Document ID: EPA-HQ-OAR-2006-1016-0197
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-12-28T05:00Z

US Response to MBTOC

Appendix A:  Methyl Bromide National Management Strategy for Field-grown
Ornamentals in Florida and California

SOCIETY OF AMERICAN FLORISTS. 

CALIFORNIA CUT FLOWER COMMISSION & FLORIDA FLORICULTURE GROWERS

METHYL BROMIDE NATIONAL MANAGEMENT STRATEGY 

FIELD GROWN ORNAMENTALS IN FLORIDA AND CALIFORNIA 

BULBS, CUT FLOWERS, CUT FOLIAGE AND PROPAGATIVE PLANT MATERIAL 

SEPTEMBER 2005 



Methyl Bromide National Management Strategy 

FIELD GROWN ORNAMENTALS IN FLORIDA AND CALIFORNIA 

BULBS, CUT FLOWERS, CUT FOLIAGE AND PROPAGATIVE PLANT MATERIAL 

SUMMARY 

Florida and California field grown ornamentals include bulbs, cut
flowers, cut foliage and plant stock used to produce propagative
material. It is a labor intensive industry characterized by high costs
of production (land, labor, energy and other inputs), urban
encroachment, intense cropping systems, rapidly changing market demands
and high risk. It is plagued by a pest spectrum in the soil that
includes nematodes, soil-borne pathogens and weeds that must be
controlled without delaying production or harming the crops. 

Weeds, especially nutsedge, tend to be particularly difficult to control
and are a limiting factor in replacing methyl bromide. Once weeds
emerge, contact herbicides cannot be used without damaging the crop and
hand weeding is cost prohibitive on a large scale. Soil persistent pre-
emergent herbicides cannot be used without risk to the current crop or
subsequent plantings. Comprehensive phytotoxicity studies can not be
conducted due to the large number of crops, numerous varieties within
crops, and the regular introduction of new varieties through aggressive
breeding programs. 

Methyl bromide has been the industry standard for soil fumigants because
it works well across the entire pest spectrum, it works consistently and
is environmentally safe on all soil types, is applied safely by expert
applicators, is not a threat to human health and safety as currently
applied, and leaves no residue that can interfere with the intense
multi-cropping and breeding practices of the field grown ornamentals
industry. The alternatives currently identified do not meet these
criteria, even if they were available to and economical for ornamentals
growers. Methyl bromide use has declined and emissions reduced through
formulation changes, tarping after application and use of alternative
control measures. Although methyl bromide use has been reduced, it
cannot be eliminated with the existing alternatives. 

Chemical alternatives listed in the U.S. Matrix (  HYPERLINK
"http://www.ewa.qov/ozone/mbr/cueea.html" 
www.ewa.qov/ozone/mbr/cueea.html ) include 1,3-D, chloropicrin, metam
sodium and their combinations. None of these alternatives provide
sufficient control over the entire pest spectrum when used-either alone
or in combination. All have use restrictions imposed by local, state and
federal agencies due to environmental risks and potential human exposure
via offsite gassing. These chemicals are also undergoing re-registration
review by U.S. EPA; registrations may be lost or additional restrictions
may be imposed, further limiting their usefulness to growers.
Non-chemical alternatives do not provide the level or consistency of
control, are too expensive, or are not compatible with current
production practices. As discussed previously, weed control is also a
limiting factor. 

Another major factor affecting the search for methyl bromide
alternatives is the need for flexibility in the types of crops produced.
Growers must be able to respond to rapidly changing market demands.
Growers must respond to peak demands, such as holidays, as well as to
changing consumer preferences. They can not afford planting or harvest
delays, or production uncertainties due to unpredictable pest control. 

Research efforts are difficult because this is a relatively small
industry, commercial acreage available for testing is limited, and the
crops and cropping systems are complicated, requiring large testing
programs to be representative of the industry. Regardless, the field
grown ornamental industry has supported public and private research and
has performed in-house testing. Research has included registered
pesticides, pesticides in various stages of development (including
biologicals), and non-pesticidal treatments. 

The research strategy of the field grown cut flower industry is to
continue to investigate ways to use existing chemicals and non-chemical
methods, as first priority. This strategy includes looking at different
application techniques, product combinations and multi-year programs
using existing chemicals; investigating various barrier films to use for
emissions reduction, solarization and optimizing pesticide efficacy;
and, testing biological control agents and other non-chemical
alternatives in integrated programs when feasible. However, the industry
has already devoted extensive, and expensive, effort and resources to
these lines of investigation and the existing alternatives do not,
singly or in combination, meet the industry's needs. 

The next level, of investigation includes testing registered products
that are seeking label expansion into field grown ornamentals or
non-registered products that fit into and are being developed for this
market. The best example of the latter is methyl iodide. However, these
alternatives remain unproven, unregistered, and cannot be viewed at
present as economically or practically feasible. 

Field grown ornamental growers will continue to look for the most
efficacious and most economical means to produce their crops and are
committed to continuing to support efforts to find methyl bromide
alternatives. However, continued reduction in methyl bromide use can not
progress much further or much faster, if at all, until viable
alternatives are available. Even the existing chemical alternatives pose
greater risks than methyl bromide -risks to crop failure, environmental
risks and human health risks. We are currently held to only 30 percent
of baseline use. We cannot further reduce our use of methyl bromide
until feasible alternatives become available and usable. 

CHARACTERISTICS OF THE FIELD GROWN ORNAMENTAL INDU.S.TRY 

The Florida and California field grown ornamental industry is very
diverse, producing bulbs, cut flowers, cut foliage and propagative plant
material. Although each sector is unique, they share common
characteristics with regard to seeking and implementing methyl bromide
alternatives: 

Land. Land available for production is expensive to purchase or lease,
which means only a high value crop like ornamentals is economical to
grow. Areas like the temperate California coast and greater part of
Florida lend themselves to mild, relatively frost free climatic
conditions with lighter soils, which are important for successful
outdoor ornamental production. These are also areas ideally suited for
the establishment of residential communities, which have consumed
available production acreage and have imposed further use restrictions
on some pesticides. Small acreage, urban encroachment and nearby
residential areas, and sensitive soil profiles are common factors
effecting use of methyl bromide alternatives. 

2. Cropping intensity and diversity. Crops are planted and harvested as
continuously as possible to maximize production and new varieties are
introduced regularly through aggressive breeding programs. A single
grower can produce as many as 50 different species and there can be as
many as 350 varieties within a species, each with different
susceptibilities to both pests and chemical treatments. There is not
enough time to research the susceptibility of each new variety to
potential pests or possible phytotoxic effects from chemical treatments.

3. 	Tarqet pests. Target pests include soil-borne and potentially
systemic pathogens (Verticilfium spp., Fusarium spp., Erwinia spp.,
Agrobacterium spp., Cylindrocladium spp., etc.), nematodes (Meloidogyne
spp., Pratylenchus spp., and some of which are regulated pests) and
weeds (general, but especially nutsedge species). The importance of
potential losses from pathogens and nematodes must not be minimized,
especially where pest free certification is required, but weed control
is often the limiting factor in finding a methyl bromide alternative for
ornamental production. 

All weed species pose problems, but nutsedge species are especially
difficult to control and populations increase rapidly if not adequately
managed. Herbicides with residual activity in the soil can not be used
because of possible phytotoxic effects on subsequent crop plantings and
the ever changing crop varieties. Use of contact herbicides within an
actively growing crop is used minimally due to the damage it can cause
to the existing crop. Hand weeding is very expensive in an already labor
intensive industry and is a regulated activity in California. The
emphasis is on weed control because there are few control options
available due to crop diversity, varietal differences, susceptibility of
crops to herbicides and a short production cycle. Weed control must be
achieved prior to planting without leaving residual activity in the soil
that can adversely affect current and subsequent crops. Methyl bromide
is currently the only registered product that addresses these issues
safely and consistently. 

4. 	Crop sensitivity. Susceptibility to target pests is generally
unknown at the time a new variety is introduced, as is its
susceptibility to phytotoxicity from pesticide applications to the soil.
Since growers can not risk crop damage, the safest approach is to reduce
the pest spectrum without leaving chemical residues in the soil at
planting. 

5.	Production flexibility. The ornamental/floriculture market requires
that products be available 52 weeks of the year. To meet this demand, a
sequential and continuous cropping system is typical among many in the
ornamental industry. U.S. growers must respond to peak market demands
such as holidays without the threat of having planting delays or crop
failures resulting from persistent soil applied pesticides. New flower
varieties are introduced each year as a result of quickly changing
consumer preference and market demands. Flexibility to respond to market
demands and market changes is a critical component for success. 

Liability. Ornamental crops have been a traditional market for chemical
manufacturers to seek initial product registrations. Expensive residue
trials and toxicity studies required for food tolerances are not
required for non-crop use, so ornamental labels are often sought in
order to generate income while pursuing food crop labels. However, a
number of companies avoid liability by not registering products for
ornamentals, especially high risk pesticides like herbicides. This
limits the number of current and future chemical alternatives available
to growers and prevents the creation of an alternatives program. 

METHYL BROMIDE ALTERNATIVES 

A discussion of methyl bromide alternatives is broken into two
categories -those that are currently available and those that are not.
Discussed are the technical (including regulatory) and economic
feasibilities of the alternatives as identified through research on
ornamental crops, extrapolation from research and practical experience
from other crops, and through common knowledge. 

AVAILABLE ALTERNATIVES (REGISTERED CHEMICALS AND OTHER) 

Methyl bromide use has decreased in field grown ornamentals as a result
of formulation changes and the adoption of alternatives. In many cases,
concentrations of methyl bromide to chloropicrin have been reduced from
98:2to 67:33, although this use rate is not always feasible. Methyl
bromide alternatives have been implemented as much as possible, reducing
use below historic levels. Reasons why alternatives can not completely
replace methyl bromide are largely because of insufficient control of
the entire pest spectrum, use restrictions imposed by regulatory
authorities, and expense. Non-chemical control options do not provide
the level of control, or the reliability of control, needed to
successfully produce floricultural crops, so are impractical at this
time. 

The following discussion is based on current availability and use
restrictions. The unknown factor is what may result from the current
cluster assessment of registered fumigants as they go through the
re-registration process by U.S. EPA. Current alternatives may not be
registered for use in the future or additional restrictions may make use
impractical. 

BARRIER FILMS 

Various types of barrier film have been investigated in an effort to
reduce methyl bromide emissions. Although this type of film does retain
methyl bromide gas, concern regarding plant- back time has surfaced
since planting operations may be delayed if the gas is retained in the
soil for an extended period of time. Additional studies need to be
conducted with this type of film to determine efficacy at lower use
rates as well as to determine appropriate plant-back times. Use of
barrier films has resulted in very good weed control, including
nutsedge, when left in place during the growing season, although not all
cut flower growers can leave the film in place due to planting density,
pole placement and pest management regulations. There is also concern
that increased soil temperatures may affect root development and
adversely affect the crop. 

Virtually impermeable films (VIF) tend to be brittle and break when
stretched across beds. Use of this type of film for broadcast treatments
has not been successful due to the difficulties in gluing the plastic
together; the glue does not harden due to the high density nature of the
film and the limited amount of free oxygen. There are a number of
different manufacturers and each has different handling and gas
retention characteristics. Application equipment is not uniform which
can result in difficulties while laying the film. It is also very
expensive, approximately $12 -$15 per bed to apply, not including
chemical. VIF can not be used in California at this time due to disposal
issues. A high density polyethylene barrier film is available in
California, but appears to be much less retentive than VIF. 

Metallic films are relatively new and have most recently been used
successfully in vegetable production, providing very good insect, weed,
disease and nematode control in addition to reducing gas emissions. The
reflective surface may keep soil temperatures cool, but air temperatures
above the film surface are hotter and may have adverse effects on the
crops. 

1,3-D is a proven nematicide but is not efficacious against diseases and
weeds as a stand alone treatment when applied at labeled rates, which is
not surprising since it registered as a nematicide only. It can only be
effective against the entire pest spectrum when combined with other
products. Efficacy can be improved if applied at higher rates, but these
rates exceed the product label. 1,3-D has not performed well when
applied through drip tape and can result in phytoxicity when injected by
chisel. 

Additionally, use of 1,3-D is limited due to setback requirements, use
restrictions in many Florida counties and township caps in California.
Demand for 1,3-D is increasing for a number of crops in California and
use may quickly exceed township caps (for example, in some areas
ornamental and strawberry growers have increased their use of 1,3-D).
1,3-D can not be applied within 100 feet of occupied structures,
limiting its use in ornamental production because of relatively small
fields, occupied structures at farm sites and urban encroachment. 

Although chloropicrin achieves good disease control at higher rates,
weed control is poor or non- existent against most of the key weed
species. Lower use rates do not provide sufficient efficacy to control
the disease complex associated with these crops. Concentrations
exceeding 2% results in phytoxicity to adjacent plantings when used in
combination with other products on propagative material production. 

Since much of field grown ornamental production is in close proximity to
residential areas, there is reluctance by both local regulators and
applicators to use chloropicrin as a stand alone treatment, especially
at high rates. Chloropicrin is classified as a toxic air contaminant in
California and California Agricultural Commissioners are extremely
concerned about using increased rates due to the liability of potential
off-site drift. Equally concerned are commercial applicators who have
stated their reluctance to use high rates of chloropicrin near populated
areas. Buffer zones are in effect, thus limiting its broad use. 

METAM SODIUM 

Metam sodium can control soil borne pathogens, nematodes and weeds but
performs erratically due to its poor fumigant properties. Performance
varies with soil type, moisture content and temperature. The level of
control from metam sodium is insufficient to prevent pest populations
from building over time. It only suppresses active forms of nematodes,
leaving eggs for future infestations, which is especially problematic
for bulb growers. 

Some growers in California and Florida are using metam sodium between
applications of methyl bromide to reduce methyl bromide use) however,
growers must eventually come back with methyl bromide to "clean up" the
field in order to prevent pest populations from building to explosive
levels. This is not an alternative that can be used alone repeatedly
without suffering significant loss. In addition, rooting problems have
been noted in chrysanthemum production in several trials with this
product. 

The odor from metam sodium makes it difficult, if not impossible, to
apply near residential or public areas. Tarping the field can help,
especially in California, but is still a problem in Florida because of
smaller fields, urban encroachment and warm, humid mornings that
prevents gas from dissipating. 

Even more problematic for Florida growers is the requirement for
applicators to be fully suited up in personal protection equipment
(PPE). Florida heat and labor restrictions would require as many as four
times the personnel normally required to provide application crews rest
periods to prevent heat related injuries. 

1,3-D + CHLOROPICRIN 

Nematode control may be achieved with this combination, but disease and
weed control is often insufficient. This treatment can not be applied
next to fields of actively growing cut flowers and propagative plants
because concentrations of chloropicrin exceeding 2% will cause
phytotoxicity in adjacent beds. Preliminary research with Telone C-17
(17% chloropicrin) on bulbs showed a 33% yield reduction. 

The same regulatory restrictions are enforced when these chemicals are
used in combination as when applied alone. 

METAM SODIUM + CHLOROPICRIN 

Metam sodium can provide good but erratic control of the pest complex of
ornamentals, but pest populations will eventually build to damaging
levels. Chloropicrin can provide good disease control at higher rates,
but there is a weakness in nematode and weed control. Nutsedge is not
adequately controlled by either chemical. 

This is a very costly alternative because these are expensive materials
that require two separate applications. Metam sodium is drenched and
rototilled into the soil, followed by the application and tarping of
chloropicrin. The treatment combination has performed better in Florida
than 1,3-D + chloropicrin, but is costly and still requires major
additional weeding inputs, especially when nutsedge species are
involved. 

The same regulatory restrictions are enforced when these chemicals are
used in combination as when applied alone. 

1-3-D+ CHLOROPICRIN + METAM SODIUM 

Some research trials have shown that 1,3-D combined with chloropicrin
followed by metam sodium one week later is almost comparable to methyl
bromide against soil borne pathogens and nematodes, but weed control is
insufficient. Research trials in Florida tomatoes have demonstrated the
need for herbicides to be used along with this combination, especially
where nutsedge occurs. It is also an expensive treatment because of
material cost and the need for two separate applications. 6' 

The same regulatory restrictions are enforced when these chemicals are
used in combination as when applied alone. 

METAM SODIUM + CROP ROTATION 

Because of high land and crop values, the only crops used for rotation
are other flower crops. There is a lack of research with crop rotation
because of the very large number of crop species and varieties,
continuous development of new varieties and various market
considerations. However, some growers are currently attempting to
implement this alternative when possible. Crop rotation is a risky
alternative at present because susceptibilities of many of the flower
crops and varieties to different nematodes and soil borne diseases are
unknown. 

In the past, growers would apply methyl bromide prior to each planting
for a total of two or three applications per year. Some growers have
learned to rotate into other crops that are less sensitive to specific
problems within specific fields and treat with metam sodium to keep
pressures down. They ultimately have to come back with methyl bromide to
"clean up" the field, otherwise pest populations will increase to
epidemic levels. 

There are unique situations in California where gladiolus growers lease
land to strawberry growers who fumigate with methyl bromide prior to
planting. Pest populations are still sufficiently reduced after
strawberry production is complete to allow a gladiolus crop to be grown
without another application of methyl bromide. However, this has not
worked well for calla lily growers because strawberry production
supports an abundant root disease complex that is extremely devastating
to calla lily bulb and cut flower production. Different crops have
different sensitivities to residual pest complexes. 

This approach is sometimes done in reverse where California growers
fumigate leased land with methyl bromide to produce cut flowers, and
then the landowner follows with a crop like lettuce, thus obtaining the
benefit of the methyl bromide treatment. 

Crop rotation strategies exist but are not widespread, nor are they
guaranteed to be available over time. A major weak link is the
assumption that methyl bromide will be available to allow for this
approach. This strategy can be implemented in unique situations in
California, but not Florida, and the use restrictions imposed on metam
sodium still apply. 

Efforts in using Dazomet have not been promising. As with metam sodium,
results are erratic. The fine granule is easily blown from the point of
application, it is difficult to apply evenly in all soil types and
applying water uniformly in order to activate the material is difficult.
The product label prohibits use within 3-4 feet of growing plants which
makes this treatment impractical in many of the floral cropping systems.
Phytotoxic effects, such as retarded root development and burning of
stems, have also been observed in chrysanthemum production. 

Steam has proven to be very efficacious against the entire pest complex
in some soils; however, the current price of fuel makes this treatment
four times the cost of methyl bromide, it is too expensive for field
applications. These costs can not be passed on to consumers. 

The actual steaming process of installing and removing pipes can be very
labor intensive and expensive in wet, heavy California soils and
sometimes the pipe can not be buried deep enough in some Florida soils.
Pipes can not be buried permanently because they interfere with cultural
operations. This is not a practical alternative on a large scale. 

BIOLOGICAL CONTROL AGENTS 

Current biocontrol agents, e.g. Trichoderma spp., have proven
ineffective in this cropping system. Biological agents are usually
limited in the species or pest group (fungi, nematodes, weeds) that they
target, and therefore they do not offer the spectrum of control, level
of control or consistency in performance to be viable options. It is
possible that biologicals can be used in certain situations after pest
populations are reduced by methyl bromide, but the research that would
be required to investigate this is too expensive and too long term to
consider, especially when chances for commercial success is remote and
the future availability of methyl bromide is at risk. There has been no
success using biological control agents in field grown ornamental trials
to date. 

SOLARIZATION 

Solarization may not penetrate the soil enough for the effects to last
long enough. The effective depth of solarization is 6-8 inches compared
to 12 inches or more with methyl bromide. A second crop would not be
possible with solarization and the pest pressure may build up enough
during the first crop to result in damage. Solarization may not fit into
the intense cropping system of field grown ornamentals. 

COMPOST 

Composting has not proven to provide sufficient control of the pest
spectrum and has actually increased pest populations in California
research trials. Composting does not provide adequate sanitation of crop
residue in bulb production. 

NON-REGISTERED CHEMICAL ALTERNATIVES 

A discussion of non-registered chemical alternatives is included to
evaluate existing products not registered for ornamentals and
developmental products that may fit into the field grown ornamental
cropping system. Registration is a business decision by the registrant.
Issues such as liability, market size and market focus may cause
registrants to overlook our industry. It often takes 3 -5 years to
incorporate a new product into normal operations once registered. 

METHYL IODIDE 

Methyl iodide has the greatest potential of all non-registered chemical
alternatives, possibly being a drop-in methyl bromide replacement.
Results from various trials suggest methyl iodide can provide good
disease control but nematode control is questionable and requires
further research. 

-

There are a number of concerns with iodide, such as trace element
accumulation in soils, groundwater contamination and phytotoxicity. 

Methyl iodide is currently in the registration review process at U.S.
EPA. Registration delays have occurred and it is unknown when or if
approval will be granted. It will take at least three to five years
after registration to experiment with methyl iodide to allow growers to
gain confidence in what it can and can not do and to learn how to use
it. It is unknown what use restrictions will be placed on the product as
a result of its high human toxicity and its potential environmental fate
issues. Pricing is unknown at this time. 

SODIUM AZlDE 

Sodium azide is an industrial chemical used in granular form as an
explosive. A more stable liquid formulation has been developed for
agricultural applications. It is applied through drip tape, making it
difficult to use in Florida soils, and it forms a very weak gas with
little lateral movement (< 1 inch). Further investigation is required to
optimize application techniques. 

It has been tested in vegetables and can control nutsedge at 75 -100
lbs/acre but persists in the soil too long, requiring one or more
"flushings" with an acre-inch of water before planting can occur;
persistence can be even greater in heavier soils. It was one of the
worst methyl bromide alternatives tested in a trial on bulbs in
California, being no better than the control. 

The manufacturer does not have expertise in agricultural markets and
registration efforts are unknown. This is not considered a near term
commercially viable alternative. 

DIMETHYL DlSULFlDE (DMDS) 

DMDS has the potential to control much of the pest complex found in
field grown cut flowers, bulbs, cut foliage and propagative material,
but limited work has been done with this product. The odor can be
objectionable, possibly causing concern around residential areas,
especially since the odor persists in the soil and can be released with
subsequent cultivations. Registration status is unknown but is not
viewed as a near term option for use. 

Fosthiazate is an organophosphate nematicide with registration being
sought for tomatoes. It is not effective against soil borne pathogens or
weeds. It does not appear registration is being sought for use on
ornamentals at this time and it is unknown whether it will be. 

Vydate is a nematicide but is not registered for ornamental use. It is
highly unlikely the registrant (DuPont) will pursue registration for
this market because of liability risks. 

RESEARCH 

RESEARCH CONSTRAINTS 

The field grown ornamental industry has supported research for years,
including public research (university, U.S.DA), private industry
research (chemical companies) and in- house research (replicated trials
and demonstration trials). The California Cut Flower Commission (CCFC)
has a research committee that contracts and oversees research studies,
then transfers the information to member growers. About 10% of such
growers offer land and other resources to support these efforts in
addition to financial support to CCFC by all members. All Florida
growers, being smaller in number, have participated in conducting and
supporting research efforts. 

A number of factors make research difficult in this market 

2. Evaluation of non-registered, near-to-market alternatives. 

Methvl iodide. The only real candidate at this time is methyl iodide,
although sodium azide and DMDS may be included if the manufacturers
express interest in the field grown ornamental market. Research trials
are currently being conducted to determine its efficacy on regulated
nematode pests. 

Other product candidates will be incorporated into testing programs as
manufacturers state their commitment to the ornamental industry. 

CONCLUSION 

California and Florida growers of field grown ornamentals are committed
to producing their crops within the regulatory and market constraints
imposed upon them. This commitment, with regard to the global ban of
methyl bromide, is demonstrated by the reduction of methyl bromide use
through the adoption of alternatives when possible and ongoing research
efforts to find the most efficacious, environmentally sound and economic
means to produce a crop. A research structure is in place and the
industry will continue to evaluate alternatives as they become
available, which is happening slowly. Even so, the ornamental industry
is continuing to look at new ways to use old products, even with
regulatory constraints, so that U.S. production of field grown
ornamentals can continue. 

California and Florida field grown ornamentals have reduced use of
methyl bromide as  much as possible without risking crop disasters.
Further reductions will come more slowly as research generates
confidence in using new and existing products. The industry is relying
on the U.S. government to limit further reductions of methyl bromide use
to the current 30% of baseline until viable alternatives become
available. 

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Response to MBTOC Questions of June 2006 for 2008 Nomination