  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 Methyl
Bromide, Chloropicrin, Dazomet, and Metam Sodium for Use in Raspberry
Nurseries, Fruit and Nut Deciduous Tree Nurseries, and Rose Bush
Nurseries in California 

FROM: 	Leonard Yourman, Plant Pathologist

		Biological Analysis Branch

		Stephen Smearman, Economist

		Economic Analysis Branch

THRU:	Arnet Jones, Chief

		Biological Analysis Branch

		Biological and Economic Analysis Division (7503P)

Timothy Kiely, Chief

		Economic Analysis Branch

		Biological and Economic Analysis Division (7503P)

TO:		John Leahy,  SEQ CHAPTER \h \r 1 

Special Review and Reregistration Division

Summary

This assessment attempts to measure the benefits of soil fumigation to
nurseries producing plant stock in open fields.  The assessment
characterizes the industry in terms of total value, area and type of
production, and the various types of pest control alternatives available
to growers.  There is little data available to conduct a quantitative
analysis of the benefits of fumigation to the nursery industry, in
general, and in particular, the nurseries growing fruit and tree nut
stock and rose bush stock.  This assessment primarily relies on nursery
practices in the western U.S., especially nurseries in California.  The
Agency is requesting information that will assist in determining the
benefits of fumigant use for this industry. 

The nursery industry is extremely diverse and is characterized by
numerous crop species and varieties, produced in multiple cropping
systems in different environments.  According to the USDA NASS Nursery
Crop 2003 Summary of a survey of 17 program states, the nursery industry
had an estimated value $3.97 billion dollars based on the gross sales
for operations exceeding $100,000 in sales.  The combined value of
nurseries producing fruit and nut trees and deciduous shrubs, which
includes rose bushes, accounted for more than 20% of the total value of
all nursery production, or $799 million according to the USDA summary.  

Methyl bromide and chloropicrin are the dominant fumigants used in
nursery stock production in the western U.S.  Methyl bromide is used in
California nurseries and some nurseries in the Pacific Northwest under a
critical use exemption.  Alternatives to methyl bromide such as
1,3-dichloropropene (1,3-D), metam sodium and dazomet are also used to
some extent, either individually or in combination, although these
alternatives have various restrictions or limitations.  Fumigants are
used in nursery production to control diseases, nematodes and weeds. 
Based on the available data, approximately 65% of nurseries in
California rely on methyl bromide (used with chloropicrin). 
Alternatives to methyl bromide are used for the balance of nursery
soils.  Nurseries must meet certification requirements for pest-free
plant material and, therefore, the benefits from fumigation are
substantial.  These benefits result in higher yields, higher quality
plant production, and lower costs of production.  

Background

As part of the Registration Eligibility Decision (RED) process, EPA is
assessing the risks and benefits of the use of several soil fumigants:
dazomet, chloropicrin, metam potassium, metam sodium, and methyl
bromide.  This document presents the assessment of the benefits provided
by soil fumigants in the production of nursery stock fruit trees, nut
trees, raspberry stock plants, and rose stock plants.  Some of the
benefits of soil fumigants are the improvements in production and/or
reductions in costs resulting from the use of the fumigant.  The social
benefits of a pesticide are divided between the users of the pesticide,
such as nursery managers, and consumers of the commodity.  Consumers
benefit because higher production and/or lower costs translate into a
cheaper and more abundant supply of goods.

This assessment of the benefits of soil fumigants to nurseries compares
the current situation in which fumigants are available for use, subject
to existing label restrictions, to the situation that could occur were
the fumigants not available.  However, due to the lack of data necessary
for a quantitative assessment, this analysis qualitatively assesses and
characterizes the likely benefits of fumigant uses on fruit and tree nut
and rose bush nursery stock.  This is somewhat different from an
assessment of the impacts of regulation, as no specific regulatory
scheme is considered.  

This assessment focuses on fruit and nut tree, raspberry, and rose bush
nurseries in the western U.S., primarily California, where large open
field nurseries provide planting stock to commercial fruit, nut, berry,
and rose growers.  This assessment assumes that other regions in the
U.S. that provide nursery stock to local growers do not rely on chemical
fumigation for production, but generally grow stock by container
production.

Introduction 

Nursery producers provide stock plants that are pest-free to allow the
establishment of plantings that are of the highest initial quality. 
Nurseries provide trees used by commercial growers of such diverse fruit
crops as apricots, peaches, prunes, nectarines, cherries, plums, apples,
pears, Asian pears, ornamental pears, as well as nut crops such as
almonds, walnuts, pistachios, pecans, and chestnuts.  In addition, other
crops such as raspberries and rose bushes rely on fumigation to produce
pest-free planting stock.  In California, approximately 95% of fruit
trees are fruiting varieties sold to commercial producers; the other 5%
are ornamental types used for landscaping (CUN, 2006).  Nurseries are
concentrated in areas conducive to early plant growth.  Deciduous trees
are primarily produced in California in the Sacramento and San Joaquin
valleys.  Many of the large raspberry nurseries are located in the
eastern San Joaquin valley and western Washington (CUN, 2006).

Nurseries must provide stock that is pest-free in order to meet state
mandated certification requirements for plant material (CDFA, 2001). 
Use of products with 1,3-D can provide an effective alternative to
methyl bromide for nematode control where allowed by township cap
regulation and where soil type (sandy type soils) and soil moisture
provide effective treatment (McKenry, 2000; Schneider et al., 2004). 
For management of pathogens, choropicrin is an important amendment to
1,3-D treatments.  Moisture restrictions for 1,3-D may be more limiting
than township caps.  Nurseries with heavy soils (those with high clay
content) or moisture greater than 12% (especially common in clay soils
at depths of 1 to 1.5 meters) may not be able to achieve effective pest
management (McKenry, 2000).  In these situations methyl bromide +
chloropicrin are necessary.

The goal in the orchard nursery industry is 99.9% control when sampled
within 30-60 days after treatment, so certification can be met when
stock is harvested 18 months later (McKenry, 2000).  Generally, less
than 98% control in the 30-60 day sampling period will yield
unacceptable stock plants.  Field moisture is carefully monitored.  A
site (e.g., walnut nursery in Davis, California) with silty clay loam
over sandy loam or clay loam has a moisture differential with the clay
textured soils holding more moisture (>12%), which can impede
distribution of an alternative such as 1,3-D and make it ineffective
(McKenry, 2000).  

Certification Requirements 

Nurseries providing plant stock of raspberry, tree fruits and nuts, and
roses are covered by certification requirements as exemplified by
California (e.g., CDFA, 2001; CDFA, 2003) and federal regulations
(USDA-APHIS, 2004).  For example, “Section 3640, CCR, makes it
mandatory that nursery stock for farm planting be commercially clean
with respect to economically important nematodes” (CDFA, 2001, 2003). 
The regulations list methyl bromide and 1,3-D as acceptable fumigants
for control of nematodes.

A recent example of complications from contaminated nursery stock is a
report by extension specialists in Florida (Noling, 2006).  Florida
growers purchase some strawberry transplants from Canada.  Nematodes
were found on potatoes in Quebec province resulting in a quarantine by
USDA of all plant material from Quebec province into the U.S.  The
quarantine by USDA initially affected 30 million bare-root strawberry
transplants and 3 million plug plants destined for Florida farms, which
could have reduced plantings in Florida by 20%.  Ultimately the problem
was resolved by strict certification requirements.  The situation
highlights the importance of fumigants to nurseries and the implications
of potentially contaminated nursery stock to farms within the U.S.  

If nematodes are found and the nursery stock is not “free of
especially injurious pests and disease symptoms”, then a total loss is
likely because the nursery stock:  1) Would not qualify for a CDFA
Nursery Stock Certificate for Interstate and Intrastate Shipments, 2)
Would probably not be marketable, since resale for planting is severely
restricted by the CDFA, 3) should be destroyed to prevent further
infestation.  Table 1 identifies major pests that are targeted by soil
fumigants for nursery soils.

Table 1.  Target pests for fumigants for nursery production of nut and
fruit trees and rose and raspberry bushes.

State	Key Pests

California Nut Trees	Nematodes: Pratylenchus vulnus (root lesion),
Meloidogyne spp. (root knot), Helicotylenchus dihystera (spiral),
Xiphinema americanum (dagger). 

California Fruit Trees	Nematodes: Helicotylenchus dihystera (spiral),
Tylenchus mexicanus (Tylenchus), Tylenchorhynchus spp. (stunt),
Trichodorus spp. (stubby root)

Raspberry Nurseries	Pathogens: Phytophthora fragariae var. Rubi (root
rot), Verticillium spp. (wilt), others including Pythium spp.,
Rhizoctonia spp.

Rose Bushes	Nematodes: Root knot nematode (Meloidogyne hapla); lesion
nematode (Pratylencus penetrans); pin nematode (Paratylenchus hamatus);

Pathogens: Verticillium dahlia; Pythium spp.; Agrobacterium tumefaciens

*Based on information supplied in critical use exemption requests for
methyl bromide submitted by requesting consortia.

Raspberry Nurseries

Raspberry nurseries in the western U.S. provide raspberry stock to most
of the growers in North America.  Dry climates and soils make these
areas ideal for production of high quality plant stock.  Although there
are relatively few raspberry nurseries, they provide all of the stock
used by commercial growers, and therefore, have a great impact on
raspberry production overall.  Methyl bromide is used on approximately
500 acres of field beds (CUN, 2006).  There is a large return in the
benefits of certified pest-free stock to numerous commercial growers
throughout the continent.  The raspberry nursery industry uses flat
fumigation techniques similar to that of the strawberry industry. 
Raspberry nursery stock is grown using a two-year production cycle
beginning with tissue culture and moving to foundation planting the
first year.  Winter dormant plants are replanted in commercial nurseries
and harvested after one year.

USDA organic standards allow the use of nursery stock propagated using
methyl bromide for organic production in recognition of the vital role
vigorous planting stock plays in organic and integrated pest management
systems.  This exemplifies that the use of methyl bromide in propagation
nurseries reduces the need for methyl bromide, and other chemical
inputs, in fruiting fields.  

Land is fallowed as part of the two-year cycle (the production system is
described in CUN, 2006 based on information from the Western Raspberry
Growers Association).  The production of one acre of raspberry nursery
is a 24-month process.  It begins with land preparation in January of
year 1.  A cover crop is then grown during the winter, spring and early
summer of year 1.  In the summer the cover crop is incorporated into the
soil and the land is prepared for fumigation.  There is a brief fallow
period in June of year 1 prior to fumigation.  The field is fumigated in
August of year 1.  The planting beds are constructed in September of
year 1.  These beds lay “fallow” through the winter, until February
of year 2.  The planted crop will grow until harvest in November and
December of year 2.  Following the harvest we begin another cycle begins
in January.  

Although the nursery is a 24-month process, some land is fumigated each
year to provide an annual supply of planting stock for our farmers. 
More important than yield for raspberry nurseries, as well as other
nurseries, is their dependence on certification of stock as
‘pest-free’ in order to meet state requirements to sell to
commercial outlets.

Fruit and Nut Deciduous Tree Nurseries

Deciduous tree nurseries range from 40 to over 1,500 acres in field beds
(the production system is described in CUN, 2006 based on information
from the California Association of Nursery & Garden Centers).  A typical
operation in California ranges between 200 and 300 acres.  The climate
and soil make this region an ideal area for tree nurseries (as well as a
major fruit and nut producing region).  While some nurseries concentrate
on specific tree crops, most nurseries grow and sell a variety of
different trees.  Nursery stock is grown on a cropping system that
includes crop rotation or cover cropping between tree production cycles;
therefore, not all of the nursery area is in tree production in a given
year.  The tree production cycle can be anywhere from a single year to
several years depending on the type of tree crop being produced. 
Nursery production of trees takes from one to four years in the ground
depending on the type being produced.  Almonds take one year and walnuts
take at least two years.  Also, target tree size determines how long
plants are grown in the nursery.  The most common cycle is for the tree
crop to be in the ground for either one or two years.  A typical nursery
cycle starts by digging the current tree crop (to be sold) then planting
a cover crop for one or two years, followed by replanting with a tree
crop.  In order to prepare the ground for planting, the fields are
disked, deep ripped, leveled, and then fumigated to meet certification
standards set by the California Department of Food and Agriculture
(CDFA, 2001).  Methyl bromide is applied by shank and treated area is
usually covered with a tarp.  The fumigation is carried out around
August and September, and planting begins in October, and may continue
through January.  The deciduous nurseries are subject to mandates set
forth by the CDFA (2001) that trees must be pest free.  This is true for
tree nurseries in California that are in areas where alternatives are
either unsuitable for meeting certification standards or subject to
regulatory restrictions.

While some nurseries concentrate on specific tree crops, most nurseries
grow and sell a variety of different trees.  Nursery stock is grown on a
cropping system that includes crop rotation or cover cropping between
tree production cycles; therefore, not all of the nursery land is in
production in a given year.

Soil moisture content of greater than 12% reduces efficacy of 1,3-D. 
Soils that are so dry are unusual at 1.5 meters (the depth required to
be nematode-free) (CDFA, 2001) especially with moderate to heavy
subsoils.  Approximately 65% of nurseries require methyl bromide to meet
certification requirements, especially in wet years (CUN, 2006).  Areas
with sandy-type soils and dry conditions generally have good results
from 1,3-D (where township caps allow its use) and combinations with
chloropicrin and/or metam-sodium.

Approximately 30% of nursery soils are clay or silt loam and require
methyl bromide, while one half of the remaining sand or sandy loam soils
do not meet the moisture requirements of less than 12% for use of 1,3-D
(CUN, 2006).  Therefore, approximately 65% of the nurseries rely on
methyl bromide.  Methyl bromide (applied with chloropicrin) and 1,3-D
(with or without chloropicrin) are the only approved fumigants for
treatment of nematodes in open field nurseries to meet California
Department of Food and Agriculture standards.  Methyl bromide is
important to the production of nematode-free stock where 1,3-D is not
feasible (estimated by industry as approximately 65% of the area)
because of incompatible soil moisture or soil type, or township cap
limitations.

Rose Bush Nurseries 

Nurseries growing rose bush stock are grown in open field nurseries (the
production system is described in CUN, 2006 based on information from
the California Rose Growers).  A typical crop rotation for a two-year
rose crop includes one year fallow, followed by one or two years of
rotational crops, and then a two-year rose crop.  The two-year rose crop
cycle begins with land preparation (removing the cover crop, deep
cultivation, and fumigation with methyl bromide), followed by planting
the rootstock and T-bud grafting.  In late winter of the first year, the
rootstock tops are removed.  The rose crop matures by the second autumn
and is then harvested. This cycle varies depending on the type of rose
crop being produced (e.g., two-year roses, one-year minis and patio
trees, or 18-month mini bushes).

Although yield and quality losses may occur due to key pests,
quantifiable benefits for various fumigants are difficult to determine. 
However, the crop must meet certification requirements or the stock will
not be accepted.  

Although 1,3-D with chloropicrin is an effective alternative in some
situations, it is not effective in all nursery sites.  In soils with
moisture levels above 12%, 1,3-D does not provide control of nematodes
(McKenry, 2000).  In addition, 1,3-D does not control Verticillium
dahilae, Pythium spp., or weeds.  There are regulatory limitations to
the use of 1,3-D, yet growers must meet certification requirements. 
Township caps may limit the availability of this alternative to growers,
especially since nursery roses are primarily produced in two townships,
where other crops that use 1,3-D are also grown.  Other alternatives,
such as metam sodium and dazomet do not provide consistent control of
target pests to a depth of 1.5 meters (CUN, 2006; McKenry, 2000).

Fumigants for Nurseries

Key fumigants for nurseries are methyl bromide + chloropicrin and 1,3-D
+ chloropicrin.  Regulations regarding certification requirements
mandate certain treatments.  Yield losses could be 100% if the nursery
stock cannot be certified as pest-free (CUN, 2006).  In California, only
methyl bromide and 1,3-D are listed as acceptable treatments for
nematode-free stock (CDFA, 2001; CDFA, 2003).  Methyl bromide is used
under a critical use exemption that is granted annually according to the
Montreal Protocols.  The amount of methyl bromide available in the
future will be dependent on an annual grant by the international body
that regulates the worldwide phase-out of methyl bromide.  

Methyl Bromide 

Raspberry Nurseries.  Plants are grown for one year in a foundation
nursery and one year in commercial nursery. The raspberry nursery
industry utilizes broadcast fumigation techniques similar to that of the
strawberry industry.  Raspberry nursery stock are grown using a two-year
production cycle beginning with tissue culture and moving to foundation
nurseries the first year.  Winter dormant plants are replanted in
commercial nurseries and harvested after one year.

Twenty-five acres of plants in a foundation nursery will provide for 250
acres of a commercial nursery.  A commercial nursery produces enough
plants to provide nearly 3,000 acres of raspberry plants for commercial
production.

Nursery stock grown in soils treated with methyl bromide and
chloropicrin are the standard by which other fumigant treatments are
measured, and therefore, no yield losses are associated with this
treatment.  Chloropicrin is a necessary amendment for use of methyl
bromide.

Table 2.   Methyl Bromide/Chloropicrin Fumigation Characteristics,
Raspberry Nurseries

Rate:	222 lb methyl bromide/treated area with 110 lb chloropicrin/acre

Method of Application:  Shank, deep injected, i.e., more than 20 inches;
broadcast 

Fumigation Period: WA: 40% Sept-Oct; 60% March-April; CA: Aug-Sept

Surface Sealing:  Tarp

Typical Field Size: 87 acres

Source: CUN, 2006.

Deciduous (Fruit and Nut) Tree Nurseries.  The tree production cycle can
be anywhere from 1 year to several years depending on the type of tree
crop.  Nursery production of trees takes from 1-4 years.  Almonds take
one year, walnuts take at least two years.  Also, desired tree size
determines how long it is grown in the nursery.  A typical cycle is for
the tree crop to be in the ground for either 1 or 2 years.  A typical
nursery cycle starts by digging the current tree crop (to be sold) then
planting a cover crop for 1 or 2 years, followed by replanting with a
tree crop.  Fields are disked, deep ripped, leveled, and then fumigated
to meet certification standards set by the California Department of Food
and Agriculture (CDFA, 2001).  A shank is used to apply a fumigation of
75% methyl bromide and 25% chloropicrin, typically at a rate of 302 lb
per acre.  The treated area is covered with a high barrier tarp.  The
fumigation is carried out around August and September, and planting
begins in October, and may continue through January.  The deciduous
nurseries are subject to mandates set forth by the CDFA, that trees must
be pest-free (CDFA, 2001).

Table 3.  Methyl Bromide/Chloropicrin Fumigation Characteristics,
Deciduous Tree Nurseries

Rate:  290 lb methyl bromide/treated area with 6 lb chloropicrin/acre

Method of Application:  Shank, deep injected, i.e., more than 20 inches;
broadcast 

Fumigation Period:  typically Fall 

Surface Sealing:  Tarp

Typical Field Size:200 acres

Source: CUN, 2006.

Rose Nurseries.  Typically, crop rotation for a two-year rose crop
includes one-year fallow, followed by one or two years of rotational
crops, and then a two-year rose crop.  This rotation varies depending on
the type of rose crop being produced (i.e., two-year roses, one-year
minis and patio trees, or an 18-month mini bush).

The perennial nature of the crop requires pest control to a depth of 1.5
meters.  Certification requires commercially clean stock.  In tree
nursery production, there must be 99.9% nematode control in the first 30
to 60 days to meet this requirement (McKenry, 2000).  Once every 4 to 5
years a typical grower fumigates and plants approximately 20-25% of the
production area each year.

Table 4.  Methyl Bromide/Chloropicrin Fumigation Characteristics, Rose
Nurseries

Rate:  300 lb methyl bromide/treated area with 6 lb chloropicrin/acre

Method of Application:  Shank, deep injected, i.e., more than 20 inches;
broadcast 

Fumigation Period:  typically Fall 

Surface Sealing:  Tarp

Typical Field Size: 125 acres

Source: CUN, 2006.

Chloropicrin

Certification guidelines do not list chloropicrin as a “stand-alone”
treatment for certification.  However, chloropicrin is always used with
methyl bromide and nearly always used when 1,3-D is used as an
alternative to methyl bromide.   Chloropicrin is currently used with
methyl bromide at a ratio of methyl bromide to chloropicrin ranging from
98:2 to 50:50, depending on the situation.  Chloropicrin is an effective
fungicide, but will not adequately control nematodes or weeds. 
Verticillium wilt is a major problem for strawberry growers and
disease-free plants are required so the pathogen is not further
distributed.  Chloropicrin is the more active fumigant against
Verticillium wilt when methyl bromide + chloropicrin is applied but
other pests (especially nematodes) would not be sufficiently controlled.
 Research trials (e.g., Kabir et al., 2003, 2005) in strawberry
nurseries suggest that 1,3-D + chloropicrin at 35% shank injected is
likely the primary alternative to methyl bromide—sometimes followed by
an application of dazomet to reduce weed populations.  Generally, the
use of 1,3-D is considered effective for nursery plants only with the
use of chloropicrin, if soil conditions (texture and moisture) are
amenable.  

Soil moisture content of greater than 12% reduces efficacy of 1,3-D and,
therefore, it is not an acceptable treatment to comply with
certification standards.  Soils that are dry are unusual at 1.5 meters
(the depth required to be nematode-free) (CDFA, 2001) especially with
moderate to heavy subsoils.  Approximately 65% of nurseries in
California require methyl bromide to meet certification requirements
(especially in wet years).  Areas with light soils and dry conditions
generally have good results from 1,3-D (where township caps allow its
use) and combinations with chloropicrin and/or metam-sodium.

Based on information from strawberry nurseries a yield loss of 2-15% can
be expected with 1,3-D + chloropicrin and 5-16% with chloropicrin used
at 267 lb/acre.

Table 5.   1,3-D/Chloropicrin Fumigation Characteristics, Raspberry
Nurseries

Rate:200 lb 1,3-D/acre with 110 lb chloropicrin/acre

Method of Application:  Shank, deep injected, i.e., more than 20 inches;
broadcast 

Fumigation Period: WA: 40% Sept-Oct; 60% March-April; CA: Aug-Sept

Surface Sealing:  Tarp

Source: CUN, 2006.

Metam-sodium, dazomet (and other methyl
isothiocyanate—MITC—producers).  

These pesticides are not effective as “stand alone” treatments for
nursery soils.  Field trials in California suggest that they might be
used following treatments such as 1,3-D (e.g., Kabir et al., 2005). 
Based on strawberry nursery information a yield loss of 13-57% might be
expected with metam-sodium (at 312 lb/acre) or dazomet if other
fumigants were not available.  However, because of regulatory
requirements, metam-sodium used alone is not an acceptable treatment
without the additional use of methyl bromide + chloropicrin or 1,3-D.

ECONOMIC BENEFITS

According to the USDA NASS Nursery Crop 2003 Summary, a survey of the 17
program states estimates that the nursery industry was valued at $3.97
billion dollars based on the gross sales for operations that exceeded
$100,000 in sales in 2003.  Combined, fruit and tree nut nurseries and
deciduous shrub nurseries (including those nurseries growing rose bush
stock) accounted for more than 20% of the total value of production, or
$799 million according to the 2003 Summary.  Fruit and tree nut
nurseries account for approximately $216 million (or 5%) of the total
value of production, and deciduous shrubs, which includes rose
nurseries, accounted for approximately 15% of the total value of
production, or $583 million, according to the 2003 Summary.  

The top three states in terms of production, according to the USDA NASS
Nursery Crop 2003 Summary, are California, Florida, and Oregon out of 17
program States surveyed.  California accounts for approximately 25
percent of the total value followed by Florida and Oregon with 16
percent respectively.  USDA NASS estimates that the number of operations
in 2003 was approximately 7,742 with sales over $10,000 per year in the
17 surveyed program states.

In terms of the benefits of fumigant use, there is ample evidence that
fumigant use increases yield, quality and production especially when a
formerly untreated area is treated for a particular pest.  However,
there is very little data available to conduct a thorough analysis of
the impacts of substituting one fumigant pest control alternative for
another on an existing site.  The data that is available suggests that
yield and quality impacts due to the unavailability of a particular
fumigant for a given industry would result in significant losses to the
industry.  This is because of the 100% certification required for pest
free stock discussed previously in the document.  Not meeting the
required certification results in a combination of direct revenue losses
due to yield loss impacts, and quality loss impacts due to stock that is
unusable or unable to be sold because the stock is not viable, has poor
marketable characteristics or is contaminated with disease or insect
pests.  Many of the references cited in this document estimate losses
could approach 100% using less effective chemical controls.

The agency is requesting information to assist with the determination of
the benefits of fumigant use in this industry.  What is needed is data
that can be used to measure changes in yield and quality of plants using
different pest control methods, and changes in the cost of production
using the different pest control methods for the various types of
nursery production.  This would include crop budgets or enterprise
budgets that present estimates of variable and fixed production costs
including: alternative fumigant control costs, cultural controls costs,
such as additional hand labor or material costs, etc.; estimated yields
using alternative pest control measures; gross and net revenues; and
other economic information for different sectors of the nursery
industry.

Limitations to assessment

This document attempts to characterize the use of fumigants in the
nursery industry.  Due to a lack of information on the industry, an
assessment of the benefits provided by the soil fumigants in the
production of nursery stock is not presented here.  The following are
limitations of this analysis:

Social benefits of pesticide use accrue to several groups, e.g., nursery
producers and consumers of nursery stock.  This document attempts to
describe qualitatively the benefits of fumigant use from the perspective
of the nursery industry in the western U.S., and does not quantify
benefits to the nursery industry due to limited information.

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.  

Due to limited information, this assessment does not use partial budget
analyses to estimate potential benefits to the industry but rather
attempts to characterize the industry in terms of value by market
segment, production methods and fumigant control alternatives and their
use.  

REFERENCES 

CDFA (California Department of Food and Agriculture). 2003. Summary of
California Laws and Regulations Pertaining to Nursery Stock.   
HYPERLINK "http://www.cdfa.ca.gov/phpps/pe/nipm.htm" 
http://www.cdfa.ca.gov/phpps/pe/nipm.htm ;   HYPERLINK
"http://www.cdfa.ca.gov/phpps/pe/nipm_pdfs/nipm_7.pdf" 
http://www.cdfa.ca.gov/phpps/pe/nipm_pdfs/nipm_7.pdf 

CDFA (California Department of Food and Agriculture). 2001. Approved
treatment and handling procedures to ensure against nematode pest
infestation of nursery stock. California Code of Regulations, Title 3,
Section 3060, et seq.  Nursery Inspection Procedures Manual, Item #12.
18 pp.;   HYPERLINK "http://www.cdfa.ca.gov/phpps/pe/nipm.htm" 
http://www.cdfa.ca.gov/phpps/pe/nipm.htm 

CUN (Critical Use Nomination) for Methyl Bromide Use for Nursery
Stock—Fruit, Nut, Rose—Open Field. 2006.
http://www.epa.gov/spdpublc/mbr/cun2009/cun2009_Nursery.pdf 

Kabir, Z., Fennimore, S. A., Duniway, J. M., Martin, F. N., Browne, G.
T., Winterbottom, C. Q., Ajwa, H. A., Westerdahl, B. B., Goodhue, R. E.,
and Haar, M. J. 2005. Alternatives to methyl bromide for strawberry
runner plant production. HortScience 40(6):1709-1715.

McKenry, M. V. 2000. Evaluation of alternatives to methyl bromide for
soil fumigation at commercial fruit and nut tree nurseries. Contractor
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Schneider, S., T. Trout, J. Gerik, and H. Ajwa. 2004. Perennial crop
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USDA-APHIS (Animal and Plant Health Inspection Service), Plant
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http://www.aphis.usda.gov/ppq/ispm/pramorum/pdf_files/sodorder4-22-04sig
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USDA NASS Nursery Crops 2003 Summary, July 2004,   HYPERLINK
"http://www.nass.usda.gov/publications/" 
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USDA NASS Agricultural Chemical Usage 2003 Nursery and Floriculture
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www.nass.usda.gov/publications/agriculturalchemicalusage/ 

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