UNITED ST ATES ENVIRONMENTAL PROTECTION AGENCY WA SHINGTO N D

. C ., 20460 

## MAY 0 4 20J5

MEMORANDUM OFFICE OF CHE M I CAL SAFETY AND POLLUTION PREVENTION



### SUBJECT: BEAD Response to the Do w AgroScie nces Co mm ent s on Rice Producti o n Practice s and Us e of Cy hal ofop

- buty l for W eed Co ntrol in Rice Production ( DP # 424433) 

### F

ROM: Su nil Ratnayake, PhD , Biologist

# ~Nl -

# k~~ Biological A nal ysis Bra nch

## ~ ,. "-JV ' \ Biological and Eco nomic Analysis D i vision (7503 P ) 

### THRU : Arnet J ones, Chief Biological Ana lysis Branc Biological and Econom ic Analysis Di n (7503P) 

### TO : Jolene Trujillo , Chemical Rev iew Manager Pesticide R e - evaluation Di v i sion (7508P) 

### Peer Review P a nel Date: March 3 2015



### IN T RODU CT IO N The Office of P est icid e Pro g ram s ( OPP) received co mme nt s from Dow AgroSciences ( D AS), the regis tran t of cyha lofop-b utyl , on the Biol og i cal and Econom ic A n a lys is Di vis io n 's memo desc r ibing rice production practices and the use of cy h alofop-buty l in rice production ( Ratnayake, 2014). This B EAD memo prov id ed needed infonnation on ri ce production for the registration r ev iew of cyhalofop-buty l herb ic id e. The informat io n provided to EFED included information on drill ( dry ) seeded and water (we t) seeded rice produc tion , use of cyhalofo p for weed co n trol in these production systems, and duratio n of holding wate r follow in g the applications of cyhalofop in these rice production systems. BEAD is th ankful for the com m ents provided by DAS and BEAD·s responses for the D AS comments ar e g ive n be low. As a resul t of these comments , B EA D is rev ising th e assess m e nt , w hi ch w ill be made ava ilabl e in th e docket. P age I

### BEAD's statement on page 3 of 15: "After the emergence of seedlings,fields are maintained with a low level of water (shallow flooding). " · 

### DAS Comment No. 1 The statement should be corrected to read : in water-seeded rice, after the emergence of the rice seedlings, fields are maintained wi th a low level of water (shallow flood) until the permanent flood is established
. In drill-seeded rice , after the emergence of rice seedlings , fields are maintained at a moist to wet condition by rainfall or quick irri gation (flush in g) of water across the fields. The fields are not flooded unti l after the rice tillers, wh ich can be 4-6 weeks after planting depending on the time of year and weather conditions
. 

### BEAD 's Response : The DAS comment is referring to a statement in the first paragraph on page 3 of the BEAD assessment under the heading of drill seeding
. This statement is accurate. For the rest of the DAS comment under the comment number 1, please check the BEAD ' s response for DAS comment number 2. 

### BEAD's statement on page 3 of 15: "Three to four weeks afterplanting , the permanent flooding is established with 6-12 inches of water and post-flood herbicide treatments are applied to control existing weeds. " 

### DAS Comment No. 2. The statement should be corrected to read: Four to s i x weeks after planting, the permanent flood is established in drill-seeded rice w ith 4-10 in ches of water and post-flood herbicide treatments are applied to control existing weeds. 

### BEAD 's Response: This statement will be revised as the permanent flood is estab li shed when the seedlings have 4 to 5 leaves or at the development of 2nd t ill er. Most rice varieties achieve this stage w ithin 4 to 6 weeks after planting. This timing may vary depending on the location, type of the planted rice variety , (late or early), soil moisture, soil fertility , and weather conditions. At the establ i shment of permanent flood , rice fields are flooded to a depth of 4 to 10 inches of water. However, depth of water depends on seedling height of the planted rice variety
. Seedlings should not be submerged and maintaining a water level abo ut 1/3 to 1/ 2 of seedling height i s important. 

### BEAD's statement on page 4 of 15 : "Mostly, pre-emergence herbicides are applied in the field before planting rice seeds. " 

### DAS Comment No
. 3. The statement should be corrected to read: Mostly , pre-emergence herbicides are app li ed in the field before planting rice seeds. Page 2Agency's Response: The Agency does not find a d ifference between th e D AS com me n t and the Agency's sta tement. Therefore , no change of the Agency's statement is needed. BEAD's statement on page 4 of 15:


### "Herbicides such as pendimethalin , molinale, thiobencarb, quinclorac are some of the pre emergence herbicides used in rice production. " Dow AgroSc i ences, LLC Report JD : NTB 112414 Page 9 of 10 DAS Comment No
. 4. T h e request to cancel molinate pest ic ide registrat io ns volu ntaril y was published in the Federal Register on 9/17 / 2003. The product cancell ati o n order and ame ndm ent to termin ate uses became effective 7/ 30 / 2008. As a conseq uence, the acti ve should not be included i n this listing. The statement shou ld be corrected so that it reads : Herb ic ides s uch as pendimethalin, clomazone, thiobencarb and quinclorac are some of the pre-emergence herbicid es used i n ric e producti on. BEAD's Response: The Age nc y agrees that the inclusion of molinate i s an error. The reference to molinate will be deleted. Clomazone wi ll be add ed to the li st of pre-emergence h erb icides. B EAD 's state ment on page 8 of 15 : 

### A summmy of the es ti mated durat ion of wa ter holding follow ing herbicide applica t ions in AR, LA , MS is presented. DAS Comment No. 5. DAS d i sagrees w ith the assumptions supporti ng the calculations in this sec ti on. The calc ulation s assume that the water is held in the field after the pre-flood app li cat io n. H oweve r, when a preflood application is made , th e field is not flooded and it may be 2-3 weeks before the permanent flood is put on the ri ce field
. Post-flood in drill seeded ric e can be established from 4 - 6 weeks after planting versus 3 -4 weeks. Dri ll seeded ri ce is not ready fo r pennane nt flood in 3 weeks
. The rice has to be till ered before th e permanent fl ood is establ ished
. Agency's Re spo n se: Th e Agency disagrees th at assumptions on calculati on s are wrong . T he Agency did no t assume that pre - flood app li cat ion s are made after the estab li shment of permanent flood. In drill seeding , pre-flood app lication s are made before the establishmen t of pem1anent flood and after t h e pre-flood applications , a shallow leve l of water is mai ntained to have good so il moisture leve l fo r seed li ng growth
. On the t im ing of estab li shment of permanent flood , p l

ease refe r to the Agency's response for DAS comment number 2
. BEAD's statement on page 9 of 15: 

### A summmy of the cyhalofop app li cations in water seeded rice production is presented. D AS Co mment No. 6. The instructions d esc ri be d in this sec tion do not apply to granul ar formulation s. This statement s ho uld be upd ated so t hat it reads: A s ummary of cyhalofop app li cation s in water seeded (we t Page 3seeded) rice production is presented for liquid formulations. BEAD ' s Response: The statement w ill be updated as s ugges te d.

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