Importation of Live 

Greenhouse-Grown 

Tomato Plantlets on 

Approved Growing 

Media from Mexico to 

the Continental United 

States

Draft Environmental 

Assessment,

January 2015

United States

Department of 

Agriculture

Marketing and 

Regulatory

Programs

Animal and 

Plant Health 

Inspection 

Service
Importation of Live 

Greenhouse-Grown Tomato 

Plantlets on Approved 

Growing Media from Mexico 

into the Continental United 

States

Draft Environmental Assessment

January 2015

Agency Contact:

Lydia E. Colón

Regulatory Policy Management

Plant Protection and Quarantine

Animal and Plant Health Inspection Service

U.S. Department of Agriculture

4700 River Road, Unit 133

Riverdale, MD 20737–1237

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Table of Contents

I. Introduction .............................................................................. 1

A. Background ........................................................................ 1

B. Purpose and Need.............................................................. 2

II. Alternatives .............................................................................. 3

A. No Action ............................................................................. 3

B. Preferred Alternative ........................................................... 4

III. Affected Environment............................................................... 8

A. Host Range of Quarantine Pests ..................................... 10

B. Climate and Host Interactions........................................... 11

C. Threatened and Endangered Species .............................. 13

IV. Environmental Impacts........................................................... 14

A. No Action ......................................................................... 14

B. Preferred Alternative........................................................ 14

C. Risk Managment.............................................................. 17

D. Endangered Species Act ................................................. 26

E. Other Considerations....................................................... 26

V. Listing of Agencies Consulted................................................ 27

VI. References............................................................................. 27
1

I. Introduction

 

A. Background

 

Currently, all plants in growing media imported into the United States 

must be approved by APHIS and must comply with all requirements 

under Title 7 of the Code of Federal Regulations, Part 319.37-8 (7

CFR § 319.37-8, 2013). In addition, §319.37-5 restricts the 

importation of tomato plants (Solanum spp.) into the United States 

unless they are accompanied by a phytosanitary certificate that 

contains an additional declaration either that the restricted articles are 

free of specified quarantine pests or that the restricted articles have 

been produced in accordance with certain requirements. 

7 CFR §319.37-5 contains conditions for the importation of Solanum

spp. restricted articles that: 1. are from countries other than Canada; 

and 2. that are from a country in which Ralstonia solanacearum race 3 

biovar 2, an extremely virulent pathogen of Solanum spp., is not 

known to occur. The regulation specifies that the Solanum spp. must 

be produced in accordance with a systems approach consisting of 

several pest mitigation measures, which are discussed in the Risk 

Management section of this document. 

The importation of tomatoes from Mexico is currently prohibited due 

to the lack of required pest mitigations in Mexico to prevent pests 

associated with tomato plants from infesting the plants and growing 

media, including Ralstonia solanacearum race 3 biovar 2. Should a 

final rule be published, APHIS would work with Mexico to visit 

production facilities and sign the bilateral work plan to finalize market 

access.

In addition, a notice published in the Federal Register on April 18, 

2013 prohibits the import of tomatoes from Mexico and all other 

countries, except Canada, to prevent the entry of Tomato Torrado 

Virus (ToTV) and Tomato Severe Leaf Curl Virus (ToSLCV). Both 

ToTV and ToSLCV are destructive plant pathogens that were not 

known to occur in the United States, and are not known to be seedtransmitted. 

The North American protected-culture tomato industry (which often 

employs the use of greenhouses using hydroponics) began in the late 

1990s. Hydroponics is a method of growing plants using a solution of 

water and nutrients, without soil. The market for protected-culture 

tomatoes, both mature green and vine ripe, is growing in importance. 

Meanwhile, the role of field-grown tomatoes, which once dominated 

the U.S. market, is shrinking (Calvin et al. 2013). 
2

In 2011, protected-culture tomatoes made up 40 percent of the U.S. 

tomato supply, up from less than 10 percent in 2004; they now 

dominate the retail industry and are becoming more common in food 

service (Calvin et al. 2013). The transition to protected-culture 

tomatoes is likely to accelerate if growers can meet foodservice 

demand, particularly from fast food buyers.

Greenhouse tomatoes are grown from plantlets raised from seed. As 

many as 18 million tomato plantlets are purchased annually by each

greenhouse facility, the largest of which are located in Arizona, Texas, 

Colorado, and coastal southern California. Currently, the domestic 

supply of these plantlets can only be supplemented by imports from 

Canada.

This environmental assessment (EA) was prepared to comply with the 

National Environmental Policy Act of 1969 (NEPA) 42 United States 

Code (U.S.C.) 4321, et seq., as prescribed in implementing regulations 

adopted by the Council on Environmental Quality (40 CFR §§1500–

1508), USDA (7 CFR part 1b), APHIS (7 CFR part 372), and to 

satisfy Executive Order (EO) 12114, “Environmental Effects Abroad 

of Major Federal Actions.”

B. Purpose and Need 

USDA–APHIS, Plant Protection and Quarantine (PPQ) is proposing to 

amend the regulations for the importation of plants and plant products 

(7 CFR part 319) to include Solanum lycopersicum (Lycopersicum 

esculentum) from Mexico to the list of plants that may be imported in 

approved growing media, subject to specified growing, inspection, and 

certification requirements. This change would allow the importation 

into the continental United States of live, commercially produced, 

greenhouse-grown, grafted tomato plantlets Solanum lycopersicum

(Lycopersicum esculentum) from Mexico, grown in APHIS-approved 

growing media from certified seed, for the purposes of commercial 

growing operations. This EA analyzes potential environmental 

consequences of the implementation of a proposal to amend the 

regulations governing the importation of plants and plant products into 

the United States (7 CFR part 319). 

Currently, the only approved source of tomato seedlings in growing 

media is Canada. The long distance transport of seedlings to the 

largest greenhouse production facilities in Arizona, Texas, Colorado, 

and coastal southern California can often result in additional plant 

stress and loss. The size and age of the imported plantlets has a direct 

impact on the size and quality of the tomatoes they grow. Plant stress 
3

and loss may be reduced with shorter transport time between supplier 

and greenhouse production facility. 

II. Alternatives 

 

Two possible alternatives are considered in this EA: maintaining the 

current regulation prohibiting the importation of Solanum spp. 

plantlets (bare rooted and in growing media) from all countries other 

than Canada (no action alternative), and changing the current 

regulation to add Solanum lycopersicum (Lycopersicum esculentum) 

from Mexico to the list of plants that may be imported in approved 

growing media (preferred alternative).

A. No Action

The no action alternative would leave 7 CFR part 319 unchanged. 

Section 319.37–8(a) of the regulations requires, with certain 

exceptions, that plants offered for importation into the United States be 

free of sand, soil, earth, and other growing media. This requirement is 

intended to help prevent the introduction of plant pests that might be 

present in unapproved growing media; the exceptions to this 

requirement take into account factors that mitigate that risk. Those 

exceptions, which are found in paragraphs (b) through (e) of 7 CFR 

§ 319.37–8, consider either the origin of the plants and growing media 

or the nature of the growing media and/or the use of a combination of 

growing conditions, approved media, inspections, and other 

requirements.

Currently, all plants in growing media imported into the United States 

must be approved by APHIS and must comply with all requirements 

under Title 7 of the Code of Federal Regulations, Part 319.37-8 (7CFR 

§ 319.37-8, 2013). Currently, under this regulation, the entry of 

Solanum spp. in growing media from all countries except Canada is 

prohibited. 

As stated in 7 CFR § 319.37–8(e), the following groups of plants

established in approved growing media are currently allowed entry to 

the United States: 

 Alstroemeria

 Ananas

 Anthurium

 Artificially dwarfed (penjing) plants from the People’s 

Republic of China of the following plant species: Buxus sinica, 
4

Ehretia microphylla, Podocarpus macrophyllus, Sageretia 

thea, and Serissa foetida; 

 Bromeliad plants of the genera Aechmea, Cryptanthus, 

Guzmania, Hohenbergia, Neoregelia, Tillandsia, and Vriesea 

from Belgium, Denmark, and the Netherlands; 

 Begonia

 Gloxinia (=Sinningia) 

 Nidularium

 Peperomia

 Dracaena from Costa Rica

 Phalaenopsis spp. from Taiwan

 Polypodiophyta (=Filicales);

 Rhipsalidopsis spp. from the Netherlands and Denmark,

 Rhododendron from Europe;

 Saintpaulia;

 Schlumbergera spp. from the Netherlands and Denmark.

Under the no action alternative, Solanum lycopersicum L. (Solanaceae) 

from Mexico would not be added to the list of taxa allowed entry into 

the continental United States established in approved growing media.

B. Preferred Alternative

The proposed rule (preferred alternative) would change 7 CFR part 

319 and thus allow importation of live, commercially produced, 

greenhouse-grown, grafted tomato plantlets Solanum lycopersicum

(Lycopersicum esculentum) from Mexico, grown in APHIS-approved 

growing media from certified seed. 

This would involve two production phases at two or more different 

locations in Mexico. During the pilot phase, the tomato plantlets will 

be grown in pest exclusionary commercial-grade greenhouses 

following the production system outlined by the national plant 

protection organization (NPPO) of Mexico, Servicio Nacional de 

Sanidad, Inocuidad y Calidad Agroalimentaria (SENASICA) 

(SAGARPA 2010, 2012a, b, 2013). Once the pilot phase is concluded 

and an analysis confirms the project feasibility, tomato plantlet 

production will be shifted to one or more yet-to-be constructed pest 

exclusionary commercial-grade greenhouses elsewhere in Mexico. 

The tomato plantlets would be shipped to a location only after passing 

through a PPQ plant inspection station located at the port of entry in 

the continental United States. Once consignments are cleared through 

a plant inspection station, tomato plantlets could be distributed to 

importing greenhouses in the continental United States. Tomato 
5

plantlets will only be used for fruit production within the green house 

and then be destroyed.

The tomato plantlets would be required to be produced, handled, and 

imported in accordance with requirements stipulated in compliance 

agreements, along with those of 7 CFR § 319.37–8(e) and § 319.37-

5(r)(3). In addition, at the time of importation, a phytosanitary

certificate issued by the Servicio Nacional de Sanidad, Inocuidad y

Calidad Agroalimentaria (SENASICA), Mexico’s NPPO, would be 

required to accompany the tomato plantlets, declaring that all

requirements have been met.

The preferred alternative includes propagation, rearing, shipping, and 

importation of live, commercially produced, greenhouse-grown, 

grafted tomato plantlets Solanum lycopersicum (Lycopersicum

esculentum) from Mexico, grown in APHIS-approved growing media 

from certified seed. Below are detailed requirements that must be met, 

as stipulated in a compliance agreement between APHIS and the 

importing greenhouse facility, 7 CFR §319.37-5(r)(3), and § 319.37–

8(e):

1. The NPPO of Mexico must enter into a bilateral workplan with 

APHIS setting out the conditions for producing and monitoring 

plant production and enforcement of the requirements of the 

regulations and;

2. The grower must enter into a written agreement with the NPPO 

of Mexico and agree to comply with the provisions of the 

regulations and to allow the NPPO access for monitoring 

inspections. The production site must be registered with and 

approved by both APHIS and the Mexican NPPO. Shipments 

of exported tomato plantlets must be traceable back to the 

production site where they originated;

3. After the initial approval, the production site must be inspected 

annually by APHIS and/or the NPPO of Mexico;

4. Plants must be grown in a APHIS-approved growing medium 

which has not been used previously and is treated as described 

in USDA (2007) to ensure freedom from Ralstonia 

solanacearum race 3 biovar 2.

5. Growing media and the containers in which the plants are 

grown must be safeguarded from contact with potentially

infested soil or media and must not come in direct contact with 

any water source such as a hose end or irrigation emitter;

6. Plants must be grown solely in pest exclusionary greenhouses 

that meet the following requirements:

a. Sanitary procedures to exclude quarantine pests must 

always be employed, including the cleaning and 

disinfection of benches, floors and tools; 
6

b. Pest management measures, including monitoring for 

pests with yellow or blue sticky traps, must be applied 

to protect against quarantine pests. While in the 

greenhouse, plants must be treated with appropriate 

pesticides as needed to maintain a pest-free condition;

7. The greenhouse must be free from sand and soil;

8. Dicotyledonous weeds must be controlled inside the 

greenhouse;

a. All vents and openings except entryways must be 

covered with screens having openings small enough to 

exclude arthropod pests including thrips;

b. Entryways must be equipped with automatic closing 

double doors;

9. Plants must be grown in a greenhouse unit that is used solely

for articles grown in compliance with these regulations;

10. Greenhouses must be constructed in such a manner to prevent 

runoff water from surrounding areas to enter the greenhouse;

11. Greenhouses must be surrounded by a one meter buffer free of 

dicotyledonous weeds and sloped so that water drains away

from the greenhouse;

12. Plants must be grown solely from certified seeds germinated in 

the aforementioned pest exclusionary greenhouse;

13. Water must be derived from an APHIS-approved source and/or 

be treated by an APHIS-approved method (USDA 2007); water 

must be tested at least annually and found free free from 

Ralstonia solanacearum race 3 biovar 2 ; 

14. Ebb and flow irrigation is not permitted and drip irrigation 

systems must be equipped with back flow preventers;

15. All equipment that comes in contact with S. lycopersicum

plants must be sanitized so that Ralstonia solanacearum race 3 

biovar 2 is not transmitted between plants or enter from outside 

the production site via the equipment;

16. Production site personnel must receive training to recognize 

and prevent the introduction of Ralstonia solanacearum race 3 

biovar 2;

17. Production personnel must adequately sanitize clothing and 

shoes and wash their hands before entering the greenhouse;

18. Plants must be grown on benches supported by legs at least 46 

cm above the floor;

19. Plants must be stored and packaged in areas free from soil, 

sand, and quarantine pests; 

20. Plants must be handled and packed to prevent the introduction 

of Ralstonia solanacearum race 3 biovar 2 and labeled to 

identify the production site;

21. Plants must be inspected in the greenhouse and found free from 

evidence of quarantine pests by APHIS or the NPPO of Mexico 

no more than 30 days prior to export;
7

22. The production site must conduct ongoing testing for Ralstonia

solanacearum race 3 biovar 2 using an APHIS-approved 

testing protocol (USDA 2007). Records must be kept and made 

available to APHIS and the NPPO of Mexico for two growing 

seasons; 

23. Detection of Ralstonia solanacearum race 3 biovar 2 at the 

production site or in consignments from the production site 

will result in removal from export eligibility until reinspection

determines the site is free from Ralstonia solanacearum race 3 

biovar 2 and APHIS is satisfied all problems have been 

addressed; and,

24. Consignments must be accompanied by a Phytosanitary

Certificate with an Additional Declaration indicating the 

requirements of 7 CFR 319.37-5(a) [potato cyst nematode], 7 

CFR 319.37-5(r)(3) [Ralstonia] and 7 CFR 319.37-8 (e) 

[growing media] have been met.

Conditions of the compliance agreement include:

25. The tomato plantlets must be imported in sealed packaging.

26. The tomato plantlets must enter through a Plant Introduction 

Station (PIS). An APHIS inspector at the PIS will confirm that 

the shipment is accompanied by a phytosanitary certificate and 

inspect the tomato plantlets. If found free of obvious pests, the 

container will be resealed and forwarded to the importing 

greenhouse.

27. Cleared tomato plantlets shall be transported by the importer to 

the importing greenhouse under APHIS seal. 

28. At the importing greenhouse, all shipping boxes and crates may

only be opened, and all repotting and other actions with respect 

to the tomato plantlets may only be performed, inside the 

importing greenhouse by trained personnel.

29. No plants, shipping boxes or crates may be removed from the 

approved greenhouse or discarded without specific instructions 

from the PPQ inspector.

30. The imported tomato plantlets will be used only for fruit 

production. No increase of these plants by cuttings, grafting, 

suckers, flowers, seeds or air layers will be made; there will be 

no distribution of the plants or increase.

31. Prior to importation, the facility manager of the importing 

greenhouse will provide a pest management plan to APHIS for 

review and approval.

32. The importing greenhouse shall inform the APHIS State Plant 

Health Director (SPHD) by sending a written notice not less 

than 24 hours before the tomato plantlets are to arrive.

33. The PPQ inspector shall inspect the importing greenhouse 

within one week of the arrival of the tomato plantlets and prior 

to the first fruit harvest. 
8

34. PPQ may conduct additional periodical inspections during the 

subsequent production cycle for each lot of tomato plantlets.

35. PPQ shall inspect the greenhouse, the tomato plantlets being 

grown therein and the surrounding area for any evidence of 

pests of quarantine significance to the United States. 

36. If pests are found, APHIS shall consult with the authorized 

facility manager to determine the appropriate action to take 

based on the circumstances and the type of pest detected.

37. If actionable pests are discovered, the level of contamination 

will be assessed by PPQ, taking into consideration the 

segregation and safeguarding of various sections of the facility. 

This may result in the need to destroy part or all of the 

importing greenhouse material.

38. Plants infested with actionable pests shall be incinerated,

heated to 170° F for 30 minutes, or otherwise destroyed. 

Waste material or infested plants shall be safeguarded and 

sterilized with agreement of the PPQ inspector. However, any

finding of insect or insect damage would be preserved until 

inspector can verify it.

III. Affected Environment

The affected environment for both the continued import restriction of 

tomato plantlets in growing media from all countries other than 

Canada (no action alternative) and the proposed importation of tomato 

plantlets from Mexico in APHIS-approved growing media (preferred 

alternative) is the United States. The facilities of the largest 

greenhouse tomato producers are currently located in Arizona, Texas, 

Colorado, and coastal southern California; however, under the 

preferred alternative, the tomato plantlets from Mexico could be

shipped to and grown in commercial greenhouses anywhere within the 

continental United States.

The tomato plantlets considered in this analysis are intended for 

commercial tomato growing. The fruits of the tomato plant develop 

via pollination. Pollination is a process of fertilization that takes place 

when pollen granules from the anthers (male parts) of a flower are 

transferred to the stigma (female parts) of the same or different flower. 

Generally, greenhouse tomatoes are either pollinated by bumblebees or 

mechanical, electric devices. Because of their proficiency (which 

results in higher fruit yield), bumblebees are the preferred method of 

pollination within the greenhouse tomato industry (Dogterom et al. 

1998, Cameron et al. 2011). Therefore, the analysis presented in this 

document assumes that the preferred method of plant pollination will 

require the use of bumblebees.
9

In recent years, a number of reports have identified commerciallyproduced bumblebee colonies used for greenhouse pollination as a 

source of plant pest and disease outbreaks (Colla et al. 2006, 

Otterstatter and Thomson 2008, Szabo et al. 2012). In particular, the 

spread of Tomato apical stunt viroid (TASVd) in European, African, 

and Middle Eastern greenhouse tomato crops has been linked with 

pollination by bumblebees (Antignus et al. 2007). The bumblebees 

that pollinate greenhouse tomatoes are also a source of pathogen 

spillover linked to the decline of other economically-important 

pollinators, such as honey bees (Colla et al. 2006, Otterstatter and 

Thomson 2008). Bumblebees are major pollinators of both wild and 

agricultural plants in temperate regions, so widespread declines have 

implications for biodiversity and food production (Szabo et al. 2012).

Upon receiving Mexico’s request to allow importation of Solanum 

lycopersicum L. (Solanaceae) established in approved growing media 

into the United States, APHIS conducted a pest risk assessment (PRA)

(USDA-APHIS 2014) to examine the potential plant pest risk. The 

risk assessment prepared by APHIS examined the plant pest risk 

associated with the importation of Solanum lycopersicum L. 

(Solanaceae) established in APHIS-approved growing media from 

Mexico into the United States. 

The PRA characterizes risks as high, medium, or low, based upon 

supporting evidence regarding climate-host interactions, host range, 

dispersal potential, economic impact, and environmental impact of 

plant pests. The methods used to initiate, conduct, and report the risk 

assessment are consistent with guidelines provided by the North 

American Plant Protection Organization and the International Plant 

Protection Convention administered by the Food and Agriculture 

Organization of the United Nations.

The PRA (USDA-APHIS 2014) analyzes the quarantine pests

reasonably expected to follow the pathway (i.e., be included in 

commercial shipments of Solanum lycopersicum L. (Solanaceae)

plants from Mexico) were analyzed. A quarantine pest is defined as “a 

pest of potential economic importance to the area endangered thereby

and not yet present there, or present but not widely distributed and 

being officially controlled” (FAO, 2002). The biological hazard of an 

organism is only assessed if the organism can be identified to the 

species; however, if in the future, pests identified only to higher taxa 

are intercepted at the port of entry, then reevaluations of their risk may

occur. 

The pests that were determined to have potential to be included in 

commercial shipments of Solanum lycopersicum L. (Solanaceae) (both 

bare rooted or in growing media) are listed in Table 1.
10

Table 1. Quarantine Pests that May Follow the Pathway on Solanum

lycopersicum L. (Solanaceae) from Mexico (USDA-APHIS 

2014). 

Type Taxonomy Pest

Arthropod Diptera: Agromyzidae Liriomyza huidobrensis

Hemiptera: Aleyrodidae Aleurodicus dispersus

Bemisia tabaci (including biotypes 

B and Q)

Trialeurodes vaporarium

Hemiptera: Pseudococcidae Maconellicoccus hirsutus

Paracoccus marginatus

Thysanoptera: Thripidae Thrips palmi

A. Host Range of Quarantine Pests

The quarantine pests associated with the importation of Solanum 

lycopersicum from Mexico and identified in the PRA pose a potential 

risk to a variety of other plants. This section lists quarantine pests and 

the respective potential host plants found in the United States.

 

The spiraling white fly, Aleurodicus dispersus, is a species of small, 

white aphid that feeds on the sap of host plants. Its wide host range 

includes many vegetable, ornamental and fruit crops, as well as 

numerous trees and shrubs. The range of agricultural host crops 

includes banana, coconut, citrus, avocado, breadfruit, mango, 

macadamia, guava, paw-paw, peppers, bell peppers, poinsettia,

soybean, tomato, frangipani, sweet potato, lettuce, melons, cucumbers, 

hibiscus, blackberry, raspberry, and rose (Waterhouse and Norris 

1987). 

The silverleaf whitefly, Bemisia tabaci, is a species of small, white 

aphid that feeds on the sap of host plants. The range of agricultural 

host crops include: bell pepper, cucumbers, lettuces, poinsettia, and 

tomatoes. The silverleaf whitefly moves from one host species to 

another and is estimated as having a host range of around 600 plant 

species. 

The greenhouse or glasshouse whitefly, Trialeurodes vaporarium, is a 

species of small, white aphid that feeds on the sap of host plants. The 

range of agricultural host crops include: eggplants, cucumbers, beans, 

sweet peppers, tomatoes, poinsettias, and a large number of 

ornamentals, including species of Fuchias, Gervera, Pelargonium, 

Solanum and chrysanthemums, primulas. The number of host plants

for T. vaporarium totals over 800 species (CABI 2013). 
11

The larval stage of the Agromyzid fly, known as the serpentine leaf 

miner (Liriomyza huidobrensis), damages plants by mining into leaves 

and petioles. The plant’s ability to make food is often greatly reduced. 

In young plants and seedlings, mining may cause considerable delay in 

plant development leading to plant loss. The range of agricultural host 

crops include: eggplants, beets, broccoli, cauliflower, celery, bell 

peppers, cucumbers, broad beans, fava beans, garlic, hemp, flax,

lettuces, melons, onions, sweet peas, garden peas, potatoes, radishes, 

spinach, and tomatoes. In addition, several ornamental plants are 

considered hosts, including: chrysanthemums, baby’s breath, 

carnation, Verbena spp., Primula spp., Amaranthus spp., Aster spp., 

Dahlia spp., Dianthus spp., nasturtium spp., and Zinnia spp. (Steck 

2006).

The pink hibiscus mealybug, Maconellicoccus hirsutus, is a sapsucking insect and releases toxic substances causing injury and death 

to the plant. The range of agricultural host crops include: papaya, 

apple, soursop, cherry, passion fruit, carambola, avocado, mango, 

plum, grape, citrus, breadfruit, guava, banana, tomato, cucumber, 

pumpkin, peppers, okra, dasheen, lettuce, cabbage, beans, and squash. 

In addition, several ornamental can be host plants, including: hibiscus, 

bougainvillea, oleander, anthurium, lantana, focus, and heliconia 

(EPPO 2005). 

The papaya mealybug, Paracoccus marginatus, is a small sap-sucking 

insect that releases a toxic substance into the leaves of the host plant, 

causing injury and death. Its agricultural hosts crops include: papaya, 

hibiscus, avocado, citrus, cotton, tomato, eggplant, peppers, beans, 

peas, sweet potato, mango, cherry, and pomegranate (Walker et al. 

2003). The thrips Thrips palmi feeds on many hosts and attacks plants in 

several families. Among primary hosts are species of:

 Actinidia chinensis spp. (A. deliciosa);

 Amaranthus spinosus spp. (A. tricolor, A. viridis);

 Mangifera indica; 

 Ageratum spp. (A. conyzoides);

 Chrysanthemun spp.;

 Helianthus annuus;

 Lactuca sativa ;

 Cucumis spp. (C. melo, C. sativus);

 Cucurbita spp. (C. moschata, C. pepo);

 Allium cepa;

 Arachis hypogaea,;

 Glycine max; 

 Phaseolus vulgaris; 

 Vigna ungiculat; 
12

 Persea americana; 

 Gossypium spp;

 Abelmoschus esculentus; 

 Oryza sativa; 

 Sesamum indicum; 

 Citrus spp. (C. medica, C. Sinensis);

 Capsicum annuum;

 Nicotiana tabacum;

 Solanum spp. (S. lycopersicum, S. melongena, and S. tuberosum)

(CABI, 2011)

The bacteria, Ralstonia solanacearum race 3, is known on tomato as 

southern bacterial wilt, on potato as brown rot, and on tobacco as 

Granville wilt. It causes wilting, stunted growth, and secretion of 

bacterial ooze from the stem. 

B. Climate-Host Interaction

Climate limits the potential distribution and survival of pest species. 

The climactic limitations of the quarantine pests of concern are as 

follows:

The spiraling white fly, A. dispersus is a strong flier and has the

potential for spread. However, outside of tropical and sub-tropical 

regions of Florida, it appears unlikely that it would establish outdoors. 

The greenhouse or glasshouse whitefly, T. vaporariorum, is widely

distributed throughout North America because of its successful 

establishment in greenhouses. However, in warmer climates (such as 

those found in U.S. Plant Hardiness Zones 9-11), the whitefly can be 

found outdoors where it may overwinter on wild plants (CABI 2013). 

Plant Hardiness Zones 9-11 are currently found within portions of 

California, Oregon, Nevada, Arizona, Texas, Louisiana, and Florida. 

One or more of its potential hosts occur in these zones (USDA 1990)

2012c; (Magarey et al. 2008)

The silverleaf whitefly, B. tabaci B biotype, has been known as a pest 

of cotton and other tropical or semi-tropical crops in the warmer parts 

of the world. It can be found outdoors in warmer climates (those 

corresponding to U.S. Plant Hardiness Zones 9-11), and in 

greenhouses throughout North America. In March 2005, the ‘Q’ strain 

of B. tabaci was identified on poinsettia plants that originated from a 

nursery in California. This is the first time this particular strain has 

been found in the United States. The Q-biotype is thought to have 

originated from the Mediterranean region and has been associated with 
13

whitefly control problems (Hodges 2014).

The pink hibiscus mealybug, M. hirsutus, occurs in most topical areas 

of the world. Within the continental U.S., it is expected to colonize all 

of Florida and spread north into southern Georgia. These states feature 

U.S. Plant Hardiness Zones 8-11, currently found within portions of 

California, Oregon, Nevada, Arizona, Texas, Louisiana, Florida, 

Hawaii, and Puerto Rico (USDA 1990). Because pink hibiscus 

mealybug attacks so many crop and ornamental plants, populations 

could become common on many plant species in the places it is able to 

establish (Hoy et al. 2008).

The papaya mealybug, P. marginatus, has been intercepted in Texas 

and California. It is expected that it could rapidly establish throughout 

Florida and through the Gulf states to California (Walker et al. 2003). 

This region includes U.S. Plant Hardiness Zones 8-11. It is possible 

that certain greenhouse crops could be at risk in areas as far north as 

Delaware, New Jersey and Maryland (Walker et al. 2003). 

The serpentine leaf miner (L. huidobrensis), greenhouse whitefly, (T.

vaporarium), and silverleaf whitefly (B. tabaci) are usually restricted 

to greenhouse cultures in temperate climates, and are not expected to 

establish on host plants outside of the greenhouse environment. 

However, these pest species can be common in greenhouses, 

houseplants, and summer garden plants throughout the continental 

United States (Speyer 1927, Brown and Nelson 1988, EPPO 2001, 

Steck 2006).

Thrips palmi (T. palmi) is a thrips that is subtropical to tropical in 

distribution. Populations in temperate climates are able to overwinter in 

greenhouses or other artificial situations because it cannot survive 

subzero temperatures for more than a few days (Lewis 1997); (Capinera 

2010)). Based on this distribution, it is estimated that T. palmi could 

establish in the continental United States in U.S. Plant Hardiness Zones 

9–11. 

The bacteria Ralstonia solanacearum race 3 biovar 2 is believed to be 

native South America. In the United States, R. solanacearum occurs 

in the southern states, but is not known to be established in North 

America and Canada. However, should it establish, the U.S. Plant 

Hardiness Zones 8-11 (USDA 1990), would be most as risk. 
14

C. Threatened and Endangered Species

The following table lists threatened and/or endangered plant species 

that may be impacted by the establishment of actionable (i.e., 

quarantine) pests identified by the PRA. These pests may follow the 

pathway of tomato plantlets from Mexico into the United States.

Table 2. Quarantine (actionable) pests that may follow the pathway on 

tomato plantlets from Mexico into the United States and the 

associated Threatened and/or Endangered plant species that 

may be affected by their establishment (USDA-APHIS 2014).

Actionable Pest Listed Plant Species Distribution of Listed Species

A. dispersus Cucurbita okeechobeensis spp. 

okeechobeensis

FL

Hibiscus dasycalyx TX

B. tabaci

T. vaporarium

L. huidobrensis

Allium munzii CA

Cucurbita okeechobeensis spp. 

okeechobeensis

FL

Verbena californica CA

P. marginatus Hibiscus dasycalyx TX

M. hirsutus Cucurbita okeechobeensis spp. 

okeechobeensis

FL

Hibiscus dasycalyx TX

T. palmi Allium munzii CA

Cucurbita okeechobeensis spp. 

okeechobeensis

FL

Helianthus paradoxus NM, TX

Helianthus schweinitzii SC, NC

Piperia yadonii CA

Spiranthes delitescens AZ

Spiranthes parksii TX

IV. Environmental Impacts 

 

A. No Action

The PRA conducted by PPQ determined that a weed risk assessment 

was not needed for Solanum lycopersicum from Mexico because the 

plant is widely cultivated in the United States. Weed risk assessments 

do not need to be conducted for plant species that are widely 

established (native or naturalized) or cultivated in the Affected 

Environment, for commodities that are already enterable into the 

Affected Environment from other countries, or when the plant part(s) 

cannot easily propagate on their own or be propagated (USDA-APHIS 

2014). 

B. Preferred Alternative

Greenhouse-grown tomatoes are normally produced by specialist 

propagators and delivered to the grower at 3 to 6 weeks old. Once 
15

received by the grower, the plantlets are planted in the greenhouse at 

8,000 to 11,000 plants per acre, and are grown indoors hydroponically. 

Several arthropod pests (L. huidobrensis, A. disperses, B. tabaci 

(including biotypes B and Q), T. vaporarium, M. hirsutus, P. 

marginatus, and T. palmi) were identified as quarantine pests likely to 

be imported with unmitigated shipments of Solanum lycopersicum

from Mexico. To help protect against accidental importation, 

phytosanitary measures are required to minimize risk. 

Whiteflies

Whitefly feeding removes nutrients from the plant which may result in 

stunting, poor growth, defoliation, reduced yields and even death in 

extreme cases. The extent of damage caused by feeding is generally 

directly proportional to the whitefly population and low populations 

rarely have much impact. On certain plants, stunting or abnormal 

coloration can be caused due to the physiological stress of the feeding. 

Plants stressed by the removal of sap due to heavy whitefly feeding 

may require more irrigation.

Whiteflies secrete significant quantities of honeydew as they feed. 

When populations of whiteflies are high, honeydew production can be 

copious, dripping down leaves onto fruit. Honeydew becomes a 

serious problem when it is colonized by black, sooty mold fungi, 

blackening leaf or fruit surfaces. This can render fruit unmarketable 

and block out sunlight, inhibiting photosynthesis. 

In places where it occurs, A. dispersus is generally considered as a 

serious pest; it may present a risk for ornamentals or vegetable crops 

grown under glasshouse conditions. Chemical and biological control 

(release of parasitoids) methods are available, but the pest is reportedly 

difficult to control (EPPO 2000).

The silverleaf whitefly, B. tabaci was estimated to have caused 

combined losses of 500 million USD to the winter vegetable crops 

through feeding damage and plant virus transmission (EPPO 2001). 

In tomato plants, the B biotype of B. tabaci can cause uneven ripening 

of tomato fruits (Hodges 2014). In addition, B. tabaci is known to 

transmit numerous destructive viruses of tomatoes, including the 

tomato leaf crumple virus, tomato leaf curl begomovirus; both T. 

vaporariorum and B. tabaci can transmit the tomato torrado 

torradovirus (USDA-APHIS 2014). 

Biological control of T. vaporariorum has been widely used in 

greenhouses, especially since the development of insecticide-resistant 

whiteflies, and is chiefly based on the chalcid wasp E. formosa and 

1. Insects
16

parasitic fungi. The predatory beetle Delphastus pusillus is also very

effective against T. vaporariorum and B. tabaci (Mound and Halsey

1978). The “Q” strain of B. tabaci is known to have resistance to 

pyriproxyfen, buprofezin and reduced susceptibility to the 

neonicotinoid insecticides imidicloprid, acetamiprid, and thimethoxam

(Hodges 2014); this may pose a challenge to control efforts by

commercial producers and, if necessary, Agency pest suppression 

efforts. 

Leafminers

The serpentine leaf miner, L. huidobrensis, damages plants by larvae 

mining into leaves and petioles, and may cause considerable delay in 

plant development leading to plant loss. It has the potential to become 

a major pest of a wide variety of ornamental or vegetable crops grown 

under glass and as protected crops. Severely infested leaves may fall, 

exposing plant stems to wind action, and flower buds and developing 

fruit to scald (Musgrave et al. 1975). The presence of unsightly larval 

mines and adult punctures in the leaf of ornamental plants can further 

reduce crop value (Musgrave et al. 1975). In young plants and 

seedlings, mining may cause considerable delay in plant development 

leading to plant loss. 

The introduction of L. huidobrensis would likely initiate control 

programs in areas of the United States because it is a major pest of 

numerous economic crops. Outbreaks in crops within the affected 

environment area would likely trigger increased chemical control 

programs. Some insecticides, particularly pyrethroids (abamectin) and 

also cyromazine are effective , but leaf miner resistance can sometimes 

make control difficult (Parrella et al. 1984). Natural enemies 

periodically suppress leaf miner populations. Dacnusa sibirica, Opius 

pallipes and Diglyphus isaea have been considered for use as natural 

enemies of the pest in European glasshouses (Parrella et al. 1982). 

Mealybugs

The damage from both the pink hibiscus mealybug (M. hirsutus) and 

the papaya mealybug (P. marginatus) included plant stunting, leaf 

deformation, early leaf and fruit drop, a heavy buildup of honeydew, 

and death. Biological control has been identified as a key component 

in a management strategy for mealybug species, including the use of 

natural enemies. These include the commercially available mealybug 

destroyer (Cryptolaemus montrouzieri), lady beetles, lacewings, and 

hover flies, all which are generalist predators that have a potential 

impact on mealybug populations. In addition to predators, several 

parasitoids may attack papaya mealybug. In addition, Anagyrus 
17

kamali has been identified as an effective parasitic control of the pink 

hibiscus mealybug (Hoy et al. 2008).

A number of chemical controls are available to control mealybugs, 

although none are currently registered specifically for control of either 

the papaya or pink hibiscus mealybug. Active ingredients in registered 

pesticide formulations include acephate, carbaryl, chlorpyrifos, 

diazinon, dimethoate, malathion, and white mineral oils. Typically, 

twice the normal dose is applied when treating for mealybugs because 

mealybugs are protected by thick waxy, cottony sacs, and often are 

concealed inside damaged leaves and buds. Thus, chemical controls 

are only partially effective and require multiple applications. 

Furthermore, problems with insecticide resistance and non-target 

effects on natural enemies make chemical control a less desirable 

control option to combat the mealybugs. 

Thrips

Thrips palmi is subtropical to tropical in distribution, and cannot 

survive subzero temperatures for more than a few days. U.S. 

populations are restricted to American Samoa, southern Florida, 

Guam, Hawaii, and Puerto Rico (APHIS, 2012a). Thrips palmi is a 

serious pest of cucurbits and eggplant. The species is a vector of 

tomato spotted wilt tospovirus (CABI, 2001), which is difficult to 

control chemically, requiring repeated applications of insecticides to 

achieve acceptable levels of control (Sakimura et al., 1986). Its 

introduction would undoubtedly initiate control programs in areas of 

the United States because it is a major pest of numerous economic 

crops (e.g., beans, peppers, and tomatoes). Outbreaks in crops within 

the affected environment area would likely trigger increased chemical 

control programs similar to those now in effect for other caterpillars. 

Heavy infestations of thrips could cause dieback or death of host 

plants; however, outbreaks in other horticultural crops and orchids are 

not likely to occur due to its restricted host range. 

 

The European and Mediterranean Plant Protection Organization 

identify tomato plants for planting and whiteflies B. tabaci and T.

vaporariorum as possible pathway risks for the introduction of the 

Tomato Torrado Virus (ToTV) (Pospieszny et al. 2007, Amari et al. 

2008, EPPO 2009). The ToTV virus causes lesions and holes in the 

stems and leaflets, and deformations of the fruits; this renders the fruits 

unmarketable.

R. solanacearum Race 3 Biovar 2 was first detected in the U.S. on 

geraniums in 1999, and subsequently eradicated. The bacterium can 

spread in soil, in which it survives for varying periods of time, and in 

2. Viruses

3. Microbes
18

irrigation (drainage) water. In tropical areas, many weeds have been 

shown to be alternate hosts and harbour the bacterium, providing a 

bridge for the pathogen between crops (Wenneker et al. 1999).

R. solanacearum constitutes a serious obstacle to the culture of many

tomato plants in both tropical and temperate regions. Chemical 

control may be difficult. Antibiotics such as streptomycin, ampicillin, 

tetracycline and penicillin would also offer limited pest control (Farag 

et al. 1986). In its recovery plan for R. solanacearum Race 3 Biovar 2, 

the USDA states that a response to the detection of R. solanacearum

would include a quarantine of infested or potentially infested 

production areas, restricted movement of infested or potential infested 

articles in commerce, and initiation of control measures such as host 

removal and destruction (USDA 2010). Host destruction is required 

along with disinfection, water decontamination, and several years of 

non-host production in infected fields or associated growing areas 

before quarantines can be removed.

C. Risk Management

Although the affected environment and the environmental 

consequences under both the no action alternative and the preferred 

alternative are the same, the risk management to prevent the 

introduction of pests differs between the two alternatives. The 

following section discusses the phytosanitary measures imposed under 

the two Alternatives: the current regulation prohibiting the importation

of Solanum spp. plantlets (bare rooted and in growing media) from all 

countries other than Canada (no action alternative); and changing the 

current regulation to add Solanum lycopersicum (Lycopersicum 

esculentum) from Mexico to the list of plants that may be imported in 

approved growing media (preferred alternative).

The phytosanitary measures of the no action alternative would leave 

7 CFR part 319 unchanged. Section 319.37–8(a) of the regulations 

requires, with certain exceptions, that plants offered for importation 

into the United States be free of sand, soil, earth, and other growing 

media. This requirement is intended to help prevent the introduction 

of plant pests that might be present in unapproved growing media; the 

exceptions to this requirement take into account factors that mitigate 

that risk. 

This section describes the phytosanitary measures required if tomato 

plantlets in approved growing media are imported into the continental 

United States from Mexico. Amendment of 7 CFR §319 would allow 

importation of tomato plantlets from Mexico in growing media, 

subject to a systems approach. The systems approach would consist of 

1. No Action 

2. Preferred 

Alternative
19

measures currently specified for tomato plants for planting not 

imported in growing media (specified in 7 CFR §319.37-5(r)(3)), as 

well as measures specific to all plants for planting imported into the 

United States in approved growing media (specified in 7 CFR § 

319.37–8(e)). Additionally, the plantlets would have to be imported 

into greenhouses in the United States that have entered into 

compliance agreements with APHIS regarding the conditions under 

which the plants must enter and be maintained within the greenhouses. 

Systems Approach

To effectively prevent the introduction of plant pests associated with 

plants grown in approved media, a series of important safeguards, 

(phytosanitary measures) must be in place. The risk management 

program used for plants in media is the systems approach—a defined 

set of phytosanitary procedures, at least two of which have an 

independent effect in mitigating pest risk associated with the 

movement of commodities. This approach relies on a series of 

phytosanitary measures that, individually and cumulatively, reduce the 

pest risk posed by pests that may be associated with plants. All phases 

associated with plants established in growing media—before planting, 

during the growing period, postharvest, during transport, and 

importation—are considered. 

The specifics requirements of the systems approach for the importation 

of tomato plantlets in growing media from Mexico would extend 

beyond those discussed above to address the importation risk of R. 

solanacearum race 3 biovar 2. These include: 

 production in registered greenhouses;

 periodic testing within the greenhouses for R. solanacearum

race 3 biovar 2;

 construction of the greenhouses in a manner which prevents 

runoff water from entering the greenhouses;

 control for dicotylendonous weeds;

 sanitization measures for equipment and personnel entering the 

greenhouse;

 use of approved growing media and water from an approved 

source, education for personnel regarding the pathways of 

transmission of R. solanacearum race 3 biovar 2;

 handling and packing of the articles in a manner to prevent the 

introduction of R. solanacearum race 3 biovar 2 into the 

articles;

 labeling of the articles destined for export, and;

 issuance of a phytosanitary certificate declaring that the articles 

have been produced in accordance with the systems approach.
20

The APHIS regulation on plants in media requires multiple 

phytosanitary measures designed to reduce the pest risk. The overall 

systems approach operates like as a fail-safe system in that tiered 

safeguards are built into the process. That is, if one mitigating 

measure fails, other safeguards exist to ensure that the risk is 

progressively reduced and managed. The systems approach is 

designed to apply all the measures to obtain the maximum risk 

reduction and to apply additional safeguards, as required. The steps or 

measures may overlap or be redundant to ensure an adequate reduction 

in pest risk, and that the reduction of risk is maintained during the 

entire process. 

a. Approved Plant Sources

7 CFR 319.37-8 requires that plants are grown from seed germinated 

in the pest exclusionary greenhouse. SAGARPA (2012a) and the PRA 

(USDA-APHIS 2014) indicate that certified seed will be obtained 

from several multinational sources but does not specify what 

pathogens the seed will be certified as free from. SAGARPA (2010)

further states that the seed will be disinfected to remove seed 

transmitted bacterial pathogens.

b. Approved Growing Media

7CFR§319.37-5 (r)(3) requires that growing media must be free of R. 

solanacearum and must be an APHIS approved growing medium as 

listed in 7CFR§319.37-8 (e)(1). (SAGARPA 2010) indicates that 

tomato plantlets will be grown in peat and rock wool; both are 

approved media. The USDA Minimum Sanitation Protocols for 

Offshore Geranium Cutting Production (USDA 2007) further requires 

that the growing media be sterilized by steam or fumigation.

The use of new, sterilized growing media reduces the risk of 

introducing Liriomyza pupae and the soilborne pathogen R. 

solanacearum into the crop (Bethke 2010). Soil sterilization,

including steam and methyl bromide are effective in controlling soil 

inhabiting pupae of Liriomyza (Cheek 1999). Soil sterilization will 

kill immature thrips, such as T. palmi, that are pupating in the soil 

(Shipp et al. 1991). In general, using sterile or sterilized growing 

media reduces the likelihood of crop infestation by soil-dwelling pest 

life stages (Cheek 1999).

c. Agreements 

Mexico’s NPPO, SENASICA, must enter into a bilateral workplan 

with APHIS setting out the conditions for producing and monitoring 

plant production and enforcement of the requirements of the 
21

regulation. Likewise, the production facility must enter into a 

compliance agreement with the producing country NPPO. Improper 

production and handling practices are often the primary means by

which pests are introduced and spread in the place of production. The 

phytosanitary written agreements and administrative measures 

included in 7CFR § 319.37-8 and 7CFR§ 319.37-5 (r)(3) provide 

additional phytosanitary quality control and rigor over other measures, 

and reduce the possibilities of improper practices being employed. 

These measures are standard for many export programs and assist in 

maintaining quality of the program.

d. Exclusionary Greenhouse 

The tomato plantlets for shipment must be grown in a pest 

exclusionary greenhouse using the following phytosanitary measures: 

“Grown solely in a greenhouse in which sanitary procedures are 

adequate to exclude plant pests and diseases are always employed, 

including cleaning and disinfection of floors, benches, and tools, and 

the application of measures to protect against any injurious plant 

diseases, and injurious insect pests, and other plant pests” (7 CFR § 

319.37–8(e)(2)(ii)). These measures may include trapping, surveying, 

and scouting to determine if pests are present, and pesticide 

applications or other control measures to eliminate pests that are 

discovered.

Runoff surface water from from fields or waterways with infected 

weed or crop hosts can carry Ralstonia (Wenneker et al., 1999). USDA 

(2007) requires that greenhouses are constructed in a manner to 

prevent contaminated runoff from entering production areas.

e. Raised Benches

The height of the benches on which the tomato plantlets are grown 

must be at least 46 centimeters above the floor. Raised benches reduce 

the chance of water being splashed onto benches from the floors that 

might be contaminated with pests, including R. solanacearum. 

f. Greenhouse pest monitoring and management plan 

Sticky traps are an efficient tool for monitoring early infestations of 

thrips (Brødsgaard, 1989).

In addition to monitoring plants for Liriomyza feeding and oviposition 

damage (stippling) and for the presence of small mines on plants, 

sticky traps are used for detection of leafminer activity. Yellow sticky

cards are the best detection method for monitoring populations of adult 

activity (Bográn, 2005; Weintraub and Horowitz, 1996).
22

A comprehensive pest management plan must be implemented, and 

must include monitoring, inspections for signs of infestation, and 

targeted pest control as appropriate. Information gathered from 

scouting is used to select and schedule appropriate control tactics 

(Bethke, 2010). The pest management plan must be approved by the 

NPPO, and if treatments are required, these must be approved and 

prescribed by the NPPO.

g. Automatic Doors 

Automatic closing double doors create a plant free area that workers 

must pass through reducing the likelihood that pests will enter the 

growing area (Dreistadt 2001). They are also used, to a limited extent, 

to keep windborne pests from being blown into the growing area and 

provide a physical barrier that reduces the exposure of the plants to 

splashing by rain and irrigation water (Agrios, 1997).

h. Screens 

7CFR§ 319.37-8 requires all vents and openings must be covered with 

screens having openings no greater than 0.6 mm (30 mesh). This mesh 

size is small enough to exclude leafminers (Bethke 1994). Adult 

Liriomyza flies are 1-3 mm in length with a wingspan of about the 

same dimensions (CABI 2014). Adults are excluded by greenhouse 

screens with an opening of 0.6 mm or smaller (Bethke 1994, Bethke et 

al. 1994); (Bográn 2005). While 0.6 mm mesh will not exclude the 

other smaller arthropod pests (e.g., aphids, whiteflies, thrips) they may

provide some limited discouragement to their entry. Mesh hole size 

does not necessarily correspond with degree of exclusion (Bell and 

Baker 2000). However, SAGARPA (2013) states, “The tomato 

plantlets are grown in the dedicated nursery area that is fitted with 

screens on all openings. These screens are small enough to exclude 

the entrance of Thrips into the growing area, therefore also excluding 

the larger insects, aphids and whiteflies.” Because of thrips small size, 

a mesh size of 80 (0.177 mm opening) or smaller is required to restrict 

their entry into the greenhouse (Bethke, 1994; Ghidiu and Roberts; 

Sood, 2010). We are specifying mesh screen to be used in conjunction 

with a pest management program to ensure that no thrips (or other 

arthropods) will move with tomato plantlets.

i. Removal of weeds

Sanitation including the removal of weeds from inside and outside

greenhouses is an important cultural practice for preventing whitefly 

infestations within greenhouses (Shipp et al., 1991). Leafminers feed 

on a large variety of plant species including weeds, keeping 
23

greenhouses and areas outside the greenhouse free of weeds, which 

can serve as reservoirs for leafminer populations and exclusion of 

immigrating adults is valuable as a cultural control (Bethke, 2010).

j. Sanitation 

Sanitation and exclusion are highly effective in controlling most pests 

(Dreistadt 2001). “Strict adherence to good sanitation practices is 

essential to the management of bacterial diseases” (Dicklow 2013). 

SAGARPA (2010) provides general information indicating that 

grafting areas will be disinfected regularly and that grafting benches 

are equipped with disinfectant for tools.

The APHIS Minimum Sanitation Protocols for Offshore Geranium 

Cutting Production (USDA 2007) requires that greenhouse floors be 

maintained free of debris and weeds and floors must drain properly to 

prevent puddling. Plant material (cuttings, trimmings, etc.) that falls to 

the floor should not be retrieved by greenhouse workers who are in the 

process of handling production stock plants; it should be removed on a 

periodic basis (minimum weekly) and disposed of by other workers or 

by same workers after harvesting of cuttings is completed. Floors are 

to be sanitized at least once annually when greenhouses are cleared of 

stock production plants or before they are set up for the next growing 

season. Furthermore, the protocol requires surfaces upon which plants 

are grown should be disinfested prior to use and constructed so water 

draining from pots does not make contact with other pots. Greenhouse 

equipment used to make grafts or cuttings or used for other functions 

involving contact with plants is to be surface disinfested prior to and 

between use on each plant or container. Alternatively, a set of knives 

can be assigned to a specific bench and rotated and disinfected 

between each plant. Carts and collection baskets are to be sprayed 

with a surface disinfectant on all surfaces that are likely to come into 

contact with plants or equipment used in processing plants. 

Equipment (knives, etc) used to harvest cuttings is to be soaked in 

surface disinfectant when not in use.

Liriomyza larvae remain inside the leaf onto which they hatched until 

they pupate. After feeding, mature larvae exit the leaf and drop to the 

ground to pupate. Pupae can remain viable in the soil or substrate for 

several months at low temperatures and cause re-infestation in the 

following crop. Sanitizing floors, benches or areas underneath benches 

lowers the potential for these areas to harbor pupae. Regular, rapid 

removal of plant debris prevents the continuing development of foliar 

stages of pests such as Lirionzyza spp. on excised leaves (Cheek 

1999).
24

k. Worker hygiene and training

 

SAGARPA (2010) provides a general description of the worker 

hygeine system in the production greenhouses. The infrastructure is 

designed to limit the access and to force the flow of the people through 

a series of stations and processes for disinfection including a grate to 

eliminate the debris from shoes; a laundry to wash uniforms; an area to 

store personal belongings so they do not enter the greenhouse; 

dedicated footwear that is disinfected upon entry; handwashing station; 

an entryway that can only be opened by placing hands in a 

disinfectatnt bath to reach the release button; a dressing area with 

dedicated coveralls. This generally follows the requirements of 

7CFR§319.37-5 (r)(3) as outlined in (USDA 2007).

7CFR§319.37-5 (r)(3) requires that production site personnel receive 

training to recognize and prevent the introduction of Ralstonia. 

Mandatory training decreases the likelihood that personnel will 

participate in activities that might introduce pests into the facility and, 

in the event of an introduction, will increase the likelihood that they

will recognize pest symptoms and take appropriate action. 

SAGARPA, 2010 states that the production facility in Mexico “has 

continuous training of supervisors and workers to assure that they

receive continuous education and qualification about sanitation 

protocols and practices...supervision personnel has...basic knowledge 

on pest identification.”

l. Clean Water Sources

The 7CFR§ 319.37-5 (r)(3) requirement for treatment of irrigation 

water is dependent upon its source and the water storage and delivery

system in use. Water treatment is not required for irrigation water 

collected from deep wells which are properly sealed and where the 

water is used directly or stored in tanks with no opportunity for 

contamination of the water supply by native soil or plant 

material/debris, or from municipal water directly from the municipal 

water system. SAGARPA (2010) states water used in the greenhouse 

is either spring or well water and is disinfected with chlorine and 

ultraviolet light. The treatment method used must be equivalent to the 

treatments described in USDA (2007)

. 

Plants may not be irrigated using ebb and flow or flood irrigation 

systems as these methods foster spread of R. solanacearum race 3 

biovar 2. Irrigation systems should be constructed so that emitters are 

not in contact with growing media and/or are equipped with backflow 

devices to prevent contamination of the watering system. The last 4’ of
25

hose closest to the bench and hose-end implements used for hand 

watering tomato plantlets should never come in contact with the floor 

of production facilities, plant material or growing media. When such 

contact is made, the hose and watering implement must be treated with 

a surface disinfectant, such as those listed in USDA (2007).

m. Phytosanitary Certificate 

A phytosanitary certificate must be issued. This document must 

accompany the plants during importation and certify that the required 

growing conditions were met. 

n. Inspection 

Phytosanitary inspections are widely recognized as an important part 

of a pest management program (Kahn and Mathur 1999). Many 

insects, mites and pathogens have visible stages and symptoms that are 

readily detected upon inspection. Inspection is the foundation of pest 

exclusion used by APHIS to prevent pests from entering the United 

States.

Adult Liriomyza females feed on leaf tissues resulting in a stippled or 

speckled appearance when they puncture the leaf surface with their 

ovipositors. Females also puncture leaf tissue to lay their eggs. Larvae 

feed on leaf tissue creating a serpentine leaf-mine. The mines 

gradually increase in size as larvae feed and grow (Bográn 2005). 

Stippling and leaf mines are readily detected by plant inspection. 

Careful inspection of all plant material before it is brought into the 

greenhouse and destruction of any infested plants helps to exclude 

leafminers. The European and Mediterranean Plant Protection 

Organization (EPPO) has recommended inspection of plants for 

planting at least every month as a means to prevent the spread of 

Agromyzidae leafminers in exported plants (CABI 2014).

o. Packing and Storing

Sanitation and exclusion are highly effective in controlling most pests 

(Dreistadt 2001). “Strict adherence to good sanitation practices is 

essential to the management of bacterial diseases” (Dicklow 2013), 

including R. solanacearum.

p. Traceability

Labelling of consignments to allow traceback is required. Traceback 

is effective at removing problem places of production from the 

systems approach. 7CFR§319.37-5 (r)(3) requires removal of export 

eligibility of a facility in the event of the detection of Ralstonia at the 
26

in consignments. Traceback enables the identification of the problem 

facility. Places of production must be registered to effectively 

maintain quality control and traceback.

Conclusions

The PRA considered the likelihood and consequences of introducing 

the pests listed in Table 1 and indicated that all of the pests received 

negligible risk ratings for likelihood of introduction (i.e., entry plus 

establishment) into the endangered area via the import pathway. For 

pests receiving a Negligible risk rating, pest introduction is considered 

highly unlikely to occur given the exact combination of events 

required for successful introduction (USDA 2012). In reaching this 

finding, the PRA considered the effects of all greenhouse 

specifications described in supporting documents provided by the 

Mexican NPPO (SAGARPA 2010, 2013). Those 

production/greenhouse specifications are listed under the Preferred 

Alternative in the Alternatives section of this document.

The analysis provided in this Environmental Assessment is in 

agreement with the PRA (USDA, 2013), which determined that the 

requirements in 7 CFR§ 319.37-8, 7CFR§319.37-5 (r)(3), and those 

described in the Risk Management section of this document under 

Systems Approach will be effective in managing the risk associated 

with the pests listed in Table 1. 

D. Endangered Species Act

Section 7 of the Endangered Species Act (ESA) and the ESA’s 

implementing regulations require Federal agencies to consult with the 

U.S. Fish and Wildlife Service (FWS) and/or the National Marine 

Fisheries Service to ensure that their actions are not likely to 

jeopardize the continued existence of threatened or endangered species 

or result in the destruction or adverse modification of critical habitat. 

Based upon program review of the systems approach conditions for 

importation in the rulemaking, PPQ determined that the action would 

result in “no effect” to any proposed or listed endangered or threatened 

species or their critical habitat in the continental United States, as the 

imported tomato plantlets will be raised within monitored greenhouses 

for fruit and destroyed. These plantlets will not be released into the 

environment, removing any risk of the plantlets in transmitting 

organisms that could potentially impact federally protected species. 

This determination precludes the need for formal or informal 

consultation with the U.S. Fish and Wildlife Service or National 

Marine Fisheries Service. A separate document will further detail this 

“no effect” determination.
27

E. Other Considerations

Executive Orders

Executive Order (EO) 12898, "Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations," focuses Federal attention on the environmental and 

human health conditions of minority and low-income communities,

and promotes community access to public information and public 

participation in matters relating to human health or the environment. 

This EO requires Federal agencies to conduct their programs, policies, 

and activities that substantially affect human health or the environment 

in a manner so as not to exclude persons and populations from 

participation in or benefitting from such programs. It also enforces 

existing statutes to prevent minority and low-income communities 

from being subjected to disproportionately high and adverse human 

health or environmental effects. Neither alternative poses 

disproportionately high or adverse human health or environmental 

effects to any specific minority or low-income group.

EO 13045, “Protection of Children from Environmental Health Risks 

and Safety Risks,” acknowledges that children may suffer 

disproportionately from environmental health and safety risks because 

of their developmental stage, greater metabolic activity levels, and 

behavior patterns as compared to adults. The EO, (to the extent 

permitted by law and appropriate, and consistent with the agency’s 

mission) requires each Federal agency to consider environmental 

health risks and safety risks that may disproportionately affect 

children. Neither alternative is expected to have disproportionately

high or adverse human health or environmental effects to children.

V. Listing of Agencies Consulted

Environmental and Risk Analysis Services

Policy and Program Development

Animal and Plant Health Inspection Service

U.S. Department of Agriculture

4700 River Road, Unit 149

Riverdale, MD 20737–1238

Phytosanitary Issues Management

Plant Protection and Quarantine

Animal and Plant Health Inspection Service

U.S. Department of Agriculture

4700 River Road, Unit 140
28

Riverdale, MD 20737–1228

Regulations, Permits, and Manuals

Plant Protection and Quarantine

Animal and Plant Health Inspection Service

U.S. Department of Agriculture

4700 River Road, Unit 141

Riverdale, MD 20737–1228

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