant height

Plant dry weight

NOEC

Mean rating

NOEC

EC25

EC50

NOEC

EC25

EC50

Soybean

0.167

0.0

0.056

0.228

0.755

0.056

0.543

2.039

Lettuce

1.5

0.1

1.5

ND

ND

1.5

ND

ND

Carrot

1.5

0.0

1.5

ND

ND

1.5

ND

ND

Tomato

1.5

0.9

0.167

ND

ND

1.5

ND

ND

Cucumber

0.167

0.0

0.167

1.102

5.547

0.167

0.787

4.984

Cabbage

0.167

0.4

0167

0.270

2.441

0.056

0.039

0.773

Oat

1.5

0.0

0.5

ND

ND

1.5

ND

ND

Ryegrass

0.167

0.0

0.0185

0.315

2.568

1.5

ND

ND

Corn

1.5

0.1

0.167

0.968

6.604

1.5

ND

ND

Onion

0.5

0.0

0.056

0.334

1.394

1.5

1.093

3.850

 

 

 

Validity criteria fulfilled:
yes
Conclusions:
It can be concluded that survival and condition of plants were not affected in any species following post-emergence foliar application at rates ≤0.167lb/A (≤ 0.19 kg ai/ha). Cabbage (plant dry weight) and soy bean (plant height) were the most sensitive species with EC50 values of 0.755 and 0.773 lb/A (equivalent to 0.85 and 0.87 kg ai/ha or 1.13 and 1.16 mg ai/kg), respectively.
Executive summary:

Tier 2 nontarget phytotoxicity studies were conducted to determine the effect of the test substance on the vegetative vigor of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn and onion. The study was conducted in accordance with EPA 123 -1 and in compliance with GLP. Seedlings were allowed to grow to 1-3 true-leaf stage prior to treatment, and each pot was thinned to five plants of uniform height. A single treatment of the test substance was applied with a track sprayer equipped with an overhead flat-fan nozzle at the equivalent of 50 gallons per acre (gpa) of water. The test substance was applied at the rates of 0.0, 0.0185, 0.056, 0.167, 0.5 and 1.5 lb/A.

 

Phytotoxicity

At the 21-day observation period, lettuce, tomato, oat, and corn showed no significant difference (p<0.05) between the control and any of the rates tested, resulting in a NOEC of 1.5 lb/A. Carrot showed a significant difference (p < 0.05) between the control and the 0.5 lb/A rate due to minor phytotoxicity on one plant in each replicate in that treatment group. However, there was no significance between the control and the maximum concentration for carrot at the 21-day observation period, resulting in a NOEC of 1.5 lb/A. At the 7- and 14-day observation periods, lettuce and tomato showed a significant difference (p < 0.05) between the control and 0.5 lb/A concentration, however, both crops outgrew the effect by the 21-day observation period. The highest treatment rate (NOEC) resulting in a phytotoxicity rating not significant from the control at the 21-day observation period, was 0.5 lb/A for onion and 0.167 lb/A for soybean, cucumber, cabbage and ryegrass. Crops listed in order of increasing sensitivity to the test substance based on phytotoxicity NOEC (lb/A) at the 21-day observation period are: Lettuce = carrot = tomato = oat = corn (1.5) < onion (0.5) < soybean = cucumber = cabbage = ryegrass (0.167).

 

Plant height

Treatment of lettuce and carrot with the test substance did not result in a significant difference (p < 0.05) in plant height at the 21-day observation period between the control and any of the rates tested.

The highest treatment rate (NOEC) not significantly different from the control was 0.5 lb ai/A for oat. The NOEC, as defined by this study for plant height, for tomato, cucumber, cabbage, and corn was 0.167 lb ai/A, 0.056 lb ai/A for soybean and onion, and 0.0185 lb ai/A for ryegrass at the 21-day observation period. With the exception of lettuce, carrot, oat, and corn, the test substance exceeded 25% reduction on plant growth at the two highest concentrations (0.5 lb ai/A and 1.5 lb ai/A) on soybean, tomato, cucumber, cabbage, ryegrass, and onion. Crops listed in order of increasing sensitivity to the test substance based on plant height NOECs (lb ai/A) at the 21-day observation period are: Lettuce = carrot (1.5) < oat (0.5) < tomato = cucumber = cabbage = corn (0.167) < soybean = onion (0.056) < ryegrass (0.0185). Due to a lack of significant rate effects in plant height or a lack of a true dose response, a probit analysis was not conducted nor EC25 and EC50 values determined on lettuce and carrot, tomato, and oat. Soybean, cucumber, cabbage, ryegrass, corn, and onion demonstrated a plant height dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EC50 values were determined. The EC50 value (lb ai/A) for each crop in order of increasing sensitivity is: Corn (6.604) < cucumber (5.547) < ryegrass (2.568) < cabbage (2.441) < onion (1.394) < soybean (0.755).

 

Plant dry weight

Statistical analysis of the plant dry weight data showed that there was no significant difference in plant dry weight between the control and any other rates on lettuce, cucumber, cabbage, oat, ryegrass, corn, and onion. Tomato produced some vigorous plants in the 0.167 lb ai/A treatment rate resulting in significance between that rate and all others including the control. The NOEC, as defined by this study for plant dry weight for tomato, was 1.5 lb ai/A. An increase in plant dry weight of carrot from 16% to 39% resulted in significance between the control and 0.0185, 0.056, 0.167 and 1.5 lb ai/A treatment rates. This response was due to vigorous plants produced in those rates. Treatment of carrot with the test substance did not result in any detrimental effects in plant dry weight and a NOEC was determined to be 1.5 lb ai/A. At 0.5 and 1.5 lb ai/A, cucumber showed a 32% and a 28% reduction in plant dry weight, respectively, but this was not statistically significant due to variability in plant dry weight in the lower rates. Cabbage showed a reduction in plant dry weight from 5% at 0.056 lb ai/A to 60% at 1.5 lb ai/A, but due to variability was not statistically significant. The non-significance in cucumber can be attributed to an increase in plant height at the 0.0185 and 0.167 lb ai/A rates were as the non-significance in cabbage can be attributed to an increase in the plant height of replicate 2 of the 0.056 lb ai/A rate. Although not statistically significant, a NOEC was determined to be 0.167 lb ai/A for cucumber, and 0.056 lb ai/A for cabbage based on biological significance. The highest treatment rate NOEC was 0.056 lb ai/A for soybean. Crops listed in order of increasing sensitivity to the test substance based on plant dry weight NOEC (lb ai/A) are: Lettuce = carrot = tomato = oat = ryegrass = com = onion (1.5) < cucumber (0.167) < soybean = cabbage (0.056). Due to the lack of significant differences in pant dry weight or a lack of a true dose response, a probit analysis was not conducted nor EC25 and EC50 values determined on lettuce, carrot, tomato, oat, ryegrass and corn. Soybean, cucumber, cabbage and onion demonstrated a plant dry weight dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EC50 values were determined. The EC50 value (lb/A) for each crop in order of increasing sensitivity is: Cucumber (4.984) < onion (3.850) < soybean (2.039) < cabbage (0.773).

 

Based on the findings, it can be concluded that survival and condition of plants were not affected in any species following post-emergence foliar application at rates ≤0.167 lb/A (≤ 0.19 kg ai/ha). Cabbage (plant dry weight) and soy bean (plant height) were the most sensitive species with EC50 values of 0.755 and 0.773 lb/A (0.85 and 0.87 kg ai/ha), respectively.

 

Description of key information

21-d EC50 = 0.84 mg ai/kg soil dw, Seedling emergence test, Maggio 1990a

21-d NOEC = 0.084 mg ai/kg soil dw, Seedling emergence test, Maggio 1990a

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:
0.84 mg/kg soil dw
Long-term EC10, LC10 or NOEC for terrestrial plants:
0.084 mg/kg soil dw

Additional information

The toxicity to terrestrial plants endpoint was determined by two studies in a weight-of-evidence approach including a seedling emergence test (Maggio 1990a) and a vegetative vigor test (Maggio 1990b).

Seedling emergence test

Tier 2 nontarget seedling emergence studies were conducted to determine the effect of the test substance on the seedling emergence of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn and onion. The study was conducted in accordance with EPA 123 -1 and in compliance with GLP. A plexiglass template was used to create planting holes in the soil, thus allowing for uniform planting depth and distribution of the seeds planted per pot. Soybean, cucumber, oat, and corn were planted at a depth of 2.5 cm while lettuce, carrot, tomato, cabbage, ryegrass, and onion were planted at a depth of 1.3 cm. The test substance was applied to the soil surface at the rates of 0.0, 0.0185, 0.056, 0.167, 0.5, and 1.5 lb ai/A.

Through day 14, percent emergence for all rates for lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion did not differ significantly from the control. The no-effect concentration for percent emergence for the eight crops at the 14-day observation period was the maximum concentration of 1.5 lb ai/A. The no-effect concentration for soybean and cabbage was reached at 0.5 lb ai/A. Crops listed in order of increasing sensitivity to the test substance based on percent emergence no-effect concentration (lb ai/A) are: Lettuce = carrot = tomato = cucumber = oat = ryegrass = corn = onion (1.5) < soybean = cabbage (0.5). Due to a lack of significant rate effects and a lack of a true dose response for seedling emergence, a probit analysis was not conducted, therefore, EC25 and EC50 values could not be determined for soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion. Cabbage demonstrated a dose response, therefore, a probit analysis was conducted and resulted in an EC50 value of 4.520 lb ai/A. At the 21-day observation period, soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion showed no significant difference in the survival rate between the control and any rate of the test substance. Cabbage showed a reduction of 49% in percent survival at the highest concentration rate resulting in a significant difference between that rate and all others including the control, therefore, a no-effect concentration for cabbage was reached at 0.5 lb ai/A. Crops listed in order of increasing sensitivity to the test substance based on percent survival no-effect concentration (lb ai/A) are: Soybean = lettuce = carrot = tomato = cucumber = oat = ryegrass = corn = onion (1.5) < cabbage (0.5). Due to a lack of significant rate effects or a lack of a time dose response for seedling survival, a probit analysis was not conducted nor EC25 or EC50 values determined on soybean, lettuce, carrot, tomato, cucumber, oat, ryegrass, corn, and onion. Cabbage demonstrated a dose response, therefore, a probit analysis was conducted and resulted in an EC50 value of 2.536 lb ai/A.

 

At the 21-day observation period, carrot, oat, and corn showed no significant difference between the control and any of the five concentrations tested and a resultant no-effect concentration of 1.5 lb ai/A. Soybean, lettuce, tomato, cucumber, and onion all showed a significant difference between the control and the highest concentration of 1.5 lb ai/A, therefore, resulting in a no-effect concentration of 0.5 lb ai/A. The highest treatment rate (no-effect concentration) resulting in a phytotoxicity rating not statistically significant (p < 0.05) from the control at the 21-day observation period was 0.167 lb ai/A for cabbage and ryegrass. Crops listed in order of increasing sensitivity to the test substance based on phytotoxicity no-effect concentration (lb ai/A) at the 21-day observation period are: Carrot = oat = corn (1.5) < soybean = lettuce = tomato = cucumber = onion (0.5) < cabbage = ryegrass (0.167).

The statistical analysis of the plant height data of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn, and onion showed significant difference between the control and the highest concentration of 1.5 lb ai/A. The highest treatment rate (no-effect concentration) not significantly different from the control was 0.5 lb ai/A for soybean, lettuce, carrot, and cucumber. The no-effect concentration, as defined by this study for plant height, for tomato, ryegrass, corn, and onion was 0.167 lb ai/A, and 0.056 lb ai/A for cabbage and oat at the 21-day observation period. Crops listed in order of increasing sensitivity to the test substance based on plant height no-effect concentration (lb ai/A) at the 21-day observation period are: Soybean = lettuce = carrot = cucumber (0.5) < tomato = ryegrass = corn (0.167) < cabbage = oat (0.056). Lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn, and onion all demonstrated a plant height dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EC50 values were determined. Soybean did not demonstrate a true dose response, therefore, the EC25 and EC50 values were not determined. The EC50 value (lb ai/A) for each crop in order of increasing sensitivity (lb ai/A) is: Oat (58.760) < carrot (41.268) < corn (8.210) < lettuce (4.267) < tomato (3.921) < cucumber (1.564) < ryegrass (0.969) < cabbage (0.684) < onion (0.615).

 

Plant dry weight of all crops was evaluated at 21 days after treatment. Statistical analysis of the plant dry weight data showed that there was no significant difference in plant dry weight between the control and any other rates on lettuce, carrot, and cucumber resulting in a no-effect concentration of 1.5 lb ai/A. The no-effect concentration as defined by this study for soybean and oat was 0.5 lb ai/A. Tomato showed a 29% detrimental effect at the 0.5 lb ai/A concentration but was not statistically different from the control, however, it was considered biologically significant. The highest treatment rate (no-effect concentration) not significantly different from the control was 0.167 lb ai/A for tomato, ryegrass and onion, and 0.056 lb ai/A for cabbage and corn. Crops listed in order of increasing sensitivity to the test substance based on plant dry weight no-effect concentration (lb ai/A) are: Lettuce = carrot = cucumber (1.5) < soybean = oat (0.5) < tomato = ryegrass = onion (0.167) < cabbage = corn (0.056). Due to a lack of significant rate effects or a lack of a true dose response, a probit analysis was not conducted nor EC25 and EC50 values determined on lettuce, carrot, and cucumber. Soybean, tomato, cabbage, oat, ryegrass, corn, and onion all demonstrated a plant dry weight dose response, therefore, a probit analysis was conducted on the data for these crops. The EC25 value (lb ai/A) for each crop in order of increasing sensitivity to the test substance is: Oat (30.836) < corn (2.694) < tomato (2.071) < soybean (2.025) < ryegrass (1.253) < onion (1.226) < cabbage (0.562).

Based on these findings, it was concluded that emergence, survival and condition of plants were not affected in any species at rates ≤0.56 kg ai/ha. Plant dry weight and height were the most sensitive parameters with EC50 values of 0. 562 (=0.63 kg/ha or 0.84 mg a.i./kg soil dw) (cabbage) and 0.615 lb/A (=0.69 kg/ha or 0.92 mg a.i./kg soil dw) (onion), respectively. The lowest NOEC value was determined to be 0.056 lb/A (= 0.063 kg/ha or 0.084 mg a.i./kg soil dw) for cabbage, oat and corn, based on plant growth.

Vegetative vigor test

Tier 2 nontarget phytotoxicity studies were conducted to determine the effect of the test substance on the vegetative vigor of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn and onion. The study was conducted in accordance with EPA 123 -1 and in compliance with GLP.Seedlings were allowed to grow to 1-3 true-leaf stage prior to treatment, and each pot was thinned to five plants of uniform height. A single treatment of the test substance was applied with a track sprayer equipped with an overhead flat-fan nozzle at the equivalent of 50 gallons per acre (gpa) of water. The test substance was applied at the rates of 0.0, 0.0185, 0.056, 0.167, 0.5 and 1.5 lb/A.

 

At the 21-day observation period, lettuce, tomato, oat, and corn showed no significant difference (p<0.05) between the control and any of the rates tested, resulting in a NOEC of 1.5 lb/A. Carrot showed a significant difference (p < 0.05) between the control and the 0.5 lb/A rate due to minor phytotoxicity on one plant in each replicate in that treatment group. However, there was no significance between the control and the maximum concentration for carrot at the 21-day observation period, resulting in a NOEC of 1.5 lb/A. At the 7- and 14-day observation periods, lettuce and tomato showed a significant difference (p < 0.05) between the control and 0.5 lb/A concentration, however, both crops outgrew the effect by the 21-day observation period. The highest treatment rate (NOEC) resulting in a phytotoxicity rating not significant from the control at the 21-day observation period, was 0.5 lb/A for onion and 0.167 lb/A for soybean, cucumber, cabbage and ryegrass. Crops listed in order of increasing sensitivity to the test substance based on phytotoxicity NOEC (lb/A) at the 21-day observation period are: Lettuce = carrot = tomato = oat = corn (1.5) < onion (0.5) < soybean = cucumber = cabbage = ryegrass (0.167).

 

Treatment of lettuce and carrot with the test substance did not result in a significant difference (p < 0.05) in plant height at the 21-day observation period between the control and any of the rates tested.

The highest treatment rate (NOEC) not significantly different from the control was 0.5 lb ai/A for oat. The NOEC, as defined by this study for plant height, for tomato, cucumber, cabbage, and corn was 0.167 lb ai/A, 0.056 lb ai/A for soybean and onion, and 0.0185 lb ai/A for ryegrass at the 21-day observation period. With the exception of lettuce, carrot, oat, and corn, the test substance exceeded 25% reduction on plant growth at the two highest concentrations (0.5 lb ai/A and 1.5 lb ai/A) on soybean, tomato, cucumber, cabbage, ryegrass, and onion. Crops listed in order of increasing sensitivity to the test substance based on plant height NOECs (lb ai/A) at the 21-day observation period are: Lettuce = carrot (1.5) < oat (0.5) < tomato = cucumber = cabbage = corn (0.167) < soybean = onion (0.056) < ryegrass (0.0185). Due to a lack of significant rate effects in plant height or a lack of a true dose response, a probit analysis was not conducted nor EC25 and EC50 values determined on lettuce and carrot, tomato, and oat. Soybean, cucumber, cabbage, ryegrass, corn, and onion demonstrated a plant height dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EC50 values were determined. The EC50 value (lb ai/A) for each crop in order of increasing sensitivity is: Corn (6.604) < cucumber (5.547) < ryegrass (2.568) < cabbage (2.441) < onion (1.394) < soybean (0.755).

 

Statistical analysis of the plant dry weight data showed that there was no significant difference in plant dry weight between the control and any other rates on lettuce, cucumber, cabbage, oat, ryegrass, corn, and onion. Tomato produced some vigorous plants in the 0.167 lb ai/A treatment rate resulting in significance between that rate and all others including the control. The NOEC, as defined by this study for plant dry weight for tomato, was 1.5 lb ai/A. An increase in plant dry weight of carrot from 16% to 39% resulted in significance between the control and 0.0185, 0.056, 0.167 and 1.5 lb ai/A treatment rates. This response was due to vigorous plants produced in those rates. Treatment of carrot with the test substance did not result in any detrimental effects in plant dry weight and a NOECwas determined to be 1.5 lb ai/A. At 0.5 and 1.5 lb ai/A, cucumber showed a 32% and a 28% reduction in plant dry weight, respectively, but this was not statistically significant due to variability in plant dry weight in the lower rates. Cabbage showed a reduction in plant dry weight from 5% at 0.056 lb ai/A to 60% at 1.5 lb ai/A, but due to variability was not statistically significant. The non-significance in cucumber can be attributed to an increase in plant height at the 0.0185 and 0.167 lb ai/A rates were as the non-significance in cabbage can be attributed to an increase in the plant height of replicate 2 of the 0.056 lb ai/A rate. Although not statistically significant, a NOEC was determined to be 0.167 lb ai/A for cucumber, and 0.056 lb ai/A for cabbage based on biological significance. The highest treatment rate NOEC was 0.056 lb ai/A for soybean. Crops listed in order of increasing sensitivity to the test substance based on plant dry weight NOEC (lb ai/A) are: Lettuce = carrot = tomato = oat = ryegrass = com = onion (1.5) < cucumber (0.167) < soybean = cabbage (0.056). Due to the lack of significant differences in pant dry weight or a lack of a true dose response, a probit analysis was not conducted nor EC25 and EC50 values determined on lettuce, carrot, tomato, oat, ryegrass and corn. Soybean, cucumber, cabbage and onion demonstrated a plant dry weight dose response after treatment with the test substance, therefore, a probit analysis was conducted on the data for each of these crops and EC25 and EC50 values were determined. The EC50 value (lb/A) for each crop in order of increasing sensitivity is: Cucumber (4.984) < onion (3.850) < soybean (2.039) < cabbage (0.773).

 

Based on the findings, it can be concluded that survival and condition of plants were not affected in any species following post-emergence foliar application at rates ≤ 0.167lb/A (≤ 0.19 kg ai/ha). Cabbage (plant dry weight) and soy bean (plant height) were the most sensitive species with EC50 values of 0.755 and 0.773 lb/A (equivalent to 0.85 and 0.87 kg ai/ha or 1.13 and 1.16 mg ai/kg), respectively.