Sodium azide

Toxicity to terrestrial plants

Administrative data

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2004

Materials and methods

Test guideline

Qualifier:

no guideline followed

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium azide

EC Number:

247-852-1

EC Name:

Sodium azide

Cas Number:

26628-22-8

Molecular formula:

N3Na

IUPAC Name:

sodium azide

Sampling and analysis

Analytical monitoring:

no

Details on sampling:

- Concentrations: 0, 50, 75, 100, 125, 150 lbs a.i. / acre.
which is equivalent to 0, 56, 84, 112, 140, 168 kg/ha.

Test substrate

Vehicle:

yes

Test organisms

Species:

other: Cyperus strigosus

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: false yellow nutsedge
- Plant family: Cyperaceae

Study design

Test type:

not specified

Study type:

field study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

5 h

Post exposure observation period:

SEP 100 was applied in 3/4" (1.9 cm) water during a 5 hr period and this was followed 7 days later with an additional 1" (2.54 cm) of water to move the residual material deeper in the soil profile, and 1/2" (1.27 cm) one week later right before planting of cantaloupe on 4 July. The number of weeds per metre of bed was determined for each treatment 7 July.

Test conditions

Test temperature:

no data

pH:

6.2

Moisture:

no data

Nominal and measured concentrations:

no data

Reference substance (positive control):

yes

Remarks:

methyl bromide, 350 lbs/acre (392 kg/ha)

Results and discussion

Effect concentrations

Effect concentrations 1

Species:

other: Cyperus strigosus

Duration:

5 h

Dose descriptor:

EC50

Effect conc.:

ca. 50 lbs/acre

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks on result:

other: EC50 estimated by regression of data given in figure 1

Effect concentrations 2

Species:

other: Cyprerus strigosus

Duration:

5 h

Dose descriptor:

EC50

Effect conc.:

ca. 56 kg/ha

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

phytotoxicity

Remarks on result:

other: calculated from the above value of 50 lbs/acre

Details on results:

Applications of Sodium azide at all rates reduced weed populations. The relation between numbers of weed and Sodium azide dosage was best described by a negative exponential model with the greatest reductions in weed populations obtained with doses [D] in the range 50

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

The efficacy of Sodium azide for control of weeds was studied with field experiments in 2003. Sodium azide was delivered into soil by drip irrigation using the SEP 100^R [American Pacific Corporation, Las Vegas, NV]. The compound was applied at rates within the range of 0 - 200 lbs a.i./acre (0 – 224 kg/ha) and methyl bromide [MB 67 - 33] was injected at 350 lbs/acre (392 kg/ha) to serve as positive control. The experiments were sited in fields naturally infested with severe nutsedge [Cyperus strigosus]. Effective weed control was obtained with rates of 75 lbs a.i./acre (84 kg/ha). Total and marketable yield increased significantly in response to rates of 50 and 75 lbs (56 and 84 kg/ha, respectively); however, there was no additional yield benefit obtained with the use of higher rates. Applications of Sodium azide at rates ≥100 lbs/acre (112 kg/ha) resulted in either no change or in gradual decline in yields with severe phytotoxicity observed for the two highest rates [175 & 200 lbs/acre (196 & 224 kg/ha)]. Control of root-knot, seedling and root diseases, and weeds with sodium azide at rates >75 lbs/acre (84 kg/ha) was equivalent to that obtained with methyl bromide. Results suggest that Sodium azide may be a good substitute for soil fumigation with methyl bromide in cantaloupe production.