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metolachlor EPA Review of Request for Emergency Exemption for Use of Metolachlor to Control Weeds in Red Beets in New York 2/04




UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460

OFFICE OF	PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

MEMORANDUM

February 11, 2004
			
SUBJECT:	Review of Request for Emergency Exemption for Use of Metolachlor 
            to Control  Weeds in Red Beets in New York (04-NY-03) [DP Barcode D297470]

FROM:	Virginia Werling, Biologist
    	Herbicide and Insecticide Branch
	
			Istanbul Yusuf, Economist
			Economic Analysis Branch
			Biological and Economic Analysis Division (7503C)

TO:		Andrew Ertman
    	Minor Use, Inerts and Emergency Response Branch
		Registration Division (7505C)

THRU:		Arnet W. Jones, Chief
			Herbicides and Insecticides Branch
		
			David Widawsky, Chief
			Economic Analysis Branch
			Biological and Economic Analysis Division (7503C)

REVIEWED BY PRP: January 21, 2004 

SUMMARY: New York has requested use of metolachlor for weed control in table beets 
for the  first time this year.  However, post-emergence use of desmedipham has been 
granted for the control of broadleaf weeds in red table beets for the past eight 
years due to loss of Antor® (diethatyl ethyl) (4,5) and has also been requested for 
2004.  Although weed spectrum controlled overlaps between these two herbicides, 
metolachlor is applied pre-emergence chiefly for grasses while desmedipham is applied 
post-emergence mainly for broadleaves.  Metolachlor was requested primarily due to 
uncertainty of the 2004 availability of cycloate (Ro-neet®), a key pre-emergence 
herbicide used on over 95% of red beets grown in New York.  Metolachlor was also 
requested to assist weed control in this emergency situation and facilitate IPM and 
resistance management programs.  However, since supplies of cycloate are adequate 
(6,7),  BEAD concludes that although an emergency situation exists and the use of 
metolachlor would help control the situation, the use of desmedipham is adequate.  
Therefore, if desmedipham is allowed to be used in 2004, the situation is not 
likely to lead to significant economic loss to growers if the request for 
metolachlor is denied.  However, if use of desmedipham is not allowed, then the 
situation meets the criteria for an urgent and non-routine situation (metolachlor 
is needed).  The rationale for this recommendation follows. 
 
BIOLOGICAL ANALYSIS:

The Request.  Metolachlor (Dual Magnum 7.62 EC at 0.32 to 0.64 lb ai/A) has been 
requested for use in the major red beet production areas in New York State for 
pre-emergence control of weeds including: various annual grasses; yellow nutsedge 
(Cyperus esculentus); hairy galinsoga (Galinsoga ciliata); redroot pigweed 
(Amaranthus retroflexus); common lambsquarters (Chenopodium album); wild mustard 
(Brassica kaber); eastern black nightshade (Solanum  ptycanthum); hairy nightshade 
(Solanum sarrachoides); and common purslane (Portulaca oleracea).  New York has 
requested the exemption for 100% of the 2,500 acres estimated to be planted to red 
beets in 2004 if the companion exemption for desmedipham is not approved, but for 
only 60% (1500 acres) of the estimated acreage if an emergency exemption for 
desmedipham is granted.

In addition, Registration Division has asked for additional information on the 
possibility of replacing desmedipham with metolachlor for this emergency situation.  
Information submitted in this package does not address this question.  For example, 
an estimate and supporting information for yield loss if metolachlor replaced 
desmedipahm has not been specifically included.  However, BEAD discusses this 
potential scenario later in the document using information that is available.

Red Beet Production.  Beets in this area are generally grown for processing.  
Planting takes place as early as March but mostly in May and June with a mechanical 
harvest from mid-July to mid-November.  

Current Weed Control Practices.   In the application for 2004, New York reported 
that 97% of the red beet acreage in New York was treated with cycloate (Ro-neet®), 
86% with pyrazon (Pyramin®), and 6% with phenmedipham (Spin-Aid®) in 2003.  Cycloate 
is applied to soil before the crop is planted and requires adequate soil moisture in 
order to be absorbed by the weed seed in order to be effective.  Pyrazon is also 
soil-applied before emergence of the crop.  Phenmedipham is applied to emerged 
weeds after emergence of the crop.    Information on the extent of use of desmedipham 
was not included in this application.  

Practical non-chemical control methods are already employed.  Most beet fields are 
mechanically cultivated  two or three times per growing season.  In addition, 
growers mow the field to the height of the beet tops to facilitate harvest.  Hand 
weeding is considered prohibitively expensive (1).  

Yield Loss from Emergency Situation.   New York table beet growers have been 
experiencing yield impacts since loss of the herbicide Antor® eight years ago.  
In previous year's submissions, New York stated that in a 1995 survey of red beet 
growers in New York, yield loss from weeds was estimated to range from 0-60% prior 
to the exemption allowing use of desmedipham.  In contrast, New York states that the 
average estimated yield loss due to weeds was nearly 8% based on grower surveys in 
1998-1999, a time period for which use of desmedipham herbicide was allowed under 
emergency exemption. Since such a large percentage of the acreage is treated with 
cycloate any significant disruption in supply of this key herbicide, would likely 
have adversely impacted yield beyond the 8% yield losses already being incurred 
even with use of desmedipham under emergency exemption.  In contrast, if an 
exemption were granted for metolachlor in addition to that for demedipham, it is 
reasonable to assume that its use could mitigate some of the estimated 8% loss being 
experienced by growers.  
  
In addition to these estimates of yield loss, New York submitted over 20 studies 
on weed control in beets which included measures of efficacy and crop tolerance of 
various herbicide treatments. 
Eleven of these studies included treatments with metolachlor in combination with 
other herbicides and seven included treatments with metolachlor alone.  (Eight 
studies contained no metolachlor treatments.)  In general, metolachlor treated 
plots yielded as well or better than those treated with the standard treatments.  
However, some plots treated with metolachlor also displayed significant levels of 
crop injury (trials BTOF1, 2, and 3, for example).

Alternatives. Cycloate is considered an adequate alternative for metolachlor, so 
with adequate stocks of cycloate available there is no emergency situation as long 
as desmedipham is approved for emergency exemption for control of broadleaf weeds 
in table beets.  However, metolachlor in addition to cycloate and desmedipham would 
offer advantages to IPM and resistance management programs for table beet production.  

Metolachlor as an Option. Metolachlor has a somewhat greater spectrum of weed 
control than desmedipham.  It effectively controls a number of annual grasses, 
yellow nutsedge, hairy galinsoga, redroot pigweed (in early season), and common 
purslane.  It also suppresses eastern black nightshade and temporarily controls 
common lambsquarters.  However, metolachlor does not control common ragweed or 
velvetleaf, important weeds that are suppressed by desmedipham.  Therefore, 
metolachlor can not be considered a complete alternative to desmedipham for control 
of broadleaf weeds in table beets.  

In 2002,  Dr. Robin Bellinder, a weed scientist from Cornell, identified the most 
beneficial future alternative as a combination of S-metolachlor (Dual Magnum®) and 
clopyralid (Stinger®) for New York beet growers (2). Clopyralid, used alone, is not 
an acceptable alternative to desmedipham.  Although it provides control of difficult 
weeds like thistle, it is not labeled  for control of the commonly occurring weeds
such as redroot pigweed and common lambsquarters (3).   

IMPACTS FROM BIOLOGICAL PERSPECTIVE:

Metolachlor in Addition to Desmedipham.   This application requests the use of 
metolachlor in addition to desmedipham which has been granted for use under 
emergency exemption for the past eight years due to loss of the herbicide Antor®.  
The principal reason for this request was due to uncertainty about the availability 
of the key herbicide, cycloate (Ro-Neet®), a pre- emergence herbicide registered in 
table beets principally for control of grass weeds.  However, the company that now 
markets cycloate in the United States has confirmed that supplies are adequate for 
2004 (6).  Adding metolachlor to desmedipham would further alleviate the emergency 
situation for which desmedipham has previously been granted, since neither of the 
two requested herbicides provides complete weed control when applied alone.  BEAD 
estimates that metolachlor would likely alleviate the yield losses of 8% that 
growers have continued to experience even with the use of desmedipham as an emergency 
exemption.

Metolachlor Instead of Desmedipham.   In a 2002 review of New York's request for 
desmedipham (02-NY-01), yield losses without the use of desmedipham were estimated 
at 24%.  If an emergency exemption is granted for metolachlor instead of 
desmedipham, metolachlor may replace cycloate as a pre-emergence herbicide and 
growers may turn to another herbicide such as clopyralid for post-emergence 
broadleaf weed control.  Since desmedipham and clopyralid differ in control of 
broadleaf weed species, control of pigweed and lambsquarters would likely be poorer 
and result in some yield loss if desmedipham is not allowed under emergency 
exemption. Discussion of this scenario was requested by Registration Division and 
was not addressed in the application.  An estimate and supporting information for 
yield loss if metolachlor replaced desmedipahm was not specifically included in the 
application.  However, BEAD would expect lower losses if metolachlor was used, and 
so BEAD estimates that yield losses would not exceed 20% if metolachlor replaced 
desmedipham.  


ECONOMIC ANALYSIS:
	The state of New York in the past requested and the Agency granted the use of 
desmedipham for the control of broadleaf weeds.  This year the state submitted two 
emergency exemption applications, one for desmedipham and one for s-metolachlor to 
control broadleaf weeds in red table beets.  The reason the state requested 
metalocholor as discussed in the biology section that another pesticide, cycolate 
supply used in conjunction  with desmedipham was becoming unavailable to do company 
takeover. If metolachor is granted, it will be likely to be used with clopyrad 
instead cycolate.

	If the state request for desmedipham is granted the expected yield loss is 8%.  
BEAD conducted an economic analysis using the loss based method.  The loss based 
method is currently a pilot project open to reduced risk chemicals and it hopes to 
reduce data requirements under certain situations.  Three tiers are identified with 
specific thresholds that BEAD believes imply significant economic loss under the 
loss based method.  Yield losses (quantity) of 20% or more qualify under Tier 1 
while total economic losses, including yield and quality (price) losses and increased 
pest control costs, of 20% of gross revenues qualify under Tier 2.  Tier 3 sets a 
threshold of 50% of net cash revenues.  These thresholds are based on an analysis 
of past Section 18 data submissions.  With the use of desmedipham, the expected 8% 
yield does not pass all the tiers of the loss based method therefore without the 
use of metolochlor the growers of red table beets will not have significant economic 
loss.

	If desmedipham is not granted the expected yield loss could be as high as 20%.  
With this scenario using the loss based method, a yield loss of 20% will lead to 
significant economic under tier 1 therefore New York growers will likely experience 
significant economic loss.. 
	

CONCLUSION:

The primary reason for this request to use metolachlor was to obtain a pre-emergence 
herbicide that could provide weed control similar to that of cycloate for which 
supplies were uncertain due to transfer of ownership.  However since supplies are 
available (6,7), the major reason for this request has been satisfied.  BEAD 
concludes that although an emergency situation exists and the use of metolachlor 
would help mitigate the eight percent loss still being experience by growers under 
this emergency situation even with emergecy use of desmedipham, the use of 
desmedipham is adequate for this original emergency situation.  Therefore, if 
desmedipham is allowed to be used in 2004, the situation is not likely to lead 
to significant economic loss to growers if the request for metolachlor is denied.  
However, if growers are not allowed use of desmedipham, they will likely suffer 
significant losses.  Registration division can obtain an analysis for dismedipham 
by submitting to BEAD this year's request for an emergency exemption for review.


REFERENCES:

1. Stivers, L. Crop Profile: Beets in New York.  Available on-line at 
	http://pmep.cce.cornell.edu/fqpa/crop-profiles/beet.html.

2. Personal communication between Virginia Werling (EPA) and Dr. Robin Bellinder 
(Associate Professor, Weed Scientist, Department of Horticulture, Cornell University) 
on February 6, 2002.

3. Personal communication between Virginia Werling (EPA) and Dr. Robin Bellinder 
(Associate Professor, Weed Scientist, Department of Horticulture, Cornell University)
 on February 6, 2003.

4.  New York Department of Agriculture and Markets.  Available on-line at 
www.agmkt.state.ny.us/HarvestCalendarTextOnly.html 

5.  Personal communication between Virginia Werling (EPA) and Dr. Robin Bellinder 
(Associate Professor, Weed Scientist, Department of Horticulture, Cornell University) 
on January 13, 2004. 

6.  Personal communication between Andrew Ertman (EPA) and Helm Agrosciences, Inc. 
on January 14, 2004.  

7.  Personal communication between Andrew Ertman (EPA) and New York Department of 
Environmental Conservation on January 14, 2004.