UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460      

	OFFICE OF PREVENTION, PESTICIDES

                                                                        
                   AND TOXIC SUBSTANCES

	

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date:	09/19/08

SUBJECT:  Pendimethalin: IR-4 Tolerance Petition for use of Prowl® H2O
Herbicide (EPA Reg. No. 241-418) on Olives.  Summary of existing data
for the stone fruit crop group 12 tolerance.

   

PC Code:  108501	DP Barcode:  356045

Decision No.: 398084	Registration No.: 241-418

Petition No.: 8E7404	Regulatory Action: Tolerance Petition

Risk Assessment Type: N/A	Case No.: N/A

TXR No.: N/A	CAS No.: 40487-42-1

MRID No.: N/A	40 CFR: 180.361

		              									

	          	

FROM:		Meheret Negussie, Chemist   SEQ CHAPTER \h \r 1 

			Registration Action Branch 3 (RAB3)

			Health Effects Division (HED; 7509P)

THROUGH:	Thurston Morton, Chemist

			Reregistration Branch 4 (RRB4)

			Health Effects Division (7509P)

				and

			Leung Cheng, Senior Chemist

			Registration Action Branch 3 (RAB3)

			Health Effects Division (HED; 7509P)

						

TO:			Daniel Rosenblatt, RM 05

Registration Division (7505P)

and

Christina Swartz

Registration Action Branch Chief (RAB2)

Health Effects Division (HED; 7509P)	  SEQ CHAPTER \h \r 1 

		

The Interregional Research Project No. 4 (IR-4) has submitted a petition
for the establishment of permanent tolerances for residues of the
herbicide pendimethalin in olives.  The proposed tolerance for the
combined residues of pendimethalin
[N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] and its
metabolite 4-[(1- ethylpropyl)amino]-2-methyl-3,5-dinitrobenzyl alcohol
(CL 202,347) is 0.1ppm.

			

Pendimethalin is a dinitroaniline herbicide, primarily controls grass
weeds and is currently labeled for use on bearing fruit trees (stone and
pome fruits). Stone fruits on the Prowl® H2O label include apricot,
aprium, sweet cherry, tart cherry, nectarine, peach, plum, chicksaw
plum, Damson plum, Japanese plum, plumcot, pluot and prune. The label
rate (2.0 to 4.0 qt/A or 1.9 to 3.8 lb ai/A in 1-2 applications) with a
60 day post harvest interval (PHI) for pendimethalin on bearing stone
fruits is the same as the proposed label for olives.

  SEQ CHAPTER \h \r 1 Regulatory Recommendations

  SEQ CHAPTER \h \r 1 HED has examined the residue chemistry database
for pendimethalin, and reviewed the residue chemistry studies on stone
fruits submitted by IR-4 in support of the requested tolerance.  HED
recommends in favor of establishing the proposed tolerance of 0.1 ppm
for residues of pendimethalin in/on olives. There are currently no
Canadian or Codex maximum residue limits (MRLs) for pendimethalin.

EXECUTIVE SUMMARY

Pendimethalin is a selective dinitroaniline herbicide which acts as a
microtubule disruptor by inhibiting cell division and cell elongation in
plants.  

 

Prowl® H2O (EPA Reg. No. 241-418) herbicide is an aqueous capsule
suspension (CS) formulation containing 38.7% active ingredient (ai),
equivalent to 3.8 lb ai/gal, and is proposed for uses on olives (table
and oil use) at 2.0 to 4.0 lb ai/A in 1-2 applications but not to exceed
a total of 4.2 lb ai/A per year with an interval of 30 days or more.
Maximum PHI is 60 days. 

				 

Applications to olives would follow the same use pattern as labeled for
stone fruits with applications sprayed directly to the ground. Prowl®
H2O may be applied surface incorporated or surface preemergence. It can
be applied as a broadcast or banded treatment using ground equipment
before weed emergence. It can be sprayed directly beneath the trees or
in areas between rows, with no applications over the top of trees with
leaves, buds or fruit. It can also be applied through chemigation
applications, flood, flooded basin or gravity flow irrigation systems. 

The IR-4 has previously submitted field trial data in Region 1 (1
trial-cherries), 2 (4-peaches, 1-plum), 5 (3 -cherries, 2-peaches,
1-plum), 10 (1-cherries, 3-peaches, 4-plums), 11 (1-cherries), 12
(1-cherries, 1-plums).   SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 At
each trial location, a single broadcast soil application of
pendimethalin, as Prowl® herbicide in the 3.3 pounds active ingredient
per gallon (lb ai/gal) emulsifiable concentrate (EC) formulation, was
made to cherries at a rate of 3.8 to 4.1 lb ai/A, 3.9 to 5.4 lb ai/A to
peaches and 3.8 to 7.4 lb ai/A to plums. Applications using ground
equipment were made in spray volumes of approximately 19 to 34 gal/A
(GPA) to cherries, 20-35 gal/A to peaches and 19-36 gal/A to plums.  No
spray adjuvant was used at any of the trial sites.  Mature s  SEQ
CHAPTER \h \r 1 amples were collected between 57 to 62 days following
application.  

Samples of cherries, peaches and plums were analyzed for residues of
pendimethalin and its metabolite (CL 202,347) using a gas chromatography
with nitrogen/phosphorus detection (GC/NPD) method entitled Herbicide,
Pendimethalin (CL 92,553):  Determination of CL 92,553 and CL 202,347
(Metabolite) Residues in Alfalfa Green Forage, Alfalfa Seed, Alfalfa Hay
and Processed Meal, SOP M1930.01, with minor modifications.  The lowest
level of method validation (LLMV) for this method was 0.050 ppm for both
pendimethalin and CL 202,347.  The calculated limit of quantitation
(LOQ) range was between 0.010 to 0.027 ppm for pendimethalin, and 0.053
to 0.074 ppm for CL 202,347, while the calculated limit of detection
(LOD) was 0.003 to 0.009 ppm for pendimethalin, and 0.020 ppm for CL
202,347.  The GC/NPD method is adequate for data collection, based on
acceptable concurrent method recovery data of samples (81-118%). 

The results of all the field trials indicated that residues of
pendimethalin and its metabolite (CL 202,347) were both below the LLMV
(0.050 ppm) in all samples harvested 57 to 62 days following a single
broadcast soil application of the Prowl® H2O EC formulation prepared at
a rate of 3.8 to 4.1 lb ai/A to cherries, 3.9 to 5.4 lb ai/A to peaches
and 3.8 to 7.4 lb ai/A to plums.  

Chem SAC minutes from June 25, 2008.

Use of Pendimethalin on Olive Trees – Discussions by electronic mail.

The SAC discussed, via electronic mail, a request from IR-4 to allow use
of pendimethalin on olive trees.  IR-4 requested that the use be
granted, in the absence of residue data, based on translation from stone
fruit.  The SAC determined that, generally speaking, stone fruit is not
a suitable surrogate for olive, primarily due to differences in oil
content.  In this case, however, the SAC is recommending that the use on
olives be permitted.  The pendimethalin use pattern in the case we are
considering is application only to the soil surface, in the row middles
or the orchard floor, to prevent weedy grasses and some broadleaves from
germinating.   There is very limited translocation of pendimethalin
(Herbicide Handbook, Weed Science Society of America, 1998).  The only
way this chemical would have residues in the fruit is by misuse of a
foliar application or drift.  Based on the stone fruit data showing
residue levels below the LOQ following a similar use pattern, an
LOQ-level tolerance (0.1 ppm combined residues of concern) is
appropriate.

  

Conclusions:

The previously reviewed (DP# D271502, W. Drew, 07/12/2006) stone fruit
(cherries, peaches and plums) residue data indicated that residues of
pendimethalin and its metabolite (CL 202,347) were both below the lowest
level of method validation (LLMV) (0.05pm). ChemSAC indicated that the
use patterns for olive and stone fruit is application only to the soil
surface and there is very limited translocation of pendimethalin. The
proposed tolerance (0.1ppm) for the combined residues of pendimethalin
[N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] and its 

metabolite 4-[(1- ethylpropyl)amino]-2-methyl-3,5-dinitrobenzyl alcohol
(CL 202,347) on olives based on the existing residue data on the stone
fruit crop group is acceptable.

DOCUMENT TRACKING

RDI:  M. Negussie (9/10/08); T. Morton (9/18/08); L. Cheng (9/18/08)

Petition Number:  8E7474

DP#:  356045

PC Code:  108501

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