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

WASHINGTON D.C., 20460

April 6, 2006

  SEQ CHAPTER \h \r 1 OFFICE OF

PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

MEMORANDUM

SUBJECT:	Preliminary Impact Analysis for Aldicarb on Major Citrus Crops
(DP 299884)

FROM:	Monisha Kaul, Biologist	

		Biological Analysis Branch

Derek Berwald, Economist	

Economic Analysis Branch

Biological and Economic Analysis Division (7503C)

THRU:	Arnet Jones, Chief 	

Biological Analysis Branch

Timothy Kiely, Acting Chief 	

Economic Analysis Branch

Biological and Economic Analysis Division (7503C)

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

		Robert McNally, Chief

Special Review and Reregistration Division 

Peer Review Panel:  March 15, 2006

Summary

Aldicarb is a systemic carbamate pesticide used to manage insects and
nematodes on citrus. 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.  There appear to be several alternatives to aldicarb
for control of mites, but there appears to be no feasible alternative to
aldicarb for nematode control.  Estimated yield losses in Florida
without aldicarb are 5 to 10 percent, which corresponds to a loss of
about $97 to $193 per acre to orange growers and $109 to $218 per acre
to Florida grapefruit growers.  Statewide, the aggregate impact of a 5
to 10 percent yield loss corresponds to an annual loss of about $4.6 to
9.3 million for oranges and grapefruit combined.  Aldicarb is not
registered for use on citrus in California.  There appear to be
alternatives to aldicarb for mite control in Texas citrus.

Background

Aldicarb (Temik® 15G) is a carbamate pesticide used to manage several
insects, mites, and nematodes on citrus.  Aldicarb poses dietary risks,
in addition to acute risks to birds, mammals, and aquatic organisms. 
There are also chronic risks to invertebrates (freshwater and
estuarine/marine) and freshwater fish.  BEAD conducted an alternatives
assessment as part of the risk management process.  

Biological Analysis

Crop Production

Florida is first in citrus production across all citrus crops,
California is second, and Texas is third (Crop Profile for Citrus in
California, 2003).   Florida is also first in production of the major
citrus crops, oranges and grapefruit, and California is second.  Table 1
shows the citrus acres grown and aldicarb usage on these two crops.  

Table 1.  Citrus Acreage and Aldicarb Usage in Major Producing States1

State	Grapefruit

Acreage2	Estimated Pounds AI Applied Grapefruit	Grapefruit Percent Crop
Treated (%)	Orange

Acreage2	Estimated Pounds AI Applied Orange	Orange Percent Crop Treated
(%)

Florida

California3

Texas	71,000

12,500

18,500	38,000

NA

43,000	14

NA

49	541,800

176,000

8,800	118,000

NA

0	7

NA

0

US Total	128,119	100,000	10	926,815	400,000	5

Sources:  USDA NASS and EPA Proprietary Data (1998-2002).  

1 Usage of aldicarb as a nematicide may not be reflected by these data
sources because these data are not available to BEAD.   

2 Bearing acres are reported at the state-level from USDA NASS Citrus
Fruits 2005 Summary 

3 Aldicarb is not registered for use on citrus in California.

Citrus production in Florida is mainly in the central ridge and southern
parts of the state.  Approximately 90 to 95 percent of Florida oranges
are processed for juice (Crop Profiles for Citrus Major)
Orange/Grapefruit in Florida, 2001).  Although more than half of Florida
grapefruit are processed, most of the grapefruit crop produced is
initially intended for the fresh market.  

Texas citrus is mainly produced in Hidalgo, Cameron and Willacy counties
of the Rio Grande Valley.  Most of the state’s citrus acreage grows
grapefruit for fresh market.  



Use and Usage of Aldicarb on Citrus

Aldicarb is a systemic and contact carbamate insecticide and nematicide.
 TEMIK® brand 15G Aldicarb is a restricted use pesticide which is used
in some citrus-producing states primarily to control mites and
nematodes.  In addition to these pests, aldicarb is registered to
control aphids, and whiteflies.  Aldicarb is applied just before or
during spring flush of foliage growth in bands along tree rows.  This
granular formulation is labeled for soil application and may be applied
only once per year.  Granules must be immediately covered with at least
two inches of soil.  

In Florida, aldicarb can only be applied between January 1 and April 30
and can never be applied within 300 feet of drinking water wells. 
Aldicarb use in Florida is further restricted based on soil
permeability.  

Aldicarb is not registered for use on citrus in California.  There are
no use restrictions specific to Texas.  The Section 3 registration
excludes aldicarb use on citrus to control nematodes in Florida, but
this use is allowed under a 24(c) registration.  Additionally, aldicarb
is now recommended by the registrant for use on the Asian citrus psyllid
in Florida and Texas.     

Aldicarb use in citrus production is significant in Florida and Texas in
terms of pounds applied and percent crop treated, respectively (Table
1).   Nationally, aldicarb use on grapefruit has decreased over the last
five years and slightly decreased on oranges. There has been no reported
use on oranges in Texas since 1998.  

Important Citrus Pests Controlled by Aldicarb

Mites

Mites are the primary citrus pest in both Florida and Texas.  

According to the Crop Profile for Citrus in Florida (2001), the citrus
rust mite is the primary insect pest in Florida.  Rust mites feed on
fruit, stems and foliage.  Fruit damage caused by rust mites is mainly a
reduction in fruit grade and size, increased water loss, fruit drop, and
reduced juice quality.  Leaf injury includes discoloration of foliage. 
Citrus rust mites are generally worse in warm, humid weather.  In
general, miticides are used three to four times per year on citrus for
fresh market, while a maximum of one treatment is applied to citrus for
processing.  

Mites are the most economically important pest in Texas citrus
production (Cartwright and Browning).  Important mites are the citrus
rust mite and spider mites, which include Texas citrus mite and citrus
red mite.  Unlike the citrus rust mite, Texas citrus and citrus red
mites thrive in hot, dry conditions.  In Texas, the citrus red mite has
not caused reductions in fruit quality although it has caused leaf drop.
 Grapefruit are more vulnerable than oranges to damage by citrus rust
mites and citrus red mites (Cartwright and Browning).  

Asian Citrus Psyllid

The Asian citrus psyllid, Diaphorina citri, is a relatively new pest to
Florida.  Although aldicarb is not the primary method of control, this
insect is considered an important pest because it vectors citrus
greening disease, which was found in Florida in late 2005 (Hall, 2006). 
Citrus greening disease causes stunted trees with leaf and fruit drop. 
Fruit can be hard, small and discolored (Grafton-Cardwell, 2005). 
Although the Asian citrus psyllid was found in Texas in 2001, citrus
greening disease does not appear to be in Texas. 

Nematodes

The main nematodes of concern in Florida are the citrus nematode and
burrowing nematode (Crop Profile for Citrus (Major) Orange/Grapefruit in
Florida, 2001).  Other nematodes with limited economic importance in
Florida are the sting nematode and lesion nematode (Duncan, et al.,
2006).  Nematodes generally do not kill citrus trees but may inhibit
growth and fruit production.  Although the citrus nematode is found in
Texas citrus orchards, only 2 percent of the crop is treated with
aldicarb (A Texas Citrus Pest Management Strategy, 2003).  Aldicarb must
be applied multiple times over the life of the orchard, and it only
provides temporary nematode suppression.  Aldicarb is registered to
control the citrus nematode.  It does not effectively control the
burrowing nematode as aldicarb only remains in the shallow part of the
root zone (Duncan et al., 2006).  

Alternatives for Aldicarb Use on Citrus

There are many pesticides registered to control mites and psyllids on
citrus in both Florida and Texas (Table 2).  Chemical controls are used
to control mites mainly on citrus intended for the fresh market.  Since
fruit growth is affected by greater than 50 to 75 percent injury,
processed fruit generally required less chemical control for mites
(Childers, 2006).  

Table 2.  Important Citrus Pests Controlled by Aldicarb and Potential
Alternatives

State	

Pest	

Potential Alternatives and their Relative Efficacy1 if Available	

Comments



Florida

Florida	Citrus Rust Mite	abamectin, dicofol, diflubenzuron,
fenbutatin-oxide (E), oxamyl, petroleum oil, propargite, spirodiclofen
(E), sulfur 	Dicofol, fenbutatin-oxide, and spirodiclofen are
recommended for use in the spring, which is when aldicarb may be used in
Florida.

	Asian Citrus Psyllid	chlorpyrifos, fenpropathrin, imidacloprid	This
pest vectors citrus greening disease.  It is unlikely it can be
completely controlled by chemicals, including aldicarb.

	Citrus Nematode	Fenamiphos*	Repeated use of fenamiphos results in
lowered efficacy due to development of resistance.  

*Registration cancelled, effective 2007.

Texas	Citrus Rust Mite	Abamectin (E), diflubenzuron (E), fenpropathrin
(G), petroleum oil (G), formetanate hydrochloride (E), propargite (G-F),
pyridaben (E), dicofol (E), chlorpyrifos (G), sulfur (G),
fenbutatin-oxide (E), oxamyl (E)



Spider Mites	Spider Mites - all

Abamectin (G), dicofol (E), fenbutatin-oxide (E), fenpropathrin (E),
pyridaben (E)

Texas Citrus Mites - only

Propargite (G), 

Citrus Red Mite - only

Propargite (E), petroleum oil (E)

	1 Efficacy rating symbols: E=Excellent (80-100% control), G=Good
(60-80% control), F=Fair (<60% control), based on A Texas Citrus Pest
Management Strategy (2002) and TAMU Insecticide and Miticide Guide. 
Additional sources include:  University of Florida’s Institute for
Food and Agricultural Science Extension (IFAS), Crop Profile for Citrus
in Florida, Florida Entomological Society Annual Meeting2003. 

Since miticides are effective at different times throughout the season,
Florida has developed the following recommendations (Childers et al.,
2006).  Petroleum oil should be applied post bloom in summer or fall,
but cannot be used when temperatures are higher than 94 degrees. 
Petroleum oil provides good control, is found to have fungicidal
properties, and does not harm beneficial organisms.  Oil is commonly
mixed with other chemicals, such as abamectin, to improve their
performance.  For example, abamectin plus oil provides broad spectrum
insect and mite control.   Sulfur provides suppression of citrus rust
mites.  Sulfur has no pre-harvest interval and can, therefore, be
applied late in the season, but may have harmful effects on beneficial
arthropods. The use of propargite is recommended in the fall. 
Propargite should not be applied to immature leaves or fruit.  The
pyridaben label states that due to mite resistance it must be alternated
with other miticides.  The Florida PMSP recommends that all miticides,
except petroleum oil, only be used once a year to prevent insect
resistance from developing (Childers et al., 2006).     

Many of the recommended pesticides have limited use or some use
restrictions, especially in Florida.  Use of pesticides, including
aldicarb, in Florida may be restricted based on distance to water
bodies, ground water and soil types.  In Florida, aldicarb can only be
applied from January 1 through April 30.  Other miticides that are
recommended for early spring include dicofol, fenbutatin-oxide, and
spirodiclofen.  Multiple uses of dicofol have resulted in mite
resistance.  Fenbutatin-oxide is considered an excellent citrus miticide
and easy on beneficials.  It is recommended for use in spring or fall. 
Spirodiclofen is also considered an excellent control of citrus rust
mites, but is best for preventative or early mite control; it does not
control adult males (Childers et al., 2006; Bell et al., 2003).  

There are more potential alternatives for aldicarb in Texas than in
Florida.  Abamectin, diflubenzuron, pyridaben, formetanate
hydrochloride, dicofol, fenbutatin-oxide, oxamyl are considered to have
good to excellent control of citrus rust mites (Browning and Cartwright,
2006).  Dicofol, fenbutatin-oxide, fenpropathrin, pyridaben, propargite,
and petroleum oil are recommended as good to excellent controls of
spider mites (Browning and Cartwright, 2006).  Oxamyl is a systemic
pesticide that provides some residual control although aldicarb has
longer residual control.  

It is unlikely that the Asian citrus psyllid can be fully controlled by
pesticides.  Foliar insecticides should be applied during major plant
flushes as this psyllid’s development and reproduction need young
leaves (Browning, et al., 2006).  Insecticides recommended for control
of this psyllid are in Table 2.  Systemic pesticides such as
imidicloprid are recommended for young citrus trees (Browning, et al.,
2006).  The effectiveness of aldicarb is questionable because it may
take up to 30 days for the pesticide to move through the trees and reach
the psyllids (Browning, et al., 2006).  Chlorpyrifos may increase spider
mite populations (Browning, et al., 2006).  Fenpropathrin is highly
toxic to bees (Browning, et al., 2006).  

According to Duncan et al., (2006), at this time there is no soil
fumigant recommended for pre-plant nematode control, although
1,3-dichloropropene, and metam sodium are registered for this use. 
Methyl bromide is also a registered alternative, but it is not
economically feasible. Additionally, there are few available pesticides
for post-plant treatment.   Established nematode populations are
difficult to control with pesticides.  Aldicarb and fenamiphos are the
only post-plant chemical controls recommended for citrus nematodes. 
Fenamiphos has been found to lose effectiveness after multiple
applications.  Fenamiphos is only available through permits for use in
Florida, and its registration will be cancelled on May 31, 2007. 
Imidacloprid is also registered to suppress citrus nematodes, but should
only be used on trees up to 8 feet tall.  Additionally, Myrothecium
verrucari, a biological nematicide, is registered but has not been
reported as a recommended chemical for controlling citrus nematodes.  

Beneficial, non-target organisms are also important when considering
alternative pesticides.  Formetanate, dicofol, sulfur, and oxamyl are
highly toxic to beneficial insects, mites, or honey bees and could be
disruptive to IPM programs and pollination.    

Non-chemical methods used to suppress spider mites in some Florida
groves include predacious mites, insects and entomopathogens.  Although
such biological controls are available, they are not well understood
(Childers et al., 2006).  Other non-chemical controls include not using
trunk wraps, removing infested trees, planting resistant rootstocks and
removing tree limbs preferred by mites (Crop Profile for Citrus (Major)
Orange/Grapefruit in Florida, 2001.)    

Biological Conclusions

According to the Crop Profile for Citrus in Florida (2001), the loss of
aldicarb may result in an estimated 5 to 10 percent citrus production
loss in Flordia.  Additionally, the loss of aldicarb may increase the
need for other pesticides because aldicarb provides a longer period of
residual insect control compared to its alternatives.  Aldicarb does not
appear to be the best available pesticide to control the Asian citrus
psyllid compared to the available alternatives.  No feasible alternative
is available for nematode control in Florida.  In Texas, there are
several potential alternatives for aldicarb to control mites.      

Economic Analysis 

The biological analysis shows that there are several possible
alternatives to aldicarb for control of mites in citrus.  Estimated
costs per acre and acreage treated with possible miticide substitutes
for aldicarb are given in table 3.  In contrast, a treatment of aldicarb
in citrus costs about $70 to $80 per acre in Florida, and about $105 per
acre in Texas.  When comparing the cost of the miticides in the table to
aldicarb, be sure to note that aldicarb also provides nematode control,
and that multiple treatments of miticides may be necessary.  The
chemicals shown in table 3 provide effective control of mites, but good
practice requires not treating with the same chemical back to back, to
avoid promoting resistance problems with mites.  Also, note that these
data are based on current practice, where aldicarb is also available to
the grower.    

				

Table 3.  Current Usage and Cost of Chemicals Identified for Mite
Control

 	Florida	 	Texas

	Oranges

Grapefruit

Grapefruit

 	Acres Treated	Cost ($/Acre)

Acres Treated	Cost ($/Acre)

Acres Treated	Cost ($/Acre)

Abamectin	219,962	33

65,723	43

15,033	48

Dicofol	10,115	26

6,737	24

30,038	22

Fenbutatin Oxide	24,493	41

33,441	44

14,237	46

Fenpropathrin	8,460	20

2,158	16

*	*

Propargite	3,027	25

*	*

11,868	54

Pyridaben	38,972	42	 	37,873	41	 	* 	* 











Source:  EPA Proprietary Data

*Insufficient use data for reliable estimates.



Mite damage does reduce the quality of fruit (preventing sale into the
fresh market), but almost all of Florida oranges are used for juice. 
Over the last five years, less than three percent of Florida oranges
have been sold into the fresh market (Florida Department of Citrus). 
Potential quality losses are more important for grapefruit, where about
35 percent of Florida (Florida Department of Citrus) and 60 percent of
Texas grapefruit (USDA NASS, 2004) are delivered to the fresh market. 
Because the miticides in table 3 are expected to provide good control,
we do not anticipate yield losses if they are used in place of aldicarb.
  However, multiple treatments may be required to match the residual
control of aldicarb.  To know whether the cost of mite control would
increase would require developing plausible management strategies, and
estimating the costs within the context of those strategies.     

  

There are few options for nematode control in citrus, other than
aldicarb.  Our biological analysis has indicated that fenamiphos is a
possible alternative to aldicarb.  However, fenamiphos has been
cancelled, effective in 2007, so it is not a feasible alternative in the
long run.  In addition, the benefits of aldicarb for control of mites as
a secondary pest will also be lost.  

Although greening disease, a bacterial disease vectored by psyllids, is
potentially a serious problem in Florida citrus, it is not clear that
aldicarb is an effective control, or that any other chemical treatment
for psyllids is available, so we do not anticipate major economic
impacts if aldicarb were not used.  

Our biological analysis suggests that the absence of aldicarb for use on
citrus acreage can result in yield losses of 5 to 10 percent. 
Therefore, the cost to growers will be quite high.  A 5 to 10 percent
yield loss to the “average” grower in Florida corresponds to a $97
to $193 in lost revenue per acre.  For the grapefruit grower, a 5 to 10
percent yield loss corresponds to a loss in revenue of $109 to $218 per
acre.  If the loss to nematodes increased over time, as nematode
populations increase, these losses may get worse.  The 2000/2001 –
2004/2005 value of orange production in Florida was about $1.1 billion
and the value of grapefruit production was about $209 million.  A 10
percent reduction on the 7 percent of acreage treated with aldicarb
would result in a loss of approximately $3.9 to $7.8 million annually to
Florida orange growers, and $0.7 to $1.5 million to Florida grapefruit
growers.  

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. and B. Cartwritght. Insecticide and miticide guide. Texas
Agricultural Extension Service, The Texas A&M University System. Web
Address:   HYPERLINK
"http://aggie-horticulture.tamu.edu/citrus/l2325.htm" 
http://aggie-horticulture.tamu.edu/citrus/l2325.htm 

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.

Cartwright, B. and H.W. Browning. Mites: description and biology, Texas
Citrus. Texas Agricultural Extension Service, The Texas A&M University
System. Web Address:   HYPERLINK
"http://aggie-horticulture.tamu.edu/citrus/l2309.htm" 
http://aggie-horticulture.tamu.edu/citrus/l2309.htm 

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 Profiles for Citrus in California, 2003.  Web address:
http://www.ipmcenters.org/cropprofiles/docs/CAcitrus2.html.

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 

EPA Proprietary Data, 1999 – 2002.  EPA proprietary data are data on
pesticide use purchased from private sector firms.

Florida Department of Citrus, Economic and Market Research Department. 
Citrus Reference Book, April 2005.  Available here:
http://www.floridajuice.com/pdfs/RB2005.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 

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 

A Texas Citrus Pest Management Strategy.  2003.  Web address:  
HYPERLINK "http://www.ipmcenters.org/pmsp/pdf/TXcitrus.pdf" 
http://www.ipmcenters.org/pmsp/pdf/TXcitrus.pdf 

United States Department of Agriculture, National Agricultural
Statistics Service (USDA NASS). Agricultural Statistics 2005, Web
Address:   HYPERLINK "http://www.usda.gov/nass/pubs/agr05/acro05.htm" 
http://www.usda.gov/nass/pubs/agr05/acro05.htm 

United States Department of Agriculture, National Agricultural
Statistics Service (USDA NASS). Citrus Fruits 2003 Summary. Web address:
http://usda.mannlib.cornell.edu/reports/nassr/fruit/zcf-bb/cfrt0903.pdf

United States Department of Agriculture, National Agricultural
Statistics Service (USDA NASS). Citrus Fruits 2005 Summary. Web address:
http://usda.mannlib.cornell.edu/reports/nassr/fruit/zcf-bb/cfrt0905.pdf

United States Department of Agriculture, National Agricultural
Statistics Service (USDA NASS). Texas Field Office 2004 Texas
Agricultural Statistics Bulletin, available here:
http://www.nass.usda.gov/Statistics_by_State/Texas/Publications/Annual_S
tatistical_Bulletin/bull2004r3.pdf

 This result is calculated using the five year average orange yield of
359 boxes per acre and the five year average price of $5.37 per acre. 
These were calculated using USDA NASS data from the Citrus Fruits 2005
Summary and the Citrus Fruits 2003 Summary.  

 For grapefruit the data are also from the Citrus Fruits 2005 Summary
and the Citrus Fruits 2003 Summary.  The 2004 – 2005 price and yield 
are not used in the average, because price is extremely high ($16.26 per
box) relative to prior years (the average from 2000/2001 through
2003/2004 is $4.87 per box) and yield is very low (180 boxes per acre)
relative to prior years (the average from 2000/2001 through 2003/2004 is
448 boxes per acre).   The average grapefruit yield used in these
calculations is 448 boxes per acre, and the average grapefruit price is
$4.87 per box.  

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