RICK SNYDER 

GOVERNOR 

March 22, 2016 

Ms. Tawanda Maignon 

STATE OF MICHIGAN 

DEPARTMENT OF AGRICULTURE 

AND RURAL DEVELOPMENT 

Risk Integration, Minor Use and Emergency Response Branch 

U.S. EPA I Office of Pesticide Programs (7505P) 

Room S4900, One Potomac Yard 

2777 S. Crystal Drive 

Arlington, VA 22202 

Dear Ms. Maignon: 

JAMIE CLOVER ADAMS 

DIRECTOR 

Approval of this application is requested pursuant to section 18 of the Federal 

Insecticide Fungicide and Rodenticide Act as Amended, 7 U.S.C. §136p, for the use of 

pyridate to control weeds in mint grown in Michigan during the 2016 growing season. 

The following information is provided as requested in 40 CFR, Part 166, Subpart B. 

A. Summary of General Information 

1. Type of Exemption: 

Specific 

2. Contact Persons: 

Brian Verhougstraete (Administration) 

Pesticide Registration Program Manager 

Michigan Department of Agriculture 

Pesticide and Plant Pest Management Division 

Constitution Hall, 5th Floor 

525 Allegan Street 

Lansing, Ml 48909 

Telephone: (517) 284-5655 

Fax: (517) 335-4540 

E-mail: verhougstraeteb@michigan.gov 

CONSTITUTION HALL • P.O. BOX 30017 • LANSING, MICHIGAN 48909 

www.mich jgan.gov/mdard • (800) 292-3939 
Steve Salisbury (Technical) 

Mint Industry Research Council 

PO Box4059 

Salem, OR 97302-1059 

Phone: 503-551-3747 

Email: steve@pacificagresources.com 

Dr. Bernard Zandstra (Scientific) 

Department of Horticulture 

Michigan State University 

1066 Bogue Street 

East Lansing, Ml48824 

Phone: 517-353-6637 

Email: zandstra@msu.edu 

Doug lrrer (Economics) 

Michigan Mint Growers Association 

6700 West Centerline Road 

St. Johns, Ml 48879 

Phone: 989-640-4472 

Email: dougi@sceoinc.com 

Liesbeth Bosman (Registrant) 

Belchim Crop Potection, Inc. 

Technologielaan 7 

1840 Londerzeel 

Belgium 

Phone: +32 (0) 473 86 52 33 

Email: Lies beth. Bosman@Belchim.com 
3. Description of Pesticide 

Active Ingredient: Pyridate 

Trade Name: Tough Herbicide 5EC, not currently registered in U.S. 

Formulation: Emulsifiable concentrate formulated at 55.8% (5.0 lb. ai. per gal.) 

and 44.2 % inert ingredients. 

Registrant/Manufacturer: Belchim Crop Protection a Belgium based company 

(EPA Company No. 91746). The U.S. distributor is Engage Agro USA Corp. 

Material Safety Data Sheet (MSDS) and labels are attached. 

4. Description of Proposed Use 

a. Sites to be Treated 

There are nearly 1 ,400 acres of mint grown in Michigan. It is estimated that 

approximately 1,250 (90%) of this acreage will need to be treated with Tough. 

The mint production areas are located in Michigan counties of Clinton, Ingham, 

Ionia, Newaygo, Saginaw, and Shiawassee. The soils of these mint growing 

counties are generally productive, deep, and fertile in agricultural areas. 

b. Method of Application 

The herbicide will be applied by ground-driven spray equipment by licensed 

applicators according to the EPA approved product label. Tough will not be 

applied by aerial methods or through any type of irrigation system. 

c. Rate of Application 

A maximum of .9375 lb. active ingredient per acre (24 ounces of product per 

acre) in 20-40 gallons of water per acre will be applied during the growing 

season. 

d. Maximum Number of Applications 

Two applications of Tough per growing season may be made if necessary with a 

minimum of 14 days between applications. Applications may be made between 

the dates of April 1 and December 31 , 2016. No applications will be made within 

49 days of harvest. 

e. Total Acreage to be Treated 

It is estimated that approximately 1,250 acres (90% of total Michigan acreage) 

will need to be treated with Tough. 

f. Total pesticide to be used 

An estimated 470 gallons (2,350 lbs of a.i.) of herbicide are expected to be 

applied. 

1,250 acre* 24 fl.oz. * 2 applications = 470 gal. of formulated product. 

470 gal* 5 lb a.i./ gal= 2,350 lbs of active ingredient. 
g. Use season 

We are requesting application beginning April1 through December 31 , 2016. A 

fall application after harvest may be necessary if conditions promoting weed 

growth occur. No applications will be made within 49 days of harvest. 

h. Harvest Dates 

The majority of peppermint acreage is harvested once in August. However, some 

peppermint growers are double cutting their crop. Double-cut mint is harvested 

twice during the growing year, once in June and again in late August or early 

September. Spearmint is harvested twice during the growing season, once in the 

middle of June and again in the middle of August. 

i. Other Restrictions. User Precautions. and Requirements 

Federal and supplemental labels address reentry and worker protection, 

environmental hazards and restrictions (see attached label). Treated fields or 

forage from treated fields may not be used for livestock feed or grazing. Tough 

will not be applied through any type of irrigation system or by air. To protect 

endangered freshwater invertebrate species, Tough will not be applied within 100 

yards of any freshwater spring. 

5. Alternative Methods of Control 

a. Registered Post-Emergent Herbicide Alternatives 

1. Bentazon (Basagran) - Provides inconsistent (partial) post-emergence 

control of Kochia. Does not control pigweed. Weeds emerging after 

application are not controlled. 

2. Bromoxynil (Maestro)- Phytotoxic to actively growing mint. Cannot be 

applied above 70 degrees F to actively growing mint. Only gives partial 

control of Kochia and Pigweed seedlings. Kochia and Pigweed seeds 

germinate (multiple flushes) throughout the growing season. 

3. Clethodim (Select Max)- Grass weed control only. 

4. Clopryalid (Stinger) - For spot treatment, post emergence control of 

broad leaf weeds (canada thistle, dandelion). Destroys mint which comes in 

contact with herbicde. Does not control Kochia or Pigweed 

5. MCPB (Thistrol) - Can only be applied early post-emergent to weeds and to 

dormant or small/newly emerged mint. It is limited to partial control of 

Canada thistle and field bindweed. Does cause crop injury and loss of oil 

yield. 

6. Quizalifop (Assure II) - Grass weed control only. 
7. Sethoxydim (Poast Plus)- Grass weed control only. 

8. Terbacil (Sinbar)- Does not control Kochia. Pigweed has developed 

resistant biotypes due to years of continuous use. It is not effective on weeds 

that have grown beyond the seedling stage. Cannot be used when rotating 

from mint into other crops the following year due to soil persistence and crop 

rotational restriction. Cannot be used on sandy, loamy sands, or soils with 

less than 1% organic matter without crop injury. 

b. Other alternatives 

Mechanical weed control methods such as tillage are not feasible or practiced in 

actively growing mint due to the destruction of the crop. Tillage in mint at any time 

also spreads the disease Verticillium Wilt, a fungal pathogen in mint which is 

spread by the movement of soil and debris. Tillage also spreads the rhizomes and 

stolons of perennial weeds. Hand rogueing is cost prohibitive and does not 

provide season long control of weeds as weed seeds continue to germinate in the 

soil throughout growing season. In addition, the labor needed for hand weeding is 

not available in most mint growing regions. Crop rotation is practiced when 

feasible, but mint being a perennial crop is left in production for 3 to 5 years, or 

longer. Research on biological control methods is currently being conducted, but 

as of to date no effective methods have been developed. 

c. On-going research for chemical alternatives 

The mint industry has placed a high priority on finding alternatives to pyridate for 

postemergence broad leaf weed control. The industry has diligently invested 

several hundred thousands of dollars of research funds for the past decade to this 

effort. Numerous preemergence and postemergence herbicides have been tested 

and evaluated with little or no success. Preemergence herbicides evaluated 

include pendamethalin, terbacil, saflufenacil, sulfentrazone, flumioxazin, 

oxyfluorfen, pyroxasulfone and both oxyfluorfen and flumioxazin impregnated on 

fertilizer have been tested. Postemergence herbicides that have been tested 

include bentazon, terbacil, bromoxynil, bicyclopyrone, mesotrione, tembotrione, 

topramezone, fluroxypyr, MCPB, and carfentrazone. These herbicides are either 

too injurious to the mint or do not adequately control the pigweed. A letter from Dr. 

Rick Boydston, USDA-ARS, is attached summarizing mint herbicide research 

since 2006. 

In summary, despite extensive efforts the mint industry has not been able to 

successfully find an adequate replacement for pyridate (Tough herbicide) to 

provide postemergence weed control that does not cause significant injury to the 

mint crop. Therefore, weed control remains an urgent situation challenging the 

ability to produce high quality mint oil. 

In addition to the urgency of the situation, it is important to note that 

postemergence broad leaf weed control has recently developed into a non-routine 

situation due to the increased demand for double-cut production acreage. Many 
acres have been forced to double-cut production to meet recent global regulatory 

and market demands. Further description of this non-routine situation is discussed 

in Section B Part 2 (Description of the Emergency Condition) of this request. 

6. Efficacy of the Proposed Use 

Results of efficacy and comparative field trials are attached. Tough selectively controls 

annual weeds in mint without causing significant crop injury. Risks to rotational crops 

are minimized due to the short half-life and low soil persistence leading to no residual 

impact to subsequent crops. Tough is the only known broad leaf herbicide that can 

provide post-emergent control of weeds without impacting crop yield. 

Since there is a limited amount of trial data from Michigan, a letter of support from Dr. 

Bernard Zandstra, Michigan State University, is attached explaining the benefits and 

usability of Tough in mint production. 

7. Residue Information 

Residue trials for mint were conducted by the IR-4 Program in 1994. Applications made 

in accordance with the requested provisions are not expected to result in residues of 

pyridate and its metabolites in excess of 0.2 ppm for peppermint and spearmint tops. 

These tolerances have been established by the EPA and are recorded under CFR 

180.462. Secondary residues in meat, poultry, and eggs are not expected to result. 

8. Risk Information 

On May 3, 2000 the EPA established tolerances of 0.2 ppm for residues of pyridate and 

its metabolites in/on peppermint and spearmint tops. Information regarding pyridate 

toxicology and aggregate exposure can be found in the final rule published in the 

Federal Register May 3, 2000, volume 65, number 86, pages 25647-25652 (attached). 
a. Human Health 

Tough herbicide poses little potential risks to humans, domestic animals, wildlife, 

and the environment. The acute oral LDSO for male rats is> 5,000 mg/kg. The 

active ingredient has a low dermal irritation potential and a low inhalation hazard. 

Acute dermal LD50 for rabbits is > 2,000 mg/kg. Inhalation LCSO >4.37 mg./L air. 

Primary dermal irritation study indicated it is mildly irritating to rabbit skin (EPA 

Health Effects Division of the Office of Pesticide Programs, 2000). 

The EPA concluded that residues of pyridate in drinking water do not contribute 

significantly to the aggregate acute human health risk. The acute human health 

risks resulting from exposure to pyridate in food and water are below EPA's level 

of concern for all population subgroups. As for chronic risk, the EPA also 

concluded that no harm will result from aggregate chronic exposure. 

It was also determined that pyridate is not carcinogenic in either rat or mouse, 

and therefore is not expected to pose a cancer risk to humans. 

The product label addresses the risks to worker/applicator by outlining handler 

precautions and required personal protective equipment. 

b. Potential to be found in drinking water 

The potential for exposure to residues of pyridate in drinking water is negligible 

due to its low water solubility (1 .5mg/L at 20 C), strong soil adsorption (Kd = .3-

26) and short half-life (7-21 days). Pyridate is essentially immobile in all soil 

types and any risks to surface or groundwater contamination will be negligible. 

The EPA Health Effects Division determined that pyridate does not possess the 

environmental fate parameters associated with a compound that could leach to 

groundwater. However, the parameters of its degradate indicate that under 

unusual conditions such as flooding, where anaerobic conditions persist in topsoil 

for up to 60 days, the degradate could possibly leach to groundwater or run off to 

surface water. Pyridate is not listed in the EPA Pesticides in Ground Water 

Database, nor is there an EPA Maximum Containment Level or health advisory. 

c. Residential Uses 

Pyridate is not registered for use in ornamentals or in residential areas. 

d. Common Mode of Action 

Pyridate is a Group 6 herbicide, HRAC Group C3 (Herbicide Resistance Action 

Committee, www.hracglobal.com). It belongs to the phenyl-pyridazine family of 

herbicides. Its site of action is inhibition photosynthesis by blocking electron 

transport in photosystem II (reactions taking place in the chloroplast thylakoid 

membranes). 
e. Endangered or Threatened Species 

Endangered or threatened species listed by the USFWS within the mint 

production counties of Clinton, Ingham, Ionia, Newaygo, Saginaw, and 

Shiawassee are listed in the attached table. 

The use of Tough herbicide in accordance to the label in mint fields should not 

pose a risk to any threatened or endangered species. 

f. Beneficial Organisms 

Tough is not toxic to bees and other beneficial insects (i.e. lady beetles, 

predatory mites). See the attached EPA Environmental Fate and Effects Division 

(EFED) report. 

g. Fish and Aquatic Organisms 

Pryridate is considered toxic to estuarine organisms. However, due to its strong 

soil adsorption and short half-life, if applied according to the label it should not 

pose a risk to estuarine organisms (see attached EPA EFED report). The label 

states that this material should not be applied within 100 yards of any freshwater 

spring, directly to water, to areas where surface water is present, or to intertidal 

areas below the mean high water mark. 

9. Coordinate with Other Agencies 

The Michigan Fish and Game Office of the U.S. Fish and Wildlife Service will receive a 

copy of this request. Any comments received will be forwarded to the U.S. EPA. 

10. Notification of Registrant 

Belchim Crop Protection has been notified and their letter of support is attached. In 

addition, Engage Agro USA Corp. is the U.S. distributor and they have also been 

notified. A letter of support from Engage Agro USA is also attached. 

11. Enforcement Program 

The Michigan Department of Agriculture and Rural Development (MDARD) has 

adequate authorities for enforcing provisions of Section 18 emergency exemptions. 

MDARD will require the registrant (or manufacturer, if unregistered) of Tough herbicide, 

Belchim Crop Protection, to prepare and make available to end users supplemental 

labeling that complies with MDARD and EPA requirements for the emergency use, if 

approved. Applicators will be required to keep adequate records of application use and 

acreage. The Mint Industry Research Council (MIRC), in cooperation with Belchim Crop 

Protection and Engage Agro USA, will be required to provide the MDARD a report 

summarizing results of the emergency use after the end of the use period. 

12. Repeat Uses 

Tough has been previously used under a Section 18 from 1999-2000. Tough was later 

registered under an SLN 24c from 2001-2007 after tolerances were established in 2000. 
13. Progress Toward Registration 

Registration and tolerance were established through the IR-4 by the EPA in May of 

2000. The Final Rule was published in the Federal Register vol. 65, No. 86, May 3, 

2000 pages 25647-25652 (attached). Tolerances were established for peppermint and 

spearmint tops at 0.20 ppm (CFR 180.462). Product registration was voluntarily 

cancelled by the registrant (Syngenta) and the product was no longer marketed in the 

U.S. Recently, Belchim Crop Protection acquired the marketing rights for pyridate from 

Syngenta. It is understood that Belchim is working with the EPA to re-register Tough in 

the U.S. 

B. Summary of Economic Loss 

1. Pest(s) to be Controlled 

The pests causing an emergency are broadleaf weeds, in particularly Red root Pigweed, 

Armaranthus retroflexus and Kochia, Kochia scoparia. 

2. Discussion of the Emergency Condition 

This request is due to the emergency condition existing in mint from the postemergence 

of pigweed, kochia, and other broad leaf weed communities that cannot be effectively 

controlled in active growing mint crops. All crops including mint suffer yield losses from 

populations of weeds, but unlike other crops, the quality of mint oil also is affected by 

weeds. A quality marketable mint crop is dependent upon weed free fields. 

The recent increase in global demand for the production of double-cut mint oil has 

created a non-routine situation that poses additional stress on the need for adequate 

postemergence broad leaf weed control. Preemergence herbicides applied in 

February/early March to dormant mint dissipate to low levels that no longer control 

weeds after 4-6 weeks. The mint crop canopy suppresses any new weed emergence or 

establishment after this period. Once the mint canopy is removed with a mid to late 

June harvest (first cutting), new weed flushes follow. These new flushes include both 

summer annual grasses and later germinating broad leaf weeds such as pigweeds. The 

grass weeds are easily controlled with registered grass active herbicides. However, 

there are no effective postemergence herbicides that are labeled in mint for pigweed 

control during the second half of the growing season following the first harvest of mint. 

The increased demand for double-cut mint is a result of both global regulatory 

challenges and the increasing desire for the oil quality that is produced in double-cut 

production. The global regulatory issues involve the concern of menthofuran and 

pulegone contents in the mint oil and the limits of these compounds that are allowable in 

oil to deem it acceptable in markets. The reduction of these compounds and the 

increase of other desirable oil quality traits can be achieved through double-cut 

production. The market has shifted to a higher demand for double-cut mint, but the 

acreage to meet the demand is not adequate due to management challenges 

associated with double-cut production. Postemergence broad leaf weed control is the 

primary management challenge facing double-cut production. Producers do not have 
viable broad leaf weed control options to address this challenge. 

Redroot pigweed present in mint at 1.6 weeds/yd2 renders mint oil unmarketable, due 

to off-flavors imparted during the distillation process (attachment). OSU research also 

demonstrated that a redroot pigweed infestation of 10 plants/ft2 caused a peppermint oil 

yield reduction 34.4 lbs/acre, a 46% reduction (attached). Furthermore, both redroot and 

prostrate (A. blitoides) pigweeds have developed terbacil resistant biotypes. 

Kochia, a summer annual, can reach heights of six feet high and several feet in 

diameter, hindering harvest operations and competes for nutrients and light. In addition, 

an infestation of 2.3 kochia plants/ft2 can reduce mint oil yields by over 30% 

(attachment) in addition to reducing oil quality. 

Mechanical tillage is not a post emergence weed control option in mint because tillage 

will destroy growing mint, eliminate irrigation rills in surface irrigated fields, and will 

spread devastating diseases in mint such as Verticillium wilt (Verticillium dahliae). 

Terbacil (Sinbar), the commonly used herbicide registered for weed control in mint, is 

weak on pigweed species and has become even less effective in controlling pigweeds 

due to the development of resistant biotypes. Additionally, terbacil cannot be used when 

weeds are beyond the seedling stage and when rotating from mint to other crops due to 

residual carryover. The only alternative method of controlling these weeds is handrogueing, but the unavailability of labor and excessive cost where labor is available, 

eliminates rogueing as a viable weed control method. Again, there are presently no 

effective post-emergent means of controlling these weeds in mint. 

The mint industry has been diligently investing research funds to discover effective postemergent broad leaf weed herbicides that are safe to the crop. Pyridate has proven to be 

effective on broad leaf weeds as well as possesses acceptable post-emergence crop 

safety needed for mint production. Populations of problem weeds have reached 

economically devastating levels and is impacting the producer's ability to compete in the 

market. Additionally, the recent increased demand for double-cut mint has forced 

production into and created a non-routine situation for mint producers who have no 

effective and viable postemergence broad leaf weed control options. The use of Tough 

herbicide for postemergence weed control in mint is critical to maintaining U.S. mint oil 

quality and market share in today's global economy. 

3. Discussion of Economic Loss 

Red root Pigweed/Kochia and broad leaf weed communities have become serious weed 

pests of mint growers in Michigan. The lack of any post emergent weed control option, 

(lack of a registered satisfactory herbicide, and the presence of herbicide resistant 

pigweed and kochia) have created an emergency situation for Michigan mint growers. 

Economic thresholds for these problem weeds are very low. Weeds resistant to 

herbicides which mature and form seeds, soon establish large populations of the 

resistant biotype, if not controlled. 

Studies performed by Oregon State University weed scientists show yield losses 
ranging from 22%to 47% from the target weeds individually (attachment). Kochia and 

Red root Pigweed are often found in complexes of other weeds, which further reduces 

the yield and quality of mint oil. 

Five-Year History of Michigan Production 

Average Average Gross Cost of Net 

Year Yield Price Revenue Production Revenue 

(lbs I acre) ($I lb) ($I acre) ($I acre) ($I acre) 

2011 71 $21 $1,488 $1,275 $213 

2012 72 $21 $1,516 $1,299 $217 

2013 58 $21 $1,208 $1,035 $173 

2014 65 $21 $1,365 $1,170 $195 

2015 69 $21 $1,449 $1,242 $207 

Average 67 $21 $1,405 $1,204 $201 

1. Yield and price data were obtained from mint industry oil growers and buyers. 

2. Cost of production is based on local industry knowledge. 

3. A loss does not necessarily mean a negative cash flow, but rather that the grower will not earn a 

return on capital and management contributions (hourly wage, labor, etc) equal to what could be 

earned in an alternative investment of the land producing the mint crop. 

Tier 2 Analysis 

A Tier 2 Significant Economic Loss (SEL) analysis illustrates the reduction of oil yield 

and quality as well as the loss of gross revenue due to the devaluation of tainted oil 

resulting from weed contaminants. The yield comparison reflects a 35% yield reduction 

(OSU trial data) on the portion of the acres (90%) faced with the impact of postemergent weed control challenges. 

Furthermore, the yield calculations are based on the five-year average (2011-15) of 67 

lbs/acre. As previously stated in this request, the estimated acreage of Michigan mint is 

1,400 acres and approximately 1,250 acres (90%) would be treated with Tough 

herbicide. 

As for marketable oil quality, it is estimated that the use of Tough herbicide would 

increase pure quality oil by 20%, thus reducing the amount of tainted devalued oil by the 

same. The devaluation of tainted oil ranges from a small percentage deduction to 
complete rejection/loss. Based on industry knowledge, an average devaluation of 35% 

was used for this analysis. 

The Emergency situation results in 20% more tainted oil that has 35% less value 

realized by the growers. In all, this is a gross revenue loss greater than $1Million to the 

mint producers in Michigan. 

Tier 2 Michigan Economic Analysis of Yield and Quality Loss 

Baseline Emergency Change %Change 

Yield (lbs/acre) 139,257 93,800 -45,457 -33% 

Pure (%of yield) 90% 70% 

(lbs/acre) 125,331 65,660 -59,671 -48% 

Tainted (% of yield) 10% 30% 

(lbs/acre) 13,926 28,140 14,214 102% 

Price, Pure ($/lb) $21.00 $21.00 

Price, Tainted ($/lb) $13.65 $13.65 

Gross Revenue ($/acre) $2,822,042 $1,762,971 -$1,059,071 -38% 
On behalf of Michigan's mint producers, I appreciate your consideration of this request. 

Should you have any questions please feel free to contact me. 

Sincerely, / 

~ ---rr--~------==--=-- Brian Verhougstraete 

Pesticide Registration Program Manager 

Pesticide and Plant Pest Management Division 

cc: Bruce Wilkinson, EPA Region V 

Steve Salisbury, Mint Industry Research Council 

Bernie Zandstra, Michigan State University 

Enclosures