Page 1 of 8 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES UNITED ST AT ES ENVIRONMENT AL PROTECTION AGENCY

WASHINGTON D.C., 20460

PC Code: 080818 DP Barcodes: 356140, 367446 Date: April 15 , 2010 MEMORANDUM SUBJECT: Memorandum: Revised Spray Drift Modeling and Terrestrial Plant Risk Characterization in Support of the Section 3 Registration of the New Chemical Indaziflam (BCS - AA10717) TO: Erik Kraft , Chemical Review Manager

Jim Tompkins , Risk Manager Registration Division (7505P) FROM: Alicia Korol, Biologist

Environmental Risk Branc h IV Environmental Fate and Effects Division (7507P ) REVIEWED BY: Melissa Panger, Acting Risk Assessment Process L eader

Chuck Peck, Environmental Engineer Environmental Risk Branch IV Environmental Fate and Effects Division (7507P ) APPROVED BY: Mar

k Corbin , Acting Branch Chief Environmental Risk Branch IV Environmental Fate and Effects Division (7507P )Page 2 of 8

EFED has re - evaluated the spray drift exposure of indaziflam on terrestrial plants based on registrant - proposed label revisions (Attachment 1) . Changes to the AgDRIFT modeling have been made to the exposure inputs, while the effects endpoints used to determine spray drift buffers have remained unchanged ( Table 1 ). The exposure inputs for AgDRIFT are presented in Table 2 . Four broa d categories of uses were modeled based on applications to food ( i.e. , citrus fruit, stone fruit, pome fruit, grapes, tree nuts, pistachios, and olives ), turf, forested areas (including Christmas tree farms) , and a combination exposure scenario reflecting applications to roadsides, rights - of

- way s, site preparation and other s. Based on proposed ground application labeling revisions to droplet size specification, all ground applications were modeled assuming an American Society of Agricultural & Biological Engineers Standard 572 (ASAE ) 1 Medium Coarse distribution. Additionally , based on propo sed turf use label restrictions for release heights of no greater than ( ≤) 2 - 3 feet , turf use was modeled assuming a low boom height. EFED ch ose to model the ≤ 2 - 3 f eet requirement as a low boom height ( 20 in) rather than high boom height (50 in) , the only release height parameter inputs in Tier I AgDRIFT, to avoid overestimating exposure . Recommendations for potential label revisions to the ≤ 2 - 3 feet release height language are provided under the Labeling Recommendations section below. In re - evaluating the spray drift exposure estimates, EFED reconsidered the protectivene ss of employing AgDRIFT’s orchard scenario t o model food use applications; a ground application exposure was found to be a more appropriate modeling scenario for these uses . Modeling inputs are presented in Table 2 . For purposes of investigating the influence of input parameters on exposure estimates, EFED modeled three exploratory scenarios that would reduce overall spray drift exposure . An alternativ e ground application exposure for food use s was modeled assuming a low boom height . Two alternative aerial application exposures were modeled assuming ASAE M edium to C oarse and ASAE C oarse to Very C oarse droplet size distributions. These scenarios are highlighted in Table 2 . Table 1: Toxicity Endpoints used to Determine a Spray Drift Buffer for Te rrestrial Plants Test Type / Crop Most Sensitive Study Species NOAEC

(lbs a.i./A) EC 25

(lbs a.i./A) Most Sensitive

Param eter Seedling Emergence : Dicot Oilseed Rape 0.00011 0 .000062 Emergence Table 2: AgDrift Exposure Input Parameters Use Application

T ype Label Application rate (lbs a.i./A) Droplet Size Boom Height 1 Food Ground Indaziflam 200 SC; Indaziflam 500 SC 0.085 ASAE Fine Medium/ Coarse Lo w Boom Ground Indaziflam 200

SC; Indaziflam 500 SC 0.085 ASAE Fine Medium/ Coarse High Boom

1 The American Society of Agricultural Engineers (ASAE) became the American Society of Agricultural and Biological Engineers (ASABE) in 200 5 . ASABE standards are labeled "ASAE" rather than "ASABE" since standards were developed before the name change .Page 3 of 8

Use Application

T ype Label Application rate (lbs a.i./A) Droplet Size Boom Height 1 Turf 2 Gr ound BCS - AA 10717 20WSP 0.017 ASAE Fine Medium/ Coarse Lo w Boom3 Roadsides/Rights of - way/Site Preparation

/ Other 3 Ground Esplanade 200 C 0.089 ASAE Fine Medium/ Coarse High Boom
Forested Areas Ground Esplanade F 0.125 ASAE Fine Medium/ Coarse High Bo om Aerial Esplanade F 0.125 ASAE Fine Medium

4 N/A Aerial Esplanade F 0.125 ASAE Medium Coarse N/A Aerial Esplanade F 0.125 ASAE Coarse Very Coarse N/A 1 Tier I Low boom height = 0.508 m (20 in); Tier I High boom height = 1.27 m (50 in) 2 Establ ished turf in areas such as parks, cemeteries, gold courses, sod farms, sports fields, home and commercial lawns. 3 Other uses include: railroads, railway yards, bareground, landscape plantings on roadsides, ornamentals, dormant woody or conifer plant sp ecies, hardscapes 4 Label specifies droplet size of 150 - 200 microns Dissipation to the EC 25 and no effect level was modeled in order to provide potential buffer distances that are protective of non listed and listed terrestrial plant species, respectivel y ( Table 3 ) . As in Table 2 , exploratory scenarios are highlighted. The results of AgDRIFT modeling show that levels of concern (LOC) for terrestrial plants are exceeded from 62 ft to greater than ~1,000 feet from the site of application, with risk extending furthest for forested area uses and extending the least for turf uses. The AgD ISP model was used to refine spray drift exposure estimates from aerial applications to forested areas based on proposed management practices, e.g. , boom length along aircra ft wing and spray volume rate; however, the refined estimates were not found to reduce the LOC for terrestrial plants be low ~1000 feet from the application site . Using the proposed labeled spray drift restrictions, spray

drift buffers of 62 feet for turf uses would be necessary to reduce spray drift deposition below the non - listed species LOC , while for listed species these buffers would need to be 131 feet. These distances are lower than the previously

calculated turf use buffer distances of 341 feet fo r nonlisted species and 528 feet for listed species, based on assumptions of an ASAE Very Fine to Fine spray

droplet distribution and a high boom height . For food uses, buffers ranging from 466 to 6 4 0 feet would be necessary to create spray

drift depositi on below the level of concern for non - listed plants, and at a minimum of 843 feet for listed species. Buffers at, or greater than , 6 66 feet are needed for ground and aerial applications to roadsides/rights - of - way s/site preparation/other and forested areas . To further characterize the exposure to terrestrial plant species, RQs per use pattern werePage 4 of 8

developed for spray

drift exposures ranging from distances of 0 (on the field) to 950 feet off the field. Figure 1 depicts the nonlisted species RQs relative to distances off field, while Figure 2 depicts the listed species RQs relative to distances off field. Table 3: Summary of AgDRIFT Modeling Results for Listed and Non - Listed Terrestrial Plant Species By Use Pattern

Use 1 (Single Max Application Rate) Distance (ft) fromedge of field where LOC is no longer exceeded
– Ground Application Distance (ft) fromedge of field where LOC is no longer exceeded

— Aerial Applications Non - listed Plants 2 Listed Plants 3 Non - l isted Plants 2 L isted Plants 3 Food

– Lo w Boom (0.085 lbs ai/A) 466 843 - - Food

– High Boom (0.085 lbs ai/A) 640 >997 - - Turf (0.017 lbs ai/A) 62 131 - - Roadsides/Rights - of

way/Site Preparation/ Other (0.089 lbs ai/A) 666 >997 - - Forested Areas Fine - Med/Coarse (0.125 lbs ai/A) 896 >997 >997 >997 Forested Areas Med - Coarse (0.125 lbs ai/A) -- -- >997 >997 Forested Areas Coarse - Very Coarse (0.125 lbs ai/A) -- -- >997 >997 1 Only proposed uses of indaziflam for broadcast spray via ground or aerial methods were modeled with AgDrift. 2 Most sensitive terrestrial plant EC 25 = 0.00011 lbs a.i./A (1.1x10E - 4 lbs a.i.A) 3 Most sensitive terrestrial plant NOAEC = 0.000062 lbs a.i./A (6.2x10E - 5 lbs a.i./A)Page 5 of 8 0 1 10 100 1000

0 100 200 300 400 500 600 700 800 900 1000 Di st ance fr om Edge of F ie ldRQ Fo od_Low Bo om Fo od_Hi gh Bo om Tu rf Roads id es /R ight s- of

-way /SitePr

eparat io n/ Ot her Fo res te d Ar

eas _Ground Fo res te d Ar

eas _A erial_Fine/ Me dium Fo res te d Ar

eas _A erial_Medium/ Coars e Fo res te d Ar

eas _A erial_Coars e/ Ve ry C oars e

Figure 1: RQs for the most sensitive nonlisted terrestrial plant exposed to spray drift from prop o sed broadcast uses of indaziflam. The risk to nonlisted species LOC is 1.0 (RQ = 1.0).

0 1 10 100 1000

0 100 200 300 400 500 600 700 800 900 1000 Distance from Edge of Fie ldRQ Food_Low Bo om Food_Hi gh Bo om Tu rf Roads id es /R ight s- of

-way /SitePreparat io n/ Other Fores te d Areas _G round Fores te d Areas _A eri al _F in e/ Medium Fores te d Areas _A eri al _M edium /C oars e Fores te d Areas _A eri al _Coars e/ Ve ry C oars e

Figure 2: RQs for the most sensitive listed terrestrial plant exposed to spray drift from proposed broadcast uses of i ndaziflam. The risk to list ed species LOC is 1.0 (RQ = 1.0).Page 6 of 8

Based on this analy sis of spray drift exposure and resulting RQs at carrying distances from the field, non - listed species LOCs for terrestrial plants are not exceeded with buffers of ~ 60 feet for turf uses. Likewis e, for turf uses, listed species LOCs are not exceeded with buffers of ~130 feet. These LOC exceedances appl y to direct effects to listed terrestrial plants and any listed species that has an obligate relationship with terrestrial plants ( i.e ., 130 ft buf fer) , and indirect effects for listed species that rel y on terrestrial plants but are not obligates ( i.e ., 60 ft buffer). Furthermore, indirect effects to other taxa that rel y on terrestrial plants may also occur. For all other uses, buffer distances < ~450 ft would not preclude risk of indaziflam toxicity to off - field nonlisted and listed species of terrestrial plants, but they are expected to reduce the number of species ultimately affected. Label ing Recommendations The following label recommendatio n s apply to proposed Esplanade F and BCS - AA10717 20 WSP formulation s .  The proposed Esplanade F formulation label states, “To reduce the potential for drift, apply large droplets ( i.e. , 150 - 200 microns) under low spray pressure”. This range overlaps the l ower drop size classification regime of ASAE Very Fine to Fine, and the next higher, ASAE Fine to Medium droplet size distribution . Label specification of a volume median diameter (VMD), D v0.5 , of 255 microns for spray droplets would reduce ambiguity beca

use 255 microns is the median diameter for an ASAE Fine to Medium droplet size distribution

 P roposed revisions to the BCS - AA10717 20 WSP formulation label (Attachment I) require that “For use on golf courses and commercial lawns, the boom height must be n o higher than 2 - 3 feet above the ground...” EFED modeled a ground application to turf assuming a low boom height (20 in) rather than a high boo m height (50 in) to avoid overestimating exposure . However, the distance from the application site where the risk t o plant species LOC is exceeded is potentially underestimated for boom heights greater than 20in (up to 36in) . EFED recommends that the specific boom height for turf be restricted to boom hei ghts no greater than 2 feet (24 in). The following label reco mmendations are relevant to the exploratory , reduced exposure scenarios modeled above and appl y to the Esplanade F, Indaziflam 200 SC, and Indaziflam 500 SC formulations.

 EFED recommends that the Esplanade F label explicitly specify the drop regime to be either ASAE Medium - Coarse or ASAE Coarse - Very Coarse for aerial applications . Alternativel y, the label could explicitly specify the D v0.5 , equal to 341 microns for ASAE Medium - Coarse and 439 microns for ASAE Coarse - Very Coarse.

 For the Indaziflam 200 SC and Indaziflam 500 SC labels, formulations for food use, EFED recommends that a boom height no greater than 2 feet (24in) be specified .Page 7 of 8



### Attachment 1 Indaziflam and Drift Potential with Spray Applications Baye r is proposing to add to their commerci al end - use indaziflam labels certain spray parameters to reduce drift. Since spray drift is not an issue for granular applied herbicides, Bayer assumes that granular applications are okay to use without further spray drift language. Since homeowner appli cations are made with either hose - in or hand wand applicators, Bayer believes that label language on the consumer (Bayer Advanced) products is adequate. is a pre - emergent herbicide with very little post - emergent activity. This has been seen in efficacy t esting with the compound and is confirmed b y the seedling emergence and vegetative vigor data submitted to the Agency . Pre - emergent applications of indaziflam to turf are made using spray volumes and spray

pressures that are conducive to reducing the potential for spray drift. In the unlikely event of spray

drift onto non - target plants, any small amount of spray

drift from indaziflam applications that reaches non - target plants will have little, if any , adverse effects. In order for indaziflam to have any e ffect on non - target seeds, it would need to get through any vegetation that is present and be moved down into the soil to the non - germinated seeds. However, any small amounts of indaziflam reaching the non - target plants will already be at sub lethal dosage and will be further degraded on the plant and the soil surface before reaching any non - germinated seed. In most cases, the first contact from spray drift will be existing vegetation and not bare ground. Therefore, the consideration of a spray buffer for the indaziflam label should be based upon vegetative vigor data rather than seedling emergence. Proposed label language: SPRAY DRIFT MANAGEMENT Ground Application Spray equipment and weather affect spray drift. Consider all factors when making appli cation decisions. Where states have more stringent regulations, they must be observed. Avoiding spray drift is the responsibility

of the applicator or grower. To reduce the potential for drift, the application equipment must be set to apply medium to large droplets (i.e., ASAE Standard 572) with corresponding spray pressure. Use high flow rate nozzles to apply the highest practical spray volume. With most nozzle ty pes, narrower spray

angles produce larger droplets. Follow the nozzle manufacturer’s directions on pressure, orientation, spray volume, etc., in order to minimize drift and optimize coverage and control. Golf Course, Residential, and Commercial Lawns Set the boom and make applications at the lowest height that safel y permits uniform coverage of the soil and minimizes droplet evaporation. For use on golf courses and commercial lawns, the boom height must be no higher than 2 - 3 feet above the ground and nozzles tips must be set to spray out medium to very

coarse spray

droplets. Applications to residential lawns must be made by equipment that maintains coarse spray droplets (to reduce drift). OrnamentalsPage 8 of 8

For deciduous ornamental plants, the spray must be directed at the base of the plant or away from the plant but as not to come in contact w ith the foliage as some leaf malformations or discoloration may

occur. Dormant deciduous trees are tolerant to Indaziflam herbicide. Conifers including Christmas trees are tolerant to foliar applications of indaziflam. In Christmas tree farm operati ons, the common practice is to direct the spray to the base of the trees on a band or broadcast application. Wind Avoid making applications when spray particles may

be carried by

air currents to areas where sensitive crops and plants are growing. Do n ot spray near sensitive plants if wind is gusty, below 2 mph, or in excess of 10 mph and moving in the direction of adjacent areas of sensitive crops or plants. Do not apply

during temperature inversions. Always make applications when there is some air m ovement to determine the direction and distance of possible spray drift. Local terrain may

influence wind patterns; the applicator should be familiar with local conditions and understand how they may impact spray

drift. Boom or nozzle shielding can red uce the effects of wind or air currents on drift. Verify that the shields do not interfere with uniform deposition of product prior to application. Aerial Application When applying by

air only , orient nozzles so that the spray is applied backwards, parallel to the airstream. This practice will produce larger droplets than other nozzle orientations. With fixed wing aircraft, the length of the boom should not exceed 3/4 the length of the wing. For helicopters, use a boom length and position that prevents the spray from entering the rotor vortices. Use a minimum of 5 gallons or more of spray volume when applyingby air. Temperature Inversion A surface temperature inversion (i.e., increasing temperature with increasing altitude) greatl y increases the pot ential for drift. Avoid application when conditions are favorable to inversion. Presence of ground fog is a good indicator of a surface temperature inversion. Sensitive Areas Sensitive areas are areas where the application of Indaziflam 20 WSP Herbicide is not labeled. These include bodies of water (ponds, lakes, rivers, streams, and ditches containing casual water), habitats for endangered species, and non - target plants including agricultural crop areas. Applications of Indaziflam 20 WSP Herbicide need to be made when wind is blowing away from sensitive areas. Maintain a practical and appropriate untreated buffer (15 ft) between application of Indaziflam 20 WSP Herbicide and any sensitive areas.