UNITED STATES ENVIRONMENTAL PROTECT ION AGENC Y WASH INGTON D .C ., 20460



### MEMORANDUM 

## JUN 1 7 20 10 O FFICE OF C HEMICAL SAFETY AN D POLLUT ION PREV£NT!ON



### SUBJECT : Addendum t o the Docwnent "Evaluati on o f a Request f or a Public Intere st Findin g f o r the Conditional Regi strati on o f Aminocycl opyra chlor and 

### Amin ocyclopyrachlor Methyl fo r Weed and Bru sh Co ntrol ( DP# 376722)" 

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T HRU: William Phillip s , U
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_ . Agronomi st 

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J "- B io log ical Analysi s Branch / 

### Bio logical and Eco nomic Ana ly s is D ivi si ( 750 P ) A rnet Jones, C hief

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### Bi ological a nd Eco nomic A naly s is i vis ion ( 503 P) TO : M i ndy O ndish Fungicides Br anch Reg i s tration D ivision (75 05P)


### P RO D UCT REV IE W P ANEL: June 1 6, 2 010

B A C KGRO UN D 

### A r eque st was s ubmitted to th e United S tate s Env i ronmental Prot ection Ag ency ( Agency) 

### by th e registrant 

### E .1. D uPont d e Ne mours a nd C o mp a ny ( DuPont) t o de termine wh ether a requ e st for th e co nditional re gi stration o f a ne w ac tive in gr edient fo r t he b road lea f h erbicide a m inoeycio pyraeh lo r aeid ( DPX-MAT28 ) and m ethyl (D PX-KJM44) (a min oey clopyraehlor) i s in th e p ublic i nte res t. To make th e dete rmination wh ether a co nditiona l re gi s tration is in th e p ub li c i nterest B EAD conducte d an an alysis th at re sulted in a m emo ' o utlining th e findin g s o f this a nalysi s. The c riteria by w hich B EAD eva luate d this request were ba sed o n th e 1 986 Fe deral Re gister Not ice on p ublic intere st fin dings, and co nsi s ted of the follo w ing : I ) that there is a n eed for th e new pe s tic ide th at i s n ot being m et by currently reg istere d pe s ticide s, and/or 2)t hat the

I Ph illips
. II
. W
. Evalu ation o f a Request for a Publi c I nt e re s t F inding f o r the C onditiona l Registration of Am inocyc1opyrachlo r and Aminocyc1 op yrachlor Methyl fo r Weed a nd Bru sh Co ntrol ( DP#37 6722)ben efits t o u se rs f r om the new pe sti cide are g reater than tho se from c u rre ntly re gistered pes tici des or n on-che mi cal c ontrol m ea sur es. In it s rev ie w o f th e o rig inal s ubmi ss ion from th e regi s trant d o cume nt, B EAD d et ermin ed that the d ata on h erbicide e ffica cy compari sons wa s incompl ete and la cked data ri gor. Ther efore , the in fo rmation pro vided by th e re gi strant f or a minocyclo pyrachlor fa iled t o me et th e crit erion that n ew h erbicid e co ntrols w eed s pec ie s th at ar e n ot controlled b y c urrently reg istered h erbicides. In a d di tion t o the e fficacy o f t his h erbi cide, th e Age ncy was as ked t o eva luate t wo additional way s in w hich th e regi strant claim ed t hat a minocyclo pyrachlor c ould meet the co nditional re gistration cr iteria for bein g i n the public int erest. Th e r egi strant a sserted that I ) th e u se o f thi s herbi cide reduced th e am ount o f herbi cide appli ed wh en comp ared to o lder ch emical s and 2) the low vo latility o f thi s herbi cide would be a benefit in re du cin g ph ytoto xi cit y t o nearb y p lant s . The eva luation o ft hese t wo a dditional a sse rtion s b y th e re gi strant were def erred b y B EAD t o RD , E FED, a nd B ED a s it w as not B EAD ' s r egulator y rol e t o ma ke the s e d eterminati ons. Thu s , th is add endum t o th e o riginal do c ument w ill n ot address th ese iss ues. S ince th e t ime that the o riginal d o cum ent wa s writt en , B E AD ha s receiv ed 

### 2 3 n ew data s ets f or as m any w eed s pe cies f rom the re gi strant. The d ata f rom D uPont w a s f rom s tatistically an alyzed ef ficacy tri al s f rom s ev er a l univer sitie s a nd incl uded ea ch w eed s pecies m enti oned in the ori ginal s ubmission. Due to th e l arge amount o f data s ubmitted and the s hort am ount o f time allo wed for re view , B EAD ha s s elected l eaf y s purge a s a model wee d for th e d et erminati on o f the co mparative e fficacy o f aminoc yclop yrachlor. Thi s weed pe st w as s elected on the b asis o f s eve r a l fa ctor s . Ove rall, thi s wee d was s elec ted b eca u se of th e s ignificant pr obl em s ass ociated w ith co ntrolling thi s we ed s pecies in v arious p arts o f the countr y . In a ddition , leafy s purg e i s c on sid ered a " n oxio us " we ed s pecie s b y the US D epartm ent of A griculture ( USDA ). T hrough their "T EAM Le af y S purge" pro gram , USD A A RS c haracterizes thi s wee d a s c ausing " .
. . 

### signifi cant problems in the n orthern Gre at Plain s b y inva ding gra zing lands f or ca ttle a nd horses , reducing ra ngel and pr oductivity a nd p lant di versity, degrad ing wil dl if e h abitat, displaci ng s ensiti ve specie s and d rastically re ducing land values. " B EAD c onsiders th ese i ssues important enou gh t o warr ant the s election of thi s s pecie s as a s ignificant t est o f a minocyclo pyrachlo r' s ability t o co ntrol n oxi ou s and inva sive w eed s as a potential a lternative to c urrently reg istered h erbi cides as a sserted b y the re gi strant. Th e f ollowin g ar e herbicide s that c an be u sed t o control w eeds lik e le af y s purge and a re re gistered f or u se in th e s ame s ite s; A minopyralid, Broma cil , 2,4-D , Di c amba , Picloram , Tricl opyr , C lopyrlid , G lyph osate, and Im azap yr .

D IS CUSS IO:\ Lea fy Sp ur ge Leaf y s purge i s a perenn ial w eed that re produces b y an agg ressiv e ro ot sys tem as we ll a s s ee d tr an sp orted and s pread b y bird s and human s. It i s con sidered a noxiou s w eed th at o ccurs primaril y in 3 5 o f the U nited S tates ? and its control i s required b y legal s tatute in 22 s tate s.' T he
2 M itchell , R
. , C
. M offet , an d R
. S ose b eez . 200 7
. A Phy siological B a sis for Co ntro lling Le afy S purge on Nebras ka Rang e land
. Rob M it chell , Cor ey M oct y, a nd Ro n S osebeez US DA Agr ic ultural Res earch Se rvice , Lin c oln, N eb ra ska
. Publi cation s from USDA ·ARS I UN L F aculty
. Un iversity of Ne braska

- Lincoln 3 USDA A RS T EAM Leafy Sp urge . http: // www. tea m. ars. u s da .gov/ in dex .h tm l 

### 2

### s ites where this w eed i s found are main l y pa stur e, ran ge land, gra ss p rairies, a s w ell a s non c ultivated ar eas. Leafy s purge is a n e conomica lly imp ortant plan t s ince it reduces viab le f orage for hi gh

- graz in g anima l s s uc h as ca ttle and hor ses , as w e ll as be ing toxic to the se s pecies. T his weed costs pri vate l a nd o wn ers, f ederal age ncies, a nd s tate gove rnme n ts m illi ons o f do llar s in c ontro l ef forts. Biolog ical and C ultural Con trol Bi o l ogical , c ultural , a nd her bicidal co ntro l s s hou l d b e u sed together in an i nte grated sys tem to c ontrol le afy s purge. M any of the se sys tems w ill u se in sects , anim al g razing, a nd b urni ng, cu ltivati on, an d herbic ide applicatio ns. Co ntrol u sing in sects incl ude th e rele ase of flea be etles , w hile th e u se of g razing as a method to c ontro l requires lo w g raz ing an imal s s uch as s heep an d/or goa ts. Res earch h as d emo n strated th at u sing m ultip l e graz ing s pecie s c an redu ce le af y sp urge p opulat ion d ensities as m uch as 8 0 -9 0% in three to fi ve yea rs u sing prescribed s tocking rates and s pecific herbivore types ." U nfortu nately, man y a nima l product i on s ys te m s f ocus on si ng le s pec i es a n d as a result, the a ddition o f d ifferent an im a l types w ould result i n a d rastic c ha nge in o peration f or man y ran chers. C ultura l c ontro l co nsists primari ly o fbumin g a nd c ultivation o f areas that a re in fested w ith le af y s purge. C ultivation i s a ve ry eff ective too l f or t he c ontro l o f this w eed and its s pread; h oweve r, c ultivation i s v ery lim ited in re mote areas of ran geland a nd e nvironmenta lly sa native areas . Ove rall , in co mbinat ion th ese me th od s p lu s c onven tio nal h e rbic id es c an result in th e s ucc e ss ful co n trol o f l eafy s p urge. Mo re inf ormation on bi o lo gical and cultur al c on tro l o f leafy s purge i s m aintained at the US DA A RS T EAM L eaf y S purge w ebsite
. 5


### Herbicide Control T h e prim ary h e rbi cides u sed to co ntro l l eaf y sp u rge are 2 ,4 -D, am i nopyra lid , pi cloram, a nd tricl opyr. T he registrant s t a t es th at a mi no cyclopyrach lor s hould be c onsidered a replacement f or the se herbicide s. I n ge neral , mo st o f th ese h erbicide s are e ffectiv e to s ome degree a t c ontro lling leaf y sp urge; and w hen i n c ombina ti o n as a t ank m i x w ith o n e an other , in seque ntia l ap p licatio n s , o r b oth, th eir e fficacy c an b e e nha nced
. T he herbicide tha t is mo s t o ften re commended to co ntrol l eafy s p urg e i s pic loram. " P icloram i s c ommonly recomme nded to c on trol le af y s purge w hen i n co mbination wi th 2 ,4

- D. Thi s co mbination i s p opu lar s ince it a llows f o r a r educed rate o fp icloram t o b e u sed, w h ich reduce s th e p er acre treatment cost. ' I n a ddition, it h as be en re po rted th at the two herbicide s w orking toge ther h ave a hi ghe r effic acy than eac h wor king al one. Nevert heless , th e hallm ark o f an effi caciou s herbicide that w ill c o n tro l pe rennial weed s pecie s i s lo ng- t e rm c ontro l.

4 S
. M erritt. 2 002
. Specie s G raz ing and Lea fy Spurge , A Comp rehensive , Ea sy- To

- Read Man ual O n U s ing M ulti

Spe ci e s Graz ing As A n Effec t ive Leafy Sp urge Management T ool. U SDA-AR S TEAM Leafy S p urge A rea-W ide I PM Progra m. http ://www . team . ars. u sda
. gov/g r azing m a nual
. pd f 5 TEAM = The Eco lo g ica l A rea-w ide Man agement. htt p: //www.tea m.a r s .usda
. gov /index.htm l 6 Vegetat ion M a na ge me nt G uide, M i ssouri Depart m ent o f Co nservation
. http ://m dc
. mo .gov/nat his /e xotic /vegmaw sixtee n.htm 7 Goo dw in , K
. R
. S heley , R
. Nowi erski a nd R
. L ym . Leafy Spurge :Bio logy , Eco logy and Management 

### 3NEW DATA SUO"1 ISSI O:\ AND EVA LUATION Data Submission The effi cacy dat a p rovided b y the reg istrant was f rom a se t of tri al result s c onducted b y coope rator s f rom 

### 24 u niver sit y r esearchers. Unive rsity h erbicide eva luation tri als a re ge nerally c onducted i n field pl ots w here va rious h erbi cide tr eatm ents ar e appl ied t o s pe c i fic p lots (s ee h ypothetical exa mple i n Ta ble 1)

. U s ually, e ach h erbicide is ap plied to thr ee plot s to replicate tr eatment ef fects. T he se pl ots co ntain a s pecie s, or multipl e s pecie s, o f tar get wee ds. T he d ata gathered f rom th ese p lots. a mong m any t ypes, ar e the p er c ent o f weeds that a re c ontrolled. Th e s e eva lua tions a re c onducted at var ious pr eplanncd i n tervals
. T able 2 p rovides an exam ple o f h ow the d ata f rom un iver si ty tri als a re anal yzed for e ach h erbicide at thr ee diff erent tim es f ollo wing tr e atmen t.
Ta ble I

. A h y poth etical example o f the s tructure of a s in g l e u niversity h erb icide tri al : Eva luation of h erbicide A l co ntrol ofweedZ ve rsu s indu stry s tandard h erbic ides a t th e Un iver sit y o f X research f arm. Rate Treatments I bs 

### a i /A A l 10 Al 5 B 3
. 5 C 7 1 "OAT -Days Afte r T re atm e nt 

### 2 0 DAT ' % Co ntrol 86 a 

### Oc 20b l 5b Eva luation Tim e s 

### 60DA T 90a 

### 2 5b 2 0b 

### 5c 100 DAT 80a 75a 

### O

b O

b

Th e d ata s ubmitted b y th e r egistrant includ ed s t at istica l a naly ses f rom e ach u niversity tr ial f or eac h w eed s pecies (e.g. wee d s pecies A , u niver s ity 

### 1 ; w eed s pecies A , uni ver sit y 

### 2..
. ). In o rder to fac ilitate a co mp rehen s ive co mparative a nalysis for eac h w eed s pec ies, th e regi s tran t' s a naly ses wo uld n eeded to have b een co nducted by an alyzing to gether th e d ata fr om a ll s tudies. Si nce the data an alysis p rovided was no t c onducted in thi s m anner BEAD's rev iew o f the e fficacy dat a regar ding th ese h erbicide u se s c anno t b e qu antitatively e v alu at e d ac ross uni ver s ity tr ials , no r c an th e m e an tr eatm ent e ffect s b e s tatistically co mpare d across eva luation d ates. Ho wever, thi s ana ly s is w ill di scuss the effec t s of h erbicide treatment s w ithin OAT s ( e . g. T able 

### 2, 2 0 OA T , 60 OAT , 100 OAT) q uantitat ively whil e di scu ssi ng the dat a acro ss O A T s (e .g. Ta ble 2, T reatment A l at 20 OA T v e rsu s IO ODAT) qu alitatively. Data Analysis U niversity t rial s s e l ec t e d f or th i s review h ad to i nclud e o ne of thr ee a minoeycl opyrac hlor treat ments , 0
. 089 , 0
. 112, 0 .178, o r 0.187 p ounds aci d e q uiva lent per ac re (lb s ac / A ). The reason for thi s re quirement i s th at t he se r ates , w hile low , a re we ll w ithin th e labeled rat es an d ar e th e m ost c on s istent a cros s tri als. Th e n ext two c r iter ia th at e ach tr ial was r e quired t o h ave are rat ings co nducted a t ap pro ximat ely 30 OAT an d 365 OAT
. Th es e t wo d ate s wo uld a llow a d etermin ation of the efficacy i n the s hort te rm as well as t he long t erm . A lso, th e s e lec t ed s tudie s mu st h ave co nta in ed at least o ne o f the h erb icides, 

### 2, 4 -0, arn inopyr alid , pi c1 orarn , o r tricl opyr

4

### alone and no t in comb in ation with o the r h e rbi c ide s. T he reason for onl y eva luating th e re gistrant' s herbicide w ith th ese chemic als a lo ne and not i n c ombination is be cause th e eva l uation c riteria i s th at ther e i s a n eed for t he n ew p e sti cide that i s n ot b eing m et b y currently re gi ster ed pestic ides . T he c riterion i s n ot 

### that th ere i s a n eed fo r the ne w p esticide that i s n ot b e in g me t b y c urre ntly r egistered p es ticid es and/or pe s t icide c ombinations
. F I NDINGS 

### Th e d ata for a ll herbicide s e xcept picloram w ere ver y s par se, ho wever , the data from the tria l s that includ ed 2 ,4

- D , am inopyra lid and triclop yr de monstrated that late s e a so n c ontro l of leaf y s purge did n ot co me clo se to th e minimum indu s try s tandard o f7 0% c ontro l (T able 2 ). How ev e r , out of the 1 6 trial s th at incl uded pi c lor am , fi ve o f the s tudi es provided late se ason contro l that wa s abo ve w ell abo ve 7 0%. O f th e fi ve , in trial number one the l ate s eason c ontrol rating w as 77 %, however t hi s wa s n ot s t atistically different than 4 3%, and in tri a l numb er t wo the late se ason rating was 7 2% which w as not s tatistica ll y diff erent from 6 9%. Ov erall , th e long term co ntro ls w ith picloram in o ver 80 % o f th e s tudies w ere b elow the indu stry s tandards. Picloram i s u sually tan k m ixed w ith 2 ,4

- D in order to reduce th e amount o fpicloram w hile maintainin g, or oft en i ncr easing the herbicide e fficacy, a nd al so reducin g th e c ost. In f act, data f rom on e uni ver sit y tri a l demon strated that the c ombination of 2,4

- D and picloram resulted in c ontrol o f 100 % and 8 0% at 4 3 and 3 48 DA T , re sp ectively
. However , th e anal ysi s requir ed in o rder to ev a luat e a pe sticide as a rep lacement f or c urrently regi stered p e sticid es i s ba sed o n t he efficac y o f the indiv idual herbicides
. A minocyclopyrac hlo r d ata f or the 17 univ ersity tr ia l s meeting th e sele ction cr iteria o f having data f or the r ates 0 .089, 0
. 11 2 , 0
. 1 78, or 0 .18 7 lb s a e f A 

### w ere s imilar f or s hort term co ntrol as w ell as l o ng-term (

- 365 DA T ) c ontrol ( Table 2 ). With th e e xc eption of tw o o f the univ ersity r e s earch tria ls , a ll rat es had l o n g -t e rm co ntrol ratings f or le af y s purge w e ll abov e the indu stry s tandards. Th e t wo s tudies that co ntained data for th e lowe st rate o f amin ocycl opyrach lor co ntained dat a f or th e h igh rate that wa s above the indu s try s tandard. In un iver s it y tr ial numb er thr ee th ere wa s o n l y a si ngle ratin g tak en a t 3 15 D AT
. The c ontrol rating for th e 0 .0891b s a e f A 

### rat e w as 47 %, however th e rating f or the 0 .l871b s ae f A 

### w a s 9 3%. In anoth er uni versity t rial, numb er e ight , the p ercent c ontro l for the lo west rate o f 0 .089 lb s a e f A 

### a t 5 5 D AT wa s 57 % , w hich was s ignificant ly l o wer th an th e ratin g of9 5% f or th e 0 .187 lb s a e f A 

### tak en on th e s ame d ate . In add ition, at 3 5 8 D AT the l ower rate w as below indu stry s ta ndards (62 %) a nd the hi gh r ate w as n ot s ignificantly diff erent from 100 % c ontrol. It i s unkn own w hy in b oth o f the se trial s those re sults in th e ratin g s f o r th e 0 .089 Ib s a e f A 

### rate were l o we r f or each eva l uation p eriod than th e 0
. 18 7 I b s ae f A r ate .

F INDING 

### B EAD ha s reviewed th e new da ta a nalyses a nd h a s det enn ined that in s ome c ases 2 ,4

- D, am inopyralid , picl oram , and triclop yr c ontrol of le afy s purge at appro ximately 3 0 D A T p erf ormed up to th e indu stry s tandard o f 70 % o r ab ove ; however , a t the on e ye ar mark a minocyclopyrach lo r c onsi stently c ontro lled le afy s purge ab ove the indu stry s tandard whi le the afo rementioned h e rbicid es did not. T herefore, th e late s eason results o f th e effic acy anal ysis

5

### meet the c riteria that there is a ne ed f or the ne w p e s ticide t hat i s n ot be ing m et by c urrently regis tered p esticides.

6

### T ab le 2 . E ffi ca cy res ults o f s u bmitted d ata f orm D uPo nt regarding th e c o nditio n a l re gist ration o f a min ocy cl opyrac h lo r. 

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