Document ID: EPA-HQ-OPP-2005-0163-0155
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-11-15T05:00Z

SEQ CHAPTER \h \r 1 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

  SEQ CHAPTER \h \r 1 OFFICE OF

PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

MEMORANDUM

SUBJECT:	Response to Comments on Preliminary Impact Analysis for
Aldicarb on Major Citrus Crops, Potatoes, and Pecans (DP 331541)

FROM:	Monisha Kaul, Biologist	

		Biological Analysis Branch

Derek Berwald, Economist	

Economic Analysis Branch

Biological and Economic Analysis Division (7503P)

THRU:	Arnet Jones, Chief 	

Biological Analysis Branch

Istanbul Yusuf, Acting Chief 	

Economic Analysis Branch

Biological and Economic Analysis Division (7503P)

TO:		Sherrie Kinard, Chemical Review Manager (7509P)

		Robert McNally, Chief

Special Review and Reregistration Division 

Peer Review Panel:  August 30, 2006

Summary

As part of the risk-benefit analysis for reregistration, BEAD conducted
an analysis of possible alternatives to aldicarb used on the major
citrus crops (oranges and grapefruit) in Florida and Texas, and also for
potatoes, and pecans.  This document responds to comments received on
BEAD’s analyses.  Most of the comments were about aldicarb use on
citrus, primarily on the use of aldicarb for the Asian citrus psyllid
(AsCP).  BEAD reviewed the comments along with newly available
information, and now concludes aldicarb may provide additional benefits
to citrus growers trying to control the AsCP, in conjunction with other
chemical and biological controls.  Comments also questioned the number
of citrus acres treated with aldicarb.  There is some uncertainty
regarding how many acres are treated with aldicarb annually, but usage
of aldicarb on citrus seems to be increasing, and newly available
estimates of acreage treated by the USDA National Agricultural
Statistics Service (USDA NASS), indicate that about 67,000 citrus acres
were treated in 2005.  Our earlier document estimated that about 57,000
acres of citrus were treated in 2004.  Several comments were also
received about aldicarb use sugar beets, and those are addressed in a
separate alternatives assessment for sugar beets.  

Response to Comments 

EPA received comments from the Florida Fruit and Vegetable Association
(FFVA), Florida Citrus Mutual (FCM), the University of Florida (UFL),
and Bayer CropScience, among others.  BEAD has summarized and responded
to the comments below.  

  

Comment:

Bayer CropScience provided a document entitled  THE BENEFITS TO
AGRICULTURE OF TEMIK® BRAND 15G ALDICARB PESTICIDE, as a comment. This
document provides estimates of the total benefits of aldicarb by summing
the estimated benefits for the following crops: citrus, cotton, peanuts,
potatoes, sugarbeets, dry beans, flue-cured tobacco, pecans, and
soybeans.  In addition, there is a chapter on the benefits of using
aldicarb as a tool that simplifies pest control management.  This
chapter states that because of the long active life of aldicarb, it can
be used as a preventative treatment, rather than applied in response to
pest activity.  Use of aldicarb can also have the advantages of fewer
trips through the field, and increased consistency in crop quality.  

The document provides estimates of the benefits of aldicarb to growers,
with a total benefit across all crops of $445.3 million per year.  The
estimated benefits by crop are reproduced in Table 1.  



Table 1.  Bayer CropScience Estimated Benefits of Aldicarb

Crop	Annual Value per Acre	Total Value per Year

Cotton	$69.16 - $70.44	$307 - 313 Million

Peanuts	$77 - $82	$ 50 Million

Potatoes	$253	$ 35.5 Million

Citrus	$230	$ 33.0 Million

Sugar Beets	(not provided)	$   9.2 Million

Dry Beans	$108	$   3.0   Million

Flue-Cured Tobacco	$566	$   2.15 Million

Pecan	$51 - $500	$ 0.7 - $7 Million

Soybeans	$16.61	$ 0.33 Million

Source:  Public Comments submitted by Bayer CropScience

Response: 

In all cases, the value of aldicarb on a per acre basis is estimated
from unpublished studies to which BEAD does not have access.  From the
descriptions in the comment, however, it appears that the values
reported compare the use of aldicarb to the use of no alternative method
of control for the target pests.  BEAD estimates benefits by comparing
the use of a chemical with the next best available alternative.  If
growers did not use aldicarb, it is unlikely that they would not attempt
to control the target pests by some other method.  In some cases, the
comment did provide estimates of the benefit of aldicarb relative to
other control methods, although they did not aggregate them to a
national level.  In all cases, however, these reported figures are a
result of unpublished studies to which EPA does not have access.  

For comparison BEAD’s estimate of aldicarb benefits are $2 - $28 per
acre for cotton, and from $77 to $257 per acre for potatoes.  Full
estimates for the benefits of aldicarb use in citrus were not calculated
by BEAD, but potential losses from nematode damage (for which we could
not find an alternative control) were in the range of 5 – 10%, or
about $97 – $218 per acre.    

Comment:

FFVA, FCM, UFL, and Bayer CropScience stated that aldicarb is effective
for controlling the AsCP and the spread of citrus greening disease. 
Aldicarb use and benefits have increased since the AsCP, which is a
vector for citrus greening disease, was found in Florida.  Additionally,
aldicarb is the only systemic, soil-applied insecticide for AsCP that
can be used on trees taller than six to eight feet.  

Response:

In mid to late February, when BEAD completed its analysis, the
University of Florida Institute of Food and Agricultural Sciences (IFAS)
did not list aldicarb as a recommended insecticide for AsCP.  IFAS has
since updated its recommendations for AsCP.  Aldicarb is now recommended
among several other insecticides.  Because the AsCP is a relatively new
pest to Florida and the spread of citrus greening disease began late in
2005, new information is emerging and research is ongoing.   Citrus
greening has not yet been found in other states.

BEAD has further investigated the available controls for AsCP, including
biological, cultural, and chemical.  To control the spread of citrus
greening disease an integrated approach that manages both the insect
vector and the disease must be addressed.  

Cultural controls of citrus greening disease include using clean nursery
stock because the disease can be transmitted through grafting with
infected budwood (Floyd and Krass, 2006).  In addition, infected trees
should be removed once identified (Floyd and Krass, 2006).   Monitoring
of AsCP populations and citrus greening disease should be done regularly
in citrus groves.  

Control of citrus greening disease is complicated because early
detection is difficult.  Symptoms may take six months to two years to
appear after infection (Floyd and Krass, 2006).  Antibiotics are
available but they only provide suppression, may not eliminate the
bacteria from the tree, and may be phytotoxic (Floyd and Krass, 2006). 

Several biological controls target the AsCP including parasitic wasps,
lady beetles, lacewings, and spiders.  In Florida, the most important
biological control includes coccinellid predators, Olla v-nigrum and
Harmonia axyridis (Halbert and Manjunath, 2004).  Parasitic wasps have
also been released in Florida and only one, T. radiata, established.  In
addition, the AsCP is vulnerable to fungi.  Pathogenic fungi may be
useful in warm, humid environments.  Although some of these biological
controls have been very effective in other countries, their
effectiveness is still being evaluated in Florida.  Therefore, chemical
controls are also recommended by state experts.          

                                                                        
                  

Although aldicarb is now a recommended insecticide for AsCP, it will
have to be used along with other forms of chemical control.  Only one
application of aldicarb may be made per year from January through April
(Browning et al., 2006).  IFAS states that aldicarb has been shown to be
effective on trees less than 6 feet in height (Browning et al., 2006). 
Effectiveness on large trees is still being investigated, although there
are no restrictions on tree height for aldicarb use.  However, it may
take up to 30 days for aldicarb to affect psyllids that are feeding on
new flush on large trees.  Therefore, applications should be made 30
days before new flush (Browing et al., 2006).

As discussed in BEAD’s analysis of aldicarb on citrus, there are
chemical alternatives to aldicarb available for AsCP control including
imidacloprid, fenpropathrin, and chlorpyrifos.  For best results,
insecticides should be used twice per year on citrus groves with AsCP. 
Imidacloprid, another soil applied systemic insecticide recommended for
AsCP, may be applied up to two times per year and is recommended for
trees up to 8 feet tall.  There are no time restrictions for use of this
pesticide as with aldicarb.  Currently, imidacloprid appears to be a
commonly recommended chemical control for AsCP.  Foliar insecticides
including fenpropathrin and chlorpyrifos are recommended for use during
major plant flushes or when fast control is required (Browning et al,
2006).  Broad-spectrum foliar insecticides, such as fenpropathrin and
chlorpyrifos, may be harmful on biological controls. 

Aldicarb appears to be a beneficial tool for control of the AsCP among
other biological and chemical controls.  Systemic insecticides such as
aldicarb and imidacloprid are particularly effective for sucking insects
such as AsCP (Halbert and Manjunath, 2004).   To maximize benefits of
biological controls, it is important to use insecticides that are safe
for such organisms (Floyd and Krass, 2006).  However, foliar
insecticides, which may be harmful to beneficial organisms, may be
required for fast-acting control.  

Comment:

FFVA and FCM stated the information used in BEAD’s analysis was
primarily based on the 2001 Crop Profile for Citrus in Florida and not
more recent information sources for pests and alternatives.  In
addition, FFVA and FCM made the following statements. “The Profile
estimates that the loss of aldicarb may result in a five to 10 percent
citrus production loss in Florida. That statement may have been true
before the establishment of the psyllid and the appearance of citrus
greening. Wherever greening becomes established in trees results in
complete loss of those trees for the remainder of time in which the
trees remain alive [sic].”

Response:

While BEAD did refer to the Crop Profile for Citrus (Major)
Orange/Grapefruit in Florida (2001), information for alternatives and
pests were primarily based on recommendations by the University of
Florida Institute of Food and Agricultural Sciences (IFAS) Extension’s
pest management guides by Browning et al. (2006); Childers et al.
(2006); Duncan et al. (2006).  These were 2006 IFAS recommendations,
which were current at the time BEAD’s analysis was conducted. 
Additional sources including Asian Citrus Psyllid and Citrus Greening-A
Closer Look at the Vector (Hall, 2006), Asian Citrus Psyllid
(Grafton-Cardwell, et al., 2005), and Efficacy of Envidor, a New
Acaricide Against Eriophyidae Mites on Florida Citrus (Bell et al.,
2003) were considered in BEAD’s analysis of citrus pests and
alternatives to aldicarb.   

At the time BEAD researched and completed the analysis, aldicarb was not
recommended by IFAS for control of the Asian citrus psyllid.  Therefore,
this pest was not considered when determining the yield loss estimate if
aldicarb was no longer available for citrus.  Because aldicarb is now
recommended by the state for AsCP control and use of aldicarb for this
pest appears to have increased, yield loss estimates would likely
increase if aldicarb were no longer available.  It is difficult to
quantify the yield loss as this is an emerging disease in southern
Florida.  However, in worst cases growers that remove infected trees
would lose all yield until replanted trees mature.  Although there are
no available controls that can eliminate citrus greening disease,
controlling the vector and using clean nursery stocks may help minimize
the spread of this disease.  Therefore, it is unlikely that aldicarb
alone can provide such control.  Biological, cultural, and other
chemical controls are parts of an integrated approach that have allowed
other countries with citrus greening disease to continue citrus
production.   

Comment:

FFVA and FCM state methyl bromide is not an alternative to aldicarb for
nematode control because it is unavailable without a critical use
exemption and not economically feasible.  

Response:

As stated in the 2006 analysis of aldicarb use on major citrus crops,
BEAD agrees that methyl bromide is not an economically feasible
alternative to aldicarb for post-plant nematode control.  BEAD
considered methyl bromide in the analysis because existing stock can be
used even though newly produced methyl bromide can only be used through
a critical use exemption as of December 31, 2004.  

Comment:

FFVA and FCM have stated that there will be an increase in dicofol’s
preharvest interval to 87 days, making it a useless insecticide for
citrus.  

Response:

Currently, the dicofol preharvest interval is seven days.  Even if
dicofol’s reentry interval is extended such that its use on citrus
becomes limited, BEAD’s finding that there are alternatives to
aldicarb for mite control will not change, as several other alternatives
are available.       

Comment:

Bayer CropScience states that EPA underestimates the impact of using
alternative control methods to aldicarb.  Bayer CropScience estimates
the benefits of aldicarb use to growers at about $33 million per year.
Estimates of the benefits of aldicarb are estimated in the comment at
$230/Acre, and estimated that 144,500 acres of citrus were treated with
aldicarb. 

Response:

The estimate of the total value of aldicarb to the citrus industry in
this comment is over three times the value estimated by EPA.  The
difference results from two factors: a difference in the estimated per
acre cost of aldicarb alternatives, and a difference in the estimated
citrus acreage to which aldicarb is applied.  

The estimated per acre benefits of aldicarb on citrus provided in the
comments are based on unpublished studies not available to EPA.  It
appears, however, that the estimated benefit of $230/Acre for aldicarb
was based on comparison with untreated control plots, rather than plots
treated with alternative pesticides.  EPA estimates benefits in
comparison to the next best alternative, based on the assumptions that
growers would continue pest control activities.   

BEAD estimated acreage treated using publicly available data from the
USDA National Agricultural Statistics Service and from EPA Proprietary
Data Sources.  In the months since our preliminary analysis was
completed, new data on aldicarb use are available.  The latest data
available from the National Agricultural Statistics Service (USDA NASS)
show that aldicarb is used on about 26% of the 71,000 grapefruit acres
in Florida, and 27% of the 18,500 grapefruit acreage in Texas, or about
23,455 acres total.  Aldicarb is used on about 8% of the 541,800 orange
acres in Florida, or about 43,334 acres, total.  Combining oranges and
grapefruit, this new data from NASS shows about 66,799 acres of citrus
treated with aldicarb.  This figure is well below the 144,500 acres
estimated in the comment.  If we were to use the NASS acreage data, and
the comment’s figure of $230 per acre for the benefits of aldicarb,
then the benefits of aldicarb would be about $15.4 million annually.  
EPA proprietary data also show about 60,000 acres of citrus treated with
aldicarb.    

Table 2 shows the USDA NASS estimates of aldicarb use on major citrus
crops for 2005.  

Table 2.  Aldicarb Applications for Major Citrus Crops, 2005

	Area	Applications	Rate per	Rate per	Total

Crop and State	Applied	per Year	Application	Crop Year	Applied

	Percent	Number	Pounds per Acre	Pounds per Acre	1,000 lbs

Grapefruit, Total1	26	1.0	4.118	4.124	110.8

Grapefruit, Florida2	26	1.0	3.871	3.879	71.8

Grapefruit, Texas3	27	1.0	5.026	5.026	25.4

	Oranges, Total4	8	1.0	3.575	3.636	208.0

Oranges, Florida5	8	1.0	3.575	3.636	157.0

Source:  USDA NASS

1 Bearing acreage in 2005 for the 3 Program States was 102,000 acres. 
States included are CA, FL, and TX.

2 Bearing acreage in 2005 for Florida was 71,000 acres.

3 Bearing acreage in 2005 for Texas was 18,500 acres

4 Bearing acreage in 2005 for the 2 Program States was 717,800 acres. 
States included are CA and FL.

5 Bearing acreage in 2005 for Florida was 541,800 acres.

However, another possible source of data for the aldicarb acres treated
in Florida is the Florida Department of Agriculture and Consumer
Services.  Permits are required for the application of aldicarb in
Florida, and the number of permits granted is available.  In fiscal year
2004 – 2005 (which corresponds with the timing of the data provided by
USDA NASS), there were permits granted for 334,314 acres of aldicarb
treatment on citrus.  Even though all of these permits may not have been
used, the permitted acres are significantly higher than use estimated by
USDA NASS.  If the number of acres treated is in fact closer to the
number of permitted acres, then the aggregate benefits to aldicarb use
are significantly higher than the estimates provided by EPA and the
comments.   It is also possible that aldicarb use has increased recently
– the number of permitted acres for aldicarb on citrus in Florida is
417,286 for fiscal year 2005 – 2006, about a 25% increase from 2004
– 2005.  This may be due to ordinary fluctuations, or to increased use
against the AsCP.  Because we do not know how many permit applications
are duplicates or not used, the data from the Florida aldicarb permit
program may not be a reliable measure of actual aldicarb use.  

Comment: 

The FFVA and FCM provided comments that include figures for the amount
of aldicarb used in Florida: “For the 2005-06 production season a
total of 417,400 citrus acres (which represents approximately 56% of the
overall citrus industry in the state) were treated with Temik [Temik®
is the trade name for aldicarb]  at 3,047 sites throughout the state.”

Response:  

The number of acres treated for citrus presented in this comment is
based on data from aldicarb application permits requested from the
Florida Department of Agriculture and Consumer Services.  These acreage
figures are much higher than we report, which were based on estimates
from USDA/NASS and EPA Proprietary Data.  As mentioned above, the
Florida Department of Agriculture and Consumer Services data do not
agree with publicly available data from USDA NASS and EPA Proprietary
data.  EPA cannot reconcile the data, but we recognize that if aldicarb
is used on 56% of the citrus acreage, the benefits and the risks of
aldicarb will be significantly higher.  

Comment: 

Dr. Mark Mossler of the University of Florida submitted comments that
provide information on aldicarb use in Florida, Puerto Rico, and the
Virgin Islands, providing an overview of the use rates and agronomic
advantages to aldicarb use in citrus, cotton, peanut, coffee, and
pecans.  This information is helpful to EPA.  However, the comment does
refer to an EPA Quantitative Usage Analysis (QUA) from 1999, and it
indicates the percent crop treated estimates in the QUA were high, and
the comment provides estimates of the percent crop treated for oranges,
grapefruit and other citrus. For example, the comment suggests that the
QUA indicates that 90% of the oranges acreage in Florida was treated
with aldicarb.  

Response:  

The estimates of percent crop treated used by EPA in our analysis are
similar to those provided in the comment.  The concern expressed in the
comment is based on a column of the QUA table that indicated which
states are the primary users of aldicarb on that specific crop.  For
example, the table indicates that 90% of the aldicarb used on oranges
was used in Florida, not that 90% of the oranges acreage in Florida was
treated with aldicarb.  In the 1999 QUA, it is estimated that 5% of the
orange crop is treated with aldicarb.  In any case, updated usage data
are used in more recent EPA analyses.  

Comment:  

Bayer CropScience commented that aldicarb improves the tolerance of
citrus trees to freezes. 

Response: 

Freeze tolerance is not a pesticidal use of aldicarb, and so was not
included in our analysis.  The benefits of freeze tolerance are
difficult to estimate, and the risks of freeze damage are unknown to
EPA.  

Comment:  

Several comments stated that Aldicarb was a critical for control of
Colorado potato beetles in Michigan in the 1980s.  When its registration
was withdrawn, growers were left with few alternatives.  From 1991-1994,
Michigan potato growers experienced $8 to 14 million/year in control
costs and crop losses due to this pest.  Growers currently rely on
imidacloprid and other neonicotinoids for Colorado potato beetle
control, but resistance to imidacloprid appears to be gradually
spreading in Michigan.  Aldicarb would be valuable for resistance
management purposes, could reduce the number of insecticide applications
needed for Colorado potato beetle control, and would reduce costs and
losses to growers.  The use of aldicarb on potatoes in Michigan should
be approved by the U.S. EPA.  

Response:

The Agency acknowledges and appreciates these comments.  However, the
comments are focusing on actions that were taken by the Agency in the
past and which are not the subject of review at this time.  When
excessive residues of aldicarb appeared on potatoes in 1990, the Agency
halted its sale and use in potato production.  In 1995, the Agency
reapproved this use, using positive displacement equipment, but only in
certain states, where the risk of ground-water contamination was
believed to be low.  Michigan was not among these states.

Comment:

The California Pecan Growers Association provided comments on behalf of
85 pecan growers in California.  In California, aldicarb is used against
yellow aphids and black aphids.  The aphids damage the tree directly,
and their honeydew secretions also cause black sooty mold growth on the
leaf surfaces.  Other control methods tried by growers in the past were
multiple treatments of organophosphates, which led to resistance and
poor control, and the release of beneficial insects, which was not
effective.   

Response:

According to data from the California Department of Pesticide
Regulation, relatively few acres of California pecans are treated with
aldicarb (1,290 acres treated in 2004).  However, that represents nearly
65% of the limited pecan acreage in California, almost 65%.       

References

Bell, J., A. Toledo, R. Morris, and R. Rudolph, 2003.  Efficacy of
Envidor, a new acaricide, against 

	Eriophyidae mites on Florida citrus.  Florida Entomological Society
2003 Annual Meeting 

	Abstracts.  Web address:   HYPERLINK
"http://www.flaentsoc.org/2003annmeetabstracts.html" 
http://www.flaentsoc.org/2003annmeetabstracts.html .

Browning, H.W., C.C. Childers, P.A. Stansly, J. Peña and M.E. Rogers. 
2006 Florida citrus pest management guide: Soft-bodied insects attacking
foliage and fruit.  University of Florida IFAS Extension. Web Address:
http://edis.ifas.ufl.edu/CG004.

California Department of Pesticide Regulation, Pesticide Information
Portal database, which can be queried here:
http://calpip.cdpr.ca.gov/cfdocs/calpip/prod/main.cfm

Childers, C.C., C.W. McCoy, H.N. Nigg, P.A. Stansly, and M.E. Rogers.
2006 Florida citrus pest management guide: rust mites, spider mites, and
other phytophagous mites. University of Florida IFAS Extension. Web
Address:   HYPERLINK "http://edis.ifas.ufl.edu/CG002" 
http://edis.ifas.ufl.edu/CG002 .

Crop Profile for Citrus (Major) Orange/Grapefruit in Florida.  2001. 
Web address:   HYPERLINK
"http://www.ipmcenters.org/CropProfiles/docs/FLcitrus(major).html" 
http://www.ipmcenters.org/CropProfiles/docs/FLcitrus(major).html 

Duncan, L.W., J.W. Noling and R.N. Inserra. 2006 Florida citrus pest
management guide: nematodes. University of Florida IFAS Extension.  Web
Address:   HYPERLINK "http://edis.ifas.ufl.edu/CG010" 
http://edis.ifas.ufl.edu/CG010 .

Hall, D.G. 2006. Asian Citrus Psyllid And Citrus Greening - A Closer
Look At The Vector. Citrus And Vegetable Magazine. 70(5):24-26.  Web
Address:   HYPERLINK
"http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_1
15=189463" 
http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_11
5=189463 .

Floyd, J. and C. Krass, 2006. Candidatus Liberibacter africanus Ca. L.
asiaticus Ca. L. americanus, Huanglongbing citrus greening disease. 
USDA APHIS PPQ New pest response guidelines: v. 1.1 May 2006. Online: 

  HYPERLINK
"http://www.aphis.usda.gov/ppq/ep/citrus_greening/pdf_files/hlb-pubversi
on.pdf" 
http://www.aphis.usda.gov/ppq/ep/citrus_greening/pdf_files/hlb-pubversio
n.pdf ).

Grafton-Cardwell, E.E., K.E. Godfrey, M.E. Rogers, C.C. Childers, and
P.A. Stansly.  Asian citrus psyllid. Web address:   HYPERLINK
"http://citrusent.uckac.edu/psyllid/psyllidbrochureAug05.pdf" 
http://citrusent.uckac.edu/psyllid/psyllidbrochureAug05.pdf 

Halbert, S. and K. L. Manjunath, 2004. Asian citrus psyllids
(Sternorrhyncha: Psyllidae) and greening disease of ctrus: A literature
review and assessment of risk in Florida. Florida Entomol. 87: 330-353.
Online:   HYPERLINK
"http://www.bioone.org/perlserv/?request=get-document&issn=0015-4040&vol
ume=087&issue=03&page=330" 
http://www.bioone.org/perlserv/?request=get-document&issn=0015-4040&volu
me=087&issue=03&page=330 )

US Department of Agriculture, National Agricultural Statistics Service
(USDA NASS), Agricultural Chemical Usage: 2005 Fruit Summary.  2006. 
Available here:
http://usda.mannlib.cornell.edu/usda/current/AgriChemUsFruits/AgriChemUs
Fruits-07-26-2006.pdf 

 EPA Proprietary Data are data on pesticide use purchased from private
sector firms.  

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