Page 2 of 5

I. CONCLUSIONS

Deficiencies from D372901 (N. Dodd, 2/16/11) concerning multiresidue methods, storage stability, and rotational crop data are revised as follows. Refer to D372901 for other

deficiencies.

860.1360 Multiresidue Methods

The ChemS AC determined on 10/19/11 that the requirement for multiresidue methods for flazasulfuron can be waived because the current (PAM) multiresidue methods are gas chromatographic methods that do not determine sulfonylureas.

860.1380 Storage Stability Data

B ased on the submitted dates of spiking and extraction, g rape storage stability samples in

MRID 47939903 were stable in frozen storage at

- 20°C for at least one year. No additional information is required.

860.1850/860.1900 Confined/Field Accumulation in Rotational Crops

A confined rotational crop study will not be required to support the use on sugarcane provided that the 12

- month plant

- back interval (PBI) is retained on the label. This conclusion is based on low residues in metabolism studies, no dete ctable residues in field studies, and limited sugarcane acreage. If additional rotatable crops are registered in the future or if the petitioner wants to shorten the PBI, the confined rotational crop study will be required ; depending on the results, a stu dy to determine field accumulation in rotational crops may be required.

II. ACTION REQUESTED

HED has been asked to reconsider the following data requirements which were identified as deficiencies in D372901 (N. Dodd, 2/16/11):

860.1360 Multiresidue Meth ods

The petitioner is required to submit multiresidue methods data since tolerances will be

established.Page 3 of 5

860.1380 Storage Stability Data

For MRID 47939903 ( Howald, M., Ullrich

- Mitzel, A. (1997) Storage Stability of SL

- 160 Residues in Grapes. Docume nt Number: 634713), t he petitioner must provide dates of sample spiking and analysis to verify reported storage intervals.

860.1850/860.1900 Confined/Field Accumulation in Rotational Crops

A confined rotational crop study is required to support permanen t registration of sugarcane. Depending on the results, a study to determine field accumulation in rotational crops may be required.

III

. BACKGROUND

ISK Biosciences Corporation proposed tolerances for the herbicide flazasulfuron ( N

- [[(4,6

- dimethoxy

- 2

- py rimidinyl)amino]carbonyl]

- 3

- (trifluoromethyl)

- 2

- pyridinesulfonamide) on citrus, grapes, and sugarcane. A residue chemistry review was completed ( D372901, N. Dodd, 2/16/11). Additional information was submitted by the company.

IV. RESULTS/DISCUSSION

Multiresidue Methods

In MRID 47939909, t he petitioner requested a waiver of the multiresidue method (MRM) data requirement based on the absence of detectab le residues (<0.003 ppm) in field trial residue samples of sugarcane, citrus, and grapes and the exp ected lack of residues in processed commodities reflecting treatment at 1x. HED determined that a waiver could not be granted

based on the absence of detectable residues since a tolerance was to be established. As stated in

an e

- mail from R ichard Lorange r to Paula Deschamp on 9/16/11

, “ t he absence of residues in the primary crop is not grounds to waive the MRM data. The MRM data are required so FDA can know whether or not their MRMs are capable of measuring the residue of concern if it were

found in food /feed, especially at levels above the tolerance. The level of residues expected in legally treated crops is not relevant.”

ISK Biosciences Corporation submitted a dditional information (MRIDs 48623100 and 48623101) in r esponse to HED’s request for multire sidue methods for flazasulfuron. Citing two literature references, the company indicated that the Pesticide Analytical Methods (PAM) multiresidue methodology, which uses gas chromatography, cannot analyze sulfonylureas, including flazasulfuron. The compa ny submitted a multiresidue method by Klein and Alder which determined flazasulfuron using liquid chromatography with tandem mass spectrometry (LC

- MS/MS).

The ChemSAC determined on 10/19/11 that the requirement for multiresidue methods for

flazasulfuron c an be waived because the current (PAM) multiresidue methods are gas chromatographic methods that do not determine sulfonylureas.Page 4 of 5

Storage Stability Data

Dates of spiking and extraction for grapes were submitted via an e

- mail from Mark Gelin to Hope Johns on on 9/29/11 (Attachment 1). In MRID 47939903, storage time was considered from the date of sample fortification to the date of extraction. HED concludes that t he s torage stability stud y (MRID 47939903) , t ogether with the spiking and extraction dates, i ndicates that the residues of flazasulfuron (parent) are stable for intervals of at least 12 months in grapes at

- 20°C. In MRID 47939903 (page 8), the petitioner indicate d that experiments were started on 9/2/96 and completed on 9/3/97. Although analysis times were not reported, no additional information is requred for this action since all grape residue samples (including the raw agricultural commodity and processed commodities) were stored less than 12 months.

Rotational Crop Data Requirements

The Che mSAC discussed rotational crop data requirements for flazasulfuron o n sugarcane in

connection with the review of flazasulfuron on citrus, grapes, and sugarcane (D372901, N. Dodd, 2/16/11). Sugarcane is the only crop which is rotated. The proposed label r equires a 12

- month interval between the last application and the planting of a rotational crop . In D372901 (N. Dodd, 2/16/11) , HED requested a confined rotational crop study as a condition of registration.

The ChemSAC determined on 10 /5/11 that a confine d rotational crop study will not be required to support the use on sugarcane provided that the 12

- month PBI is retained on the label. This conclusion is based on low residues in metabolism studies, no detectable residues in field studies, and limited suga rcane acreage. If additional rotatable crops are registered in the future or if the petitioner wants to shorten the PBI, the confined rotational crop study will be required.Page 5 of 5 Attachment 1