UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

 WASHINGTON D.C. 20460 

 

 

 

 

O FFICE O F CHEMICAL SAFETY AND

 P O LLUTIO N PREVENTIO N

PC code: 128997

DP Barcode: D385878

May 10, 2011

Memorandum

To: Cassi L. Walls, Ph.D.

Risk Assessment Branch 3

Health Effects Division, 7509P

Lisa Jones

Risk Manager Reviewer, RM 20

Registration Division, 7505P

From: William P. Eckel, Ph.D.

Senior Science Advisor, ERB6

Environmental Fate & Effects Division, 7507P

Through: Mark Corbin, Chief

Environmental Risk Branch 6

Environmental Fate & Effects Division, 7507P

Subject: Drinking Water Assessment for Tebuconazole: Fluopyram/Tebuconazole 400 SC 

Fungicide (EPA Reg. No. 264-RNOR)

EFED has examined the use rate table (attached) for the proposed tebuconazole-fluopyram 

combination product (Fluopyram/Tebuconazole 400 SC fungicide), containing 1.67 lb/gallon of each 

active ingredient. The proposed tebuconazole use rates for all crops listed in the table are equal to, or 

lower than, rates previously assessed for the single active ingredient tebuconazole products Elite 45 

DF foliar fungicide (EPA Reg. No. 264-749) and Folicur 3.6F foliar fungicide (EPA Reg. No. 264-

752). 

The previous drinking water assessments (D311610, D311622, D313985, D319241, D319245, 

D332177, D332261, dated Feb. 7, 2007) and D362939 (dated June 3, 2009) are therefore still 

current. The EDWCs from these two assessments are reproduced below for your convenience.
EDWCs from Feb. 7, 2007 DWA

Table 1. Tebuconazole Estimated Drinking Water Concentrations from Surface Water Sources.

Scenario

Application 

Type/Annual 

Fungicide 

Application Rate 

(kg ai/ha) )

Estimated Drinking Water Concentrations (μg/L)

1 in 10 year annual 

peak

1 in 10 year 

annual mean

36 year annual 

mean

FL Turf a aerially applied

1.65 x 3 = 4.95 

96.6 c 51.4 33.7

Commercial Ornamentals

simulated with PA turfb aerially applied

0.56 x 8 = 4.48 

77.4 59.0 d 46.2 d

PA apples a airblast

0.25 x 6 = 1.50

27.4 16.6 10.9

a

- Modeled with the lowest non-sand KD as the partition coefficient input parameter. b

- Modeled with the average KOC as the partition coefficient input parameter. c

– It is the highest estimated DW peak concentration. d – These are the highest estimated DW annual mean concentrations.

EDWCs from June 3, 2009 DWA

Table 1. Maximum Estimated Drinking Water Concentrations (EDWCs) resulting from applications of 

Tebuconazole on Fruiting Vegetables (Crop Group 8)

Drinking Water 

Source (Model)

Scenario

(first app date) Method 1

Application Rate

(interval between 

applications)

1 in 10 yr 

annual 

peak (μg/L)

1 in 10 yr 

annual mean 

(μg/L)

30 yr 

annual 

mean 

(μg/L)

Surface Water 

(PRZM/EXAMS)

PCA = 0.872

PA Tomato

(September 03) A 6 app @ 0.225 lb. a.i./acre 

(7 days)

-- 16.97 12.14

FL Tomato

(April 03) G 47.23 -- --

Values denote maximum Estimated Drinking Water Concentrations (EDWCs)

1 For foliar applications, A = aerial application, G = ground application. All applications are liquid unless otherwise noted. 2 Adjustment Factors: PCA = Percent Crop Area

Note on Turf Uses: Label Uncertainties

An ecological risk assessment including the new use of tebuconazole on turf was completed in 2006 

(review dated 11/2/06; D311610+). However, the turf new use was not granted at that time.

Supplemental labeling for golf course turf and ornamentals use of tebuconazole was approved on 

April 28, 2010 for Tebuconazole 3.6F Fungicide (EPA Reg. No. 69361-27). At that time, a DWA 

was not performed. The use rates for golf course turf appear to be similar to those in the FL turf 

scenario used to generate EDWCs for the DWA performed in 2007. However, the label is unclear 

in its label directions for ornamentals (see table below).
Use Rate Analysis for Label 69361-27 Tebuconazole 3.6F Fungicide (3.6 lb a.i./gal)

Use site Maximum single 

application rate

Maximum No. of 

Applications

Minimum 

Application 

Interval

Maximum Yearly 

Use rate

Golf Course turf 0.6 fl.oz./1000 

sq.ft. = 

0.74 lb/acre

6 28 days 3.6 fl.oz./1000 

sq.ft. = 4.41 

lb/acre

Field, Nursery & 

Container 

ornamentals & 

Commercial and 

Residential 

Landscapes

4 – 10 fl.oz./acre 

= 0.11 – 0.28 

lb/acre

Preventative: “at 

least 3 times” or 

for roses, “every 

14 – 21 days 

during the 

growing season”

Petal Blight: not 

specified

Existing Disease: 

“total of 3 

applications”

14 – 21 days

“2 – 3 times per 

week”

14 days

0.84 lb/acre or 

more

Not specified

0.84 lb/acre

30 fl.oz./acre = 

0.84 lb/acre

4 at highest rate Not specified 120 

fl.oz./acre/year = 

3.38 lb/acre/year

Calculations:

Golf Course: lb/acre = fl.oz/1000 sq.ft. x 3.6 lb/gal x gal/128 fl.oz. x 43560 sq.ft./acre

Ornamentals etc.: lb/acre = fl.oz./acre x 3.6 lb/gal x gal/128 fl.oz.

Attachment: (Use rate table for Fluopyram/Tebuconazole 400 SC fungicide, and single active 

ingredient tebuconazole products Elite 45 DF foliar fungicide (EPA Reg. No. 264-749) and Folicur 

3.6F foliar fungicide (EPA Reg. No. 264-752).