Document ID: EPA-HQ-OPP-2005-0123-0320
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-05-02T04:00Z

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

WASHINGTON D.C., 20460

OFFICE OF

PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

MEMORANDUM

SUBJECT:	Assessment of the Benefits of Soil Fumigation with
Chloropicrin, Methyl Bromide, and Metam-Sodium in Cucurbit Production
(DP# 337490)

FROM:	Bill Chism, Ph.D. 

Senior Agronomist 

Biological Analysis Branch

David Donaldson, Economist 

Economic Analysis Branch

Biological and Economic Analysis Division (7503P)

THRU:	Arnet Jones, Chief 	

Biological Analysis Branch

Timothy Kiely, Chief, 

Economic Analysis Branch

Biological and Economic Analysis Division (7503P)

TO:		John Leahy, Senior Policy Advisor

Special Review and Reregistration Division (7508P)

BEAD Product Review Panel date:	 11 April 2007

Summary

This assessment measures the benefit of chloropicrin, metam-sodium, and
methyl bromide use in cucurbit production in the Midwestern U.S., the
Southeastern U.S., and the Western U.S.   

Cucurbit crops are grown in open fields on plastic tarps, often followed
by various other vegetable crops on the same plastic tarps.  Nationally,
1,3-dichloropropene is used on approximately 10% of the crop and is
sometimes mixed with chloropicrin (approximately 5% of crop treated).  
Metam-sodium is applied to 5% of cucurbit acreage, while metam potassium
is used on less than 1%.  Methyl bromide is used on approximately 5% of
the acreage, and is always applied in combination with chloropicrin.  

Western cucurbit fields are fumigated to control fungi and nematodes. 
If these pests are not controlled, cucurbit yields would be 6 to 64%
less under moderate to severe pest pressure.  In the Western U.S.,
controlling these pests in cucurbit production with fumigants is valued
at $100 million.  In the Midwest fields are fumigated to control fungi. 
If these pests cannot be controlled, yields would be 5 to 20% less under
moderate to severe pest pressure.  In the Midwestern U.S., controlling
these cucurbit pests with fumigants is valued at $4.5 million.  In the
southeastern U.S. fields are fumigated to control fungi, nematodes, and
weeds.  Yields, if these pests are not controlled using fumigants, would
be 6 to 64% less.  In the southeastern U.S., controlling these pests
with fumigants is valued at $75 million.  In total, U.S. cucurbit
production derives $180 million in value from the use of soil fumigants
in cucurbit production, a benefit shared by consumers and cucurbit
producers.

Statement of Purpose

As part of the Registration Eligibility Decision (RED) process, EPA is
assessing the risks and benefits of the use of several soil fumigants as
a group:  chloropicrin, metam-potassium, metam-sodium, and methyl
bromide.  This document presents the assessment of the benefits to
cucurbit production that is provided by the soil fumigants, particularly
methyl bromide and chloropicrin, the most widely used of these
chemicals. Conceptually, the benefits of a pesticide like a soil
fumigant are comprised of the improvements in production and/or
reductions in cost resulting from the pesticide use.  The social
benefits of a pesticide are divided between the users of the pesticide,
e.g., cucurbit producers, and consumers of cucurbit and
cucurbit-containing products.  Consumers benefit because higher
production and/or lower costs translate into a cheaper and more abundant
supply of cucurbits. The impact of fumigant regulation on this consumer
benefit is not explicitly evaluated in this document.

In evaluating the benefits of soil fumigants, this document compares the
current situation in which fumigants are available for use, subject to
existing label restrictions, to the situation that is estimated to occur
were the fumigants not available.  This is somewhat different from other
BEAD assessments of the impacts of regulation, in that no specific
regulatory scheme is considered.

General Background

This assessment focuses on fresh market cucurbits (e.g. cucumber, melon,
honeydew melon, watermelon, pumpkin, and squash) grown in three U.S.
production regions, the Midwest U.S. (Indiana, Illinois, Michigan, and
Ohio), the Southeast U.S. (Alabama, Arkansas, Florida, Georgia,
Kentucky, Louisiana, Maryland, North Carolina, South Carolina,
Tennessee, and Virginia), and the West U.S. (Arizona, California,
Colorado, Oklahoma, and Oregon).  Cucurbits in these regions are grown
in open fields on plastic tarps, often followed by various other
vegetable crops.  A more detailed discussion of key fumigant usage, key
target pests, and impacts of changes in fumigant availability is
presented below.  Because of the small amount of processing cucumbers
fumigated (<5%), and because of the small amount of fumigant use in the
Northeastern U.S. production region, this document does not evaluate
those cucurbit production systems. 

The Midwestern, Southern, and Western regions were selected for
examination because (1) they have unique cucurbit cropping systems, pest
occurrence, fumigant use, etc.; (2) produce large quantities of
cucurbits and treat significant portions of cucurbit production with
fumigants; (3) growers from these areas submit to EPA annual requests
for methyl bromide under the critical use exemption process of the
Montreal Protocol, and have thus provided a database that BEAD could
draw upon.  

The Agency has access to extensive data that describes states throughout
the southeastern cucurbit production region, based on submissions for
critical use of methyl bromide.  We also have extensive information
describing cucurbit production in Michigan and California, but do not
have the same information for other production states in the Midwestern
and western cucurbit production regions.  For this reason, most
information describing the Midwestern and Western cucurbit production
regions will be based on data from Michigan and California, states which
produce the majority of cucurbits in the regions and account for most
reported fumigant use.

The fresh market cucurbit production areas as surveyed by the USDA
National Agricultural Statistics Service (NASS) are presented in Table 1
by state and region. The percent that states and regions contribute to
total U.S. acreage is also provided.  The Southeastern production region
is the largest, in terms of harvested acres, and California is the
largest single cucurbit producing state.

Table 1.  Cucurbit Acreage Grown by State – Fresh Market,  2001 –
2005.

Regions and State	Harvested Acreage	% of U.S. Acres	% of Regional Acres

Midwestern Region

Illinois	10,220	2%	22%

Indiana	9,780	2%	21%

Michigan	19,740	5%	42%

Ohio	7,340	2%	16%

Midwest	47,080	11%	100%

Southeastern Region

Alabama	3,560	1%	2%

Arkansas	2,360	1%	1%

Florida	44,440	11%	23%

Georgia	53,340	13%	27%

Louisiana	1633	0%	0%

Maryland	3,676	1%	2%

Missouri	4,540	1%	2%

Mississippi	2,900	1%	1%

North Carolina	17,760	4%	9%

South Carolina	11,560	3%	6%

Tennessee	1,040	0%	1%

Texas	46,100	11%	23%

Virginia	4,860	1%	2%

Total	197,766	48%	100%

Western Region

Arizona	25,260	6%	19%

California	99,660	24%	74%

Colorado	1,640	0%	1%

Oklahoma	5,500	1%	4%

Oregon	2,280	1%	2%

Total	134,340	33%	100%

Northeastern Region

Delaware	2,406	1%	7%

New Jersey	6,220	2%	19%

New York	14,520	4%	45%

Pennsylvania	8,640	2%	27%

Total1	32,344	8%	100%

United States

Total	410,320	100%	-

Source: USDA/NASS Vegetable 2003 and 2005 Summary, January, 2004 and
2006.  Crops include: cucumber, melon, honeydew melon, watermelon, and
squash

1.Northeastern Region includes 558 Acres of unspecified harvested acres.

Average cucurbit harvested acreage, annual production, and value of
production are provided in Table 2 by production region and specific
crop.  U.S. cucurbit production averages $1.3 billion in total value per
year, the result of 10 billion pounds of production.  The Southern
production region is the largest, with about half of total production. 
This is followed, in order of largest to smallest, by the Western,
Midwestern, and Northeastern production regions.

  

Table 2. U.S. Fresh Market Cucurbit Acreage, Production, and Value of
Production by Region and State, 2001~2005 Average

Commodity	Acres Harvested	Total Production (1,000 CWT)	Value Of
Production ($1,000)

Midwestern Region

Cucumber	6,500	1,179	21,616

Cantaloupe	3,360	608	10,778

Watermelon 	6,920	2,557	20,875

Pumpkin	22,440	5,651	39,263

Squash	8,260	1,537	22,078

All Cucurbits	47,480	11,532	114,611

Southeastern Region

Cucumber	37,184	6,744	127,641

Cantaloupe	16,972	3,304	75,299

Honeydew	1,440	400	12,082

Watermelon	115,173	25,455	204,425

Squash	27,000	3,294	102,868

All Cucurbits	197,769	39,197	522,315

Western Region

Cucumber	4,400	1,056	32,783

Cantaloupe	68,880	18,343	277,630

Honeydew	21,540	4,528	77,562

Watermelon 	24,120	9,800	101,315

Pumpkin	5,440	1,446	17,027

Squash	9,960	2,050	41,375

All Cucurbits	134,340	37,223	547,691

Northeastern Region

Cucumber	7,560	1,306	30,612

Cantaloupe	1,550	158	3,551

Watermelon 	2,320	865	7,215

Pumpkin	13,440	2,072	34,335

Squash	7,260	1,155	35,003

All Cucurbits	32,130	5,557	110,716

United States

Cucumber	55,728	10,291	212,780

Cantaloupe	89,608	22,253	364,796

Honeydew	22,980	4,928	89,644

Watermelon	148,204	38,644	333,990

Pumpkin	41,320	9,169	90,625

Squash	52,480	8,037	201,324

All Cucurbits	410,320	93,321	1,293,159

Source: USDA/NASS Vegetable 2003 and 2005 Summary, January, 2004 and
2006.

Use of Fumigants 

The following section provides a summary of our understanding of the use
of fumigants in cucurbit production.  In preparing this summary, we
referred to all available pesticide use data for the period 2001 to
2005.  These included data from the U.S. Department of Agriculture,
National Agricultural Statistics Service (NASS), The California
Department of Pesticide Regulation, Pesticide Use Reports (PUR),
information provided in methyl bromide critical use nomination packages,
and proprietary pesticide use data.  It is worth noting that these
sources are frequently divergent.  In addition, because cucurbits
pesticide use data is collected by specific crop, there are many
geographical and temporal collection gaps.  For this reason, we have
reviewed each of the sources carefully and have used what we concluded
to be the most appropriate and accurate information.  Thus, the data
provided below reflects an element of professional judgment.  It may
therefore be difficult to independently calculate the same estimates of
fumigant use.  Nonetheless, the information is intended to provide an
indication of the scale of regulatory impacts, not to calculate exact
values of these impacts.

As shown in Table 3, fresh market cucurbits are commonly fumigated with
chloropicrin, 1,3-dichloropropene, methyl bromide, metam-sodium, or
metam potassium.  Over seven million pounds of fumigants are used on
cucurbits per year in the U.S.  1,3-Dichloropropene is used on over 10%
of the crop with 2.5 million pounds used per year.  Chloropicrin,
metam-sodium, and methyl bromide are all used on approximately 5% of the
cucurbit acres.  Metam-potassium is used on less than 1% of the crop
acres.  In total, about 22% of the U.S. cucurbit crop is treated with
one or more fumigant (12% excluding 1,3-dichloropropene).  Again, from
the available information it appears that few processing cucumber acres
are fumigated and therefore their usage information is not provided in
this document.  

Table 3.  Fumigant Use on Fresh Cucurbits, 2001-2005 Average.

State	Active Ingredient	% Acres Treated1	Acres Treated	Pounds Applied

Arizona	Dichloropropene	16	4,000	250,000

	Metam-Sodium	18	4,500	1,500,000

California	Chloropicrin	3	2,300	105,000

	Dichloropropene	4	3,500	215,000

	Metam-Sodium	10	10,000	1,500,000

	Methyl Bromide	1	1,000	135,000

Florida	Chloropicrin	11	5,000	180,000

	Dichloropropene	9	4,000	240,000

	Methyl Bromide	9	4,000	675,000

Georgia	Chloropicrin	5	4,000	125,000

	Dichloropropene	35	20,000	1,350,000

	Methyl Bromide	20	4,000	425,000

Michigan	Chloropicrin	5	500	35,000

	Methyl Bromide	5	500	100,000

North Carolina	Chloropicrin	5	4,000	175,000

	Methyl Bromide	5	4,000	650,000

Texas	Chloropicrin	2	1,000	10,000

	Dichloropropene	10	5,000	275,000

United States	Chloropicrin	5	17,000	700,000

	Dichloropropene	10	45,000	2,500,000

	Methyl Bromide	5	13,500	1,200,000

	Metam-sodium	5	15,000	3,000,000

	Metam-Potassium	<1	1,100	200,000

	US TOTAL	22	91,600	7,600,000

Sources:  NASS Pesticide Use Reports (  HYPERLINK
"http://www.pestmanagement.info/nass/" 
http://www.pestmanagement.info/nass/ ), California PUR (  HYPERLINK
"http://www.cdpr.ca.gov/docs/pur/purmain.htm" 
http://www.cdpr.ca.gov/docs/pur/purmain.htm ), and EPA proprietary data.

Note that percent crop treated data and pounds applied were taken from
the above data sources.  Total area treated and pounds applied are
calculated from these.

Percent crop treated is calculated based on acres grown data from Table
1: Arizona, 25,260; California, 99,660; Florida, 44,440; Georgia,
53,340; Michigan, 19,740; North Carolina, 17,760; Texas, 46,100; US
Total, 410,320.

FUMIGATION CHARACTERISTICS

Target Pests

Table 4 summarizes all major pests targeted by fumigation in the three
regions, as reported by growers in their annual requests for critical
use exemptions (CUEs) for methyl bromide.

Table 4.  Key Diseases, Pests, and Weeds

Region 	Key diseases, Pests and weeds 

Western (Primarily California)	Diseases: Fusarium wilt, Verticillium
wilt, Pythium spp.

Nematodes: Root Knot nematodes (Meloidogyne spp.)

Midwestern (Primarily Michigan)	Diseases:  Soilborne fungal diseases:
Phytophthora capsici and Fusarium oxysporum

Southeastern US (Alabama, Arkansas, Delaware, Florida, Georgia,
Kentucky, Louisiana, Maryland, North Carolina, South Carolina,
Tennessee, and Virginia)	Diseases: Phytophthora, Fusarium spp.) Fusarium
oxysporum niveum (4 races in DE & MD).  Weeds: Nutsedges: yellow
(Cyperus esculentus), and purple (Cyperus rotundus).  Nematodes: Root
knot nematodes (Meloidogyne incognita)

Use Characteristics

Tables 5 through 8 provide information describing typical fumigant use
in fresh cucurbit production.  This information was derived in part from
information submitted by cucurbit growers as part of the annual
nominations prepared by BEAD for methyl bromide Critical Use Exemptions
under the Montreal Protocol. 

Table 5.  Fumigant Application Information For Chloropicrin.

	Western U.S., (Primarily California) 1	Midwestern U.S. (Primarily
Michigan)	Southeastern U.S.

Application Rate (lb ai/acre)	46	70	34

Acres Treated per Day per tractor	10 to 40 	10 to 40 	10 to 40 

Time of Fumigation	Dec – Apr or 

Oct - Dec	March and April	SE – Jan.-Feb. or March-Apr. or June-Sept.

FL – Aug.–Sept. (double cropping) 

Aug.-Jan. (not double cropped)

Application Method	Primarily shank injected under tarp	Shank injected
under tarp	Shank injected under tarp

Strip Application	Primarily strip treated with 58% of area treated
Primarily strip with 58 % of area treated	Primarily strip with 58 % of
area treated

Tarps or Water Caps	HDPE	LDPE with some metalized film	LDPE with some
HDPE and metalized tarps

Southeastern U.S consists of: Alabama, Arkansas, Florida, Georgia,
Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South
Carolina, Tennessee, and Virginia.    

1. Typical application rate range, based on California Department of
Pesticide Regulation, Pesticide Use Reporting,   HYPERLINK
"http://www.cdpr.ca.gov/docs/pur/purmain.htm" 
http://www.cdpr.ca.gov/docs/pur/purmain.htm .

Table 6.  Fumigant Application Information For 1,3-Dichloropropene.

	Western U.S., (Primarily California) 1	Southeastern U.S.

Application Rate (lb ai/acre)	61	64

Acres Treated per Day per tractor	10 to 40 	10 to 40 

Time of Fumigation	Dec – Apr or 

Oct - Dec	SE – Jan.-Feb. or March-Apr. or June-Sept.

FL – Aug.–Sept. (double cropping) 

Aug.-Jan. (not double cropped)

Application Method	Primarily shank injected under tarp	Shank injected
under tarp

Strip Application	Primarily strip treated with 58% of area treated
Primarily strip with 58 % of area treated

Tarps or Water Caps	HDPE	LDPE with some HDPE and metalized tarps

Southeastern U.S consists of: Alabama, Arkansas, Florida, Georgia,
Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South
Carolina, Tennessee, and Virginia.  

1. Typical application rate range, based on California Department of
Pesticide Regulation, Pesticide Use Reporting,   HYPERLINK
"http://www.cdpr.ca.gov/docs/pur/purmain.htm" 
http://www.cdpr.ca.gov/docs/pur/purmain.htm .

Table 7.  Fumigant Application Information For Metam-Sodium / Potassium.

	Western U.S., (Primarily California)1 	Midwestern U.S. (Primarily
Michigan)

Metam-Sodium Application Rate 

(lb ai/acre)	150	200

Acres Treated per Day per tractor	10 to 40 	10 to 40 

Time of Fumigation	Dec – Apr or 

Oct - Dec	March and April

Application Method	Injected into drip system	Shank injected under tarp

Strip Application	Primarily strip treated with 58% of area treated
Primarily strip with 58 % of area treated

Tarps or Water Caps	HDPE	LDPE with some metalized film

Southeastern U.S consists of: Alabama, Arkansas, Florida, Georgia,
Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South
Carolina, Tennessee, and Virginia.  

1. Typical application rate range, based on California Department of
Pesticide Regulation, Pesticide Use Reporting,   HYPERLINK
"http://www.cdpr.ca.gov/docs/pur/purmain.htm" 
http://www.cdpr.ca.gov/docs/pur/purmain.htm .

Table 8.  Fumigant Application Information For Methyl Bromide.

	Western U.S., (Primarily California)1	Midwestern U.S. (Primarily
Michigan)	Southeastern U.S.

Application Rate (lb ai/acre)	135	200	146

Acres Treated per Day per tractor	10 to 40 	10 to 40 	10 to 40 

Time of Fumigation	Dec – Apr or 

Oct - Dec	March and April	SE – Jan.-Feb. or March-Apr. or June-Sept.

GA – July

FL – Aug.–Sept. (double cropping) 

Aug.-Jan. (not double cropped)

Application Method	Primarily shank injected under tarp	Shank injected
under tarp	Shank injected under tarp

Strip Application	Primarily strip treated with 100% of area treated?
Primarily strip with 58 % of area treated	Primarily strip with 58 % of
area treated

Tarps or Water Caps	HDPE	LDPE with some metalized film	LDPE with some
HDPE and metalized tarps

Southeastern U.S consists of: Alabama, Arkansas, Florida, Georgia,
Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South
Carolina, Tennessee, and Virginia.  

1. Typical application rate range, based on California Department of
Pesticide Regulation, Pesticide Use Reporting,   HYPERLINK
"http://www.cdpr.ca.gov/docs/pur/purmain.htm" 
http://www.cdpr.ca.gov/docs/pur/purmain.htm .

PEST CONTROL PRACTICES

Chemical Control Alternatives

In the Western U.S. (primarily California), the Midwest U.S. (primarily
Michigan), and the Southeast U.S. , the chemical alternative to any
given fumigant is most likely another fumigant combination.  However,
the availability of alternatives and their regulatory restrictions will
directly impact the selection of an alternative.  In California
metam-sodium / potassium are the main fumigants, if they are not
available growers might switch to methyl bromide plus chloropicrin or
1,3-dichloropropene plus chloropicrin.  In Michigan where the main
fumigant combination is methyl bromide plus chloropicrin growers might
change to 1,3-dichloropropene plus chloropicrin or possibly to
metam-sodium alone.  In the Southeastern U.S. the main fumigant
combination is methyl bromide plus chloropicrin.  Growers there might
change to 1,3-dichloropropene plus chloropicrin or possibly to
metam-sodium alone or a combination of 1,3-dichloropropene plus
chloropicrin followed by metam-sodium.  Current research has
demonstrated that under moderate to severe pest pressure there are no
other alternative pesticides that can effectively control the pest
spectrum.

Cultural Control Practices

Currently, cultural control practices have not provided technically or
economically effective control of the key pest problems.  Many of the
pests are long lived and crop rotation out of host crops for several
years is technically feasible but is not an effective control practice. 
A totally organic production system is not possible for areas with
moderate to high pest pressure.  In 2005 only 4.6% of the U.S. vegetable
production was grown organically (USDA ERS 2006).  

For regions where Phytophthora capsici is a key pest, crop rotations are
virtually ineffective because the pathogen can survive for several years
in the soil, and can infect more than 50 plant species (Hausbeck &
Cortright 2004) and because these alternate host species act as
reservoirs re-infection can occur quite readily. 

BENEFITS OF FUMIGATION

Yield and Quality

The subsections below describe studies used by BEAD to explore possible
yield losses due to key pests in specific regions.  Table 11 summarizes
the range of yield losses BEAD believes are plausible for cucurbits in
each region.  In all regions, a situation where the growers are able to
switch from the most widely used fumigant regime to the next best
available fumigant/herbicide combination constitutes the lower bound of
yield loss estimates.  The upper bound of yield loss estimates was
derived from the results from studies where a ‘no fumigation’
treatment was included.  The next best fumigant regime varies for each
region and is described in each subsection below.

Midwestern U.S.  (Primarily Michigan)

A field trial was conducted in small plots in 2004 in Michigan by
Hausbeck and Cortright (2004) of Michigan State University.  This study
examined a number of vegetable crops including the cucurbits zucchini,
acorn squash, and melons.  Results, submitted with Michigan’s 2004 CUE
request, indicated that 1,3 D + 35 % chloropicrin treatments
(shank-injected at 56.7 liters/ha) showed an average of 44% yield loss
compared to Methyl bromide plus chloropicrin (due to both Phytophthora
and Fusarium combined).  Chloropicrin alone (shank-injected at 233.6
l/ha) showed an average 15.5% loss compared to MB.  Metam-potassium
showed yields similar to those seen with MB.  Metam-sodium was not
tested, but can reasonably be assumed to be equivalent to
metam-potassium (since the active ingredient is identical).  Methyl
iodide (currently unregistered for cucurbits) with 33% chloropicrin
(shank-injected, at 36.8 kg/ha, respectively), also showed yields
similar to that of MB.  It should be noted that even large differences
in average yields across various treatments were often not statistically
significant, suggesting that there was high variability in the data. 

Research by Hausbeck in 2006 on Phytophthora root rot tested foliar
applied fungicides on solanaceous and cucurbit crops.  Results indicated
that one of the best treatments was mefenoxam, but even with this option
there was a 20 % yield loss.  1,3 D is not a feasible option in this
region because of low soil temperatures typical during the time of
season that fumigation is needed.  In the event of a loss of the
standard fumigation strategy (methyl bromide + chloropicrin), most
growers would probably turn to metam-sodium + chloropicrin.  If no
chemical fumigants were available, growers would probably try to use the
best available fungicide, mefenoxam, despite the yield losses associated
with it.  

Southeastern U.S. 

Yield losses of 6 to 64% are estimated when fumigation is converted from
methyl bromide plus chloropicrin to the best available alternative
fumigant combination.  If a fumigant combination were not available due
to regulatory constraint the losses would be greater (see Table 11).   

In research conducted in Florida (Motis et al 2003) pepper fruit yields
were reduced 10% relative to yields with no nutsedge, in plots with
fewer than 5 planted tubers per m2.  While this research was not
conducted on cucurbits specifically, the results are from a closely
related vegetable production system with a similar life history and pest
vulnerability.  Yield losses increased more rapidly with an increase in
initial nutsedge density from 0 to 30 than from 30 to 120 tubers/m2. 
With 30 nutsedge tubers/m2, large fruit yield was reduced 54 to 74%
compared to that with no nutsedge.  Nutsedge shoots overtopped the
pepper plants as early as 6 wk after treatment when, with 15 planted
tubers/m2, nutsedge interference reduced pepper plant biomass by 10 to
47%.  Taken together, these data indicate losses possible if no
fumigation or other effective controls are applied for severe nutsedge
infestations.

In southeastern cucurbits, combinations of fungal pathogens, nematodes,
and nutsedge weeds have also been studied with the goal of quantifying
efficacy of methyl bromide alternatives. Some of these studies also
included untreated controls, which provide some measure of the impact of
these pests in situations where no fumigation occurs.  For example,
Santos et al. (2006) used sites with a history of heavy infestations of
Fusarium, nematodes, and nutsedges.  In untreated plots, yield losses
(relative to a methyl bromide plus chloropicrin standard) over 2 years
of sampling ranged from 41.9 % to 91.4 %.  In plots treated with 1,3 D +
chloropicrin, 0 to 4 % yield losses were observed.

Studies done in southeastern cucurbits using only Fusarium or root knot
nematodes have also been performed.  The results of such studies provide
some measure of the impact of these pests without the presence of
nutsedges, and are may be used to infer an estimate of the impact of the
pest complex on California cucurbit production (where nutsedges are not
a major concern). 

McGovern et al. (1998) compared the efficacy of methyl bromide +
chloropicrin and metam-sodium where Fusarium spp. were the pest present.
 Trials were performed in small plots in fields in commercial Florida
farms.  Compared to methyl bromide, the use of metam-sodium gave yield
losses of 2.8 to 20 %.  In untreated plots, losses due to Fusarium
ranged from 9.9 to 42.9 %.  In a study that illustrated the impact of
root knot nematodes on cucurbits, Noling and Gilreath (2004) compared
the efficacy of methyl bromide + chloropicrin with that of 1,3 D +
chloropicrin.  In this small-plot study, losses due to nematodes in
untreated fields ranged from 30.6 to 57.8 % (relative to yields in the
methyl bromide treatment).  Yields in the 1,3 D treatment ranged from a 
7.6 % loss to a 7.1 % gain. 

In the southeastern US, cucurbit growers who lose methyl bromide +
chloropicrin (the dominant fumigation regime) would probably turn to
either a combination of 1,3 D plus chloropicrin, and herbicides, or (in
areas where 1,3 D is prohibited due to soil types present) metam-sodium
plus chloropicrin.  Losses in either case would be about 6 %, based on
the studies summarized above and in Table 11. If no fumigation were
possible, losses in untreated fields could be as high as 64 % (Table
11).

Information from Stanley Culpepper, University of Georgia states  “The
loss of chloropicrin will be devastating to Georgia’s vegetable
industry, especially over time.  1,3-Dichloropropene (Telone™)
followed by metam –sodium (Vapam™) produced 23% less cantaloupe
fruit when compared to the UGA 3-WAY (Telone followed by chloropicrin
followed by Vapam) in a large acreage on farm trial (Table 9). 
Additionally, 20% less fruit weight was produced by 1,3-D followed by
Vapam when compared to the UGA 3-Way.  This trial was conducted in an
area that followed more than 10 years of methyl bromide applications.
Repeated use of a fumigant system such as Telone followed by Vapam would
cause a continual increase in pest competition along with a continual
increase in yield loss.”  An additional trial was conducted during
2006 to determine the impact of chloropicrin rate on cucumber yield.  As
chloropicrin rates decreased, cucumber fruit number and weights
decreased when averaged over seven harvests (Table 10).  

Western U.S.  (Primarily California)

BEAD has thus far been unable to locate research done on comparative
efficacy of alternatives to methyl bromide + chloropicrin or
metam-sodium (the dominant fumigants of fresh and processed cucurbits,
respectively, in this region).  However, the pests targeted are similar
to those listed for southeastern US cucurbits (Table 4), a notable
exception being nutsedges, which are apparently not major pests in
California.  Therefore, BEAD used estimates of yield losses derived from
selected studies done in Florida and other southeastern states to
analyses economic impacts of fumigant loss.  For a discussion of these
studies and a summary of yield loss estimates, please see the section
for the southeastern US, as well as Table 11.  The predominant fumigant
used in California is metam-sodium.  If it were not available the next
alternative would be 1,3-dichloropropene plus chloropicrin.  The least
used combination is chloropicrin plus methyl bromide.  There are areas
where only 1,3-dichloropropene is used alone to control nematode
problems.  BEAD does not have enough information to determine the
benefits or impacts of using 1,3-dichloropropene alone in areas of
moderate to severe plant pathogen, nematode, and weed problems.  

Table 9.  Cantaloupe Response To Alternatives When Averaged Over Eight
Harvests, Tifton GA.

	MeBr

(67:33 @ 350 lb ai/acre)	UGA 3 Way

(114 1,3-D fb 150 lb Pic fb 320 lb Metam)	Pic / Vapam

(150 lb Pic fb 320 lb metam-sodium)	Telone / Vapam

(114 lb 1,3-D fb 320 lb metam-sodium)

Number of Fruit	336 b	376 a	368 a	291 c

Pounds of Fruit	1296 a	1314 a	1321 a	1056 b

Probability = 0.05.  Values in a row are not different if followed by
the same number.  

Plot Size 3 bed by 100 feet, 4 reps, averaged over 8 harvests. 

Table 10.  Cucumber Response To Reduced Rates of Chloropicrin in the GA
3Way When Averaged Over Seven Harvests, TyTy GA 2006.  

 	UGA 3 Way Mix, Pounds of Chloropicrin (broadcast equivalent)

	150 lb	100 lb	75 lb	50 lb

Number of Fruit	289 a	276 ab	265 ab	255 b

Pounds of Fruit	189 a	181 ab	172 bc	160 cd

Probability = 0.05.  Values in a row are not different if followed by
the same number.  

Plot Size 1 bed by 50 feet, 4 reps, averaged over 7 harvests. 

Table  11.  cucurbit Yield Loss Data  

Alternative	Type of Pest Tested 	Range of Yield Loss (%)	Best Estimate
of Yield Loss (%)

1,3 dichloropropene + chloropicrin (35%) 	Phytotphora and Fusarium

Michigan (Hausbeck, 2004)	15.5% vs MeBr + chloropicrin	15 %

Metam-potassium	Phytotphora and Fusarium

Michigan (Hausbeck, 2004)	0 % yield + 2 week planting delay  vs MeBr +
chloropicrin	> 20%

No fumigation but with mefenoxam Fungicide	Phytophthora root rot in
Michigan (Hausbeck 2006)	5 to 42  vs MeBr + chloropicrin

20% with mefenoxam	5 to 20 %

Metam-sodium (with or without chloropicrin)	Nutsedges, fungal pathogens,
nematodes;

Southeastern US (McGovern et al. 1998; Noling and Gilreath 2004; Santos
et al. 2006)	0-15 vs MeBr + chloropicrin	7

No fumigation	Nutsedge in Southeastern US (Motis et al. 2003)	54 to 74
vs MeBr + chloropicrin	64 

1,3 dichloropropene + chloropicrin (with or without additional
herbicides and additional chloropicrin)	Nutsedges, fungal pathogens,
nematodes; 

Southeastern US

 (McGovern et al. 1998; Noling and Gilreath 2004; Santos et al. 2006)	0
– 13  vs MeBr + chloropicrin	6 

1,3 dichloropropene + metam-sodium 	Nutsedges, fungal pathogens,
nematodes; 

Georgia  (Culpepper, 2006)	23% loss vs MeBR + Pic or 1,3-D + Pic +
metam-sodium	23

No fumigation	Combination of fungal, nematode and weed pests in 

Southeastern US (Santos et al.2006)	41 – 91 vs MeBr + chloropicrin	64 

Overall Loss Estimate for All Alternatives to Pests	Midwest 5 to 20%

Southeast 6 to 64%

West 6 to 64%

Note: Lower bound of yield loss is a situation where the growers are
able to switch from the most widely used fumigant regime to the next
best available fumigant/herbicide combination.  The upper bound of yield
loss estimates was derived from the results where no fumigation
treatment was used.

Economic Benefits

In the following section we evaluate the benefits of fumigants on
cucurbit yield and on the economic viability of cucurbit producers. 
BEAD uses a partial budget analysis to estimate the impacts of changes
in production.  That is, we evaluate the consequences on a typical acre
of the crop grown, rather than attempt to assess the impacts in the
context of a whole enterprise, which could include multiple crops under
cultivation.  This approach allows the Agency to compare losses to net
operating revenue, which is defined as the difference between gross
revenue and variable operating costs, on a per-acre basis.  The analysis
ignores fixed costs, which are highly dependent on land ownership and
the size and diversity of the grower’s operation, and therefore
difficult to define on a per-acre basis.  As such, this analysis may
understate the impacts as a percentage of the grower’s income.  

Estimated benefits of fumigant use in California, Michigan, and Florida
cucurbit production are summarized in Tables 12, 13, and 14.  Analysis
of economic feasibility is done for the most promising fumigant
alternative, which will vary by production region and is given above.   

Midwestern U.S.

The Midwestern cucurbit production region is represented here using
economic cost and return data from Michigan.  Michigan represents over
40% of Midwestern regional cucurbit production, by acres harvested. 
Fumigant use data is available for only Michigan.  The following cost
and return data is for cucumber production using methyl bromide, and is
based on Michigan’s critical use exemption request under the phase-out
of methyl bromide.  We assume similar impacts for other crops growing in
the region.

As shown in Table 12, without the use of methyl bromide and
chloropicrin, Michigan cucurbit producers would experience losses of 5
percent of yields using their best alternative fumigant combination,
metam-sodium plus chloropicrin. Should no fumigant be available, growers
would rely on mefenoxam and losses would be expected to approach 20% of
yield.  Yield losses of 20% would be unsustainable  These conclusions
apply to that part of Michigan cucurbit acreage that is treated with
methyl bromide and chloropicrin, which is about 5% of acres grown.  In
addition to lost yields, we also anticipate reductions in prices
received by growers due to missed market windows, but have not
quantified these impacts here.  

The 5% of the crop treated with methyl bromide represents about 500
acres.  Regional losses could be higher if additional acres in other
Midwestern states are treated with methyl bromide and chloropicrin.  If
cucurbits could not be grown on these acres, we would expect regional
losses of over $4.5 million.  These acres could be put to a different
use, such as producing a different crop, so these losses could
ultimately be less.

Table 12.  Economic Analysis Michigan Cucumber, Fresh Market.

	Methyl bromide + chloropicrin	Metam sodium

+ chloropicrin	Mefenoxam 

(no fumigation)

Estimated Yield Loss	0%	5%	20%

Yield (CWT)	793	753	634

Price  per CWT	$12 	$12 	$12 

Gross Revenue  	$9,453 	$8,980 	$7,562 

Fumigant and Alternative Costs1	$500 	$300 	$50 

Land Preparation and Growing Period Costs  ($/acre)	$4,030 	$3,830 
$3,580 

Harvest Costs 	$4,543 	$4,316 	$3,634 

Total Operating Costs  	$8,573 	$8,146 	$7,214 

Net Operating Revenue  	$880 	$834 	$348 

Percentage Change in Net Operating Revenue	0%	5%	60%

Source:  Michigan Methyl Bromide Critical Use Nomination, 2006.  

Lower bound of yield loss is a situation where the growers are able to
switch from the most widely used fumigant regime to the next best
available fumigant/herbicide combination.  The upper bound of yield loss
estimates was derived from the results where no fumigation treatment was
used. 

Includes the cost of fumigant and labor.  

Southeastern U.S.

The Southeastern cucurbit production region is represented here using
economic cost and return data from Florida.  Florida represents over 23%
of regional cucurbit production, by acres harvested.  Our data indicates
that there are about 12,000 Southeastern cucurbit acres treated with
methyl bromide and chloropicrin in the states of Florida, Georgia, and
North Carolina.  Substantial 1,3-dichloropropene use also occurs in the
region.  The following cost and return data is for cucumber production
using methyl bromide plus chloropicrin, and is based on data collected
by the University of Florida.  We assume similar impacts for other crops
growing in the region.

As shown in the below table, without the use of methyl bromide and
chloropicrin, Florida cucurbit producers would not be able to sustain
production given losses of 6 to 55 percent of yields using their best
alternative fumigant. Should no fumigant be available, losses would be
expected to exceed 55% of yield.  These estimates are upper bounds,
given that the cost estimates from cost and return studies are typically
upper bounds.

These conclusions apply to that part of Southeastern cucurbit acreage
that is treated with methyl bromide and chloropicrin, which is about
12,000 acres. If cucurbits can no longer be grown on these acres, we
would expect loss in revenues of approximately $75 million.  These acres
could be put to a different use, such as producing a different crop, so
these losses could ultimately be less.

Table 13.  Economic Analysis Florida Cucumber, Fresh Market.

	Methyl bromide + chloropicrin	1,3 dichloropropene + chloropicrin +
s-metolachlor + halosulfuron	S-metolachlor + halosulfuron (no
fumigation)

Estimated Yield Loss	0%	6% - 55%	64%

Yield (CWT)	278	261 – 125	100

Price  per CWT2	$22 	$22 	$22 

Gross Revenue  	$6,211 	$5,838 - $2,795	$2,236 

Fumigation Costs and Alternative Costs	$660 	$303 	$0

Non-Fumigant alternatives cost	$0 	$50 	$50 

Land Preparation and Growing Period Costs  ($/acre)	$2,561 	$2,254 
$1,951

Harvest Costs  ($/acre)	$2,225 	$2,092	$801 

Total Operating Costs  ($/acre)	$4,786 	$4,346 - $3,255 	$2,752 

Net Operating Revenue  ($/acre)	$1,425 	$1,492 - ($461) 	($516)

Percentage Change in Net Operating Revenue	0%	5% - 132%	136%

Source:  Cost of One Acre of Cucumbers on Plastic, North Florida 2007,
prepared by Timothy D. Hewitt, Extension Economist, Food and Resource
Economics Department, University of Florida, NFREC, Marianna.  

  HYPERLINK "http://nfrec.ifas.ufl.edu/Hewitt/budgets.htm#Vegetables" 
http://nfrec.ifas.ufl.edu/Hewitt/budgets.htm#Vegetables .

Lower bound of yield loss is a situation where the growers are able to
switch from the most widely used fumigant regime to the next best
available fumigant/herbicide combination.  The upper bound of yield loss
estimates was derived from the results where no fumigation treatment was
used.

Western U.S.

The Western cucurbit production region is represented here using
economic cost and return data from California.  California represents
nearly 75% of regional cucurbit production, by acres harvested. 
Fumigant use data is available for Arizona and California showing 20%
and 10% of acres treated with metam-sodium, respectively.  There is also
substantial existing regional use of 1,3-dichloropropene.  The following
cost and return data is for watermelon production using Metam-sodium,
and is based on cost and returns studies from the University of
California.  We assume similar impacts for other crops growing in the
region.

As shown in the below table, without the use of metam-sodium, California
cucurbit producers would have difficulties sustaining production with
losses of 6 percent of yields and 100% of net revenues using their best
alternative fumigant, 1,3-dichloropropene plus chloropicrin.  It should
be noted, however, that the cost and return estimates used to draw these
conclusions are typically upper bound estimates.  For this reason, these
impacts will likely be smaller.  Should no fumigant be available, losses
would be expected to approach 64% of yield, which are certainly
unsustainable.  

Assuming that these conclusions apply to all Western cucurbit production
that is treated with metam-sodium, which is about 15,000 acres,
cucurbits could not be grown on these acres.   We expect regional losses
in revenue of approximately $100 million.  These acres could be put to a
different use, such as producing a different crop, so these losses would
ultimately be less.

Table 14.  Economic Analysis California Watermelon, Fresh Market.

	Metam sodium	1,3 dichloropropene + chloropicrin	No fumigation

Estimated Yield Loss	0%	6%	64%

Yield (CWT)	653	614	235

Price per CWT	$10 	$10 	$10 

Gross Revenue  	$6,453 	$6,066 	$2,323 

Fumigation Costs and Alternative Costs	$200 	$300 	$0 

Land Preparation and Growing Period Costs  ($/acre)	$3,498 	$3,598 
$3,298 

Harvest Costs  	$2,774 	$2,608 	$999 

Total Operating Costs  	$6,272 	$6,205 	$4,296 

Net Operating Revenue  	$181 	($139)	($1,973)

Percentage Change in Net Operating Revenue	0%	177%	1187%

Sample Cost To Establish And Produce Watermelon, Imperial County –
2004, Herman S Meister Farm Advisor, U.C. Cooperative Extension,
Imperial County,    HYPERLINK
"Http://Coststudies.Ucdavis.Edu/Outreach/Cost_Return_Articles/Watermelon
04.Pdf" 
Http://Coststudies.Ucdavis.Edu/Outreach/Cost_Return_Articles/Watermelon0
4.Pdf .  

Lower bound of yield loss is a situation where the growers are able to
switch from the most widely used fumigant regime to the next best
available fumigant/herbicide combination.  The upper bound of yield loss
estimates was derived from the results where no fumigation treatment was
used.

National Benefits

There are over 410,000 acres of fresh market cucurbits grown in the U.S.
annually.  Approximately 22% of these acres are treated with fumigants
(12% excluding 1,3-dichloropropene).  Because fumigants are available
for disease, weed and nematode control, BEAD estimates U.S. cucurbit
production is enhanced by $180 million, the impact of which is shared by
consumers in the form of lower prices and cucurbit producers in the form
of higher revenue.   

CONCLUSION

This assessment measures the benefit of chloropicrin, metam-sodium, and
methyl bromide use for the control of nematodes, weeds, and soil borne
disease in U.S. cucurbit production.  Of the soil fumigants currently
being reviewed by EPA, chloropicrin, methyl bromide, and metam-sodium
are all used on cucurbits in the west, Midwest, and southeast U.S. 
Pests driving fumigant use are soil pathogens in all regions, nematodes
in the west and southeast, and weeds in the southeast.  In all regions
with moderate to severe pest pressure, the only economically feasible
alternatives to those fumigants that are currently being used are other
fumigants or fumigant combinations.  If not controlled, pests targeted
by the fumigants could cause yield losses of between 5 and 20% in The
Midwestern U.S. and between 6 and 64% in the western and southeastern
U.S.  Fumigants are used on 22% or 91,600 of the cucurbit acres grown in
the U.S.  The total value of fumigant use in U.S. cucurbit production is
approximately $180 million, which is shared by consumers and producers.

Limitations to this assessment

This document presents the assessment of the benefits provided by the
soil fumigants in the production of cucurbits.  The following are
limitations of this analysis:

The assessment does not account for transition to new agronomic
practices such as a conversion to greenhouse production, introduction of
new growing areas, or the introduction of newer as yet unregistered
fumigants.  

The assessment is based on partial budget analysis and does not account
for price or income distribution effects resulting from changes in
supply. 

REFERENCES

California Pepper Commission.  2005  Yield loss due to Phytophthora
capsici root rot, Red Bell Pepper Yield Loss, Deardorff Jackson Farms,
Ventura CA. 2005.  Letter in support of 2009 California Critical Use
Exemption Request for Peppers. 

Hausbeck, M. and B. Cortright.  2004.  Comparing Fumigants for the 
Control of Control of Phytophthora capsici in Vegetable Crops in
Vegetable Crops.  Methyl Bromide Alternatives Outreach presentation in
2004.  Available at:
http://www.mbao.org/2004/PowP/039Cortright%20%2039.pdf

Hausbeck, M.  2006.  Vegetable Crop Advisory Team Alert newsletter. 
Vol. 21, No. 13, July 19, 2006.  Available at:   HYPERLINK
"http://ipm.msu.edu/cat06veg/v07-19-06.htm#3" 
http://ipm.msu.edu/cat06veg/v07-19-06.htm#3  

McGovern, R.J., C.S. Vavrina, J.W. Noling, L.A. Datnoff, and H.D. Yonce.
1998. Evaluation of application methods of metam-sodium for management
of Fusarium crown and root rot in cucurbit in southwest Florida. Plant
Disease 82: 919-923.

Motis, T. N., S. J. Locasio, J. P. Gilreath, and W. M. Stall.  2003. 
Season-Long Interference of Yellow Nutsedge (Cyperus esculentus) with
Polyethylene-Mulched Bell Pepper (Capsicum annuum).  Weed Technology.
Volume 17:543–549

Noling, J.W. and J.P. Gilreath. 2004. Evaluations of chemical
alternatives to methyl bromide for nematode control and cucurbit yield
in field microplots. Methyl Bromide Alternatives Outreach presentation
in 2004.  Available at:   HYPERLINK "http://www.mbao.org" 
http://www.mbao.org .

Santos, B.M., J.P. Gilreath, T.N. Motis, J.W. Noling, J.P. Jones, and
J.A. Norton. 2006. Comparing methyl bromide alternatives for soilborne
disease, nematode and weed management in fresh market cucurbit. Crop
Protection 25: 690-695.

USDA ERS.  2006.  Organic Production.  USDA, Economic Research Service. 
2006.  Available at :    HYPERLINK
"http://www.ers.usda.gov/data/Organic/" 
http://www.ers.usda.gov/data/Organic/ 

USDA NASS.  2002-2006. Crop Production, Summary.  National Agricultural
Statistics Service, U.S. Department of Agriculture, January, at  
HYPERLINK
"http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID
=1047" 
http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=
1047 .

USDA NASS.  2005.  Agricultural Chemical Usage, 2004 Field Crops
Summary.  National Agricultural Statistics Service, U.S. Department of
Agriculture, May, at   HYPERLINK
"http://usda.mannlib.cornell.edu/usda/nass/AgriChemUsFC//2000s/2005/Agri
ChemUsFC-05-18-2005.pdf" 
http://usda.mannlib.cornell.edu/usda/nass/AgriChemUsFC//2000s/2005/AgriC
hemUsFC-05-18-2005.pdf .

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