UNITED STATES ENV IRONMENTAL PROTECTION AGENCY WAS HINGTON D .C , 20 460

MEMORAND UM 

### M AY 1 4 

## 20 10 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVE N TION

SUBJE CT :

F ROM : TIIR U:

T O: Res ponse to a Co mment R egarding " Usc an d Us age lnf onn ation f or Azoxys trobin ", a Part o f Azoxystrob in Re gistration Re view ( Docket No. E PAH Q- OPP- 2009-0835) ( DP365674) 

# r.: Le onard Yo unn an , P lant Pathologist 

# (I Bio logical Anal ysis B ranch A rnet Jon es, C h ief B iological A nalysis B ranch Bio logical an d Eco nomic A naly s i s D ivision Ke lly Ba llard , C he mica l Review M anager Pes ticide Reev aluation D ivision (75 08P) Product Rev iew Panel : May 5, 2 010 A s p art of th e azoxystro bin regi str ation review ( Docket N o. E PA-HQ-OPP-2009-0835) B EAD p rovided " Use and Us a g e Info rmation f or Az oxystrobin" (Ste bbins an d Yo u nnan, 2 009) to the Pe sti cide Re evaluation Di vi si on. Th e m em orandum i ncluded inf orm ation co ncerning th e fun gicide azoxys trobin s uch as usage d ata , use s ites , tar get di s ea s e s , f ormul ations , application m ethod s, and a d iscu s sion o f " plant h ealth " is s ues related to azoxys trobin. Th e p lant he alth is s ue re fer s t o u se s f or improving y ields an d certai n pl ant health c haracteri s tic s in th e ab s ence of f unga l d isease . Dr . U lric h G isi , a p rofe s sor at th e Unive rsity of B asel and a co nsultant f or Syngen ta Co rp. s ubmitted a co mment regarding t he "P lant H ealth Properties" sec tion o f the " U s e an d U sage" m emora ndum . B ACKGROUND Sy ngent a's azoxys trobin product labels do no t h ave pl ant h ealth cla im s. Ano ther registrant, BASF, obt ained a sup plemental label fo r a r elated fung icide Hea dline <g: · ( py ra cl ostro b in), w hich s tate s that t he fu ngic ide ca n b e u sed fo r " imp roved pl ant health ." in a ddition to trad itional pl ant d isease m anagement. The l abel li st s s everal c harac teristic s th at th e fun gicide c an p rovideinclud ing improved straw s trength in w heat an d c om , i ncreased fru it s i ze in citrus , improved tolerance to fro st in mint an d s u g ar be et , and imp roved qualit y in p otato and soy bean . A fter th e approval of th e s upp le m e n ta l l abel f or He adlin e " , 4 6 s tate e xte nsion pl ant p athologi sts wro te a l etter to th e Age ncy (EPA, 2 0 09a ). T he l etter voice d conc erns that th e approval o f a label maki ng plan t h ealth claim s wa s un wise s i nce it wo uld e ncourage the u s e o f a fu ngicide f or pu rposes se p arate fro m pl ant d isease m anagem ent u s es, f or w hich i t was o riginally reg i s tered . Th ere wa s a c oncern th at pr oduct s wi th s im i lar ac t ive ingredient s ( including azoxyst robin) wo uld a lso be g iven s upplemental l abels a nd thi s u se wo uld i nterfere wi th IP M p est man agement s trategie s. T he pl ant p athologi s t s s tated that " the use o f a fungicid e fo r g rowth regulating propertie s i s a seri ou s bl ow to l PM prin ciple s an d almost guara ntee s e arlier se lection f or re s i s tance in certain p athogen p opulat ions to a v aluable cla ss o f fun gicide s." Th ey a lso s tated that data to s upport clai ms that fu ngicide s ca n e nhance s uch ch aracteri s tic s as see d qu ality i n s oyb e an ha s n ot b een properl y s ub s tanti ated. In addi tion to th e re sistance i ssu es th e plan t pathologi sts s ta t e d th at "th ere are al so non-target e ffects o f f ungicides (i ncluding stro bilurin s [e.g ., p yraclostrobin , az oxystrobinJ) to co n s ider s uch a s s uppre ss io n o f b eneficial fu ngi in man y cro pping sy ste ms." 

### COMMENT In hi s co mme nt , Dr. G i s i noted th at th e letter by th e plant p athologists re ferred to H eadline ®, but c o uld apply ge nerall y to a ll Qo l ( quinine o ut si de i nhibitor) fun gicides (a lso ca lled s trobilurin f ungicide s), including azoxys trobin . D r . Gi si co mmented o n th e s itua tio n f or c om and p otential re si stance to a zoxys tr ob i n b y c omm on co m p athogens an d co ncluded t hat: "If th e number ofazox ystro bin appli cations is s trictly l imited to o ne to m aximum 2 per sea s on an d t he t reatment s are m ade b ef ore a po tenti al o utbreak of e pidemic s oc cur s, th e u s e o f Qo I s as g rowth reg ulating co mpound s in c om c an be rec ommen ded w ithout runn ing i nto un acceptable resi stan ce ri sk s. If a dditi onal Qo I ap plications wo uld b e n eeded for d isease co ntrol in co m , a new [resistance] r isk a ssess ment s h ou ld b e mad e. In a ddition, s e n sit iv ity m onitoring prog ramm es for imp ortant c om pathogen s m ay b e implemented in area o f intensive Qo I u sage to f ollow any chan ges in s en s itivity o f pa thogen p opulations . A s to the plant p athologi st s c oncern o f non-t arget e ff e ct s, Dr. G isi s t at ed t hat " There are no d ata a vailable o n QoI act ivity a gain st ' be neficial f ungi' ; th erefore , n o fun gicide resistance ri sk a ss essment can b e ma de . "

2

### AGENCY RESPONSE Dr . G isi be lieve s tha t the i ncidence o f resi st ance by com p athogens to azoxy strobi n woul d be low due to th e n at ure of th e m ajor com p athogens an d the typical one o r two fu ngicide a pplicati ons o n c om. Wh i le some p athogen s an d c rop s yste ms m ight have a reduced in c i dence o f devel opi ng re s i stance to az oxy strobin , overall th i s and o ther Qo I fu ngicide s are c o n s idered " h igh ri sk" fo r deve lo pment of re sis tance by some pat hogen s (FRAC , 2009 ) . The Age ncy agree s wi th Dr . G i si tha t h igh rate s of re s i s tance m ight be expected ( a nd h ave been o bse rved) wi th so m e p athogen s o r "c rops s uch as grapes an d potatoe s w ith up to f our and e ight tre a tment s , re spectively , " It is not o nly the number of applic at ions th at mi ght affect t he inc idence of re sistance, but the co mbination of repeated expo sure to the pe sticide and genetic makeup of a p athogen po pulation . A s de scribed in th e " Use and Usag e" memorandum ( Stebbins and Yourman. 2 009), re si stance to azox ystrobi n and o the r Q oI fun gicide s h as devel oped by l east 32 path ogen s pecies th at are important o n several crop s ( FRAC, 2 008) . The re sistance i ssue s peaks to the c oncern s o f the s tate plant pathol ogists and the re ason th at the A gency i s currently lookin g int o the i ssue of the u se o f fun gicides for non-dise ase mana gement purpo ses . Dr . Gi si s tated th at f or com if mo re th an on e or tw o app licati o n s were nece ssary , an ass essme nt c o uld be c o nducted to de termine th e lik elihood of re si stance d evelopment and p athogen s e ns itivi ty program s c o ul d be imple mented . H oweve r, it i s unclear who wo uld co nduct th e as sess ments and wh at wou ld be th e i mplicatio n s for s ubseque n t pe st icide use o n a cro p i f a hi gh probab ility o f re s i stance we re iden tified . Th ere is evo lv ing i nte re s t in th e is su e o f t he us e of pe s ticide s fo r no n-p e s t man age ment purp o s es . I s sue s s uc h a s pe s ticide effect s o n benefi cial org anisms require fiel d d ata that c urrently are l a ckin g. T he Ag ency is a l so i nterested in th e impl ications o f po ss ible in crea s e s in pes ticide u se fo r p urpo ses o ther th an pe st man agement . A s th e "Us e and U sage" memorandum noted, E PA 's O ffice o f Pe st i c id e Programs h as recentl y f ormed a n int ernal resi stan ce m ana gement work group t o review thi s is sue an d to de velop a s trategic work pl an to ad dress e merging a reas o f c o n ce rn ( EPA, 2009b) . T his w orkgro u p wi ll exam in e fi eld d ata su pplied by var ious s ources , i ncludin g the regi stra nt a nd p lant pa tho lo gists w ho s ig n ed th e 2 009 l e tt e r (E PA, 2009 a). T he Ag ency appreciates co mment s o n thi s m atter, w hich w ill b e co nsidered in it s regulatory deci s ion s. 

### CITATIONS E PA. 2 009a. Letter f rom U nivers i ties Reg ardin g th e S trobi l urin , Py raclo s t ro bin { Headline) 

### S upplementa l La bel. Feb ruary 13, 20 09 (Ad dendum February 20 , 2009) . http ://www .epa.gov/pe sticide s/regulati nglhead line-Ietter .pdf E PA. 2009b . E PA Re spo nse to Letter f rom Un iv e rs iti es Regarding the Strobil urin, Pyraclos trobi n ( Head line) Sup plemental Labe l. J une 4 , 2009 . http :// \\ ,,",,w . epa.gov/ pesticide s/ regulatinglhead line

- response.pdf

3FRA C (Fu ng icide Re sis tance Ac tion Com mitt ee). 2008 . Li s t o f p athogen s wit h fi eld r e s istance t owar d s Qo I fun g icide s. (updated 02 / 12 /08) . F ungicide Re sis tance Act io n C o m mittee. http ://Yiww,[r ac.info /frac /meetin g/2008IPathogen s with field re si stance toward s 2008 .pdf FRA C (F ungicide Resis tan c e A ctio n Committee) . 2009 . Q o l W ork in g Grou p-2009 Mi nutes . December 3 . 2009 . http ://\\'ww .frac .info /fr a clworkIFRAC 

### 0 01 Minut es 2009Final .pdf Stebbin s. K . an d Younna n , 

### L. 2009 . U se and Us age Informat io n f or Az oxystrob in . BEAD document , Oc tober 8 , 2009 . Docket N o. EPA -HQ -OPP -20 09 -0835 .

4