crop-chem-docs/corpus/epa_ppls/264-862.md

# PROSARO 421 SC FUNGICIDE

- EPA Reg No: **264-862**
- Registrant: BAYER CROPSCIENCE, LLC
- Signal word: Caution
- Active ingredients: Prothioconazole (19%); Tebuconazole (19%)
- Label accepted: 2025-03-24
- Source PDF: https://www3.epa.gov/pesticides/chem_search/ppls/000264-00862-20250324.pdf

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March 24, 2025 
 
Daljit Singh 
Senior Regulatory Affairs Manager 
Bayer CropScience LP 
800 N. Lindbergh Blvd. 
St. Louis, MO 63167 
 
Subject: Label Amendment – Updated Environmental hazards language for surface water 
advisory and ground water advisory, Mitigation measures and Mixing 
Instructions section. Registration Review Label Amendment – Incorporating 
Mitigation Measures from the Registration Review Interim Decision for 
Prothioconazole. 
 Product Name: PROSARO 421 SC FUNGICIDE 
 EPA Registration Number: 264-862 
 Application Date: 09/30/2024 
Case Number: 00635406 
 
Dear Daljit Singh: 
 
The amended label referred to above, submitted in connection with registration under the 
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as amended, is acceptable. This 
approval does not affect any conditions that were previously imposed on this registration. You 
continue to be subject to existing conditions on your registration and any deadlines connected 
with them. 
 
The Agency, in accordance with FIFRA, as amended, has completed reviewing all the 
information submitted with your application to support the Registration Review of the above 
referenced product in connection with the Prothioconazole Interim Decision. The Agency has 
concluded that your submission is acceptable. 
 
A stamped copy of your labeling is enclosed for your records. This labeling supersedes all 
previously accepted labeling. You must submit one copy of the final printed labeling before you 
release the product for shipment with the new labeling. In accordance with 40 CFR 152.130(c), 
you may distribute or sell this product under the previously approved labeling for 12 months 
from the date of this letter. After 12 months, you may only distribute or sell this product if it 
bears this new revised labeling or subsequently approved labeling. “To distribute or sell” is 
defined under FIFRA section 2(gg) and its implementing regulation at 40 CFR 152.3.

Page 2 of 2 
EPA Reg. No. 264-862 
Case No. 00635406 
 
 
 
 
Should you wish to add/retain a reference to the company’s website on your label, then please 
be aware that the website becomes labeling under FIFRA and is subject to review by the 
Agency. If the website is false or misleading, the product would be misbranded and unlawful to 
sell or distribute under FIFRA section 12(a)(1)(E). 40 CFR 156.10(a)(5) lists examples of 
statements EPA may consider false or misleading. In addition, regardless of whether a website 
is referenced on your product’s label, claims made on the website may not substantially differ 
from those claims approved through the registration process. Therefore, should the Agency find 
or if it is brought to our attention that a website contains false or misleading statements or 
claims substantially differing from the EPA approved registration, the website will be referred 
to the EPA’s Office of Enforcement and Compliance. 
 
Your release for shipment of the product constitutes acceptance of these conditions. If these 
conditions are not complied with, the registration will be subject to cancellation in accordance 
with FIFRA section 6. 
 
If you have any questions, please contact Senedu Alemu at alemu.senedu@epa.gov. 
 
 
 Sincerely, 
 
Kable Bo Davis 
Kable Bo Davis, Senior Advisor 
FB, RD 
Office of Pesticide Programs 
 
 
 
 
 
 
Enclosure

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PROTHIOCONAZOLE GROUP 3 FUNGICIDE 
PROSARO® 421 SC Fungicide 
ABN: PROVOST® SILVER 
For control of specified diseases on various crops. 
Active Ingredients: Prothioconazole, 2-[2-(1-Chlorocyclopropyl)-3- 
(2-chlorophenyl) -2-hydroxypropyl]-1, 2-dihydro-3H-1, 2, 4-triazole-3-thione ................................................................. 19.0% 
Tebuconazole, alpha-[2-(4-chlorophenyl) ethyl]-alpha-(1, 1-dimethylethyl)-1H-1, 2, 4-triazole-1-
ethanol……………………………………………………………………………………………………………………………...19.0% 
Other Ingredients: ...................................................................................................................................................... 62.0% 
TOTAL: 100.0% 
Contains 1.76 lbs/gal of prothioconazole plus1.76 lbs/gal of tebuconazole 
EPA Reg. No. 264-862 EPA Est. 
STOP - Read the label before use 
KEEP OUT OF REACH OF CHILDREN 
CAUTION 
For MEDICAL and TRANSPORTATION Emergencies ONLY Call 24 Hours A Day 1-800-334-7577 
For PRODUCT USE Information Call 1-866-99BAYER (1-866-992-2937) 
Please refer to [back panel] [booklet] for additional precautionary statements and directions for use. [Note to 
reviewer: Location of additional precautionary statements and directions for use will vary between those listed, 
depending on container type/size.] 
 
 
03/24/2025
264-862

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FIRST AID 
IF SWALLOWED: • Call a poison control center or doctor immediately for treatment advice. 
• Do not induce vomiting unless told to do so by a poison control center or doctor. 
• Have person sip a glass of water if able to swallow. 
• Do not give anything to an unconscious person. 
IF INHALED: • Move person to fresh air. 
• If person is not breathing, call 911 or an ambulance, and then give artificial respiration, preferably 
mouth-to-mouth if possible. 
• Call a poison control center or doctor for treatment advice. 
IF ON SKIN OR 
CLOTHING: 
• Take off contaminated clothing. 
• Rinse skin immediately with plenty of water for 15-20 minutes. 
• Call a poison control center or doctor for treatment advice. 
IF IN EYES: • Hold eye open and rinse slowly and gently with water for 15-20 minutes. 
• Remove contact lenses, if present, after the first 5 minutes, then continue rinsing eye. 
• Call a poison control center or doctor for treatment advice. 
For MEDICAL Emergencies Call 24 Hours A Day 1-800-334-7577. 
Have the product container or label with you when calling a poison control center or doctor or going for treatment. 
NOTE TO PHYSICIAN: No specific antidote. Treat symptomatically. 
 
PRECAUTIONARY STATEMENTS 
HAZARDS TO HUMANS AND DOMESTIC ANIMALS 
CAUTION 
Harmful if swallowed, inhaled, or absorbed through the skin. Causes moderate eye irritation. Avoid contact with skin, eyes, and clothing. 
Avoid breathing vapor or spray mist. Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, or 
using tobacco. Remove and wash contaminated clothing before reuse. 
 
Personal Protective Equipment (PPE) 
Applicators and other handlers must wear: 
• Long-sleeved shirt and long pants 
• Chemical resistant gloves made of any waterproof material 
• Shoes plus socks 
Follow manufacturer’s instructions for cleaning/maintaining PPE. If no such instructions exist for washables, use detergent and hot 
water. Keep and wash PPE separately from other laundry. 
Engineering Control Statements 
When handlers use closed systems, enclosed cabs, or aircraft in a manner that meets the requirements listed in the Worker Protection 
Standard (WPS) for agricultural pesticides [40 CFR 170.607(d-f)], the handler PPE requirements may be reduced or modified as 
specified in the WPS. 
 
User Safety Recommendations 
Users should: 
• Wash hands before eating, drinking, chewing gum, using tobacco, or using the toilet. 
• Remove clothing/PPE immediately if pesticide gets inside. Then wash thoroughly and put on clean clothing. 
• Wash the outside of gloves before removing.

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ENVIRONMENTAL HAZARDS 
This product is toxic to mammals, fish, aquatic invertebrates, and freshwater/estuarines/marine aquatic plants. Do not apply directly to 
water, or to areas where surface water is present or to intertidal areas below the mean high water mark. Runoff may be hazardous to 
aquatic organisms in neighboring areas. Do not contaminate water when disposing of equipment washwater or rinsate. 
 
Surface Water Advisory: This product may impact surface water quality due to runoff of rainwater. This is especially true for poorly 
draining soils and soils with shallow water tables. This product is classified as having high potential for reaching surface water via runoff 
for several months after application. A level, well maintained vegetative buffer strip between areas to which this product is applied and 
surface water features including ponds, streams, and springs will reduce the potential loading of prothioconazole or degradates from 
runoff water and sediment. Runoff of this product will be reduced by avoiding applications when rainfall is forecasted to occur within 48 
hours. 
 
Groundwater Advisory: Degradates of prothioconazole are known to leach through soil into groundwater under certain conditions as a 
result of label use. These chemicals may leach into groundwater if used in areas where soils are permeable, particularly where the 
water table is shallow. 
 
DIRECTIONS FOR USE 
It is a violation of federal law to use this product in a manner inconsistent with its labeling. 
Do not apply this product in a way that will contact workers or other persons, either directly or through drift. Only protected handlers 
may be in the area during application. For any requirements specific to your State or Tribe, consult the agency responsible for pesticide 
regulation. 
DO NOT use with handheld application equipment, including backpack or mechanically/manually pressurized hand equipment. 
 
AGRICULTURAL USE REQUIREMENTS 
Use this product only in accordance with its labeling and with the Worker Protection Standard, 40 CFR part 170. This Standard contains 
requirements for the protection of agricultural workers on farms, forests, nurseries, and greenhouses, and handlers of agricultural 
pesticides. It contains requirements for training, decontamination, notification, and emergency assistance. It also contains specific 
instructions and exceptions pertaining to the statements on this label about personal protective equipment (PPE) and restricted-entry 
interval (REI). The requirements in this box only apply to uses of this product that are covered by the Worker Protection Standard. 
Do not enter or allow worker entry into treated areas during the REI of 12 hours. Some crops have longer crop-specific REIs. Crop-
specific REIs are listed in the Directions for Use section associated with the crop. 
PPE required for early entry to treated areas that is permitted under the Worker Protection Standard and that involves contact with 
anything that has been treated, including plants, soil, or water is: 
• Coveralls over long-sleeved shirt and long pants 
• Chemical-resistant gloves made of any waterproof material 
• Shoes plus socks 
 
PRODUCT INFORMATION 
PROSARO® 421 SC Fungicide is a broad-spectrum systemic fungicide for the control of Ascomycetes, Basidiomycetes and 
Deuteromycetes diseases in barley, corn (field corn, field corn grown for seed, popcorn, and sweet corn), peanut, and wheat. Under 
conditions conducive to extended infection periods or high disease pressure, another registered fungicide may be needed once this 
product’s maximum application rates have been reached. Under these conditions use another fungicide registered for the crop/disease. 
 
FUNGICIDE RESISTANCE MANAGEMENT (FRAC) RECOMMENDATIONS 
For resistance management, Prosaro 421 SC Fungicide contains Group 3 (prothioconazole and tebuconazole) fungicides. Any fungal 
population may contain individuals naturally resistant to Prosaro 421 SC Fungicide and other Group 3 (prothioconazole and 
tebuconazole) fungicides. A gradual or total loss of pest control may occur over time if these fungicides are used repeatedly in the same 
fields. Appropriate resistance-management strategies must be followed. 
 
To delay fungicide resistance, take one or more of the following steps: 
• Rotate the use of Prosaro 421 SC Fungicide or other Group 3 (prothioconazole or tebuconazole) fungicides within a growing 
season sequence with different groups that control the same pathogens. 
• Use tank mixtures with fungicide from a different group that are equally effective on the target pest when such use is 
permitted. Use at least the minimum application rate as labeled by the manufacturer. 
• Adopt an integrated disease management program for fungicide use that includes scouting, uses historical information related 
to pesticide use, and crop rotation, and which considers host plant resistance, impact of environmental conditions on disease 
development, disease thresholds, as well as cultural, biological and other chemical control practices. 
• Where possible, make use of predictive disease models to effectively time fungicide applications. Note that using predictive 
models alone is not sufficient to manage resistance. 
• Monitor treated fungal/bacterial populations for resistance development.

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• Contact your local extension specialist or certified crop advisor for any additional pesticide resistance-management and/or IPM 
recommendations for specific crops and pathogens. 
• For information or to report suspected resistance contact Bayer CropScience at 1-866-99BAYER (1-866-992-2937). 
 
You can also contact your pesticide distributor or university extension specialist to report resistance. 
 
Spray Equipment/Volumes 
PROSARO 421 SC FUNGICIDE may be applied by either ground, aerial and/or chemigation application equipment. Equipment must be 
properly calibrated before use. 
For ground application, a pply in a minimum of 10 gallons of spray solution per acre. For aerial application, apply in a minimum of 2 
gallons of spray solution per acre unless stated differently in the USE DIRECTIONS FOR SPECIFIC CROPS section. Check equipment 
calibration frequently. Complete coverage and uniform application are essential for the most effective results, especially when lower 
spray volumes are applied. If necessary, increase the spray volume per acre for complete crop coverage. 
Mixing Procedures 
Prepare no more spray mixture than is necessary for the immediate operation. Thoroughly clean spray equipment before using this 
product. Maintain maximum agitation throughout the spray operation. Do not let the spray mixture stand overnight in the spray tank . 
Flush the spray equipment thoroughly following each use and apply the rinsate to the previously treated area or dispose of the rinsate 
according to local regulations . Do not tank mix with products containing a prohibition against tank mixing. Follow the most restrictive 
labeling requirements of any tank mix product. 
 
NOTE: Thoroughly mix contents before use and application. Recirculate or mix the product for at least 5 minutes prior to each use. For 
large containers, 15 gallons containers or more, mix the product with the built-in mixer for 5-10 minutes before each use. 
 
PROSARO 421 SC FUNGICIDE Alone: Add ½ of the required amount of water to the mix tank . With the agitator running, add the 
PROSARO 421 SC FUNGICIDE to the tank . Continue agitation while adding the remainder of the water . Begin application of the 
solution after the product has completely and uniformly dispersed into the mix water . Maintain agitation until all of the mixture has been 
applied. 
 
PROSARO 421 SC FUNGICIDE + Tank-Mix Partners: Add ½ of the required amount of water to the mix tank . Start the agitator 
running before adding any of the tank -mix partners. In general, tank -mix partners must be added in this order: products packaged in 
water-soluble packaging*, wettable powders, wettable granules (dry flowables), liquid flowables, liquids, and emulsifiable concentrates. 
Always allow each tank-mix partner to become fully and uniformly dispersed before adding the next product . Provide sufficient agitation 
while adding the remainder of the water. Maintain agitation until all of the mixture has been applied. 
* Note: When using PROSARO 421 SC FUNGICIDE in tank mixtures, all products in water -soluble packaging must be added to the 
tank before any other tank -mix partner, including PROSARO 421 SC FUNGICIDE . Allow the water -soluble packaging to completely 
disperse before adding any other tank-mix partner to the tank. 
If using PROSARO 421 SC FUNGICIDE in a tank mixture, observe all directions for use, crop/sites, use rates, dilution ratios, 
precautions, and limitations; which appear on the tank -mix product label . No label dosage rate must be exceeded, and the most 
restrictive label precautions and limitations must be followed. This product must not be mixed with any product that prohibits such 
mixing. Tank mixtures or other applications of products referenced on this label are permitted only in those states in which the 
referenced products are registered. 
PROSARO 421 SC FUNGICIDE is compatible with most insecticide, fungicide, herbicide, and foliar nutrient products . However, the 
physical compatibility of PROSARO 421 SC FUNGICIDE with tank-mix partners must be tested before use. To determine the physical 
compatibility of PROSARO 421 SC FUNGICIDE with other products, use a jar test, as described below. 
Using a quart jar, add the proportionate amounts of the products to 1 qt. of water . Add wettable powders and water-dispersible granular 
products first, then liquids and emulsifiable concentrates last. After thoroughly mixing, let stand for at least 5 minutes. If the combination 
remains mixed or can be remixed readily, it is physically compatible. Once compatibility has been proven, use the same procedure for 
adding required ingredients to the spray tank. For information, contact your local Bayer CropScience representative. 
The crop safety of all potential tank mixes including additives and other pesticides on all crops has not been tested. Before applying any 
tank mixture not specifi ed on this label, the safety to the target crop must be confirmed. To test for crop safety, apply PROSARO 421 
SC FUNGICIDE to the target crop in a small area and in accordance with label instructions for the target crop. 
Aerial Application: Avoid application under conditions when uniform coverage cannot be obtained or when excessive spray drift may 
occur. Aerial application is prohibited in New York State. 
Chemigation Application: Apply PROSARO 421 SC FUNGICIDE through irrigation equipment only to crops for which chemigation is 
specified on this label. 
PROSARO 421 SC FUNGICIDE alone or in combination with other pesticides, which are registered for application through irrigation 
systems, may be applied through irrigation systems. Apply this product only through center pivot, solid set, hand move, or moving 
wheel irrigation systems. Do not apply this product through any other type of irrigation system. Illegal pesticide residues i n the crop can 
result from nonuniform distribution of treated water. If you have questions about c alibration, you must contact State Extension Service 
specialists, equipment manufacturers, or other experts. Do not connect an irrigation system (including greenhouse systems) us ed for

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pesticide application to a public water system, unless the pesticide label -prescribed safety devices for public water systems are in 
place. A person knowledgeable of the chemigation system and responsible for its operation, or under the supervision of the responsible 
person, shall shut the system down and make necessary adjustments if the need arises.

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Operating Instructions 
1. The system must contain a functional check-valve, vacuum relief valve, and low-pressure drain appropriately located on the irrigation 
pipeline to prevent water-source contamination from backflow. 
2. The pesticide injection pipeline must contain a functional, automatic, quick -closing check -valve to prevent the flow of fluid back 
toward the injection pump. 
3. The pesticide injection pipeline must also contain a functional, normally closed, solenoid-operated valve located on the intake side of 
the injection pump and connected to the system interlock to prevent fluid from being withdrawn from the supply tank when the irrigation 
system is either automatically or manually shut down. 
4. The system must contain functional interlocking controls to automatically shut off the pesticide injection pump when the w ater pump 
motor stops. 
5. The irrigation line or water pump must include a functional pressure switch, which will stop the water pump motor when the water 
pressure decreases to the point where pesticide distribution is adversely affected. 
6. Systems must use a metering pump, for example a positive displacement injection pump (e.g. , diaphragm pump), effectively 
designed, and constructed of materials that are compatible with pesticides and capable of being fitted with a system interlock. 
7. Do not apply when wind speed favors drift beyond the area intended for treatment. 
 
Center Pivot Irrigation Equipment 
Notes: (1) Use only with drive systems, which provide uniform water distribution. (2) Do not use end guns when chemigation 
PROSARO 421 SC FUNGICIDE through center pivot systems because of non-uniform application. 
Determine the size of the area to be treated. Determine the time required to apply 1/8- 1/2 inch of water over the area to be treated 
when the system and injection equipment are operated at normal pressures as specified by the equipment manufacturer. When 
applying PROSARO 421 SC FUNGICIDE through irrigation equipment use the lowest obtainable water volume while maintaining 
uniform distribution. Run the system at 80-95% of the manufacturer’s rated capacity. Using water, determine the injection pump output 
when operated at normal line pressure. Determine the amount of PROSARO 421 SC FUNGICIDE required to treat the area covered by 
the irrigation system. Add the required amount of PROSARO 421 SC FUNGICIDE and sufficient water to meet the injection time 
requirements to the solution tank. Make sure the system is fully charged with water before starting injection of the PROSARO 421 SC 
FUNGICIDE solution. Time the injection to last at least as long as it takes to bring the system to full pressure. Maintain constant 
solution tank agitation during the injection period. Continue to operate the system until the PROSARO 421 SC FUNGICIDE Fungicide 
solution has cleared the sprinkler head. 
Solid Set, Hand Move, and Moving Wheel Irrigation Equipment 
When applying PROSARO 421 SC FUNGICIDE through irrigation equipment use the lowest obtainable water volume while maintaining 
uniform distribution. Determine the amount of PROSARO 421 SC FUNGICIDE required to treat the area covered by the irrigation 
system. Add the required amount of PROSARO 421 SC FUNGICIDE into the same quantity of water used to calibrate the injection 
period. Operate the system at the same pressure and time interval established during the calibration. Stop injection equipment after 
treatment is completed. Continue to operate the system until the PROSARO 421 SC FUNGICIDE solution has cleared the last sprinkler 
head. 
Adjuvants: PROSARO 421 SC FUNGICIDE is advised to be used with a registered non-ionic surfactant at the lowest specified labeled 
rate for most uses. Refer to the USE DIRECTIONS FOR SPECIFIC CROPS for adjuvant recommendations on corn. 
SPRAY DRIFT ADVISORIES 
The applicator is responsible for avoiding off-site spray drift. Be aware of nearby non-target sites and environmental conditions. 
 
Importance of Droplet Size 
An effective way to reduce spray drift is to apply large droplets. Use the largest droplets that provide target pest control. While applying 
larger droplets will reduce spray drift, the potential for drift will be greater if applications are made improperly or under unfavorable 
environmental conditions. 
Controlling Droplet Size - Ground Boom 
• Volume -Increasing the spray volume so that larger droplets are produced will reduce spray drift. Use the highest practical 
spray volume for the application. If a greater spray volume is needed, consider using a nozzle with a higher flow rate. 
• Pressure -Use the lowest spray pressure specified for the nozzle to produce the target spray volume and droplet size. 
• Spray Nozzle -Use a spray nozzle that is designed for the intended application. Consider using nozzles designed to reduce 
drift. 
 
Controlling Droplet Size – Aircraft 
Adjust Nozzles - Follow nozzle manufacturers recommendations for setting up nozzles. Generally, to reduce fine droplets, orient 
nozzles parallel with the airflow in flight. 
Boom Height-Ground Boom 
For ground equipment, the boom must remain level with the crop and have minimal bounce. 
Release Height – Aircraft 
Higher release heights increase the potential for spray drift. 
Shielded Sprayers 
Shielding the boom or individual nozzles can reduce spray drift. Consider using shielded sprayers. Verify that the shields are not 
interfering with the uniform deposition of the spray on the target area.

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Temperature And Humidity 
When making applications in hot and dry conditions, use larger droplets to reduce effects of evaporation. 
Temperature Inversions 
Drift potential is high during a temperature inversion. Temperature inversions are characterized by increasing temperature with altitude 
and are common on nights with limited cloud cover and light to no wind. The presence of an inversion can be indicated by ground fog or 
by the movement of smoke from a ground source or an aircraft smoke generator. Smoke that layers and moves laterally in a 
concentrated cloud (under low wind conditions) indicates an inversion, while smoke that moves upward and rapidly dissipates indicates 
good vertical air mixing. Avoid applications during temperature inversions. 
Wind 
Drift potential generally increases with wind speed. AVOID APPLICATIONS DURING GUSTY WIND CONDITIONS. Applicators need to 
be familiar with local wind patterns and terrain that could affect spray drift. 
 
ROTATIONAL RESTRICTIONS 
Treated areas may be replanted with dry beans, peanuts and soybeans as well as any crop specified on this label as soon as practical 
after last application. For additional crops, do not plant back within 120 days of last application.

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USE DIRECTIONS FOR SPECIFIC CROPS 
PROSARO 421 SC FUNGICIDE provides control or suppression of many important diseases of barley, corn (field corn, field corn grown 
for seed, popcorn, and sweet corn), peanut, and wheat . When reference is made to disease suppression, suppression can mean either 
erratic control from good to fair or consistent control at a level below that obtained with the best commercial disease control products. 
 
APPLICATION DIRECTIONS 
CROP DISEASE CONTROLLED RATE OF PROSARO 421 SC FUNGICIDE 
 
Barley 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fusarium Head Blight (Suppression) 
(Fusarium spp.) 
 
Leaf and Stem Diseases 
Net Blotch 
(Pyrenophora teres) 
 
Powdery Mildew 
(Blumeria graminis f. sp. hordei) 
 
Scald 
(Rhynchosporium secalis) 
 
Spot Blotch 
(Bipolaris sorokiniana) 
 
Rusts (Puccinia spp.) 
 
 
 
 
 
 
 
 
 
 
6.5 - 8.2 fl oz per acre 
 
 Application Directions: Straw cut after harvest may be fed or used for bedding. 
 
Spray Equipment/Volumes: PROSARO 421 SC FUNGICIDE may be applied by either ground, aerial or 
chemigation application equipment. For ground applications, apply a minimum of 10 gpa spray solution. For aerial 
applications, apply a minimum of 2 gpa spray solution. When applied through chemigation, large carrier volumes 
may result in reduced activity against Fusarium head blight. 
Disease Control: 
Fusarium Head Blight (Suppression Only): 
The optimal time to apply PROSARO 421 SC FUNGICIDE is as a preventative foliar spray when barley heads on 
the main stem are fully emerged (~ Feekes Growth Stage 10.5). Spray equipment must be set to provide good 
coverage of barley heads. For thorough coverage of the barley head using ground application equipment, use 
forward, forward and backward mounted nozzles, or nozzles that have a two-directional spray. Nozzles must be 
operated within the spray pressure directions suggested by the manufacturer. For aerial applications, apply a 
minimum of 5 gpa spray solution. 
 
Leaf and Stem Diseases: 
Apply PROSARO 421 SC FUNGICIDE as a preventive foliar spray when the earliest disease symptoms appear on 
the leaves and stems. Barley fields must be observed closely for early disease symptoms, particularly when 
susceptible varieties are planted and/or under prolonged conditions favorable for disease development. 
 
For optimum disease control, the lowest specified rate of a spray surfactant must be tank-mixed with PROSARO 
421 SC FUNGICIDE. 
Restrictions: Do not apply more than 8.2 fl oz of Prosaro 421 SC Fungicide per acre per crop year. Do not apply within 30 days of 
harvest. Grazing livestock or feeding of green forage is only permitted 6 or more days after the last application of PROSARO 421 SC 
FUNGICIDE. DO NOT use with handheld application equipment, including backpack or mechanically/manually pressurized hand 
equipment.

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APPLICATION DIRECTIONS 
CROP DISEASE RATE OF PROSARO 421 SC FUNGICIDE 
Corn1 
(field corn, field 
corn grown for 
seed, popcorn 
and sweet corn) 
Anthracnose 
(Colletotrichum graminicola) 
 
Eye spot 
(Aureobasidium zeae) 
 
Gray leaf spot 
(Cercospora zeae-maydis) 
 
Northern corn leaf blight 
(Setosphaeria turcica)* 
 
Northern corn leaf spot 
(Cochliobolus carbonum)* 
 
Rust 
(Puccinia spp.) 
 
Southern corn leaf blight 
(Cochliobolus heterostrophus)* 
 
*The above diseases are also known as 
Helminthosporium leaf blights 
 
 
 
 
 
 
 
 
 
 
6.5 fl oz per acre 
Application Directions: 
Spray Equipment/Volumes: PROSARO 421 SC FUNGICIDE may be applied by either ground, aerial or 
chemigation application equipment. For ground applications, apply a minimum of 10 gpa spray solution. For aerial 
applications, apply a minimum of 2 gpa spray solution. 
 
Adjuvants: Under some conditions, the lowest specified labeled rate of a spray adjuvant may be tank-mixed with 
PROSARO 421 SC FUNGICIDE to improve performance. 
 
Disease Control: Apply PROSARO 421 SC FUNGICIDE when disease first appears. In sweet corn, continue 
applications on a 5- to 14-day interval if favorable conditions for disease development persist. In all other corn, 
continue applications on a 7- to 14-day interval if favorable conditions for disease development persist. Application 
of PROSARO 421 SC FUNGICIDE is not advised at times when corn is under severe environmental stress 
conditions. 
 
Restrictions: Do not apply more than 26 fl oz of PROSARO 421 SC FUNGICIDE per acre per crop season. For field corn, field corn 
grown for seed and popcorn, do not apply within 21 days before the harvest of forage and 36 days before the harvest of grain or 
fodder. For sweet corn, do not apply within 7 days before harvest of ears or forage and 49 days before the harvest of fodder. 
Do not use adjuvants if PROSARO 421 SC FUNGICIDE is applied between corn growth stages V8 (8 leaf collar) and VT (lowest 
branch of the tassel is visible but silks have not emerged). DO NOT use with handheld application equipment, including backpack or 
mechanically/manually pressurized hand equipment. 
 
1 Not for use on corn in New York.

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APPLICATION DIRECTIONS 
CROP DISEASE RATE OF PROSARO 421 SC FUNGICIDE 
Peanut 
Foliar diseases 
 
Early Leaf Spot 
(Cercospora arachidicola) 
 
Late Leaf Spot 
(Cercosporidium personatum) 
 
Leaf Rust 
(Puccinia arachidis) 
 
Web Blotch 
(Phoma arachidicola) 
 
Leaf Scorch and Pepper Spot 
(Leptosphaerulina crassiasca) 
 
10 - 13 fl oz per acre 
 
 
Soil-Borne diseases 
 
Sclerotium Rot, White Mold, 
Southern Blight, Southern Stem Rot 
(Sclerotium rolfsii) 
 
Rhizoctonia Limb Rot, Peg Rot, Pod Rot (Rhizoctonia 
solani) 
 
Cylindrocladium Black Rot 
(Cylindrocladium crotalariae) 
(Suppression Only) 
 
13 fl oz per acre 
Application Directions: PROSARO 421 SC FUNGICIDE may be applied by ground, chemigation, or aerial application equipment. 
 
Disease Control Program: For foliar diseases, apply the specified rate in a preventive spray schedule using a 14 day interval. For 
optimum control of the specified soil-borne diseases, it is advised that four consecutive applications of PROSARO 421 SC FUNGICIDE 
be made at 14-day intervals. In a typical 7 spray application program, PROSARO 421 SC FUNGICIDE must be applied in a block 
(sprays 3, 4, 5 and 6). If fewer than 7 calendar-based applications are typically made, the number of consecutive block sprays with 
PROSARO 421 SC FUNGICIDE can be reduced accordingly. For control of soil-borne diseases when using a Leaf Spot Advisory 
Program schedule, apply PROSARO 421 SC FUNGICIDE in the first advisory spray in July and continue applications at 14-day 
intervals for at least three applications. Soil-borne disease control will be improved with four applications. PROSARO 421 SC 
FUNGICIDE must be carried by rainfall or irrigation into the root and pod zone for control of root and pod rots. Use the higher specified 
use rate when conditions are favorable for severe disease pressure and/or when growing less disease resistant varieties. 
 
For resistance management: No more than 4 foliar applications of fungicides containing sterol biosynthesis inhibitors (Group 3) are 
recommended per season for resistance management. Applications of fungicides with a different mode of action must be made prior to 
and following block applications of PROSARO 421 SC FUNGICIDE to discourage development of resistant strains of fungi. Use in 
conjunction with cultural practices that are known to reduce the severity of soil-borne diseases, including proper crop rotation practices. 
Restrictions: Do not apply more than 52 fl oz per acre of PROSARO 421 SC FUNGICIDE per season. Do not exceed a maximum of 
0.8 lb tebuconazole/acre/season or 0.71 lb prothioconazole/acre/season. Do not apply within 14 days of harvest. Do not feed hay or 
threshings or allow livestock to graze in treated areas. DO NOT use with handheld application equipment, including backpack or 
mechanically/manually pressurized hand equipment.

11 
APPLICATION DIRECTIONS 
CROP DISEASE CONTROLLED RATE OF PROSARO 421 SC FUNGICIDE 
 
Wheat 
(spring, durum, and 
winter) 
 
 
 
 
 
 
 
 
 
 
 
 
Fusarium Head Blight 
 (Fusarium spp.) 
 
Leaf and Stem Diseases 
Powdery Mildew 
(Blumeria graminis f. sp. tritici) 
 
Rusts 
(Puccinia spp.) 
 
Septoria Leaf and Glume Blotch (Septoria tritici) 
 
Stagonospora Blotch 
 (Stagonospora nodorum) 
 
Tan Spot 
 (Pyrenophora tritici-repentis) 
 
 
6.5 - 8.2 fl oz per acre 
Application Directions: Straw may be fed or used for bedding. 
 
Spray Equipment/Volumes: PROSARO 421 SC FUNGICIDE may be applied by either ground, aerial or 
chemigation application equipment. For ground applications, apply a minimum of 10 gpa spray solution. For 
aerial applications, apply a minimum of 2 gpa spray solution. When applied through chemigation, large carrier 
volumes may result in reduced activity against Fusarium head blight. 
Disease Control: 
Fusarium Head Blight: 
The optimal time to apply PROSARO 421 SC FUNGICIDE is as a preventative foliar spray at early flower 
(Feekes Growth Stage 10.51). Spray equipment must be set to provide good coverage to wheat heads. For 
thorough coverage of the wheat head using ground application equipment, use forward, forward and backward 
mounted nozzles, or nozzles that have a two-directional spray. Operate nozzles within the spray pressure 
directions suggested by the manufacturer. For aerial applications, apply a minimum of 5 gpa spray solution. 
 
Leaf and Stem Diseases: 
Apply PROSARO 421 SC FUNGICIDE as a preventive foliar spray when the earliest disease symptoms appear 
on the leaves and stems. Wheat fields must be observed closely for early disease symptoms, particularly when 
susceptible varieties are planted and/or under prolonged conditions favorable for disease development. 
 
For optimum disease control, the lowest specified rate of a spray surfactant must be tank-mixed with 
PROSARO 421 SC FUNGICIDE. 
Restrictions: Do not apply more than 8.2 fl oz of PROSARO 421 SC FUNGICIDE applied per acre per crop year. Do not apply within 
30 days of harvest. Do not allow livestock to graze or feed green forage to livestock prior to 6 days after treatment with PROSARO 
421 SC FUNGICIDE. DO NOT use with handheld application equipment, including backpack or mechanically/manually pressurized 
hand equipment.

12 
OBSERVE THE FOLLOWING RESTRICTIONS WHEN SPRAYING IN THE VICINITY OF AQUATIC AREAS INCLUDING LAKES, 
RESERVOIRS, RIVERS, PERMANENT STREAMS, MARSHES OR NATURAL PONDS, AND ESTUARIES. 
Apply only during alternate years in fields adjacent to aquatic areas listed above. 
Do not apply by ground or air within 100 feet of aquatic areas listed above. 
Do not cultivate within 10 feet of an aquatic area to allow growth of a vegetative filter strip. 
Spray Drift Management: For aerial applications, the spray boom must be mounted on the aircraft so as to minimize drift caused by 
wing tip vortices. The minimum practical boom length must be used, and must not exceed 75% of the wingspan or rotor diameter. 
Use the largest droplet size consistent with pest control. Formation of very small droplets may be minimized by appropriate nozzle 
selection, by orienting nozzles away from the air stream as much as possible and by avoiding excessive spray boom pressure. Apply in 
a minimum of 5 gallons of spray solution per acre by aircraft spray equipment. 
Spray must be released at the lowest possible height consistent with good pest control and flight safety. Applications more than 10 feet 
above the crop canopy must be avoided. 
Make aerial or ground applications when wind velocity favors on-target product deposition (approximately 3 to 10 mph). Do not apply 
when wind velocity exceeds 15 mph. Avoid applications when wind gusts approach 15 mph. 
Risk of exposure to sensitive aquatic areas can be reduced by avoiding applications when wind direction is toward the aquatic area. 
Low humidity and high temperatures increase the evaporation rate of spray droplets and therefore the likelihood of spray drift to aquatic 
areas. Avoid spraying during conditions of low humidity and/or high temperature. 
Do not make aerial or ground applications during temperature inversions. Inversions are characterized by stable air and increasing 
temperatures with height above the ground. Mist or fog may indicate the presence of an inversion in humid areas. The applicator may 
detect the presence of an inversion by producing smoke and observing a smoke layer near the ground surface.

13 
STORAGE AND DISPOSAL 
Do not contaminate water, food, or feed by storage or disposal. 
Pesticide Storage: Store in a cool, dry place and in such a manner as to prevent cross contamination with other pesticides, fertilizers, 
food, and feed. Store in original container and out of the reach of children, preferably in a locked storage area. 
Handle and open container in a manner as to prevent spillage. If container is leaking, invert to prevent leakage. If the container is 
leaking or material is spilled for any reason or cause, carefully dam up spilled material to prevent runoff. Refer to Precaut ionary 
Statements on label for hazards associated with the handling of this material. Do not walk through spilled material. Absorb s pilled 
material with absorbing type compounds and dispose of as directed for pesticides below. In spill or leak incidents, keep unauthorized 
people away. 
Pesticide Disposal: Wastes resulting from the use of this product may be disposed of on site or at an approved waste disposal facility. 
Container Handling: 
[Non-Seed Treatment Products in Non-Refillable Containers] 
 
Rigid, Non-refillable containers (equal to or less than 5 gallons) 
Non-refillable container. Do not reuse or refill this container. Offer for recycling, if available. Triple rinse or pressure rinse container (or 
equivalent) promptly after emptying. Triple rinse as follows: Empty the remaining contents into application equipment or a mix tank and 
drain for 10 seconds after the flow begins to drip. Fill the container 1/4 full with water and recap. Shake for 10 seconds. Pour rinsate 
into application equipment or a mix tank or store rinsate for later use or disposal. Drain for 10 seconds after the flow begins to drip. 
Repeat this procedure two more times. 
 
Pressure rinse as follows: Empty the remaining contents into application equipment or a mix tank and continue to drain for 10 seconds 
after the flow begins to drip. Hold container upside down over application equipment or mix tank or collect rinsate for later use or 
disposal. Insert pressure rinsing nozzle in the side of the container, and rinse at about 40 PSI for at least 30 seconds. Drain for 10 
seconds after the flow begins to drip. 
 
Once container is rinsed, offer for recycling if available or puncture and dispose of in a sanitary landfill. 
 
Rigid Non-refillable Containers that are too large to shake (i.e., with capacities greater than 5 gallons or 50 lbs) 
Non-refillable container. Do not reuse or refill this container. Refer to Bottom Discharge IBC or Top Discharge IBC, Drums, Kegs 
information as follows. 
 
Bottom Discharge IBC (e.g. – Schuetz Caged IBC or Snyder Square Stackable) 
Pressure rinsing the container before final disposal is the responsibility of the person disposing of the container. To pressure rinse the 
container before final disposal, empty the remaining contents from the IBC into application equipment or mix tank. Raise the bottom of 
the IBC by 1.5 inches on the side which is opposite of the bottom discharge valve to promote more complete product removal. 
Completely remove the top lid of the IBC. Use water pressurized to at least 40 PSI to rinse all interior portions. Continuously pump or 
drain rinsate into application equipment or rinsate collection system while pressure rinsing. Continue pressure rinsing for 2 minutes or 
until rinsate becomes clear. Replace the lid and close bottom valve. 
Top Discharge IBC, Drums, Kegs (e.g.– Snyder 120 Next Gen, Bonar B120, Drums, Kegs) 
Triple rinsing the container before final disposal is the responsibility of the person disposing of the container. To triple rinse the 
container before final disposal, empty the remaining contents from this container into application equipment or mix tank. Fill the 
container at least 10 percent full with water. Agitate vigorously or recirculate water with the pump for 2 minutes. Rinse all interior 
surfaces. Pour or pump rinsate into application equipment or rinsate collection system. Repeat this procedure two more times. 
 
Top Discharge IBC, Drums, Kegs (e.g.– Snyder 120 Next Gen, Bonar B120, Drums, and Kegs) 
Triple rinsing the container before final disposal is the responsibility of the person disposing of the container. To triple rinse the 
container before final disposal, empty the remaining contents from this container into application equipment or mix tank. Fill the 
container at least 10 percent full with water. Agitate vigorously or recirculate water with the pump for 2 minutes. Rinse all interior 
surfaces. Pour or pump rinsate into application equipment or rinsate collection system. Repeat this procedure two more times. 
 
Once container is rinsed, offer for recycling if available or puncture and dispose of in a sanitary landfill or by incineration. 
 
Non-Seed Treatment Products in Non-Refillable Fiber Drums with Liners 
Non-refillable container. Do not reuse or refill this container. Completely empty liner by shaking and tapping sides and bottom to 
loosen clinging particles. Empty residue into application equipment, then offer for recycling if available or dispose of in a sanitary landfill 
or by incineration. If drum is contaminated and cannot be reused, dispose of it in the manner required for its liner. 
 
 
Non-Seed Treatment Products in Non-Rigid, Non-refillable Containers 
Nonrefillable container. Do not reuse or refill this container. Completely empty container into application equipment. Then offer for 
recycling if available or dispose of in a sanitary landfill or by other procedures approved by state and local authorities." 
 
[Non-Seed Treatment Products in Refillable Containers]

14 
Refillable container. Refer to Bottom Discharge IBC or Top Discharge IBC, Drums, Kegs information as follows. Refill this container with 
pesticide only. Do not reuse this container for any other purpose. Contact your Ag retailer or Bayer CropScience for container return, 
disposal and recycling information. 
 
Bottom Discharge IBC (e.g. – Schuetz Caged IBC or Snyder Square Stackable) 
Pressure rinsing the container before final disposal is the responsibility of the person disposing of the container. Cleaning before 
refilling is the responsibility of the refiller. To pressure rinse the container before final disposal, empty the remaining contents from the 
IBC into application equipment or mix tank. Raise the bottom of the IBC by 1.5 inches on the side which is opposite of the bottom 
discharge valve to promote more complete product removal. Completely remove the top lid of the IBC. Use water pressurized to at least 
40 PSI to rinse all interior portions. Continuously pump or drain rinsate into application equipment or rinsate collection system while 
pressure rinsing. Continue pressure rinsing for 2 minutes or until rinsate becomes clear. Replace the lid and close bottom valve. 
 
Top Discharge IBC, Drums, Kegs (e.g.– Snyder 120 Next Gen, Bonar B120, Drums, Kegs) 
Triple rinsing the container before final disposal is the responsibility of the person disposing of the container. Cleaning before refilling is 
the responsibility of the refiller. To triple rinse the containers before final disposal, empty the remaining contents from this container into 
application equipment or mix tank. Fill the container at least 10 percent full with water. Agitate vigorously or recirculate water with the 
pump for 2 minutes. Rinse all interior surfaces. Pour or pump rinsate into application equipment or rinsate collection system. Repeat 
this procedure two more times. 
 
Once container is rinsed, offer for recycling if available or puncture and dispose of in a sanitary landfill or by incineration. 
 
End users are authorized to remove tamper evident cables as required to remove the product from the container unless the container is 
equipped with one way valves and refilling or returning is planned. If this is the case, end users are not authorized to remove tamper 
evident cables, one way valves or clean container. 
 
 
You may contact the Bayer CropScience Emergency Response Team for decontamination procedures or any other assistance that 
may be necessary. The Bayer CropScience Emergency Response Telephone No. is 1-800-334-7577.

15 
IMPORTANT: READ BEFORE USE 
Read the entire Directions for Use, Conditions, Disclaimer of Warranties and Limitations of Liability before using this product . If terms 
are not acceptable, return the unopened product container at once. 
By using this product, user or buyer accepts the following Conditions, Disclaimer of Warranties and Limitations of Liability. 
CONDITIONS: The directions for use of this product are believed to be adequate and must be followed carefully. However, it is 
impossible to eliminate all risks associated with the use of this product . Crop injury, ineffectiveness or other unintended consequences 
may result because of such factors as weather conditions, presence of other materials, or the manner of use or application, all of which 
are beyond the control of Bayer CropScience. To the extent consistent with applicable law, all such risks shall be assumed by the user 
or buyer. 
DISCLAIMER OF WARRANTIES: TO THE EXTENT CONSISTENT WITH APPLICABLE LAW, BAYER CROPSCIENCE MAKES NO 
OTHER WARRANTIES, EXPRESS OR IMPLIED, OF MERCHANTABILITY OR OF FITNESS FOR A PARTICULAR PURPOSE OR 
OTHERWISE, THAT EXTEND BEYOND THE STATEMENTS MADE ON THIS LABEL. No agent of Bayer CropScience is authorized to 
make any warranties beyond those contained herein or to modify the warranties contained herein. TO THE EXTENT CONSISTENT 
WITH APPLICABLE LAW, BAYER CROPSCIENCE DISCLAIMS ANY LIABILITY WHATSOEVER FOR SPECIAL, INCIDENTAL OR 
CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR HANDLING OF THIS PRODUCT. 
LIMITATIONS OF LIABILITY: TO THE EXTENT CONSISTENT WITH APPLICABLE LAW, THE EXCLUSIVE REMEDY OF THE 
USER OR BUYER FOR ANY AND ALL LOSSES, INJURIES OR DAMAGES RESULTING FROM THE USE OR HANDLING OF THIS 
PRODUCT, WHETHER IN CONTRACT, WARRANTY, TORT, NEGLIGENCE, STRICT LIABILITY OR OTHERWISE, SHALL NOT EXCEED THE 
PURCHASE PRICE PAID, OR AT BAYER CROPSCIENCE’S ELECTION, THE REPLACEMENT OF PRODUCT. 
 
 
NET CONTENTS: 
 
 
 
Prosaro is a registered trademark of Bayer. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Bayer CropScience LP 
P.O. Box 12014, 2 T.W. Alexander Drive 
Research Triangle Park, North Carolina 27709 
1-866-99BAYER (1-866-992-2937) 
 
PROSARO 421 SC Fungicide (PENDING) 07/24/2024, 09/13/2024, 01/15/2025