Prometryn

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:

4 May 1988 to 31 May 1988

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)

Deviations:

yes

Remarks:

See protocol deviation in "Any other information on materials and methods incl. tables"

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Remarks:

acetone

Details on preparation and application of test substrate:

- The test substance was applied at the rates of 0, 0.1, 0.2, 0.4, 0.8, and 1.6 lb ai/a on the initial date of the test. The rates of application on the additional treatment dates were 0, 0.019, 0.038, 0.075, 0.15, and 0.3 lb ai/a. Treatment application rates were calibrated on the weight of the test material (98% a.i.). Plants were sprayed at the equivalent of 467.7 L/ha (50 gpa) of water.
- Calculations for the spray solutions are as follows: 1. The maximum compound concentration was applied at the equivalent of 1.6 lb ai in 50 gal. of water; 2. The test spray solution of 3.834 gm ai/1 was prepared by adding 757.3 mg of the test substance in 184 ml of water and 10 ml acetone.
- Based on the side of the pot (5.35 ft2), it was calculated that 23.2 ml of liquid was required to spray each pot.
- Application: All applications were performed with a belt sprayer 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 was adjusted to obtain 23..3 ml per plot. The nozzle pressure ranged from 38 (July 19) to 66 psi (May 4). The higher nozzle pressure was used in the May 4 study to help prevent nozzle clogging by the test compound.

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Family: Leguminosae

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Lettuce
- Family: Compositae

Species:

Daucus carota

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Carrot
- Family: Umbelliferae

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Family: Solanaceae

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cucumber
- Family: Cucurbitaceae

Species:

Brassica oleracea var. capitata

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cabbage
- Family: Cruciferae

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Oat
- Family: Gramineae

Species:

Lolium perenne

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Perennial ryegrass
- Family: Gramineae

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Corn
- Family: Gramineae

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Family: Amaryllidaceae

Test type:

seedling emergence toxicity test

Study type:

laboratory study

Substrate type:

not specified

Remarks:

Obtained from the test facility

Limit test:

no

Total exposure duration:

28 d

Remarks:

Carrot amd ryegrass were exposed to the test substance for 28 days, the rest crops were exposed to the test substance for 21 days.

Test temperature:

Not recorded

pH:

Not recorded

Details on test conditions:

TEST SYSTEM
- Test container: Plastic balck growing pot (7.5 x 7.5 x 6.0 cm)
- No. of seeds per container: 10
- No. of contrainer per plant species: 1
- No. of replicates per treatment group: 3
- Thre treatment replicate was placed on an aluminum tray (6.125 x 31.125 cm). The spray plot was 3.21 x 1.67 ft, for an area of 5.35 ft2.
- After treatment, the pots were randomized within crops and among treatments and placed in greenhouse at the test facility.

SEED PLANTING
- 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 and com were planted at a depth of 2.5 cm while the remaining eight species were planted at a depth of 1.3 cm.

IRRIGATION SCHEDULE
- Plots were watered using Perfect Nozzle placed 4.0 feet apart. Irrigation duration and intervals were set for three minutes of irrigation at 9:00 am, 12:00 pm, and 3:30 pm. The irrigation cycle was monitored.
- Calculations determined that a total of 26.15 ml of water was used to irrigate each pot per day. On days in which environmental conditions reduced the irrigation requirements, pots were watered one to two times daily for an average of 8.72 and 17.4 ml per day, respectively.

EFFECT PARAMETERS MEASURED
- Seedling height and phytotoxicity ratings were recorded at 7, 14, and 21 days after treatment. In crops which the control pots exhibited less than 50% emergence, the study was continued until 28 days after treatment. Twenty-one or wenty-eight days after treatment, the plants within treatment replicates were cut at the soil level and dried in a pre-weighed paper bag. Plant material was dried at 70°C for 48 hours. After drying, the dry weight of the plant material was recorded.

CALCULATIONS
- Plant Height Measurements: Plant height was measured by extending the seedling to its maximum height and recording the height to the nearest millimeter. The mean plant height was calculated for each treatment.
- Percent Seedling Emergence: The percentage of the ten seeds planted in each plot which emerged was calculated for each treatment.
- Phytotoxicity Rating System: Plants were observed for signs of phytotoxicity resulting from the treatments. The phytotoxicity rating system used to evaluated the five observable toxic effects is as follow:
0 - indicates no injury or effect;
1 - indicates slight plant effect, or restriction to one area of the plant (e.g., a leaf);
2 - indicates a moderate effect (engrossing the whole plant - mild stunting, chlorosis);
3 - indicates a severe effect (severe leaf desiccation);
4 - indicates a total effect or plant death resulting from the compound
- Mean and Percent Effect Calculation: Treatment mean were used to calculate the percent detrimental effect resulting from the treatment. The percent effect was calculated using the following equation: % effect = [(treatment mean - control mean)/control mean] x 100

Nominal and measured concentrations:

- Nominal rate (on Initial date): 0.0, 0.1, 0.2, 0.4, 0.8 and 1.6 lb ai/a (equivalent to 0, 0.15, 0.30, 0.60, 1.20 and 2.39 mg ai/kg soil dw)
- Additional rates: 0, 0.019, 0.038, 0.075, 0.15 and 0.3 lb ai/a (equivalent to 0.028, 0.057, 0.11, 0.22 and 0.45 mg ai/kg soil dw)

Reference substance (positive control):

no

Key result

Species:

other: B. oleracea var capitata, A. cepa, C. sativus, L.sativa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.057 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks:

and dry weight

Remarks on result:

other: Equivalent to 0.038 lbs/a

Remarks:

(most sensitive species)

Key result

Species:

Brassica oleracea var. capitata

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

0.093 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks:

dry weight

Remarks on result:

other: Equivalent to 0.062 lbs/a

Remarks:

(most sensitive species)

Details on results:

Overview of the results are provided in "Any other information on results incl. tables".

PHYTOTOXICITY
- Results of the phytotoxicity rating data showed that the test substance generally did not have an effect on emerged seedling until the 14 day observation period. At the 14 and 21 observation periods, many of the emerged seedlings had died as a result of treatment with the higher rates of the test substance. Mean phytotoxicity rating of tomato plants treated with 1.6 lb ai/a increased from 0.0 to 3.9 from the 7 day to the 14 day observation period. Phytotoxicity rating showed cucumber and cabbage were the most sensitive crops tested, based on no-effect levels. Carrot did not exhibit a significant effect on phytotoxicity rating following treatment with the highest concentration tested, therefore, the no- effect level is greater or equal to 1.6 lb ai/a. Crops listed in order of increasing sensitivity to the test substance, based on phytotoxicity rating no – effect levels (corresponding no-effect level expressed in lb ai/a), are as follows: carrot (≥ 1.6 lb) < corn (0.8 lb) < soybean = ryegrass (0.4 lb) < oat (0.3 lb) < tomato (0.2 lb) < lettuce = onion (0.15 lb) < cucumber = cabbage (0.1 lb).

SEEDLING EMERGENCE
- Results of the seedling emergence data showed that the test substance did not significantly effect (p < 0.05) the percentage of seedlings emerging until after the seven day observation period, regardless of plant species or test concentration. Treatment with 1.6 lb ai/a the test substance resulted in a significant decrease (p < 0.05) in the number of established seedlings at the 21 day observation period in all crops except soybean, carrot, cucumber and oat. Since soybean, carrot, cucumber, and oat did not exhibit a significant effect on percent emergence at 1.6 lb ai/a, the no-effect level is equal to or greater than 1.6 lb ai/a. Treatment with the test substance resulted in death of many of the emerged seedlings and is represented as a decrease in percent emergence. Tomato seedlings emerging through soil treated with 1.6 lb ai/a exhibited a decrease in percent emergence from 97% to 7% from the 14 day to the 21 day observation period. Results showed that cabbage was the most sensitive crop tested to the test substance based on the percent emergence no-effect levels. Crops listed in order of increasing sensitivity to the test substance, based on the percent emergence no-effect levels (corresponding no-effect level expressed in lb ai/a), are as follows: soybean = carrot = cucumber = oat (≥ 1.6 lb) < corn (0.8 lb) < onion (0.3 lb) < ryegrass = tomato (0.2 lb) < lettuce (0.15 lb) < cabbage (0.075 lb).

EFFECT VALUES
- Soybean, cucumber, oat and corn did not exhibit a dose response curve, therefore, probit analysis could not be conducted on these crops. Probit analysis on the remaining crops showed that cabbage was the most sensitive crop to the test substance based on EC50 vales for percent emergence. Crops listed in order of increasing sensitivity to the test substance, based on EC50 value (corresponding EC50 value expressed in lb ai/a), are as follows: carrot (3.21 lb) < ryegrass (0.545 lb) < tomato (0.410 lb) < onion (0.317 lb) < lettuce ( 0.157 lb) < cabbage (0.129 lb).

- Treatment of the soil surface with 1.6 lb ai/a the test substance did not result in a significant effect (p < 0.05) on plant height at the seven day observation period, regardless of plant species or treatment concentration. All crops, except carrot, exhibited a significant decrease in the height of emerged seedling at the 21 day observation period following treatment with 1.6 lb ai/a. In many of the plant species, such as lettuce, tomato, and cabbage, treatment with the test substance resulted in death of all emerged seedlings and is reflected in a 100% decrease in plant height. Results showed that cabbage and onion were the roost sensitive crop to the test substance, based on the plant height no-effect level. The no-effect level for carrot was equal to or greater than the highest treatment concentration of 1.6 lb ai/a. Crops listed in order of increasing sensitivity to the test substance based on plant height no-effect level (corresponding no-effect level in lb ai/a), are as follows: carrot (≥1.6 lb) < corn (0.8 lb) < soybean = ryegrass (0.4 lb) < oat (0.3 lb) < tomato (0.2 lb) < cucumber (0.15 lb) < lettuce (0.075 lb) < cabbage = onion (0.038 lb).

- Carrot seedlings emerging through soil treated with the test substance did not exhibit a plant height dose response, therefore a probit analysis could not be conducted. Probit analysis on the remaining crops showed cabbage was the roost sensitive plant species tested, based on EC50 values. Crops listed in order of increasing sensitivity, based on plant height EC50 values (corresponding EC50 value in lb ai/a) are as follows: corn (4.12 lb) < soybean (0.959 lb) < oat (0.590 lb) < ryegrass (0.491 lb) < tomato (0.425 lb) < cucumber (0.284 lb) < onion (0.247 lb) < lettuce (0.168 lb) < cabbage (0.094 lb).

- Results of the plant dry weight data showed lettuce and cucumber were the most sensitive crops to the test substance, based on the statistical no-effect level. The no-effect level for carrot and ryegrass was equal to or greater than the highest treatment concentration of 1.6 lb ai/a. Crops listed in order of increasing sensitivity to the test substance, based on dry weight no-effect level (corresponding no-effect level in lb ai/a) are as follows: carrot = ryegrass ( ≥ 1.6 lb) < onion (0.3 lb) < soybean = tomato = corn (0.2 lb) < cabbage (0.1 lb) < oat (0.075 lb) < cucumber = lettuce (0.038 lb).

- Carrot and ryegrass seedlings emerging through soil treated with the test substance did not exhibit a plant dry weight dose response, therefore, probit analysis could not be conducted. Probit analysis on the remaining crops showed com was the least sensitive crop to the test substance while cabbage was the most sensitive. Crops listed in order of increasing sensitivity to the test substance, based on plant dry weight EC50 values (corresponding EC50 values in lb ai/a) are as follows:
corn (1.79 lb) < soybean (0.778 lb) < tomato (0.308 lb) < oat (0.282 lb) < onion (0.236 lb) < lettuce (0.189 lb) < cucumber (0.160 lb) < cabbage (0.062 lb ).

Reported statistics and error estimates:

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 data from the percentage seedling emergence portions of the study. A one-way analysis of variance model for data with unequal subsamples was used to analyze the seedling height data. Treatment mean separation was achieved using either MSTAT or the Lotus 1-2-3 spreadsheet. The percent detrimental effect values were input into a MSTAT probit analysis program.

Table 1. Mean phytotoxicity rating¹of the tetst crops 7, 14, and 21 days after treatment of the soil surface with the test substance.

Plant Species	Treatment (lb ai/a)	Adays after treatment^2
		7	14	21
Soybean	0.0	0.0 A^3	0.1 C	0.1 B
	0.1	0.0 A	0.0 C	0.0 B
	0.2	0.0 A	0.1 C	0.1 B
	0.4	0.0 A	0.3 C	0.7 B
	0.8	0.0 A	1.0 B	2.7 A
	1.6	0.0 A	1.5 A	3.0 A
Lettuce	0.0	0.0 A	0.0 B	0.1 A
	0.1	0.0 A	0.3 B	0.5 A
	0.2	0.0 A
	0.4	0.0 A
	0.8	0.0 A		2.0 A
	1.6	0.3 A	2.0 A	2.0 A
Lettuce	0.0	0.0 A	0.0 C	0.0 B
	0.019	0.1 A	0.0 C	0.0 B
	0.038	0.0 A	0.1 C	0.0 B
	0.075	0.0 A	0.7 BC	1.0 AB
	0.15	0.0 A	1.1 B	1.2 AB
	0.3	0.0 A	2.6 A	2.6 A
Tomato	0.0	0.0 A	0.0 B	0.0 B
	0.1	0.0 A	0.0 B	0.0 B
	0.2	0.0 A	0.8 B	0.1 B
	0.4	0.0 A	3.3 A	2.3 A
	0.8	0.0 A	3.9 A
	1.6	0.0 A	3.9 A	4.0 A
Cucumber	0.0	0.0 A	0.0 C	0.0 C
	0.1	0.0 A	0.1 C	0.4 C
	0.2	0.0 A	1.9 B	3.0 B
	0.4	0.0 A	2.9 A	4.0 A
	0.8	0.0 A	3.2 A	4.0 A
	1.6	0.0 A	3.3 A	4.0 A
Cucumber	0.0	0.0 A	0.0 C	0.0 C
	0.019	0.0 A	0.0 C	0.0 C
	0.038	0.0 A	0.0 C	0.0 C
	0.075	0.0 A	0.6 B	0.3 BC
	0.15	0.3 A	1.0 B	0.9 B
	0.3	0.0 A	2.0 A	2.9 A
Plant Species	Treatment (lb ai/a)	Adays after treatment^2
		7	14	21
Cabbage	0.0	0.0 A^3	0.0 C	0.0 A
	0.1	0.0 A	1.6 B	0.1 A
	0.2	0.0 A	4.0 A
	0.4	0.0 A	4.0 A
	0.8	0.0 A	4.0 A
	1.6	0.0 A	4.0 A
Cabbage	0.0	0.0 A	0.1 C	0.0 B
	0.019	0.0 A	0.2 C	0.2 B
	0.038	0.0 A	0.3 C	0.1 B
	0.075	0.0 A	2.8 B	3.8 A
	0.15	0.0 A	3.9 A	4.0 A
	0.3	0.0 A	4.0 A	4.0 A
Oat	0.0	0.0 A	0.0 C	0.0 C
	0.1	0.0 A	0.1 C	0.2 C
	0.2	0.0 A	0.8 BC	1.9 B
	0.4	0.0 A	1.7 B	4.0 A
	0.8	0.0 A	2.8 A	4.0 A
	1.6	0.0 A	2.6 A	4.0 A
Oat	0.0	0.0 A	0.0 A	0.0 A
	0.019	0.0 A	0.0 A	0.0 A
	0.038	0.1 A	0.0 A	0.0 A
	0.075	0.0 A	0.0 A	0.0 A
	0.15	0.0 A	0.0 A	0.0 A
	0.3	0.0 A	0.0 A	0.0 A
Corn	0.0	0.0 B	0.0 A	0.0 B
	0.1	0.0 B	0.3 A	0.1 B
	0.2	0.1 A	0.2 A	0.2 B
	0.4	0.0 B	0.3 A	0.2 B
	0.8	0.0 B	0.4 A	0.9 B
	1.6	0.0 B	0.4 A	2.0 A
Onion	0.0	0.0 A	0.0 C	0.0 C
	0.1	0.0 A	0.1 C	0.0 C
	0.2	0.0 A	1.8 B	0.9 B
	0.4	0.0 A	2.5 AB	3.1 A
	0.8	0.0 A	3.7 A
	1.6	0.0 A	3.7 A	3.0 A
Onion	0.0	0.0 A	0.0 B	0.0 B
	0.019	0.0 A	0.0 B	0.1 B
	0.038	0.0 A	0.0 B	0.0 B
	0.075	0.0 A	0.0 B	0.1 B
	0.15	0.0 A	0.3 B	0.5 AB
	0.3	0.0 A	1.3 A	1.1 A

Table 2. Mean phytotoxicity rating¹of crops 7, 14, 21 and 28 days after treatment of the soil surface with the test substance.

Plant Species	Treatment (lb ai/a)	Adays after treatment^2
		7	14	21	28
Carrot	0.0	0.0 A^3	0.0 A	0.2 A	0.0 A
	0.1	0.0 A	0.0 A	0.1 A	0.1 A
	0.2	0.0 A	0.0 A	0.1 A	0.2 A
	0.4	0.0 A	0.1 A	0.1 A	0.1 A
	0.8	0.0 A	0.4 A	0.6 A	0.0 A
	1.6	0.0 A	0.1 A	0.1 A	0.1 A
Ryegrass	0.0	0.0 A	0.0 C	0.0 C	0.0 B
	0.1	0.0 A	0.1 C	0.0 C	0.0 B
	0.2	0.0 A	0.8 BC	0.6 BC	0.5 B
	0.4	0.0 A	2.0 B	2.0 B	0.9 B
	0.8	0.0 A	3.7 A	3.7 A	3.6 A
	1.6	0.1 A	3.8 A	3.8 A	3.3 A

1.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.

2. Treatment concentrations not listing a phytotoxicity rating illustrate a treatment in which all of the emerging plants were completely decomposed.

3. Means for each plant species and observation date not followed by the same letter differ significantly according to Duncan’s New Multiple Range Test (p ≤ 0.05).

 

Table 3. Percentage of the crops seedlings emerging¹ 7, 14, and 21 days after treatment of the soil surface with the test substance. The percent detrimental effects² of each treatment was calculated.

Species	Treatment (ib ai/a)	Day after treatment
		7		14		21
		% Emergence	% Effect	% Emergence	% Effect	% Emergence	% Effect
Soybean	0.0	90 A^3		93 A		93 A
	0.1	93 A	4	97 A	4	97 A	4
	0.2	90 A	0	90 A	-4	90 A	-4
	0.4	93 A	4	97 A	4	97 A	4
	0.8	93 A	4	100 A	7	100 A	7
	1.6	90 A	0	100 A	7	100 A	7
Lettuce	0.0	60 A		63 A		60 A
	0.1	77 A	28	20 B	-68	20 B	-67
	0.2	70 A	17	0 B	-100	0 B	-100
	0.4	77 A	28	0 B	-100	3 B	-94
	0.8	83 A	39	0 B	-100	3 B	-94
	1.6	53 A	-11	3 B	-95	0 B	-100
Lettuce	0.0	67 A		73 A		77 A
	0.019	77 A	15	87 A	18	90 A	17
	0.038	83 A	25	90 A	23	97 A	26
	0.075	83 A	25	87 A	18	77 A	0
	0.15	87 A	30	90 A	23	73 A	-4
	0.3	80 A	20	37 B	-50	23 B	-70
Tomato	0.0	83 A		87 A		87 A
	0.1	83 A	0	93 A	8	93 A	8
	0.2	83 A	0	87 A	0	80 A	-8
	0.4	77 A	-8	87 A	0	43 B	-50
	0.8	87 A	4	97 A	12	0 C	-100
	1.6	80 A	-8	97 A	12	7 C	-92
Cucumber	0.0	100 A		100 A		100 A
	0.1	100 A	0	100 A	0	100 A	0
	0.2	100 A	0	100 A	0	90 A	-10
	0.4	97 A	-3	100 A	0	77 A	-23
	0.8	97 A	-3	100 A	0	87 A	-13
	1.6	93 A	-7	100 A	0	93 A	-7
Cucumber	0.0	97 A		97 A		97 A
	0.019	100 A	3	100 A	3	100 A	3
	0.038	100 A	3	100 A	3	100 A	3
	0.075	100 A	3	100 A	3	100 A	3
	0.15	97 A	0	100 A	3	100 A	3
	0.3	100 A	3	100 A	3	97 A	0
Species	Treatment (ib ai/a)	Day after treatment
		7		14		21
		% Emergence	% Effect	% Emergence	% Effect	% Emergence	% Effect
Cabbage	0.0	80A		87A		87A
	0.1	77A	-4	83A	-4	43B	-50
	0.2	87A	8	83A	-4	0C	-100
	0.4	90A	13	83A	-4	0C	-100
	0.8	87A	8	70A	-19	0C	-100
	1.6	80A	0	73A	-15	0C	-100
Cabbage	0.0	87A		90A		90A
	0.019	83A	-4	87A	-4	87A	-4
	0.038	87A	0	93A	4	93A	4
	0.075	87A	0	90A	0	83A	-7
	0.15	90A	4	93A	4	47B	-48
	0.3	90A	4	90A	0	30B	-67
Oat	0.0	97 A		97 A		97 A
	0.1	100 A	3	100 A	3	100 A	3
	0.2	100 A	3	100 A	3	100 A	3
	0.4	100 A	3	97 A	0	87 A	-10
	0.8	100 A	3	100 A	3	73 A	-24
	1.6	100 A	3	100 A	3	83 A	-14
Oat	0.0	93 A		93 A		93 A
	0.019	97 A	4	97 A	4	97 A	4
	0.038	100 A	7	97 A	4	97 A	4
	0.075	93 A	0	93 A	0	93 A	0
	0.15	100 A	7	100 A	7	100 A	7
	0.3	100 A	7	100 A	7	100 A	7
Corn	0.0	93 A		93 A		93 A
	0.1	87 A	-7	90 A	-4	93 A	0
	0.2	97 A	4	97 A	4	93 A	0
	0.4	93 A	0	100 A	7	100 A	7
	0.8	97 A	4	100 A	7	97 A	4
	1.6	100 A	7	97 A	4	77 B	-18
Onion	0.0	87 A		93 A		93 A
	0.1	80 A	-8	97 A	4	97 A	4
	0.2	70 A	-19	83 A	-11	50 B	-46
	0.4	57 A	-35	90 A	-4	23 BC	-75
	0.8	70 A	-19	77 A	-18	0 C	-100
	1.6	67 A	-23	90 A	-4	7 C	-93
Onion	0.0	77 A		83 A		83 A
	0.019	70 A	-9	80 A	-4	80 A	-4
	0.038	83 A	9	90 A	8	90 A	8
	0.075	90 A	17	87 A	4	87 A	4
	0.15	80 A	4	87 A	4	87 A	4
	0.3	80 A	4	80 A	-4	57 A	-32

1. Ten seeds were planted in each pot prior to treatment.

2. Percent detrimental effect was calculated from the raw data which was compiled using Lotus 1-2-3 software. Percent effect, variance, and standard deviation of each treatment was calculated on the raw data calculation sheets.

3. Means for each plant species and observation date not followed by the same letter differ significantly according to Duncan’s New Multiple Range Test (p ≤ 0.05).

Table 4. Percentage of carrot and ryegrass seedlings emerging¹ 7, 14, 21 and 28 days after treatment of the soil surface with the test substance. The percent detrimental effect² of each treatment was calculated.

Species	Treatment (lb ai/a)	Days after treatment
		7		14		21		28
		% Emergence	% Effect	% Emergence	% Effect	% Emergence	% Effect	% Emergence	% Effect
Carrot	0.0	3 A		70 A^3		73 A		70 A
	0.1	7 A	100	63 AB	-10	67 AB	-9	67 A	-5
	0.2	7 A	100	43 C	-38	47 C	-36	50 A	-29
	0.4	7 A	100	47 BC	-33	47 C	-36	47 A	-33
	0.8	3 A	0	47 BC	-33	53 BC	-27	43 A	-38
	1.6	3 A	0	47 BC	-33	47 C	-36	47 A	-33
Ryegrass	0.0	93 A		93 A		93 A		93 A
	0.1	93 A	0	97 A	4	97 A	4	97 A	4
	0.2	90 A	-4	93 A	0	83 A	-11	80 AB	-14
	0.4	90 A	-4	90 A	-4	77 A	-18	53 BC	-43
	0.8	80 A	-14	87 A	-7	43 B	-54	23 C	-75
	1.6	90 A	-4	87 A	-7	47 B	-50	20 C	-79

1. Ten seeds were planted in each pot prior to treatment.

2. Percent detrimental effect was calculated from the raw data which was compiled using Lotus 1-2-3 software. Percent effect, variance, and standard deviation of each treatment was calculated on the raw data calculation sheets.

3. Means for each plant species and observation date not followed by the same letter differ significantly according to Duncan’s New Multiple Range Test (p≤0.05).

Table 5. Height¹ of crops seedlings 7, 14, 21 and 28 days after treatment of the soil surface with the test substance. The percent detrimental effect² of each treatment was calculated.

Species	Treatment (ib ai/a)	Day after treatment^3
		7					14					21
		Plant height (mm)			% Effect		Plant height (mm)			% Effect		Plant height (mm)		% Effect
Soybean	0.0	18 A^4					109 AB					185 A
	0.1	23 A			26		123 A			12		189 A		2
	0.2	19 A			8		109 AB			0		182 A		-2
	0.4	14 A			-9		109 AB			-2		166 A		-10
	0.8	24 A			31		97 B			-11		96 B		-48
	1.6	21 A			18		77 C			-30		54 B		-71
Lettuce	0.0	3A					14 A					35 A
	0.1	4 A			9		11 A			-25		23 A		-34
	0.2	4 A			2					-100				-100
	0.4	4 A			15					-100		4 B		-89
	0.8	4 A			25					-100		5 B		-86
	1.6	3 A			-4		2 A			-86				-100
Lettuce	0.0	14 A					45 A					57 AB
	0.019	17 A			19		44 A			0		59 A		3
	0.038	16 A			10		44 A			-1		56 AB		-3
	0.075	16 A			12		34 AB			-23		46 BC		-19
	0.15	16 A			9		30 BC			-33		41 CD		-29
	0.3	16 A			11		19 C			-58		27 D		-52
Tomato	0.0	16 A					47 A					60 A
	0.1	15 A			-9		46 A			-3		62 A		3
	0.2	17 A			5		39 A			-17		57 A		-5
	0.4	16 A			-2		22 B			-52		52 B		-55
	0.8	16 A			-3		14 B			-71				-100
	1.6	15 A			-9		14 B			-71		8 B		-87
Cucumber	0.0	30 A					54 A					62 A
	0.1	29 A					52 A			-3		58 A		-6
	0.2	29 A			-2		42 B			-22		28 B		-55
	0.4	27 A			-210		36 C			-34		10 C		-84
	0.8	29 A			-2		31 D			-43		9 C		-85
	1.6	24 A			-18		28 D			-49		12 C		-81
Cucumber	0.0	61 A					121 A					150 A
	0.019	57 A			-8		113 AB			-6		141 A		-6
	0.038	59 A			-3		115 AB			-5		147 A		-2
	0.075	61 A			0		108 AB			-10		141 A		-6
	0.15	55 A			-10		100 B			-18		124 A		-17
	0.3	56 A			-9		69 C			-43		69 B		-54
Species	Treatment (ib ai/a)	Day after treatment
		7					14					21
		Plant height (mm)			% Effect		Plant height (mm)			% Effect		Plant height (mm)		% Effect
Cabbage	0.0	11 A					29 A					48 A
	0.1	12 A			11		23 A			-19		52 A		8
	0.2	11 A			-2		9 B			-69				-100
	0.4	10 A			-12		8 B			-71				-100
	0.8	9 A			-21		7 B			-74				-100
	1.6	9 A			-20		7 B			-77				-100
Cabbage	0.0	20 A					47 A					64 AB
	0.019	19 A			-6		46 A			-1		67 A		6
	0.038	19 A			-7		42 A			-10		60 B		-6
	0.075	18 AB			-14		24 B			-49		15 C		-76
	0.15	15 BC			-28		14 C			-71		8 C		-88
	0.3	13 C			-35		11 C			-76		7 C		-88
Oat	0.0	51 A					130 AB					208 AB
	0.1	45 A			-11		138 A			6		220 A		6
	0.2	47 A			-6		112 BC			-14		157 B		-25
	0.4	46 A			-10		97 CD			-25		86 C		-59
	0.8	48 A			-6		89 D			-31		81 C		-61
	1.6	44 A			-13		86 D			-34		75 C		-64
Oat	0.0	104 A					269 A					334 A
	0.019	104 A			0		278 A			3		348 A		4
	0.038	111 A			7		267 A			-1		341 A		2
	0.075	113 A			9		276 A			3		345 A		3
	0.15	110 A			6		263 A			-2		340 A		2
	0.3	104 A			0		253 A			-6		333 A		0
Corn	0.0	26 A					113 A					180 AB
	0.1	24 A			-8		96 A			-15		169 AB		-6
	0.2	25 A			-5		103 A			-8		189 A		5
	0.4	26 A			1		96 A			-15		167 AB		-7
	0.8	26 A			1		91 A			-19		148 BC		-18
	1.6	30 A			14		96 A			-15		121 C		-33
Onion	0.0	6 A					62 A					116 A
	0.1	5 A			-15		61 A			-3		106 B		-9
	0.2	5 A			-19		37 B			-40		67 C		-43
	0.4	5 A			-17		27 BC			-57		33 D		-71
	0.8	5 A			-27		15 C			-76				-100
	1.6	6 A			-2		13 C			-78		23 D		-80
Onion	0.0	29 A					70 A					123 A
	0.019	26 A			-9		72 A			4		117 AB		-5
	0.038	22 A			-23		73 A			4		108 AB		-12
	0.075	25 A			-15		70 A			0		93 BC		-24
	0.15	28 A			-3		59 AB			-16		74 C		-40
	0.3	24 A			-16		50 B			-29		69 C		-44
Species	Treatment (lb ai/a)		Days after treatment
			7			14			21				28
			Plant height (mm)	% Effect		Plant height (mm)		% Effect	Plant height (mm)		% Effect		Plant height (mm)		% Effect
Carrot	0.0		10 A			27 A			40 A				60 A
	0.1		11 A	10		30 A		11	46 A		13		59 A		-1
	0.2		9 A	-10		33 A		22	48 A		19		59 A		-2
	0.4		6 A	-45		29 A		8	43 A		7		61 A		1
	0.8		9 A	-10		29 A		6	36 A		-10		58 A		-4
	1.6		9 A	-10		28 A		3	42 A		5		58 A		-3
Ryegrass	0.0		17 A			78 A			142 A				162 A
	0.1		15 A	-15		63 B		-20	138 A		-3		169 A		4
	0.2		17 A	-1		45 C		-42	86 B		-39		131 A		-19
	0.4		21 A	24		44 C		-44	69 B		-51		122 A		-25
	0.8		22 A	28		33 CD		-58	22 C		-84		17 B		-90
	1.6		16 A	-9		25 D		-69	21 C		-86		20 B		-88

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

2. Percent detrimental effect was calculated from the raw data which was compiled using Lotus 1-2-3 software.

3. Treatment concentrations not listing a plant height measurement illustrate a treatment in which all of the emerged plants were completely decomposed.

4. Means for each plant species and observation date not followed by the same letter differ significantly according to Duncan's New Multiple Range Test (p ≤ 0.05).

Table 6. Mean dry weight¹of the studied crops 21 days after treatment of the soil surface with the test substance corresponding percent detrimental effect was calculated.

Plants species	Treatment (lb ai/a)	Dry weight (mg)	% effect	Plants species	Treatment (lb ai/a)	Dry weight (mg)	% effect
Soybean	0.0	198 A^2		Cabbage	0.0	42 A
	0.1	199 A	1		0.1	27 A	-35
	0.2	171 A	-14		0.2	0 B	-100
	0.4	127 B	-36		0.4	0 B	-100
	0.8	74 C	-63		0.8	0 B	-100
	1.6	82 C	-59		1.6	0 B	-100
Lettuce	0.0	8 A		Cabbage	0.0	45 A
	0.1	0 A	-100		0.019	46 A	1
	0.2	0 A	-100		0.038	29 B	-35
	0.4	0 A	-100		0.075	4 C	-91
	0.8	0 A	-100		0.15	4 C	-91
	1.6	0 A	-100		0.3	3 C	-92
Lettuce	0.0	15 A		Oat	0.0	70 A
	0.019	13 AB	-9		0.1	57 B	-18
	0.038	11 ABC	-25		0.2	24 C	-66
	0.075	8 BC	-47		0.4	9 D	-87
	0.15	6 C	-59		0.8	8 D	-89
	0.3	6 C	-58		1.6	8 D	-89
Tomato	0.0	18 AB		Oat	0.0	57 B
	0.1	22 A	25		0.019	65 A	14
	0.2	14 B	-22		0.038	57 B	0
	0.4	4 C	-76		0.075	60 AB	5
	0.8	0 C	-100		0.15	49 C	-14
	1.6	1 C	-94		0.3	42 D	-27
Cucumber	0.0	119 A		Corn	0.0	65A
	0.1	75 B	-37		0.1	57AB	-13
	0.2	29 C	-75		0.2	58AB	-10
	0.4	19 CD	-84		0.4	47BC	-28
	0.8	13 D	-89		0.8	38C	-41
	1.6	11 D	-90		1.6	36C	-45
Cucumber	0.0	140 A		Onion	0.0	9A
	0.019	131 AB	-6		0.1	7A	-18
	0.038	124 AB	-11		0.2	2B	-71
	0.075	110 BC	-21		0.4	1B	-85
	0.15	91 C	-35		0.8	0B	-100
	0.3	40 D	-71		1.6	0B	-100
Carrot	0.0	16 B		Onion	0.0	6A
	0.1	20 AB	25		0.019	7A	17
	0.2	25 A	58		0.038	7A	15
	0.4	24 A	47		0.075	6A	3
	0.8	25 A	54		0.15	6A	-5
	1.6	19 AB	21		0.3	8A	-37
Ryegrass	0.0	20 A
	0.1	21 A	1
	0.2	14 A	-32
	0.4	21 A	3
	0.8	23 A	13
	1.6	18 A	-10

1. Plants were cut at the soil level and placed in a pre-weighed 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.

2. Means for each plant species not followed by the same letter differ significantly according to Duncan’s New Multiple Range Test (p ≤ 0.05).

Validity criteria fulfilled:

yes

Conclusions:

Based on these findings, the EC50 values for dry weight are 0.872 (soybean), 0.345 (tomato), 0.179 (cucumber), 0.069 (cabbage), 0.316 (oat), 2.006 (corn), and 0.265 (onion) kg a.i./ha , EC50 for percentage of seedlings emerged were 0.176 (lettuce) and 3.598 (carrot) kg a.i./ha and EC50 for phytotoxicity ratings was 0.55 (ryegrass) kg a.i./ha. The lowest NOEC was determined to be 0.043 kg a.i./ha from lettuce, cucumber, cabbage and onion.

Executive summary:

A nontarget phytotoxicity study was performed to determine the effects of the test substance on the seedling emergence and subsequent early growth of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, com, and onion. This study followed EPA OPP 123 -1 guideline and was compliant with GLP. A plexiglass template was used to uniformly plant ten seeds of each crop in plastic pots (7.5 x 7.5 x 6.0 cm), using previously sterilised soil as the substrate. The test substance was applied to the soil by spray application in aqueous dilution at the equivalent of 467.7 L/ha of water using a belt sprayer equipped with a single nozzle. The nominal application rates were 0, 0.15, 0.30, 0.60, 1.20 and 2.39 mg a.i./kg soil dw. Due to significant effects of the high doses on seedling emergence in some species, additional treatment rates of 0.028, 0.057, 0.11, 0.22 and 0.45 mg a.i./kg soil dw were applied in a second test phase to lettuce, cucumber, cabbage, oat, and onion. Seed germination, percentage of seedlings emerged, plant height and dry weight and phytotoxicity ratings were recorded 7, 14 and 21 days after treatment.

The treatment with the test substance as described above had no significant effect on the percentage of seeds germinating or on radicle length in any of the tested plant species up to the highest test concentration equivalent to a soil concentration of 2.39 mg/kg soil dw. The radicle elongation was inhibited in only two species, tomato and oat. Probit analysis resulted in respective EC50 values of 79.8 mg/kg soil dw and 2.54 mg/kg soil dw for tomato and oat. The seedling emergence data showed that the number of established seedlings at day 21 of the study was significantly reduced in a number of plant species. Cabbage was most sensitive to this effect, and the corresponding 21-day NOEC was calculated as 0.11 mg/kg soil dw and the EC50 was calculated as 0.19 mg/kg soil dw. The substance generally had low effects on emerged seedlings until day 7 of the observation period. However, many of the emerged seedlings were severely affected or had died as a result of treatment at the 14 and 21-day observations. Phytotoxicity ratings showed that cucumber and cabbage were most sensitive to these effects. The lowest 21-day NOEC for phytotoxicity was calculated as 0.15 mg/kg soil dw. No EC50 values were provided in the study report for phytotoxicity due to the insignificance of effects. Treatment also had an inhibitory effect on the plant height at the 21-day observation. Cabbage was the most sensitive species, having a 21-day NOEC value corresponding to 0.057 mg/kg soil dw and an EC50 value of 0.14 mg/kg soil dw. Furthermore, the treatment also adversely affected the dry weight of plants on day 21 of the study. The corresponding lowest 21-day NOEC was 0.057 mg/kg soil dw (cucumber, lettuce) and the lowest EC50 was 0.093 mg/kg soil dw (cabbage). Based on these findings, the 21-day NOEC and 21-day EC50 were determined to be 0.057 and 0.093 mg/kg soil dw.

Reference 2

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 Apr 1988 to 4 May 1988

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)

Deviations:

yes

Remarks:

See protocol deviation in "Any other information on materials and methods incl. tables"

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Remarks:

acetone

Details on preparation and application of test substrate:

- A seed treatment solution concentration of 3.0 ppm is equivalent to a 1.0 lb ai/a application rate to a 3.0 inch depth. Therefore, a 1.6 lb ai/a application would be equal to a 4.8 ppm solution of the test substance. Serial dilutions were made of the maximum application solution to achieve the lower application rates. Treatment application rates were calibrated on the weight of the technical material, which was 98.1% active ingredient.
- Seven milliliters of the test solution was added to each petri plate using a pipetter.

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Family: Leguminosae

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Lettuce
- Family: Compositae

Species:

Daucus carota

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Carrot
- Family: Umbelliferae

Species:

Lycopersicon esculentum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Family: Solanaceae

Species:

Cucumis sativus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cucumber
- Family: Cucurbitaceae

Species:

Brassica oleracea var. capitata

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Cabbage
- Family: Cruciferae

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Oat
- Family: Gramineae

Species:

Lolium perenne

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Perennial ryegrass
- Family: Gramineae

Species:

Zea mays

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Corn
- Family: Gramineae

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Onion
- Family: Amaryllidaceae

Test type:

seed germination/root elongation toxicity test

Study type:

laboratory study

Substrate type:

artificial soil

Remarks:

Obtained from the test facility

Limit test:

no

Total exposure duration:

7 d

Test temperature:

25 ± 1°C

pH:

Not recorded

Details on test conditions:

TEST SYSTEM
- Test container: Plastic petri plate (100 x 15 mm, 91 mm diameter) with 2 pieces of filter paper
- No. of seeds per container: 10
- No. of replicates per treatment group: 3

TEST CONDITIONS
- Petri plates were placed in plastic boxes (12.25 x 9.0 x 4.1 inches) in which the lids were seeded with parafilm to prevent moisture loss.
- The petri plates were incubated in dark for 6 -7 days.

EFFECT PARAMETERS MEASURED
- After incubation, the seeds were removed from the petri plates and the radicle length was measured to the nearest millimeter.

CALCULATIONS
- Radicle Length Measurement: After removal of the seeds from the petri plates, the radicle length was measured to the nearest millimeter. The mean radicle length was calculated for all ten seeds placed in the petri plate.
- Percent Seed Germination: Seeds were considered germinated if the radicle was 5 mm in length or greater. The percent seed germination was calculated.

Nominal and measured concentrations:

- Nominal concentrations (Initial date): 0.0, 0.1, 0.2, 0.4, 0.8 and 1.6 lb ai/a

Reference substance (positive control):

no

Species:

Avena sativa

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

2.54 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Radicle length

Remarks on result:

other: Equivalent to 1.7 lbs/a

Remarks:

(most sensitive species)

Species:

other: all species

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

>= 2.39 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Radicle length

Remarks on result:

other: Equivalent to >= 1.6 lbs/a

Remarks:

EC50 values were not determined

Details on results:

Overview of the results are provided in the "Any other information on results incl. tables".

Results of the seed germination portion of the study showed that the test substance did not have a statistically significant (p < 0.05) effect on radicle length or the percentage of seeds germinating, regardless of plant species or treatment concentration. Since no significant differences were observed among treatments, all crops tested had a no-effect level equal to or greater than the highest treatment concentration of 1.6 lb ai/a.None of the crops tested exhibited a dose response for inhibition of radicle elongation by the test substance, except tomato and oat. Probit analysis resulted in EC50 values of 53.4 and 1.70 lb ai/a for tomato and oat seeds, respectively. Treatment with the test substance did not result in a dose response curve for seed germination, therefore, probit analysis could not be conducted.

Reported statistics and error estimates:

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 data from the seed germination (radicle length and percent germination). Treatment mean sparation was achieved using either MSTAT or the Lotus 1-2-3 spreadsheet. The percent detrimental effect values were input into a MSTAT probit analysis program.

Table 1. Radicle length and the percentage (1) of the studied crops seeds germinated six and seven days, respectively, after treatment with the test substance. The percent detrimental effect (2) was calculated for each treatment.

Plant species	Treatment (lb ai/a)	Radicle length (mm)	% Effect	% Germination	% Effect
Soybean	0.0	58 A^3		90 A
	0.1	77 A	33	97 A	7
	0.2	55 A	-6	93 A	4
	0.4	31 A	-46	97 A	7
	0.8	55 A	-5	97 A	7
	1.6	60 A	3	97 A	7
Lettuce	0.0	19 A		90 A
	0.1	22 A	16	100 A	11
	0.2	21 A	13	100 A	11
	0.4	17 A	-9	97 A	7
	0.8	22 A	20	97 A	7
	1.6	19 A	3	100 A	11
Carrot	0.0	18 A		70 A
	0.1	19 A	5	73 A	5
	0.2	23 A	28	83 A	19
	0.4	23 A	29	80 A	14
	0.8	16 A	-10	73 A	5
	1.6	18 A	4	77 A	10
Tomato	0.0	70 A		93 A
	0.1	73 A	4	97 A	4
	0.2	67 A	-5	90 A	- 4
	0.4	59 A	-15	90 A	- 4
	0.8	61 A	-13	80 A	- 14
	1.6	63 A	-10	93 A	0
Cucumber	0.0	106 A		100 A
	0.1	97 A	-9	100 A	0
	0.2	112 A	6	100 A	0
	0.4	117 A	10	100 A	0
	0.8	122 A	15	100 A	0
	1.6	114 A	7	100 A	0
Cabbage	0.0	47 A		90 A
	0.1	37 A	-21	83 A	-7
	0.2	41 A	-13	87 A	-4
	0.4	45 A	-5	87 A	-4
	0.8	39 A	-18	97 A	7
	1.6	46 A	-3	93 A	4
Oat	0.0	58 A		100 A
	0.1	67 A	16	100 A	0
	0.2	55 A	-5	100 A	0
	0.4	58 A	1	100 A	0
	0.8	44 A	-24	97 A	-3
	1.6	29 A	-49	73 A	-27
Ryegrass	0.0	44 A		90 A
	0.1	56 A	26	100 A	11
	0.2	50 A	12	93 A	4
	0.4	46 A	4	93 A	4
	0.8	43 A	-2	87 A	-4
	1.6	36 A	-19	80 A	-11
Corn	0.0	76 A		100 A
	0.1	65 A	-14	93 A	-7
	0.2	85 A	12	93 A	-7
	0.4	61 A	-19	97 A	-3
	0.8	75 A	-1	97 A	-3
	1.6	79 A	4	87 A	-13
Onion	0.0	36 A		90 A
	0.1	29 A	-19	90 A	0
	0.2	27 A	-26	87 A	-4
	0.4	24 A	-34	83 A	-7
	0.8	27 A	-25	87 A	-4
	1.6	31 A	-14	97 A	7

1. Seeds with radicle lengths exceeding 5 mm were considered germinated.

2. Percent detrimental effect was calculated from the raw data which was compiled using Lotus 1-2-3 software. Percent effect, variance, and standard deviation of each treatment was calculated on the raw data calculation sheets.

3. Means for each plant species and parameter measured not followed by the same letter differ significantly according to Duncan’s New Multiple Range Test (p ≤ 0.05).

Validity criteria fulfilled:

not specified

Conclusions:

None of the crops tested exhibited a dose response for inhibition of radicle elongation by the test substance, except tomato and oat. Based on the finding, the EC50 values for tomato and oat were determined to be 1.70 lb a.i./a (1.91 kg a.i./ha or 2.54 mg/kg soil dw) and 53.4 lb a.i./a (59.85 kg a.i./ha or 79.8 mg/kg soil dw), respectively. Treatment with the test substance did not result in a dose response curve for seed germination, therefore, probit analysis could not be conducted.

Executive summary:

A nontarget phytotoxicity study was performed to determine the effects of the test substance on the seed germination of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, com, and onion. This study followed EPA OPP 123 -1 guideline and compliant with GLP. Ten seeds of each crop were placed in a plastic petri plate containing two pieces of filter paper. Seven milliliters of the test solution were applied to each plate and the nominal concentrations of were 0.0, 0.1, 0.2, 0.4, 0.8 and 1.6 lb ai/a. The radicle length was measured after six or seven days incubation at 25°C.

Results showed that the test substance did not have a statistically significant (p <. 0.05) effect on radicle length or the percentage of seeds germinating, regardless of plant species or treatment concentration. No significant differences were observed among treatments, therefore all crops exhibited a no-effect level equal to or greater than the highest treatment concentration of 1.6 lb ai/a. None of the crops tested exhibited a dose response for inhibition of radicle elongation by the test substance, except tomato and oat. Treatment with the test substance did not result in a dose response curve for seed germination, therefore, probit analysis could not be conducted. Based on the finding, the EC50 values for tomato and oat were determined to be 1.70 lb a.i./a  (1.91 kg a.i./ha or 2.54 mg/kg soil dw) and 53.4 lb a.i./a (59.85 kg a.i./ha or 79.8 mg/kg soil dw), respectively. Treatment with the test substance did not result in a dose response curve for seed germination, therefore, probit analysis could not be conducted. The NOEC was determined to be 2.54 mg/kg soil dw for all species.

Description of key information

21-d EC50 = 0.093 mg/kg soil dw, growth (dry weight), EPA OPP 123 -1, Canez, 1988a

21-d NOEC = 0.057 mg/kg soil dw, growth (dry weight) and phytotoxicity, EPA OPP 123 -1, Canez, 1988a

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

0.093 mg/kg soil dw

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

0.057 mg/kg soil dw

Additional information

A nontarget phytotoxicity study was performed to determine the effects of the test substance on the seedling emergence and subsequent early growth of soybean, lettuce, carrot, tomato, cucumber, cabbage, oat, ryegrass, corn, and onion. This study followed EPA OPP 123 -1 guideline and was compliant with GLP. A plexiglass template was used to uniformly plant ten seeds of each crop in plastic pots (7.5 x 7.5 x 6.0 cm), using previously sterilised soil as the substrate. The test substance was applied to the soil by spray application in aqueous dilution at the equivalent of 467.7 L/ha of water using a belt sprayer equipped with a single nozzle. The nominal application rates were 0, 0.15, 0.30, 0.60, 1.20 and 2.39 mg a.i./kg soil dw. Due to significant effects of the high doses on seedling emergence in some species, additional treatment rates of 0.028, 0.057, 0.11, 0.22 and 0.45 mg a.i./kg soil dw were applied in a second test phase to lettuce, cucumber, cabbage, oat, and onion. Seed germination, percentage of seedlings emerged, plant height and dry weight and phytotoxicity ratings were recorded 7, 14 and 21 days after treatment.

 

The treatment with the test substance as described above had no significant effect on the percentage of seeds germinating or on radicle length in any of the tested plant species up to the highest test concentration equivalent to a soil concentration of 2.39 mg/kg soil dw. The radicle elongation was inhibited in only two species, tomato and oat. Probit analysis resulted in respective EC50 values of 79.8 mg/kg soil dw and 2.54 mg/kg soil dw for tomato and oat. The seedling emergence data showed that the number of established seedlings at day 21 of the study was significantly reduced in a number of plant species. Cabbage was most sensitive to this effect, and the corresponding 21-day NOEC was calculated as 0.11 mg/kg soil dw and the EC50 was calculated as 0.19 mg/kg soil dw. The substance generally had low effects on emerged seedlings until day 7 of the observation period. However, many of the emerged seedlings were severely affected or had died as a result of treatment at the 14 and 21-day observations. Phytotoxicity ratings showed that cucumber and cabbage were most sensitive to these effects. The lowest 21-day NOEC for phytotoxicity was calculated as 0.15 mg/kg soil dw. No EC50 values were provided in the study report for phytotoxicity due to the insignificance of effects. Treatment also had an inhibitory effect on the plant height at the 21-day observation. Cabbage was the most sensitive species, having a 21-day NOEC value corresponding to 0.057 mg/kg soil dw and an EC50 value of 0.14 mg/kg soil dw. Furthermore, the treatment also adversely affected the dry weight of plants on day 21 of the study. The corresponding lowest 21-day NOEC was 0.057 mg/kg soil dw (cucumber, lettuce) and the lowest EC50 was 0.093 mg/kg soil dw (cabbage). Based on these findings, the 21-day NOEC and 21-day EC50 were determined to be 0.057 and 0.093 mg/kg soil dw.