Document ID: EPA-HQ-OAR-2010-0280-0012
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-07-18T04:00Z

Nominating Party: 	The United States of America

NAME USA CUN13 Soil Tomatoes Open Field 

Brief descriptive Title of Nomination:

Methyl Bromide Critical Use Nomination for Pre-plant Soil Use for Tomato
Grown in Open Fields (Submitted in 2011 for 2013 Use Season)

Crop name (open field or protected): Tomatoes Open Field

Quantity of methyl bromide requested:

Table 1: Quantity of Methyl Bromide Requested in Each Year of Nomination

Year	Nomination Amount (Kilograms)

2013	10,741 kg

NOMINATING PARTY CONTACT DETAILS:

Contact Person:	John Thompson	

Title:	Division Director	

Address:	Office of Environmental Policy	

	U.S. Department of State	

	2201 C Street, N.W. Room 2658	

	Washington, D.C. 20520	

	U.S.A.	

Telephone:	(202) 647-9799		

Fax:	(202) 647-5947	

E-mail:	thompsonje2@state.gov	

Following the requirements of Decision IX/6 paragraph (a)(1) The United
States of America has determined that the specific use detailed in this
Critical Use Nomination is critical because the lack of availability of
methyl bromide for this use would result in a significant market
disruption.     .                 ■  Yes  	     ( No

					

Signature			       Name				Date

Title:      			

(Details on this page are requested under Decision Ex. I/4(7), for
posting on the Ozone Secretariat website under Decision Ex. I/4(8).) 

This form is to be used by holders of single-year exemptions to reapply
for a subsequent year’s exemption (for example, a Party holding a
single-year exemption for 2005 and/or 2006 seeking further exemptions
for 2007).  It does not replace the format for requesting a critical-use
exemption for the first time.

In assessing nominations submitted in this format, TEAP and MBTOC will
also refer to the original nomination on which the Party’s first-year
exemption was approved, as well as any supplementary information
provided by the Party in relation to that original nomination.  As this
earlier information is retained by MBTOC, a Party need not re-submit
that earlier information.   

CONTACT OR EXPERT(S) FOR FURTHER TECHNICAL DETAILS:

Contact/Expert Person:	Jack Housenger	

Title:	Director 	

Address:	Biological and Economic Analysis Division			

	Office of Pesticide Programs

	U.S. Environmental Protection Agency

	1200 Pennsylvania Avenue, N.W. Mailcode 7503P

	Washington, D.C. 20460

	U.S.A.	

Telephone:	(703) 308-8200		

Fax:	(703) 308-7042	

E-mail:	  HYPERLINK "mailto:Housenger.Jack@epa.gov" 
Housenger.Jack@epa.gov 

		

LIST OF DOCUMENTS SENT TO THE OZONE SECRETARIAT IN OFFICIAL NOMINATION
PACKAGE:

1.  PAPER DOCUMENTS:  

Title of paper documents and appendices	No. of pages	Date sent to Ozone
Secretariat

USA CUN13 Soil Tomatoes Open Field 	27

	2.  ELECTRONIC COPIES OF ALL PAPER DOCUMENTS:  

*Title of each electronic file (for naming convention see notes above)
No. of kilobytes 	Date sent to Ozone Secretariat

USA CUN13 Soil TOMATOES Open Field 

* Identical to paper documents

 METHYL BROMIDE CRITICAL USE RENOMINATION FOR Preplant Soil Use (OPEN
FIELD OR PROTECTED ENVIRONMENT)

TOMATOES

SUMMARY OF THE NEED FOR METHYL BROMIDE AS A CRITICAL USE

This nomination is for methyl bromide use in the production of tomatoes
in Florida, Georgia, The Mid-Atlantic (Maryland, and Virginia), and the
Southeast.  U.S. tomato growers have been reducing methyl bromide use
rates in all production areas.

The USG has reviewed all factors affecting transition rates in this
sector. Based on this assessment the transition rate has been greatly
increased for most portions of this sector.  For the area covered in
this nomination, the USG believes that the narrative discussion included
in this document is technically valid. The USG has nominated amounts of
methyl bromide based only on those sub-sectors that cannot transition
away from methyl bromide at the accelerated rate.

The primary fumigant alternatives for methyl bromide that have shown
promise against key tomato pests the spring application of the fumigant
combination of 1,3 D, followed by chloropicrin alone, followed by
metam-sodium and the newly registered fumigant iodomethane.

Current research has demonstrated that in many cases iodomethane
(MIDAS®) formulated with chloropicrin can be an efficacious methyl
bromide alternative, however, transition time will be needed for many
tomato producers to adapt production to using this material. Growers
will need this time to adapt to the use of new application equipment
appropriate to the lower flow rates typical with iodomethane, to
retro-fit equipment in order to avoid corrosion by iodomethane, etc. 
Increased costs due to using iodomethane are described in the "economic
assessment" section below.  

For 2009, crop experts at the University of Georgia reported that the
price of iodomethane went up so dramatically that they did not advise
growers to use the product, despite its good efficacy. It is not clear
whether or not these high prices affected other tomato growing regions
included in this nomination, or how long the high prices will persist.
However, at the very least, this information does suggest that adoption
of iodomethane by tomato growers will be significantly affected by price
fluctuations. Application protocols have not been sufficiently
established due to limited results of long term on-farm research.  A
major concern with the use of iodomethane is the potential increase of
plant-back timing to avoid potential crop injury and loss.  

In other recent work, some research results with dimethyl disulfide
(DMDS) indicate that this fumigant is promising. However, preliminary
research results from a single year of fumigation in pepper production
demonstrate that, as a stand-alone product, the efficacy of DMDS is not
comparable to methyl bromide and will require chloropicrin (MacRae and
Culpepper, 2008).  Treatments with DMDS plus chloropicrin and/or
metam-sodium are not significantly different from methyl bromide +
chloropicrin, though growers will need time to adapt to this alternative
and the strong odor created by DMDS.

The application of a sequential 3 way fumigant combination, the
“Georgia 3 Way” (consisting of 1,3-D, followed by chloropicrin,
followed by metam-sodium or metam-potassium), continues to be evaluated.
It is considered to be useful as a spring applied fumigant mix in the
state of Georgia.  It should be noted that a major part of developing a
commercially feasible protocol to use this system in all regions will
require adjustment of rates and application timing for field and strip
applications.  Trials evaluating the “Georgia 3 Way” show that it
can be as efficacious against key southern US tomato pests as methyl
bromide and/or iodomethane + chloropicrin. An exception to this is a
study by Chellemi (2008) where, in some trials, pepper plant height and
yield was reduced due to crop injury. However, the injury was later
correlated with high levels of soil potassium and probably not a direct
result of the fumigation.  Weed and nematode control for the “Georgia
3 Way” as compared to methyl bromide were not different. Adding to the
slow adoption of this system is the lack of established protocol that
will be based on mitigating potential problems such as plant-back
timing, soil moisture, and location/edaphic variability.  The increased
production costs, and cost of new or altered equipment needed for
application will also be an impediment to adoption of the three fumigant
mix.

Florida

Some production areas in Florida are located above karst topographic
formations which places restrictions on the use of 1,3-D.  Stinging
nematode problems require either methyl bromide or 1,3-D.  Some fields
with key disease problems have achieved good control with chloropicrin,
although there may be regulatory restrictions on its use at high rates. 
Where 1,3-D is allowed, the application of the three fumigant mix
continues to be evaluated but is not considered a viable alternative.

Preliminary research has demonstrated that iodomethane can be an
efficacious methyl bromide alternative, but protocols have not been
sufficiently established. Given sufficient time to transition this
fumigant can be worked into the production system.  

Georgia

The three way fumigant combination (the ‘Georgia 3 Way’) continues
to be evaluated, and has proven to be efficacious for spring application
in Georgia.  However, the lack of established protocol and the cost of
new or altered equipment have been a limiting factor in the adoption of
this fumigant combination.

Preliminary research has demonstrated that iodomethane can be an
efficacious methyl bromide alternative, but protocols have not been
sufficiently established.  Given sufficient time to transition these
fumigants can be worked into the production system.  

Mid-Atlantic

Current research in this region has not been submitted and it is thus
assumed that the use of iodomethane as a methyl bromide replacement,
given time to transition, will be sufficient.  However, just as in many
areas of the country, the establishment of protocols will slow farmer
adoption.  Until results from on-farm research projects have established
a protocol a period of transition will be needed.

Southeast

The “Georgia 3 Way” fumigant combination continues to be evaluated
in the southeast.   In a comment by Craig Anderson of the University of
Arkansas, the cool temperatures and wet soils in early spring will
extend the plant back timing due to the additional time needed for soil
fumigant levels to dissipate to avoid crop injury and subsequent yield
loss (Toth, 2008)

Preliminary research conducted in states other than those in the
southeast have demonstrated that iodomethane can be an efficacious
methyl bromide alternative, but protocols have not been sufficiently
established.  Concerns in the southeast about injury and delayed
planting have lead some to question their usefulness in this region. 
Currently, there are several economic drawbacks that include the cost of
iodomethane, the cost of using VIF or metalized mulches, and an initial
cost of some minor equipment alteration.

U.S. reliance on methyl bromide has dramatically and rapidly been
reduced over the last eight years.  Critical use exemption (CUE)
requests have decreased every year since the U.S. phase-out process
began.  The development, registration, and use of new pest control
products and production methods have been key to the progress and
reductions made to-date.  As alternatives have demonstrated their
suitability, as thorough reviews of research results and applicant
information have been conducted, and contacts have been made with
regional crop experts to assess the technical and economic feasibility
of alternatives, U.S. Government (USG) requests have reduced by 99%, for
the fruiting vegetables, over the last 9 years.  However, as the amount
of methyl bromide available for use decreases each year, substantial
challenges exist in the collection of needed data to substantiate
on-going critical needs through the CUE process.  

There are now several alternatives for soil fumigation, including
1,3-dichloropropene plus chloropicrin, the “UGA 3 Way” combination
(1,3-dichloropropene plus chloropicrin followed by metam sodium),
iodomethane plus chloropicrin, and dimethyl disulfide (DMDS) which have
demonstrated some technical and economic feasibility for pest control in
a number of vegetable crops in the U.S. Southeast.  However, CUE
applicants in this nominated sector have indicated that they are not
always suitable for all situations.  While DMDS has a Federal
registration and has demonstrated effectiveness, it is not currently
registered in all the relevant states.  Given the timing of state
registrations, lack of experience using this alternative, and
application methods still under development to minimize odor in
communities surrounding treated fields there is uncertainty in
predicting when this alternative can be reasonably expected to
adequately replace methyl bromide in specific application scenarios. 
While the DMDS registrant has been working with the product to reduce
the odor, and growers are gaining experience in its use, work is still
needed on application approaches for the alternative to be fully
available for use in U.S. southeast vegetable crops.  For example
individual operators and small farms, which account for up to eighty
percent of the growers in this nominated sector are especially
hard-pressed to make this transition, because one of the most promising
alternatives requires additional money to convert their fumigation
equipment and custom fumigation applicators are not available in all
areas.  In addition to the expense to convert to the alternatives, there
have been reports that the alternatives do not perform as well as the
MeBr:pic combination.   

These concerns about the alternatives have only recently been brought to
the USG attention and insufficient supporting information was provided. 
Because of the uncertainties and challenges associated with the use of
the available alternatives, the USG believes it most prudent and the
best public policy to collect additional information so that the
technical and economic impacts of these reported problems can be
evaluated.  The USG will request the applicants provide additional
information to us no later than June 1, 2011 so that the information can
be analyzed and provided to MBTOC by July 15, prior to the Open Ended
Work Group (OEWG) meeting in early August.  The quality of any
additional information received will first be evaluated in terms of
whether or not it supports a compelling case and confirms problems with
the feasibility of alternatives. Then, on that basis, the USG will
either support or withdraw this nominated sector at that meeting.  

The nomination attached specifies the correct year (2013) and amount of
methyl bromide that is being requested for the individual crops within
this sector.  However, there has been no attempt to update the
information in this document regarding the new research, availability of
alternatives, etc.  Since the USG learned of the issues facing the
growers within this sector, after speaking directly with researchers
familiar with the specific problems only very recently, this information
was not available at the time the USG recommendation was developed.    

2.	SUMMARIZE why KEY alternatives are not feasible

Our review of available research on other methyl bromide alternatives
discussed by MBTOC for tomatoes suggests that, of the registered (i.e.,
legally available) chemistries, iodomethane, and combinations of metam
sodium, 1,3-D, and/or chloropicrin have shown some potential as
commercially viable replacement to methyl bromide.  Non-chemical
alternatives are either not viable for US tomatoes or require more
research and commercial development before they can be technically and
economically feasible. For some areas in the state of Georgia, a 3 way
fumigant combination of 1,3 D, followed by chloropicrin alone, followed
by metam-sodium, has shown promise against key tomato pests in spring
season only fumigation. However, the aforementioned fumigant combination
has not met with success in other areas of the southeast.  The
transition rate included in the BUNNIE incorporates an estimate of
projected use of this strategy as well as the use of iodomethane. 

Many of the alternatives require the evaluation of their relationship
between fumigant alternatives, various mulches, and herbicide systems
under different growing conditions.  From this information on-farm
protocols can be established.

Alternatives are considered not feasible where:

they have not been sufficiently tested or protocols have not been
sufficiently developed for their use

costs are excessive

application difficulties exist due to such factors as equipment
requirements

pest pressure is so high that alternatives are not effective

not registered for use in the US (such as DMDS).

There are significant restrictions on which crops can be rotated through
after use of a given alternative (e.g., halosulfuron has rotational
restrictions that prevent its use in southeastern US tomatoes).

Resistance management prevents use of the alternative (e.g., glyphosate
resistant weeds, such as Amaranth, in the southern US, prevent use of
this alternative as a post-emergent weed control in those regions).  

The US nomination is only for those areas where the alternatives are
still under extensive evaluation and pest pressure is high.  In US
tomato production there are several factors that make some of the
assumed alternatives, other than iodomethane, unsuitable.  These
include:

Pest control efficacy of alternatives: the efficacy of alternatives may
not be comparable to methyl bromide in some areas, making these
alternatives technically and/or economically infeasible for use in
tomato production.

Geographic distribution of key target pests: i.e., some alternatives may
be comparable to methyl bromide as long as key pests occur at low
pressure.  The US is only nominating a CUE for tomato where the key pest
pressure is moderate to high such as nutsedge in the Southeastern US.

Regulatory constraints: e.g., in Florida due to the presence of karst
topographical features.

In Virginia and much of the mid-Atlantic, high water tables and the
close proximity of production areas to environmentally sensitive
estuaries makes the use of 1,3-D limited.  

Delay in planting and harvesting: e.g., the plant-back interval for
telone+chloropicrin is two weeks longer than methyl
bromide+chloropicrin.  Delays in planting and harvesting result in users
missing key market windows, and adversely affect revenues through lower
prices.

Alternatives that are nonselective are restrictive as a preplant
burndown only.

3.	is the use covered by A certification STANDARD?

Not used to meet a certification standard.

4.	If part of the crop area is treated with methyl bromide, indicate the
reason why methyl bromide is not used in the other area, and identify
what alternative strategies are used to control the target pathogens and
weeds without methyl bromide there. 

In the areas where methyl bromide is not currently used there is often
low weed and/or pathogen pressure and/or no restrictions on 1,3-D use. 
In areas where 1,3-D can be used, there are a many  growers have
cooperated with universities and others on developing application
protocols specific to their conditions for the 3 way fumigant
combination (1,3 D, followed by chloropicrin alone, followed by
metam-sodium).  

5.	Would it be feasible to expand the use of these methods to cover at
least part of the crop that has requested use of methyl bromide? What
changes would be necessary to enable this?

No, areas that use methyl bromide do so because environmental
sensitivity and/or heavy pest pressure preclude the use of fumigants
that are employed when these conditions are not present.

The USG has reviewed all factors affecting transition rates in this
sector. Based on this assessment the transition rate has been greatly
increased for most portions of this sector.  For the area covered in
this nomination, the USG believes that the narrative discussion included
in this document is technically valid. The USG has nominated amounts of
methyl bromide based only on those sub-sectors that cannot transition
away from methyl bromide at the accelerated rate.

Researchers are continuing to evaluate fumigant concentration and mulch
interaction using the 3 way fumigation combination and iodomethane
(Culpepper et al, 2007).  However, there is still the need for more
research to determine the fumigant rates and mulch combinations needed
for pest control and crop safety where there is heavy pest pressure.  In
a study by Culpepper (Georgia CUE appendix 2011; see Appendix A for a
reproduction of this submission), the 3 way fumigant combination
resulted in tomato plant heights that were lower than the methyl bromide
treated plots.  When using the Blockade mulch (low permeability tarp)
injury was severe with plant damage and tomato yields being reduced even
when the soil was allowed to air, but they have seen good results in
spring applications.  This is similar to information provided by growers
and university personnel in the southeast (Toth, 2008)

Table 2.  Tomato plant yields and height in response to time of planting
after fumigating.

Fumigant	Mulch	Planting days after fumigation	Gas in bed at planting

(ppm)	Yield

(#/plot, highest value fruit only; no difference noted with total fruit)
Heights (cm)

(3 wk after planting)

MB	LDPE	7	29	127 a	38 a

3-WAY	LDPE	7	77	127 a	32 cd

3-WAY	Blockade	7	368	55 c	14 f

MB	LDPE	7 + 1	2	117 a	37 ab

3-WAY	LDPE	7 + 1	13	132 a	33 cd

3-WAY	Blockade	7 + 1	31	99 b	27 e

MB	LDPE	14	2	142 a	37 ab

3-WAY	LDPE	14	4	132 a	34 bc

3-WAY	Blockade	14	38	114 a	30 de

MB	LDPE	14 + 1	0	133 a	35 abc

3-WAY	LDPE	14 + 1	3	127 a	33 cd

3-WAY	Blockade	14 + 1	27	119 a	30 de

Source: Georgia CUE Appendix; see Appendix A for a reproduction of this
submission.

Developing a protocol for this system includes the titration of rates
for field and strip applications (table 3).  In preliminary data
comparing the 3 fumigant combination, results have demonstrated that
methyl bromide and iodomethane do not significantly differ in efficacy. 
However variability among results across locations demonstrates the need
for further research (Toth, 2008).  An exception to these findings was a
study by Chellemi (2008) where pepper plant height and yield was reduced
due to crop injury; however, the injury was later correlated with high
levels of soil potassium and probably not a direct result of the
fumigation.  On the other hand, in three of the trials weed and nematode
control for the three fumigant combination and methyl bromide were low;
less than 0.01 weeds / foot of row and nematode concentration was less
than 1.0 / 100 cc of soil. 

Table 3. UGA Three FUMIGANT COMBINATION Adjusted Rates 11-2008.

Fumigant(s)	Rate

(lb/acre)	Rate Adjusted for Strip Treatment (lb / acre)	Method

	Methyl Bromide	143	83

83	bedded, shank, standard tarp

Chloropicrin	143

Methyl Bromide	143	83

83	bedded, shank,

high barrier tarp

Chloropicrin	143

1,3-Dichloropropene	171	99

87

186	bedded, shank, standard tarp

Chloropicrin	150

Metam Sodium	320

1,3-Dichloropropene	171	99

87

186	bedded, shank,

high barrier tarp

Chloropicrin	150

Metam Sodium	320

Source: Rates and application methods represent likely scenarios based
on information from USDA NASS, EPA proprietary data, and/or
stakeholder-submitted comments.

Table taken from Georgia CUE Appendix; see Appendix A for a reproduction
of this submission.

Tomato growers in Maryland have again requested methyl bromide.  These
growers have historically used methyl bromide in their tomato
production, purchasing it from the stockpile since the 2005 ban. 
Maryland growers, in common with other tomato growers in the
mid-Atlantic region, have production areas with high water tables and in
close proximity to environmentally sensitive estuaries; these factors
make the use of 1,3-D limited, and thus the three fumigant combination
cannot be considered as an alternative.

Techniques such as grafting, resistant rootstocks immune to target
fungal pathogens, plant breeding, soil-less culture, organic production,
substrates, plug, are not commercially feasible.  Availability of such
transplants is further hampered by the lack of infrastructure to make
grafted tomato plants available on a large scale, concomitant with this
is the high premium associated with these transplants at this time. 
Grafting and plant breeding are thus also rendered technically
infeasible as methyl bromide alternatives for control of fungal
pathogens, nutsedges and nematodes.  Grafting of solanaceous plants is
relatively new to US growers, and has met with a great deal of concern
regarding the potential for the establishment of off-type plants
developing from the rootstock and/or fruit seeds. N. Burell et al.
(2008) evaluated various grafted tomato cultivars in fields where
iodomethane, DMDS, or methyl bromide were applied.  The results of their
research demonstrated that regardless of rootstock, yields of tomato
plants responded equally without regard to fumigant type.  In this case
it would seem that the steady pace of on going transitioning to
alternative herbicides such as iodomethane would be more advantageous to
pursue.

6.	SUMMARY OF RECENT RESEARCH

As mentioned earlier in this document, iodomethane formulated with
chloropicrin has shown good efficacy against key tomato pests, including
nutsedge, in a number of trials with tomato and related vegetables such
as peppers (e.g., Louws et al. 2006, Culpepper 2006, 2007, 2008,
Culpepper et al. 2008, Olsen 2008). Iodomethane had time limitations
removed from its federal label in October, 2008, and has received
state-level approval in 47 US states (California, Washington, and New
York are the exceptions at this time).  However, other important
constraints must be considered when assessing the feasibility of
iodomethane as a methyl bromide alternative. These include: (1) the cost
of iodomethane formulations is higher than methyl bromide, and will
probably remain so for the next several years, (2) growers and
researchers will need time to evaluate iodomethane use in the various
local production conditions covered by this nominations, and (3) growers
and applicators will need to make some equipment modifications to adapt
to the lower flow rates typical with less expensive iodomethane
application rates and to avoid the corrosion of some metals that can
occur with iodomethane (Sumner 2005, Noling et al. 2006).  The economic
impact of using iodomethane is further described in item 7 in this
document (below). A consideration of these aspects has led the USG to
conclude that while iodomethane appears to be technically feasible to
manage key tomato pests in all parts of the US where it has been
registered, time will be needed for growers and extension service
experts to adapt its use successfully. Therefore, the amount of methyl
bromide nominated for tomato has been adjusted downward while also
considering the time needed to transition to iodomethane. 

Performance data presented by B. Olsen at the November 2008 MBAO
conference reported tomato yield data from 12 field sites where the
average increase in yields from iodomethane treated plots over methyl
bromide treated plots was 11 percent.  Ten of the 12 study sites were in
the southeast.  It must be noted that there was no statistical analysis
present with this data and as such there is no confirmation on whether
this reported average increase in yields is significant.  Despite these
results, representatives of the southeast tomato growers’ consortia
are currently cautious about recommending iodomethane as a methyl
bromide replacement (Toth, 2008).

Research conducted in Georgia demonstrated that, in small plots, purple
nutsedge control for methyl bromide, iodomethane, and DMDS were not
significantly different under LDPE, metalized, or VIF mulch (table 4). 
Yields of pepper and cucumber plants fumigated with iodomethane under
VIF were not different from yields for untreated plots (Culpepper et al,
2007).  The reader should keep in mind here that DMDS is not registered
for use in the USA. 

In a study by Chellemi (2008), pepper plant height and yield was reduced
due to crop injury. However, the injury was later correlated with high
levels of soil potassium and probably not a direct result of the
fumigation.  In this same study, three of the four trials reported weed
and nematode control for the three fumigant combination and methyl
bromide at less than 0.01 weeds / foot of row and nematode concentration
at less than 1.0 / 100 cc of soil. 

Table 4.  Purple nutsedge plants in small plot pepper crop (20 sq ft)

*Fumigant(s)	Mulch

	LDPE	Metalized	VIF

Methyl Bromide	0.5 a	0.0 a	0.3 a

Iodomethane	0.8 a	0.3 a	0.8 a

DMDS	2.5 a	0.5 a	0.0 a

Untreated	84 d	76 d	54 c

*All fumigation treatments contain chloropicrin.Table taken from
Culpepper et al (2007)

Hausbeck and Cortright (2007) measured cucurbit plant vigor to determine
fumigant/mulch interactions using either LPDE or VIF plastic mulch for
the control of Fusarium oxysporum.  Of the fumigants used in the study,
the methyl bromide and iodomethane treatments resulted in cantaloupe
plants with the highest vigor (Table 5).  In general, treatments under
LPDE had higher plant vigor when compared with plants grown under VIF. 
It is noteworthy that in this study VIF tarps were prone to wind
removal, which reduced their reliability under some growing conditions. 

Table 5:  Evaluation of Fumigants and Plastic Mulches for Managing
Fusarium in Cucurbit Crops 2007  

Treatment (time after treatment to planting)	Rate of formulated product
Vigor* 

Untreated control under LDPE (5 days)

1.0-1.3	a**

Iodomethane+chloropicrin 50:50 under LDPE (10 days)	196 kg/ha	1.0	a

Iodomethane+chloropicrin 50:50 under VIF (10 days)	196 kg/ha	3.0	c

Methyl bromide+chloropicrin 67:33 under LDPE (10 days)	 280 kg/ha	1.0	a

Methyl bromide+chloropicrin 67:33 under VIF (10 days)	 280 kg/ha	2.7	bc

1,3 D + chloropicrin 65:35 under LDPE (21 days)	187 liters/ha	2.3	bc

1,3 D + chloropicrin 65:35 under VIF (21 days)	187 liters/ha	4.7	d

Chloropicrin under LDPE (14 days)	187 liters/ha	2.7	c

Chloropicrin under VIF (14 days)	187 liters/ha	3.3	cd

*Vigor rating of plant health; 1=healthy plants with no stunting, 5=
moderated plant stunting with variable stand, 10=complete plant death.

**Column means with a letter in common are not significantly different
(Fisher LSD Method; P=0.05).

From Hausbeck and Cortright 2007.

In addition to the limitations of VIF discussed above, the USG notes
that the plant vigor in 1,3 D treatments in these new trials is lower
than that seen in methyl bromide treatments. This is similar to what was
seen in previous years’ tests (Hausbeck and Cortright 2004; see also
discussion in the cucurbit nominations). 

As far as the USG has been able to determine, no other studies have been
conducted since 2007 to evaluate the technical and commercial
feasibility of fumigant alternatives to methyl bromide for controlling
F. oxysporum subtypes under production conditions relevant to the
Maryland/Delaware regions.

7.  ECONOMIC FEASIBILITY OF ALTERNATIVES 

The following economic analysis is organized by methyl bromide critical
use application regions.  

Readers should note that in this study net revenue is calculated as
gross revenue minus operating costs.  This is a good measure as to the
direct losses of income that may be suffered by the users.  It should be
noted that net revenue does not represent net income to the users. Net
income, which indicates profitability of an operation of an enterprise,
is gross revenue minus the sum of operating and fixed costs.  Net income
should be smaller than the net revenue measured in this study.  Fixed
costs were not included because they are often difficult to measure and
verify.

Summary of Economic Feasibility

The economic analysis of the tomato application compared data on yields,
crop prices, revenues and costs using methyl bromide and using
alternative pest control regimens in order to estimate the loss of
methyl bromide availability.  The alternatives identified as technically
feasible - in cases of low pest infestation – for different regions by
the U.S. are: (a) iodomethane and (b) 1,3-dichloropropene and
chloropicrin followed by chloropicrin, followed by
metam-sodium/potassium (otherwise referred to as the Georgia 3-Way).  

The economic factors that drive the feasibility analysis for fresh
market tomato uses of methyl bromide alternatives are: (1) yield losses,
referring to reductions in the quantity produced, (2) increased
production costs, which may be due to the higher-cost of using an
alternative, additional pest control requirements, and/or resulting
shifts in other production or harvesting practices (3) quality losses,
which generally affect the quantity and price received for the goods,
and (4) missed market windows due to plant back time restrictions, which
also affect the quantity and price received for the goods.

The economic reviewer then analyzed crop budgets for pre-plant sectors
to determine the likely economic impact if methyl bromide were
unavailable.  Various measures were used to quantify the impacts,
including the following: 

(1) Loss per Hectare.  For crops, this measure is closely tied to
income.  It is relatively easy to measure, but may be difficult to
interpret in isolation.

(2) Loss per Kilogram of Methyl Bromide.  This measure indicates the
value of methyl bromide to crop production.

(3) Loss as a Percentage of Gross Revenue.  This measure has the
advantage that gross revenues are usually easy to measure, at least over
some unit, e.g., a hectare of land or a storage operation.  However,
high value commodities or crops may provide high revenues but may also
entail high costs.  Losses of even a small percentage of gross revenues
could have important impacts on the profitability of the activity.

(4) Loss as a Percentage of Net Operating Revenue.  We define net cash
revenues as gross revenues minus operating costs.  This is a very good
indicator as to the direct losses of income that may be suffered by the
owners or operators of an enterprise.  However, operating costs can
often be difficult to measure and verify.

(5) Operating Profit Margin.  We define operating profit margin to be
net operating revenue divided by gross revenue per hectare.  This
measure would provide the best indication of the total impact of the
loss of methyl bromide to an enterprise.  Again, operating costs may be
difficult to measure and fixed costs even more difficult, therefore
fixed costs were not included in the analysis.

These measures represent different ways to assess the economic
feasibility of methyl bromide alternatives for methyl bromide users, who
are tomato producers in this case.  Because producers (suppliers)
represent an integral part of any definition of a market, we interpret
the threshold of significant market disruption to be met if there is a
significant impact on commodity suppliers using methyl bromide.  The
economic measures provide the basis for making that determination.

Eastern US

We conclude that, at present, iodomethane would be the economically
feasible alternative to methyl bromide for use in Eastern US tomato
production in areas exhibiting karst topographical features.  However,
see the technical discussion above for a description of reasons why time
will be needed for growers to transition to routine, commercially
feasible iodomethane use. In areas where karst features are not present
it appears that tomato growers can use a combination of three fumigants
applied sequentially (1,3-D, chloropicrin, and metam-sodium/potassium)
and achieve yields that are comparable to those produced by using methyl
bromide for spring crops only.  The USG factored this new technique into
their request by adding a four year transition (assuming that all
non-karst spring fumigations for tomatoes in the Southeast will
transition away from methyl bromide over four years) for spring
fumigations.  

Table 6. Virginia: Economic Impacts of Methyl Bromide Alternatives 

Virginia TOmato Growers	Methyl Bromide	Iodomethane	Ga – 3 Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (cwt)	920	920	920

* Price per Unit (us$)	$           33	$               33	$              
33

= Gross Revenue per Hectare (us$)	$     29,902	$         29,902	$       
 29,902

- Operating Costs per Hectare (us$)*	$     26,907	$         28,354	$    
    27,687

= Net Revenue per Hectare (us$)	$      2,995	$           1,548	$        
  2,215

1. Loss per Hectare (us$)	$           -	$           1,447	$            
780

2. Loss per Kilogram of Methyl Bromide (us$)	$           -	$            
  17	$                 9

3. Loss as a Percentage of Gross Revenue (%)	0%	5%	3%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	48%	26%

5. Operating Profit Margin (%)	10%	5%	7%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

Table 7.  Maryland: Economic Impacts of Methyl Bromide Alternatives

Maryland TOmato Growers	Methyl Bromide	Iodomethane	Ga – 3 Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (BOX 25lbs)	 4,953 	4,953 	4,953 

* Price per Unit (us$)	 $                     7 	 $                    
7 	 $                     7 

= Gross Revenue per Hectare (us$)	 $             35,287 	 $            
35,287 	 $             35,287 

- Operating Costs per Hectare (us$)*	 $             30,269 	 $          
  31,969 	 $             31,888 

= Net Revenue per Hectare (us$)	 $               5,018 	 $              
3,319 	 $               3,399 

1. Loss per Hectare (us$)	 $                    -   	 $              
1,699 	 $               1,619 

2. Loss per Kilogram of Methyl Bromide (us$)	 $                    -   	
$                   23 	 $                   22 

3. Loss as a Percentage of Gross Revenue (%)	0%	5%	5%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	34%	32%

5. Operating Profit Margin (%)	14%	9%	10%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

  Impacts of Methyl Bromide Alternatives" \f F \l "1"  

Table 8.  Southeastern US: Economic Impacts of Methyl Bromide
Alternatives

Southeastern Tomato Consortium **	Methyl Bromide	Iodomethane	Ga – 3
Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (BOX 25lbs) 	4,942	4,942	4,942

* Price per Unit (us$)	$                      7	$                      7
$                      7

= Gross Revenue per Hectare (us$)	$             35,830	$            
35,830	$             35,830

- Operating Costs per Hectare (us$)*	$             33,913	$            
35,428	$             34,762

= Net Revenue per Hectare (us$)	$               1,918	$                 
402	$               1,069

1. Loss per Hectare (us$)	$                    -	$               1,516	$
                 849

2. Loss per Kilogram of Methyl Bromide (us$)	$                    -	$   
                20	$                    11

3. Loss as a Percentage of Gross Revenue (%)	0%	4%	2%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	79%	44%

5. Operating Profit Margin (%)	5%	1%	3%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

** Includes: South-Eastern United States (Alabama, Arkansas, Kentucky,
Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee).

Table 9. Georgia: Economic Impacts of Methyl Bromide Alternatives

Georgia Fruit & Vegetable Growers Association 	Methyl Bromide
Iodomethane	Ga – 3 Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (BOX 25lbs) 	6,830	6,830	6,830

* Price per Unit (us$)	$                9	$                9	$          
     9

= Gross Revenue per Hectare (us$)	$        58,342	$        58,342	$     
  58,342

- Operating Costs per Hectare (us$)*	$        56,522	$        57,763	$  
     58,178

= Net Revenue per Hectare (us$)	$          1,820	$             578	$    
        164

1. Loss per Hectare (us$)	$               -	$          1,241	$         
1,656

2. Loss per Kilogram of Methyl Bromide (us$)	$               -	$        
       8	$              11

3. Loss as a Percentage of Gross Revenue (%)	0%	2%	3%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	68%	91%

5. Operating Profit Margin (%)	3%	1%	0%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

Florida

We conclude that, at present, iodomethane would be the economically
feasible alternative to methyl bromide for use in Florida tomato
production in areas of karst topography.  Where karst features are not
present the USG assumed that the sequential application of the three
chemicals (discussed above) would have results that are similar to the
performance of methyl bromide for spring plantings.  Consequently, as
described above, the transition was adjusted to account for the new
combination

Table 10. Florida North: Economic Impacts of Methyl Bromide Alternatives

Florida Fruit & Vegetable Association – north florida	Methyl Bromide
Iodomethane	GA – 3 Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (BOX 25lbs) 	3,548	3,548	3,548

* Price per Unit (us$)	$            10	$           10	$                
10

= Gross Revenue per Hectare (us$)	$          34,874	$          34,874	$ 
        34,874

- Operating Costs per Hectare (us$)*	$          30,804	$          32,515
$          31,848

= Net Revenue per Hectare (us$)	$            4,070	$            2,359	$ 
          3,026

1. Loss per Hectare (us$)	$                   -	$            1,711	$    
       1,044

2. Loss per Kilogram of Methyl Bromide (us$)	$                -	$       
        20	$                 12

3. Loss as a Percentage of Gross Revenue (%)	0%	5%	3%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	42%	26%

5. Operating Profit Margin (%)	12%	7%	9%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

Table 11. Florida ruskin palmetto: Economic Impacts of Methyl Bromide
Alternatives

Florida Fruit & Vegetable Association – Ruskin Palmetto	Methyl Bromide
Iodomethane	GA – 3 Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (BOX 25lbs) 	3,548	3,548	3,548

* Price per Unit (us$)	$               10	$                10	$         
      10

= Gross Revenue per Hectare (us$)	$           34,874	$           34,874
$          34,874

- Operating Costs per Hectare (us$)*	$         32,722	$         33,452	$
         32,785

= Net Revenue per Hectare (us$)	$           2,152	$           1,422	$   
        2,089

1. Loss per Hectare (us$)	$                 -	$               730	$     
          63

2. Loss per Kilogram of Methyl Bromide (us$)	$                -	$       
            7	$                    1

3. Loss as a Percentage of Gross Revenue (%)	0%	2%	0%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	34%	3%

5. Operating Profit Margin (%)	6%	4%	6%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

Table 12. Florida palm Beach: Economic Impacts of Methyl Bromide
Alternatives

Florida Fruit & Vegetable Association – palm beach	Methyl Bromide
Iodomethane	GA – 3 Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (BOX 25lbs) 	4,666	4,666	4,666

* Price per Unit (us$)	$                11	$                11	$        
      11

= Gross Revenue per Hectare (us$)	$         50,152	$         50,152	$   
     50,152

- Operating Costs per Hectare (us$)*	$          48,230	$         49,197
$       48,530

= Net Revenue per Hectare (us$)	$            1,922	$               955	$
           1,622

1. Loss per Hectare (us$)	$                  -	$         967.11	$       
 300.23

2. Loss per Kilogram of Methyl Bromide (us$)	$                  -	$     
      8.63	$               2.68

3. Loss as a Percentage of Gross Revenue (%)	0%	2%	1%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	50%	16%

5. Operating Profit Margin (%)	4%	2%	3%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

Table 13. Florida Southwest: Economic Impacts of Methyl Bromide
Alternatives

Florida Fruit & Vegetable Association – Southwest	Methyl Bromide
Iodomethane	GA – 3 Way Method

Production  Loss (%) 	0%	0%	0%

   Production per Hectare (BOX 25lbs) 	4,666	4,666	4,666

* Price per Unit (us$)	$                11	$                11	$        
      11

= Gross Revenue per Hectare (us$)	$         50,152	$         50,152	$   
     50,152

- Operating Costs per Hectare (us$)*	$          48,230	$         49,197
$       48,530

= Net Revenue per Hectare (us$)	$            1,922	$               955	$
           1,622

1. Loss per Hectare (us$)	$                  -	$         967.11	$       
 300.23

2. Loss per Kilogram of Methyl Bromide (us$)	$                  -	$     
      8.63	$               2.68

3. Loss as a Percentage of Gross Revenue (%)	0%	2%	1%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	50%	16%

5. Operating Profit Margin (%)	4%	2%	3%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

Table 14. Florida Dade: Economic Impacts of Methyl Bromide Alternatives

Florida Fruit & Vegetable Association – Dade	Methyl Bromide
Iodomethane	Metam Plus Chloropicrin

Production  Loss (%) 	0%	0%	15%

   Production per Hectare (BOX 25lbs) 	3,548	3,548	3,016

* Price per Unit (us$)	$               10	$               10	$          
    10

= Gross Revenue per Hectare (us$)	$         34,874	$         34,874	$   
     29,643

- Operating Costs per Hectare (us$)*	$         34,172	$         34,665	$
        34,202

= Net Revenue per Hectare (us$)	$              702	$              209	$ 
        (4,559)

1. Loss per Hectare (us$)	$                -	$              493	$       
   5,261

2. Loss per Kilogram of Methyl Bromide (us$)	$                -	$       
         3	$               35

3. Loss as a Percentage of Gross Revenue (%)	0%	1%	15%

4. Loss as a Percentage of Net Operating Revenue (%)	0%	70%	750%

5. Operating Profit Margin (%)	2%	1%	-15%

*Note that the measures in the tables below must be interpreted
carefully.  Operating costs do not include fixed costs and net revenue
equals gross revenue minus operating costs.

8.  RESULTANT CHANGES TO REQUESTED EXEMPTION QUANTITIES

The USG has applied an aggressive transition rate, which is reflected in
the nomination amount and detailed in Table 15. 

Table 15. Nomination Amount.

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APPENDIX A

Reproduced from the 2011 Critical Use Exemption Application submitted by
the Georgia Fruit & Vegetable Association

Summarized and Compiled by

A. Stanley Culpepper, University of Georgia, Tifton

1. Methyl Bromide Data Generated in Georgia

Continued efforts are underway in Georgia to implement effective and
economical alternatives to methyl bromide.  During the spring of 2008,
at least 40% of the land fumigated for vegetable crops in the spring was
treated with the 3-WAY which includes a systems approach of
1,3-dichloropropene, chloropicrin, and metam sodium.   It is likely that
30 to 40% of Georgia’s total crop will be treated with this
alternative during 2008.  Dimethyl disulfide (DMDS) plus chloropicrin
also has proven to be effective in managing many pests and has the
potential to be adopted once the price structure is known.

Although both the 3-WAY and DMDS appear promising, neither fumigant
system will stand alone in managing pests.  A herbicide program must be
developed to compliment these fumigant systems.  The 3-WAY does not
provide adequate nutsedge control with summer/fall fumigations and the
DMDS system does not adequately control grasses or Amaranthus species. 
Until program using fumigants and herbicides can be developed, having
methyl bromide available is essential.

The two aforementioned fumigant systems also pose significant challenges
when determining the time interval needed between fumigating and
planting.  Initial research results suggest the plant back interval for
the 3-WAY will be at least 3 times longer than that noted with methyl
bromide (Item 3 below).  For DMDS, the research is currently in progress
with results available by September of 2008.  Early indications suggest
that the plant back for DMDS plus chloropicrin applied under a high
barrier mulch will be similar to that noted with the 3-WAY system.

Future research will focus on developing and implementing a herbicide
program to compliment both the 3-WAY and DMDS fumigant systems as well
as determining the amount of time that must pass between fumigating with
these alternatives and planting.



2. A herbicide system must be developed for the UGA 3-WAY during
summer/fall fumigation

Introduction

Georgia growers are adopting an effective alternative to methyl bromide
during the spring fumigation cycle.   However, research is needed to
determine if this alternative is effective during the summer/fall
fumigation period.  Fumigants may be less effective in the summer/fall
when compared to the spring because of warmer soils causing increased
gas dissipation.

Materials and Methods

An experiment was conducted in TyTy Georgia at the University of
Georiga’s Ponder Farm.  The trial was conducted on a Tifton sandy loam
soil with 92% sand, 2% silt, and 6% clay with a pH of 6.4 and 1% organic
matter.  Land was prepared by disking the trial area multiple times and
then roto-tilling a 6 foot wide bed by 60 feet in length for each plot
immediately prior to fumigating and installing mulch.

The study was fumigated during the fall of 2007 on July 17.  Soil
temperature was 84 degrees at 8 inches. The experiment consisted of 4
treatments (Table 1) that were replicated three times.  The UGA 3-WAY
consisted of a system of Telone II (12 gal/A) followed by chloropicrin
(150 lb/A) followed by Vapam (75 gal/A).  The Telone II was placed 12
inches deep using a Yetter system having 3 injection knives on a 32 inch
bed top, methyl bromide and chloropicrin were injected 8 inches deep
with a super bedder using 3 injection knives on a 32 inch bed top, and
Vapam was injected 4 inches deep and 4 inches apart using disc blades in
the final bed just prior to covering with mulch.  Methyl bromide was
applied at 240 lb/A.  All fumigant rates are provided as broadcast rates
but were actually only applied in the bed.  Mulch used included low
density polyethylene or Blockade high barrier mulch.

Visual crop injury, visual weed control, and the number of nutsedge
shoots penetrating the mulch were measured throughout the season.  No
visual injury was noted.  Percent control and nutsedge penetrating the
crop provided similar results thus only percent control is reported. 
Jumbo pepper was harvested four times, once a week for four weeks.

Table 1.  Comparing methyl bromide and the 3-Way for the control of
nutsedge and tomato yield.

Fumigant	Mulch

Late-season purple nutsdege control

Harvests 1-2

(Jumbo pepper)

Harvests 1-4

(Jumbo pepper)

	%

# fruit/plot	lbs/plot

# fruit/plot	lbs/plot

3-WAY	LDPE

48 d

34 c	16 c

44 c	19 c

3-WAY	Blockade

60 c

50 b	24 b

71b	32 b

MB	Blockade

85 b

106 a	48 a

136 a	61 a

None	LDPE

0 f

13 d	6 d

19 d	8 d

Results and Discussion

Poor nutsedge control was noted with the UGA 3-WAY system when applied
under LDPE or Blockade mulch.  Fumigant gas emissions occurred so
rapidly that nutsedge tubers were likely not under a high enough
concentration of gases long enough to provide adequate control as is the
case in the spring.  Methyl bromide was far more effective with nearly
twice the level of control noted with the 3-WAY even under blockade
mulch. As expected, yields followed trends in nutsedge control since it
was the only pest impacting the crop.  Yields from plots treated with
methyl bromide were more than double that of the UGA 3-WAY applied under
LDPE mulch.  Although yield was improved with the 3-WAY applied under
blockade mulch compared to LDPE mulch, this higher yield was only
approximately half of that noted with the methyl bromide system.

Conclusions

The UGA 3-WAY is not a stand alone replacement to methyl bromide during
a summer/fall fumigation in Georgia.  Either an effective and economical
herbicide system must be developed to compliment this alternative
program or another more effective fumigant system must be developed.



3.  Determining plant back intervals when fumigating with the UGA 3-WAY

Introduction

The UGA 3-WAY system is replacing methyl bromide rapidly in Georgia. 
Although this system has been effective during the spring, the program
has the potential to delay planting after fumigation.  Research is
needed to determine the time interval needed between fumigation and
planting vegetable crops.

   

Materials and Methods

An experiment was conducted in Tifton Georgia at the University of
Georgia’s Tifton Vegetable Park.  The trial was conducted on a Tifton
sandy loam soil with 94% sand, 2% silt, and 4% clay with a pH of 6.2 and
1% organic matter.  Land was prepared by disking the trial area multiple
times and then roto-tilling a 6 foot wide bed by 20 feet in length for
each plot immediately prior to fumigating and installing mulch.

The study was fumigated during the spring of 2007 on February 27.  Soil
temperature was 59 degrees at 8 inches. The experiment consisted of 12
treatments (Table 1) that were replicated three times.  The UGA 3-WAY
consisted of a system of Telone II (12 gal/A) followed by chloropicrin
(150 lb/A) followed by Vapam (75 gal/A).  The Telone II was placed 12
inches deep using a Yetter system having 3 injection knives on a 32 inch
bed top, chloropicrin was placed 8 inches deep with a super bedder using
3 injection knives on a 32 inch bed top, and Vapam was injected 4 inches
deep and 4 inches apart using disc blades in the final bed just prior to
covering with mulch.  Methyl bromide (MB) was included for comparison
and was applied at 350 lb/A.  All fumigant rates are provided as
broadcast rates but were actually only applied in the bed.  Mulch used
included low density polyethylene or Blockade high barrier.  Crops were
planted 7 or 14 days after fumigating while poking the plant hole
through the mulch.  Crops were also planted on days 8 or 15 which was 1
day after poking the hole on days 7 and 14 in an attempt to air the bed.
 Crops planted included tomato, pepper and cucumber.

Visual crop injury and crop heights (7 tomato, 20 pepper, 7 cucumber
plants per plot) were measured throughout the season.  Tomato, pepper
and cucumber were harvested five, four, and nine times, respectively.

Table 1.  Plant heights in response to time of planting after
fumigating.

Fumigant	Mulch	Planting days after fumigation	Gas in bed at planting

Heights (cm)

(3 wk after planting)

	ppm

Tomato	Pepper	Cucumber

MB	LDPE	7	29

38 a	21 ab	30 ab

3-WAY	LDPE	7	77

32 cd	17 d	24 d

3-WAY	Blockade	7	368

14 f	4 f	12 f

	MB	LDPE	7 + 1	2

37 ab	20 abc	32 a

3-WAY	LDPE	7 + 1	13

33 cd	18 cd	26 cd

3-WAY	Blockade	7 + 1	31

27 e	11 e	20 e

	MB	LDPE	14	2

37 ab	22 a	32 a

3-WAY	LDPE	14	4

34 bc	20 abc	31 ab

3-WAY	Blockade	14	38

30 de	18 cd	28 bc

	MB	LDPE	14 + 1	0

35 abc	22 a	31 ab

3-WAY	LDPE	14 + 1	3

33 cd	21 ab	31 ab

3-WAY	Blockade	14 + 1	27

30 de	19 bcd	28 bc

Table 2 .  Plant yields in response to time of planting after
fumigating.

Fumigant	Mulch	Planting days after fumigation	Gas in bed at planting

Yield

(#/plot, highest value fruit only; no difference noted with total fruit)

	ppm

Tomato	Pepper	Cucumber

MB	LDPE	7	29

127 a	227 a	45 de

3-WAY	LDPE	7	77

127 a	195 ab	60 a

3-WAY	Blockade	7	368

55 c	114 c	40 e

	MB	LDPE	7 + 1	2

117 a	212 a	47 cde

3-WAY	LDPE	7 + 1	13

132 a	193 ab	57 ab

3-WAY	Blockade	7 + 1	31

99 b	159 bc	47 cde

	MB	LDPE	14	2

142 a	220 a	49 bcde

3-WAY	LDPE	14	4

132 a	190 ab	55 abc

3-WAY	Blockade	14	38

114 a	188 ab	49 bcde

	MB	LDPE	14 + 1	0

133 a	204 ab	49 bcde

3-WAY	LDPE	14 + 1	3

127 a	202 ab	50  bcd

3-WAY	Blockade	14 + 1	27

119 a	190 ab	42 de

Results and Discussion

No visual stunting from methyl bromide was noted with any treatment at 3
wk after transplanting (data not shown).  When planting 7 days after
fumigating with the 3-WAY under LDPE mulch, crop heights were reduced at
least 20% when compared to the methyl bromide control (Table 1).  Growth
reduction from the 3-WAY under Blockade mulch was far greater and ranged
from 60 to 80%.  Airing the bed for one day did not alleviate stunting. 
Waiting 14 days after fumigating before planting did alleviate fumigant
stunting when crops were planted on the LDPE mulch.  However,
significant reduction in plant growth was still noted when planting into
the blockade mulch.  Airing the bed for 1 d did not eliminate crop
stunting when planting on the blockade mulch.  

Tomato and cucumber were resilient in overcoming early season reduction
in plant growth with only minor trends for reduced yields when planted
on LDPE mulch, when compared to the methyl bromide control.  Yield
reductions were noted with tomato when planted on Blockade mulch at 7 or
8 d after fumigating.  Pepper tended to be more sensitive than other
crops with lower yields or a trend for lower yields when planting on
both mulches at each planting date except for the 15 day plant date on
LDPE mulch. 

Results and Discussion

This research is the first step in determining the time interval needed
between fumigating and planting.  The most effective tactic will likely
not be days after fumigating but ppm of fumigant in the bed at planting
as the environment plays such a role in the dissipation of gas from the
soil.  This research suggests that for the UGA 3-WAY, less than 5 ppm
should be in the bed at time of planting.

 It should be noted that the USG does not request methyl bromide for use
in areas of low to moderate pest pressure.  Only cases where key pests
are present at moderate to high levels require methyl bromide for pest
pressure.

USA CUN13 Soil Tomatoes Open Field		Page   PAGE  1  of   NUMPAGES  28 

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