OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

PC Code: 129223 

DP Barcode: 419898 

April 21, 2015 

MEMORANDUM

SUBJECT: Ecological Risk Assessment for the Proposed New Use of Sedaxane as a 

Seed Treatment on Sugar Beet and Cotton 

TO: Cynthia Giles-Parker, Chief

Fungicide Branch

Registration Division (7505P)

THROUGH: Dana Spatz, Branch Chief

Environmental Risk Branch 3

Environmental Fate and Effects Division

FROM: Katherine Stebbins, Biologist

Environmental Risk Branch 3

Environmental Fate and Effects Division (7507P)

PEER REVIEW: Rosanna Louie-Juzwiak, RAPL

Environmental Risk Branch 3

Environmental Fate and Effects Division

Syngenta is proposing the use of sedaxane as a seed treatment on cotton and sugar beet. The 

proposed new uses are only included on the label for Sedaxane 500FS/VibranceTM (A16148C; 

EPA Reg. No. 100-137)—the single active ingredient formulation. The proposed application rates 

for cotton and sugar beet are provide in Table 1. For these new uses, up to two applications may 

be made per year, which permits an initial planting of sedaxane treated seeds followed by either 

replanting of treated seeds in the event of crop failure or from multiple plantings as part of a 

crop rotation. 
Table 1. Proposed Sedaxane Application Rates 

Crop 

MaxApp 

Rate 

lb a.i./ 

100 lb of 

seed 

Max 

Seeding 

Ratea 

lb seed /A 

Max Single 

App Rate 

lb a.i./A 

(kg a.i./ha) 

Max Total 

App Rate 

Max 

Number of 

Apps 

PHI (days)b 

REI (hours)b 

MRI (days)b 

Minimum 

Planting 

Depth in 

Inches Per Year 

lb a.i./A 

Per Year 

lb a.i./A 

Cotton 0.02 18.8c 0.004

(0.004) 0.008 2 NS 12 0

1 (Texas 

A&M 

AgriLife 

extension

Sugar 

beet 

except 

those 

grown 

for seed

0.36 4.8d 0.017

(0.019) 0.034 2 NS 12 0 1 (MSU 

Extension)

a. The maximum seeding rate was developed based on data provided by BEAD—J. Becker; S. Ratnayake. 

Acres Planted per Day and Seeding Rates of Crops Grown in the United States, March 24, 2011.

b. PHI – Preharvest interval; REI – reentry interval; MRI – Minimum retreatment interval

c. 1 lb seed/4,500 seeds x 85,000 seeds/A = 18.8 lb seed/A

d. 1 lb seed/22,000 seeds x 104,544 seeds/A (processing sugar beets) = 4.8 lb seed/A

NS= not specified

Sedaxane is currently used to protect against certain soil-borne and seed-borne diseases. 

Registered uses include seed treatments for: small grain cereals (barley, wheat, oats, rye and 

triticale), soybean, canola, corn, sorghum, dried shelled pea and bean (Subgroup 6C; except 

soybean), rapeseed (subgroup 20A), and potato. In the latest ecological risk assessment for 

corn, sorghum, dried shelled peas and beans, chick peas, lentils, fava beans, rapeseed subgroup 

and potato pieces (03/21/13; DP: 405155,407045), 1 there were no LOC exceedances or risks 

identified for aquatic or terrestrial organisms at the two highest application rates (corn: 0.013 lb 

a.i./A applied up to two times; potato: 0.1 lb a.i./A applied once). For the proposed uses on 

cotton and sugarbeet, both the rates are lower than the highest previously assessed rate 

(potato) and the proposed sugarbeet rates are close to those previously assessed for cotton, 

thus, given the conclusions from the past assessment were that risk to aquatic and terrestrial 

organisms is considered low (no LOC exceedances), additional assessment is not needed for this 

new use. 

At this time there are insufficient data to conduct a Tier 1 assessment for risk to pollinators. 

Given that there are currently only the acute contact and oral studies available for the honeybee, 

and that sedaxane has systemic properties, the exposure and risk to pollinators cannot be 

precluded or fully assessed at this time. The additional data that are needed for conducting a 

pollinator assessment are summarized in Table 2. 

1 U.S. EPA. (2013) Ecological Risk Assessment for New Seed Treatment Uses of Sedaxane including Corn, Sorghum, 

Dried shelled Peas and Beans, Chick peas, Lentils, Fava beans, Rapeseed subgroup and Potato pieces. March 21, 

2013. 

2

 
Table 2. Recommendations for Bee Exposure and Effects Testing 

Number Study Type Is Study Needed 

Tier 1 (Non-guideline, OECD TG 

237) Honey bee larvae acute oral toxicity

Yes

No data are available to assess 

potential larval toxicity

Tier 1 (Non-guideline) Honey bee adult chronic oral toxicity

Yes

No data are available to assess

potential chronic toxicity to adult 

honey bees

Tier 1 (Non-guideline) Honey bee larvae chronic oral toxicity

Yes

No data are available to assess 

potential larval toxicity

Tier 2 (Non-guideline) Field trial of residues in pollen and 

nectar

Yes, In Reserve

No data are available to determine 

the amount of residues that may 

occur in pollen and nectar

Tier 21 (Non-guideline, OECD 

Guidance 75)

Semi-field testing for pollinators 

(tunnel or colony feeding studies)

Yes, In Reserve

These data may be needed to 

inform on potential toxicity to 

honey bees from exposure to 

sedaxane-treated plants

Tier 21(Guideline 850.3030) Honey bee toxicity of residues on 

foliage

No

Based on the existing acute contact 

adult honey bee study (i.e. 48-hour 

LD50 >98.2 ug a.i./bee) does not 

trigger the need for this study

Tier 2 and 31 (Guideline 850.3040) Field testing for pollinators

Yes, In Reserve

These data may be needed to 

inform on potential toxicity to 

honey bees from exposure to 

sedaxane-treated crops (seed 

treatment)

1Higher tier studies (Tier 2 and Tier 3) may be needed pending the results and evaluation of Tier 1 studies. Higher tier studies 

may be needed if the ratio of the EEC and larval or adult bee acute LD50 >0.4 or the ratio of the EEC and chronic NOAEC 

>1. Incident data and/or compelling open literature studies can also serve as rationale for requiring Tier 2 and Tier 3 studies.

3