Prothioconazole/Trifloxystrobin

New York State Department of Environmental Conservation 

Division of Materials Management 

Bureau of Pest Management 

Product Registration & Pest Management Alternatives Section 

625 Broadway, Albany, New York 12233-7257 

Phone: (518) 402-8788 • Fax: (518) 402-9024 

Website: www.dec.ny.gov 

E-mail: ppr@gw.dec.state.ny.us 

Via UPS (Co. No. 264) 

Ms. Karen Cain 

Bayer CropScience LP 

2 T.W. Alexander Drive 

Research Triangle Park, NC 27709 

Dear Ms. Cain: 

August 10, 2011 

Re: Registration of a Major Change in Labeling for the Active Ingredients 

Prothioconazole and Trifloxystrobin as Contained in Stratego YLD 

Fungicide (EPA Reg. No. 264-1093) 

Joe Martens 

Commissioner 

The New York State Department of Environmental Conservation (Department) has 

evaluated your application (received September 13, 2010) and supplemental materials received 

to date in support of the registration of the above-referenced pesticide product. 

Trifloxystrobin (active ingredient code 113961) was initially registered by the 

Department on March 15, 2000 for control of foliar, stem, and root diseases in pome fruits, 

grapes, cucurbit vegetables, turfgrass, and ornamentals. The maximum application rate on food 

crops was 0.75 pounds active ingredient per acre per year. The maximum application rate on turf 

was 1.08 pounds active ingredient per acre per year. The maximum rate for seedlings and plants 

grown in greenhouses, containers and other enclosed structures was 3.75 pounds active 

ingredient per acre per year. 

Prothioconazole (active ingredient code 129112) was initially registered by the 

Department on August 7, 2009 for control of specific fungal diseases in barley, canola, chickpea, 

dried shelled peas and beans subgroup (except soybeans), lentil, rapeseed, Indian rapeseed, field 

mustard, crambe, peanut, soybean, sugar beet, and wheat. The maximum application rate was 

0.54 pounds active ingredient per acre per year. 

The major change in labeling application for Stratego YLD Fungicide proposed to add 

ground and aerial broadcast spray and irrigation application to sweet corn, field corn, and 

soybeans. The maximum labeled use rate for broadcast spray is 5 fluid ounces of product (0.04 

pounds of prothioconazole and 0.12 pounds of trifloxystrobin) per acre per application and 20

Ms. Karen Cain 2. 

fluid ounces of product (0.16 pounds of prothioconazole and 0.48 pounds of trifloxystrobin) per 

acre per year. Near the end of the technical review process, Bayer CropScience LP (Bayer) 

petitioned to add barley and wheat to the list of proposed crops. These crops were previously 

approved for prothioconazole but not trifloxystrobin. The proposed use rates for wheat and 

barley are less than or equal to the corn and soybean rates. In addition, corn and soybean acreage 

in New York State is several times higher than the acreage of wheat and barley in the State. 

Therefore, no additional review parameters were required for the wheat and barley use. 

The application package was deemed complete for purposes of technical review on 

January 27, 2011. Pursuant to the review time frame specified in Environmental Conservation 

Law §33-0704.2, a registration decision date of June 24, 2011 was established. Technical 

reviews of the proposed uses included on the Stratego YLD label have been performed by the 

Department and the New York State Department of Health. On June 2, 2011, the Department 

sent a “Technical Issues” letter to Bayer describing concerns with respect to the aerial 

application and chemigation methods of application described on the Stratego label. Bayer’s 

response was received by the Department on July 12, 2011. The Department has determined that 

Bayer’s response sufficiently mitigates the Department’s concerns. The technical reviews are 

shown below. 

HUMAN HEALTH ASSESSMENT: 

The following assessment was prepared by staff within the Bureau of Toxic Substance 

Assessment at the New York State Department of Health. 

On an acute basis, the formulated product Stratego YLD Fungicide was not very toxic 

via the oral, dermal and inhalation routes of exposure. This pesticide product did not cause skin 

or eye irritation (tested on rabbits) or skin sensitization (tested on guinea pigs). 

Trifloxystrobin 

We have previously reviewed the active ingredient trifloxystrobin for the pesticide 

products Flint Fungicide and Compass Fungicide. The available information on trifloxystrobin 

indicated that it is not very toxic or irritating following acute exposures in laboratory animals, 

but is a strong skin sensitizer. Data from chronic and developmental/reproductive toxicity 

studies showed that trifloxystrobin has the potential to cause some toxicity, principally liver 

effects. The U.S. Environmental Protection Agency (U.S. EPA) classified this chemical as “not 

likely to be carcinogenic to humans” based on a lack of evidence of carcinogenicity in rat and 

mouse chronic feeding studies. The U.S. EPA Office of Pesticide Programs (OPP) established 

an acute oral reference dose (aRfD) for females 13–49 years of age of 2.5 milligrams per 

kilogram body weight per day (mg/kg/day) based on a no-observed-effect level (NOEL) of 250 

mg/kg/day from a developmental toxicity study in rats (increased fetal skeletal anomalies) and an 

uncertainty factor of 100. The U.S. EPA OPP additionally established a chronic oral reference 

dose (cRfD) for trifloxystrobin of 0.038 mg/kg/day based on a NOEL of 3.8 mg/kg/day from a 

two-generation reproductive toxicity study in rats (decreased body weight, body weight gain and 

food consumption; liver, kidney and spleen effects) and an uncertainty factor of 100. A current


search of the toxicological literature did not find any significant new information on the toxicity 

of trifloxystrobin. 

The U.S. EPA established tolerances for trifloxystrobin residues in or on field corn, 

sweet corn and popcorn which ranged from 0.05 parts per million (ppm) to 7 ppm depending on 

the corn commodity (Federal Register Vol. 67:35,915–35,924, May 22, 2002; Vol. 71:15,597– 

15,604, March 29, 2006; and Vol. 75:33,190–33,195, June 11, 2010) and in or on soybeans of 10 

ppm (forage), 25 ppm (hay) and 0.08 ppm (seed). The U.S. EPA established an acute 

population adjusted dose (aPAD) of 2.5 mg/kg/day for females 13–49 years of age that has the 

same basis as the aRfD. The U.S. EPA estimated that the acute dietary exposure to 

trifloxystrobin residues from all crops for which there are tolerances, and from drinking water, 

would be less than one percent of the aPAD for this subgroup. The chronic population adjusted 

dose (cPAD) for trifloxystrobin for the general public and all population subgroups is 0.038 

mg/kg/day and has the same basis as the cRfD. The U.S. EPA estimated that the chronic dietary 

exposure to trifloxystrobin residues in food and drinking water from all registered uses would be 

15 percent of the cPAD for the general population, 34 percent for all infants and 43 percent for 

children 1–2 years of age, the most highly exposed subgroup. These exposure analyses are based 

on the conservative assumptions that 100 percent of the crops are treated and that these treated 

crops contain tolerance level residues. 

The U.S. EPA conducted an occupational risk assessment for short- (1–30 days) and 

intermediate-term (1–6 months) dermal and inhalation exposures to trifloxystrobin. Exposure 

estimates were created for scenarios involving aerial and groundboom application methods to 

soybeans or corn. For determining margins of exposure (MOEs), the U.S. EPA compared 

estimated short- and intermediate-term dermal exposures to a NOEL of 100 mg/kg/day from a 

28-day dermal toxicity study in rats (increased liver and kidney weights). Short- and 

intermediate-term inhalation exposures were compared to a NOEL of 3.8 mg/kg/day from a twogeneration 

reproductive toxicity study in rats (decreased body weight, body weight gain and food 

consumption; liver, kidney and spleen effects). Estimated short- and intermediate-term dermal 

MOEs were 2,100 for mixers/loaders, 20,000 for groundboom applicators, 9,600 for aerial 

applicators and 14,000 for flaggers (supporting aerial applications). The estimated MOEs for 

short- and intermediate-term inhalation exposures to trifloxystrobin were 1,500 for 

mixers/loaders, 15,000 for groundboom applicators, 27,000 for aerial applicators and 18,000 for 

flaggers. These estimates assumed that workers wore long-sleeved shirt and long pants, shoes 

plus socks and chemical resistant gloves, except for aerial applicators who are assumed not to 

wear gloves because of lowered expected exposures from engineering controls (enclosed 

cockpit). The U.S. EPA conducted a screening level assessment of dermal risks to workers 12hours 

post-application; the estimated MOE for detasseling of corn grown for seed, the highest 

potential contact activity, was 190. The U.S. EPA considered MOEs of 100-fold or greater for 

dermal and inhalation exposures to provide adequate worker protection for trifloxystrobin. 

Prothioconazole 

In the past, the New York State Department of Health reviewed the toxicological 

properties of the active ingredient prothioconazole (and prothioconazole-desthio, its primary 

metabolite/degradate) in the pesticide product Proline 480 SC Fungicide. Prothioconazole and


prothioconazole-desthio were not very acutely toxic, irritating to the eyes or skin, nor sensitizers. 

Data from chronic and developmental/reproductive animal studies indicate that both 

prothioconazole and prothioconazole-desthio have the potential to cause toxicity, with 

prothioconazole-desthio generally being more toxic than prothioconazole. However, neither 

prothioconazole nor prothioconazole-desthio (unlike many other fungicides in the triazole 

chemical class) demonstrated carcinogenic potential in laboratory animals. The U.S. EPA 

classified prothioconazole as “not likely to be carcinogenic to humans” based on the absence of 

significant tumor increases in two adequate rodent carcinogenicity studies. The U.S. EPA OPP 

established an aRfD for females 13–49 years of age of 0.02 mg/kg/day based on a NOEL of 2.0 

mg/kg/day from a developmental toxicity study in rabbits with prothioconazole-desthio 

(structural alterations and multiple malformations) and an uncertainty factor of 100. The U.S. 

EPA OPP additionally established a cRfD for prothioconazole of 0.01 mg/kg/day based on a 

NOEL of 1.1 mg/kg/day from a chronic toxicity/oncogenicity study in rats (liver histopathology) 

and an uncertainty factor of 100. A current search of the toxicological literature did not find any 

significant new information on the toxicity of prothioconazole. 

The U.S. EPA established tolerances for prothioconazole residues in or on sweet corn 

(kernel plus cob with husks removed) of 0.04 ppm and soybeans of 4.5 ppm (forage), 17 ppm 

(hay) and 0.15 ppm (seed). The U.S. EPA established an aPAD of 0.02 mg/kg/day for females 

13–49 years of age that has the same basis as the aRfD. The U.S. EPA estimated that the acute 

dietary exposure to prothioconazole residues from all crops for which there are tolerances, and 

from drinking water, would be 38 percent of the aPAD for this subgroup. The cPAD for 

prothioconazole established by the U.S. EPA for the general public and all population subgroups 

is 0.01 mg/kg/day and has the same basis as the cRfD. The U.S. EPA estimated that the chronic 

dietary exposure to prothioconazole residues in food and drinking water from all registered uses 

would be 21 percent of the cPAD for the general population, 35 percent for children 1–2 years of 

age and 62 percent for all infants (less than one year of age), the most highly exposed subgroup. 

These exposure analyses are based on the conservative assumptions that 100 percent of the crops 

are treated and that these treated crops contain tolerance level residues. 

The U.S. EPA conducted an occupational risk assessment for short- (1–30 days) and 

intermediate-term (1–6 months) dermal and inhalation exposures to prothioconazole and/or 

prothioconazole-desthio. Exposure estimates were created for scenarios involving aerial, 

chemigation and groundboom application methods to soybeans or corn. For determining MOEs, 

the U.S. EPA compared estimated short- and intermediate-term dermal exposures to a NOEL of 

30 mg/kg/day from a dermal developmental toxicity study in rats with prothioconazole-desthio 

(increased incidence of supernumerary rib). Short- and intermediate-term inhalation exposures 

were compared to a NOEL of 2 mg/kg/day from a developmental toxicity study in rabbits with 

prothioconazole-desthio (structural alterations and multiple malformations). Estimated short- 

and intermediate-term combined dermal and inhalation MOEs for mixers/loaders were 4,000 

supporting chemigation or aerial applications and 5,700 supporting groundboom applications to 

soybeans. The estimated MOEs for applicators of prothioconazole to soybeans were 11,000 for 

groundboom applications and 6,600 for aerial applications. In addition, the MOE for flaggers 

supporting aerial applications was 8,200. The estimated MOEs for short- and intermediate-term 

combined dermal and inhalation exposures to prothioconazole from application to corn were 

3,800 and 5,300 for mixers/loaders, 10,000 for groundboom applicators, 6,000 for aerial


applicators and 7,500 for flaggers. These estimates assumed that workers wore long-sleeved 

shirt and long pants, shoes plus socks and mixer/loaders additionally wore chemical resistant 

gloves. The U.S. EPA considered MOEs of 100-fold or greater for dermal and inhalation 

exposures to provide adequate worker protection for prothioconazole and prothioconazoledesthio. 

The U.S. EPA additionally conducted an occupational risk assessment for day zero postapplication 

dermal exposures to prothioconazole for several activities to soybean, corn and sweet 

corn. For determining MOEs, the U.S. EPA compared short- and intermediate-term dermal 

exposures to a NOEL of 30 mg/kg/day from the dermal developmental toxicity study in rats with 

prothioconazole-desthio. The estimated dermal MOEs for hand weeding/scouting and 

irrigation/scouting soybeans were 11,000 and 740, respectively. For the post-application 

activities to corn of scouting/weeding, irrigation/scouting and detasseling, the estimated dermal 

MOEs were 4,200, 420 and 590, respectively. The estimated MOEs for sweet corn were 110 for 

hand harvesting, 18,000 for scouting/weeding and 1,800 for irrigation/scouting. For this risk 

assessment, dermal MOEs of 100-fold or greater were considered by the U.S. EPA to provide 

adequate protection for post-application worker exposures to prothioconazole and 

prothioconazole-desthio. 

There are no chemical specific federal or New York State drinking water/groundwater 

standards for trifloxystrobin or prothioconazole (or their degradates). Based on their chemical 

structures, these chemicals each fall under the 50 microgram per liter (μg/L) New York State 

drinking water standard for “unspecified organic contaminants” (10 NYCRR Part 5, Public 

Water Systems). The New York State drinking water standard for the sum of “unspecified 

organic contaminants” and “principal organic contaminants” is 100 µg/L. 

Summary 

The available information on trifloxystrobin, prothioconazole and Stratego YLD 

Fungicide indicates that they are not very acutely toxic in laboratory animal studies. Both 

trifloxystrobin and prothioconazole were classified by the U.S. EPA as “not likely to be 

carcinogenic to humans.” Although data from subchronic, chronic and 

developmental/reproductive studies showed that these two chemicals have the potential to cause 

some toxicity, especially liver toxicity, trifloxystrobin and prothioconazole have different modes 

of action and the effects are not expected to be cumulative. Dietary exposure of the general 

public to trifloxystrobin and prothioconazole residues on currently labeled crops is not expected 

to pose significant health risks. Also, the estimated risks to workers from use of Stratego YLD 

Fungicide are within the range that is generally considered acceptable. 

Given the above, we do not object to expanding the uses of trifloxystrobin and 

prothioconazole in the state on sweet corn, field corn and soybeans on the basis of direct health 

risks from dietary and worker exposure.


ENVIRONMENTAL FATE ASSESSMENT: 

The following assessment was prepared by Engineering Geology staff within the Bureau 

of Pest Management. 

Technical Review of Trifloxystrobin 

No environmental fate information was submitted for this active ingredient, so this review was 

taken from the November 12, 1999 technical review of trifloxystrobin done for Flint and 

Compass. 

Solubility: Trifloxystrobin has a solubility of 0.61 ppm. 

. 

Hydrolysis: Trifloxystrobin was stable in pH 5, has a half-life of 55.2 days at pH 7, and 

19.8 hours at pH 9. 

Aqueous Photolysis: Trifloxystrobin had a half-life of 14.8 days; however EPA had 

problems with this study. 

Soil Photolysis: Degradation was too rapid to determine a half-life. 

Aerobic Soil Metabolism: The half-life was biphasic with an apparent half-life of 0.72 days. 

The registrant calculated half-life was 2.0-2.4 days. Degradate CGA 321113 was found at 85.2% 

at 7 days in one study, at 93.2% at day 14 in a second study, and at 84.7% at 28 days and 39.5% 

at one year in a third study. CGA-357276 was found at 4.9% at 270 days, CGA-373466 and 

CGA-357262 were each found at < 4.1% from days 90 to 365 in the second study. CGA- 

373466, CGA-357261, CGA-331409 and CGA-320299 were each found at 1% throughout the 

third study. 

Aerobic Aquatic Metabolism: EPA was not satisfied with this study, but did state that the 

study indicated that trifloxystrobin degraded rapidly in aquatic aerobic environments. 

Anaerobic Aquatic Metabolism: The half-life was 0.72 days 

Aged Leaching: EPA did not accept this study, but did indicate that degradate CGA-321113 was 

very mobile in loamy sand, sandy loam and silt loam as well as mobile in loam and clay loam. 

CGA-356276 was present in quantities too low to assess mobility. 

Adsorption-Desorption Parent: 

Soil Type Adsorption Koc Desorption Koc 

Loamy sand 2354 3294 

Sandy loam 951 1387 

Low OM sand 3064 3528 

High OM sand 3927 2202 

Clay loam 9871 2504 

Silt loam 951 1203


Adsorption-Desorption for CGA-321113: 


Loam 127 194 

Sandy soil 235 335 

Clay loam soil 130 188 






Loam 6587 8386 


Sand soil 9756 13575 

Clay soil 6934 8434 



Loam 476 587 




Sand 567 864 




Loam 98 142 


Sand 166 220 


Terrestrial Field Dissipation: Three field dissipation studies were performed, but the EPA did 

not accept any of them. The first study indicated that dissipation was biphasic with an initial 

half-life of 15.6 days and a second half-life of 182 days in a loamy sand. The parent was found 

at 158.2 ppb at day 14, dropping to 11.2 ppb at day 364, CGA-321113 was found at 156.1 ppb at 

day 78, dropping to 16.8 ppb at 364 days. It was found at the 6-12 inch depth at 32.2 ppb on day 

91, dropping to 12.4 ppb at 364 days in the 12-18 inch depth at 19.9 ppb at day 124, dropping to 

126 ppb at day 364. CGA-357262 was found in the 0-6 inch depth at a maximum of 15.8 ppb on 

day 7, dropping to 10.3 ppb on day 364. CGA-357261 was found in the 6-12 inch depth at 13.2 

ppb on day 7. CGA-373466 was found in the 0-6 inch depth at 11.6 ppb at day 92. CGA 

331409 was found in the 0-6 inch depth at 10.8 ppb on day 7.


The second study indicated an initial half-life of 1-3 days. The parent was found in the 0-6 inch 

depth at 80 ppb at 3 days, dropping to 10.2 ppb at 62 days. CGA-357261 was found in the 0-6 

inch depth at 31.4 ppb at day one, dropping to 10.5 ppb at day 13. CGA-321113 was found in 

the 0-6 inch depth at a maximum of 62.5 ppb at day one, dropping to 11.4 ppb on day 360. 

CGA-373466 was found in the 0-6 inch depth at 15.7 ppb at day 27. 

In the third study in a loamy sand, the parent was found at the 0-6 inch depth at a maximum of 

93 ppb. CGA-321113 was found in the 6-12 inch depth once at 11 ppb; CGA-474366 was found 

in the 0-6 inch depth at a maximum of 24 ppb; CGA-257261 was found once in the 0-6 inch 

depth at 18 ppb, and once in the 12-18 inch depth at 19 ppb; CGA-357262 was found once in the 

12-18 inch depth at 23 ppb. 

Technical Review of Prothioconazole 

PARENT 

Solubility: Prothioconazole has a solubility of 5 ppm at pH 4 and 300 ppm at pH 8. 

Hydrolysis: (MRID 46246505 acceptable) Prothioconazole was stable in pH 4 (>10 years), 7 

(>1 year), and 9 (>1 year) aqueous buffer solutions. 

Aqueous Photolysis: (MRID 46246507 supplemental) Prothioconazole had an environmental 

phototransformation half-life of 9.7 days with major transformation products JAU6476-desthio 

at 54.8% and JAU6476-thiazocine at 14.1% on the phenyl label, and JAU6476-desthio at 55.7% 

and 1,2,4-triazole at 11.9% in the triazole label. 

Soil Photolysis: (MRID 46246510 acceptable) Prothioconazole data indicated the same half-life 

for the irradiated samples as the dark samples, therefore phototransformation on soil does not 

appear to be a route of degradation. Major transformation product JAU6476-desthio was found 

in the irradiated sample at 38%. 

Aerobic Soil Metabolism: 

Soil 

Silt 1 

Loamy sand 1 

Sandy loam 2 

pH % OC Observed T 2 

Transformation products 

7.1 2.14 0-1 days JAU6476-desthio 49.4% 

JAU6476-S-methyl 12.8% 


JAU6476-S-methyl 14.6% 


Silty clay loam 2 


1 2 

MRID 46246511 acceptable; MRID 46246512 acceptable.


Aerobic Aquatic Soil Metabolism: 

Soil 

Water/loam 1 

Water/loamy 

sand 1 

Water/sandy 

clay loam 2 

pH 

Soil 

6.6 

8.5 

% OC 

Soil 

Observed T 2 

water/soil/system 

4.8 14.9 days water 

48.5 days system 

1.37 17.8 days water 

33.6 days system 

1-3 days water 

91-120 days system 

1 MRID 46246515 supplemental; 2 MRID 46246515 acceptable. 

Transformation products 

JAU6476-desthio 32.3 


1,2,4-triazole 37.2 

JAU6476-S-methyl 26.9 


JAU6476-S-methyl 77.0 

Aged Leaching: (MRID 46246539 supplemental) Sorption coefficients could not be 

determined due to instability of the compound in the systems. 

(MRID 46246504 acceptable) Kocs could not be calculated due to low column resolution. 

However, U.S. EPA went on to say that prothioconazole showed very little potential for leaching 

as very low total radioactive residues were detected in the leachate and very little unchanged 

parent compound was translocated below the aged soil layer. The studies also indicate that the 

parent has lower mobility than the degradates JAU6476-desthio, and JAU6476-S-methyl, and 

batch studies for these two transformation products indicate that they have low mobility. 

Terrestrial Field Dissipation: (MRID 46246517 supplemental) Field dissipation studies 

performed on a sandy loam-loam (pH 7.9, % OC 0.27) indicated an observed half-life of 7 days. 

Major transformation product JAU6476-desthio was found at 21.5%. Observed major 

transformation half-lives were JAU6476-desthio at 63 days and JAU6476-S-methyl at 14-29 

days. 

(MRID 46246518 supplemental) Field dissipation studies performed on a loamy sand-sandy 

loam (pH 6.2, % OC 1.1) indicated an observed half-life of


(MRID 46246523 supplemental) Prothioconazole dissipated in paddy water with a calculated 

half-life of 4.8 days. The half-life in the sediment/soil could not be determined due to too few 

detections. 

(MRID 46246524 supplemental) Prothioconazole dissipated in paddy water with a calculated 

half-life of 0.6 days. The half-life in the sediment/soil could not be determined due to too few 

detections. 

TRANSFORMATION PRODUCTS: 

Solubility JAU6476-desthio: The solubility of JAU6476-desthio is 22 ppm. 

Hydrolysis JAU6476-desthio: (MRID 46246506 supplemental) JAU6476-desthio was stable at 

pH 5, 7, and 9. 

Aerobic Metabolism JAU6476-desthio: (MRID 46246513 supplemental). No major 

transformation products found. 

Soil 

Silt loam 

Silt loam 

Sandy loam 

Silty clay 

pH 

7.3 

7.9 

7.2 

6.3 

% OC 

T 2 JAU6476-desthio 

linear/nonlinear/empirical 

1.55 55.5/29.4/3-7 days 

0.98 45.3/29.0/14-30 days 

1.02 22.6/6.8/3-7 days 

1.46 30.3/18.6/7-14 days 

T 2 JAU6476-desthio 

and bound residues 


165.0/144.4/


Aerobic Metabolism JAU6476-S-methyl: (MRID 46246514 supplemental). 

Soil 

Silt loam 

Silt loam 

Sandy loam 

pH 

7.3 

7.9 

7.2 

% OC T 2 JAU6476-S-methyl 


1.55 25.1/5.6/1-3 days 

0.98 47.5/26.1/14 days 

1.02 28.4/7.5/3 days 

T 2 JAU6476-S-methyl 

and bound residues 


86.6/74.5/7-14 days 

173.3/154/>125 days 

123.8/92.4/14 days 

Silty clay* 6.3 1.46 55.0/44.4/14-30 days 128.4/111.8/125 days 

*Major transformation products found only in silty clay were M2 at 10.0% and M6 24.7%. 

Adsorption/Desorption Transformation Product JAU6476-S-methyl: (MRID 462464501 

acceptable) 

Soil type 

Sandy loam 

Silt 

Silty clay loam 

Loamy sand 

pH %OC Adsorption Koc 

7.2 2.02 2772 

7.1 2.14 2995 

5.9 1.66 2484 

6.8 0.79 1973 

Desorption Koc 

3124 

3358 

2926 

2532 

Label statements: AProthioconazole-desthio (a degradate of prothioconazole) is known to leach 

through soil into groundwater under certain conditions as a result of labeled use. Use of this 

chemical in areas where soils are permeable, particularly where the water table is shallow, may 

result in ground-water contamination. 

Drift and runoff are hazardous to aquatic organisms in water adjacent to treated areas. This 

product has a high potential for runoff for several months or more after application. Poorly 

draining soils and soils with shallow water tables are more prone to produce runoff that contains 

this product. A level, well maintained vegetative buffer strip between areas to which this 

product is applied and surface water features such as ponds, streams, and springs will reduce the 

potential for contamination of water from rainfall-runoff. Runoff of this product will be reduced 

by avoiding applications when rainfall is forecasted to occur within 48 hours.@ 

Environmental Fate Summary: Given that the use rates for this product are less than those 

already allowed for use in NYS, and neither active ingredient was found to be a groundwater 

concern in past reviews, staff do not object to the use of this product on sweet corn, field corn 

and soybeans.


ECOLOGICAL EFFECTS ASSESSMENT: 

The following assessment was produced by the Department’s Bureau of Habitat 

(BOH) within the Division of Fish, Wildlife, & Marine Resources: 

Both active ingredients in Stratego YLD Fungicide have been reviewed previously by 

BOH, trifloxystrobin most recently in May 2010 and prothioconazole in May 2009. 

USE PATTERN: 

Stratego YLD Fungicide is a broad spectrum fungicide for use on corn (sweet, pop, and 

field varieties) and soybeans. Applications of 4-5 fl oz. (4.65 fl oz. upper limit on soybeans) per 

acre (/A) are made using water as the carrier. 

On sweet corn sequential applications are not allowed. Each Stratego YLD application 

must be alternated with a fungicide with a different mode of action. No more than 20 fl oz. /A 

may be applied per season. 

On field corn and soybeans two sequential applications are allowed before rotating to a 

different mode of action. The retreatment interval is 7-14 days for field corn and 10-21 days for 

soybeans. No more than 10 fl oz./A may be applied to field corn per season. The seasonal limit 

for soybeans is 13.95 fl oz/A. 

The label allows aerial, ground, and chemigation applications. 

Application rates for both Stratego YLD active ingredients individually are lower than 

those reviewed previously. The total seasonal maximum Stratego YLD combined ai application 

rate is lower than previously reviewed trifloxystrobin rates. It is 0.1 lb ai/A higher than the 

maximum previous prothioconazole rate reviewed. 

EXPOSURE MODELING & RISK ASSESSMENT: 

Terrestrial- Standard BOH post application food-item residue exposure modeling for 

birds and mammals showed no potential for acute or chronic toxicity. These two groups are not 

discussed further. 

Aquatic- Application of Stratego YLD directly to the surface of a water body, the 

condition by which aerial application threat is evaluated, results in trifloxystrobin concentrations 

that far exceed lethal values. As described in previous trifloxystrobin reviews, trifloxystrobin is 

a rapidly lethal aquatic toxin. While its half-life in water is relatively short at 14.4 hours, the 

very high toxicity, rapid lethality, and resulting multiples of LC50s far outweigh its short resident 

time. Therefore, aerial applications of Stratego YLD pose an unacceptable risk to aquatic nontarget 

organisms.


Runoff of the two active ingredients was modeled separately assuming the seasonal 

maximum rate of Stratego YLD had been applied. The resulting fish and invertebrate chronic 

toxicity is somewhat misleading. That toxicity is primarily a result of the trifloxystrobin content 

which degrades fairly rapidly in water. Exposures will not be of sufficient duration to result in 

chronic toxicity. 

One other issue requires attention. All previous prothioconazole labels, and the EPA 

Prothioconazole Pesticide Fact Sheet state that it may not be applied through any type of 

irrigation system. The Stratego YLD label allows chemigation applications. While not a 

significant fish or wildlife issue, it should be determined if this is a regulatory oversight. None 

of the materials submitted in support of registration of Stratego YLD give any explanation of this 

change. Based on the issues stated above with respect to aerial application and chemigation, 

Bureau of Habitat staff objected to the registration of the Stratego YLD as then labeled. 

In response to BOH concerns, Bayer has added a New York State aerial application 

prohibition to the label for Stratego YLD. The Bureau of Habitat has reviewed the revised 

labeling and other materials submitted and is satisfied with their content. The NY specific aerial 

application prohibition and the explanation of the chemigation label language resolve the only 

concerns BOH had with Statego YLD registration. Therefore, Bureau of Habitat staff does not 

object to registration of Stratego YLD in New York State. 

REGISTRATION DECISION 

Bayer CropScience LP has sufficiently mitigated the Department’s concerns expressed 

during the technical review of the Stratego product. Specifically, a New York State aerial 

application prohibition has been added to the Stratego YLD Fungicide label to protect aquatic 

species from a direct spray of trifloxystrobin to a water body. Therefore, the Department has 

registered Stratego YLD Fungicide (EPA Reg. No. 264-1093) for use in New York State. 

Enclosed for your record are copies of the Certificate of Pesticide Registration and stamped 

“Accepted for Registration” label. 

Please contact the Pesticide Product Registration Section, at (518) 402-8768, if you have 

any questions regarding this letter. 

Enclosures 

Sincerely, 

Scott Menrath 

Scott Menrath 

Director 

Bureau of Pest Management

Prothioconazole/Trifloxystrobin

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