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January 21,
2004
from
USDA/APHIS
Recent
detections of Ralstonia
solanacearum race 3 biovar 2, in December 2003, have
been traced to an importer of geraniums from Guatemala. In
response to the recent detections, the U.S. Department of
Agriculture‘s (USDA) Animal and Plant Health Inspection Service
(APHIS) has temporarily suspended imports of geraniums from one
producer in Guatemala. APHIS will not lift the import ban, until
it inspects the affected facilities and specifies future
preventative measures to be implemented.
The disease
was found in two varieties of geraniums—Americana Coral and
Americana Bright Red. A third variety, Americana Cherry Rose II,
is implicated because it was produced in the same vicinity in
Guatemala as the two varieties that tested positive. More than
400 customers have received the potentially infected varieties.
Customers that have purchased affected varieties from Guatemala
are encouraged to monitor potentially affected plants for wilt
and to report any symptoms to their local State Plant Health
Director(SPHD) .
In
cooperation with the importer of the affected plants, APHIS is
actively tracing the whereabouts of the suspect material. APHIS’
priority is to locate, evaluate, and destroy, if necessary,
infected plant material.
Ralstonia solanacearum
race 3 biovar 2, a bacterial pathogen, poses a significant
threat to the flower and potato industries. While other races of
Ralstonia solanacearum
exist in the United States, Ralstonia solanacearum race 3 biovar
2 is newly detected in this country. Ralstonia solanacearum race
3 biovar 2 was first officially confirmed by APHIS in imported
geraniums in the United States in February 2003, and was
eradicated.
Ralstonia solanacearum
race 3 biovar 2 is known to infect ornamental plants (e.g.,
geraniums) and several important agricultural crops (e.g.,
tomatoes, eggplants, peppers, and potatoes). Plants infected
with Ralstonia
solanacearum develop yellowing,
wilting, and browning of the lower leaves. In geraniums, the
symptoms of Ralstonia solanacearum may be confused with
bacterial blight caused by
Xanthomonas pelargonii.
Both diseases cause the infected plants to wilt. Bacterial
blight also causes leaf spots, which Ralstonia solanacearum does
not.
Ralstonia solanacearum
is transmitted especially well in water and soil, as well as
through certain greenhouse practices. The disease is spread very
easily by transplanting infected plants and propagative
material. Pruning and grafting without disinfecting associated
equipment between plants may also facilitate spread of the
disease.
In
potatoes, Ralstonia
solanacearum race 3 biovar 2 causes bacterial wilt,
which has severely limited crop production in parts of Asia,
Africa, and South and Central America, where it has occurred.
Bacterial wilt is one of the most destructive diseases of
potatoes.
February, 2004
General
Q.
What is
Ralstonia?
A.
Ralstonia solanacearum
race 3 biovar 2 is a bacterial pathogen that infects numerous
plants. Various races of
Ralstonia affect different crops around the world
including tomato, potato, eggplant, and banana. While race 1 is
endemic to the Southeastern United States where it affects
tomato crops, Ralstonia
solanacearum race 3 biovar 2 is not known to occur
in the United States and is considered of quarantine importance.
Q.
What are the horticultural and agricultural risks of
Ralstonia?
A.
Ralstonia solanacearum
race 3 biovar 2 is known to infect ornamental plants (e.g.,
geraniums) and
several important agricultural crops (e.g., potatoes, tomatoes,
eggplants, and peppers). In potatoes,
Ralstonia solanacearum
race 3 biovar 2 causes brown rot, or bacterial wilt, which
renders the potatoes unmarketable. Global damage estimates on
bacterial wilt of potatoes currently exceed $950
million per year.
Q.
How is
Ralstonia
transmitted between plants?
A.
Ralstonia
solanacearum
race 3 biovar 2 can be transmitted through irrigation water,
contaminated soil, equipment, or people. For example, it may be
spread by propagating infected plants, taking cuttings without
disinfecting cutting implements between plants, pinching buds of
plants without sanitizing hands, and especially by shared water
irrigation systems.
Q.
Does
Ralstonia
pose a threat to human health?
A.
Ralstonia solanacearum
race 3 biovar 2 does not cause disease in humans or
animals.Scope of Recent
Ralstonia
Infestation
Q.
How many geranium plants have tested positive in the United
States?
A.
Ralstonia solanacearum
race 3 biovar 2 was found in two varieties of
geraniums—Americana Coral and Americana Bright Red in a
greenhouse in New York in December 2003. A third variety,
American Cherry Red II, is implicated because it was produced in
the same greenhouse in Guatemala as the two varieties that
tested positive.
Q.
How many greenhouses are thought to be affected?
A.
Approximately 450 facilities in 41 States have received suspect
geraniums from the infected Guatemalan facility.
Q.
How were greenhouse owners notified that they may have received
potentially infected plants?
A.
Based on records provided by the plant importer, U.S. Department
of Agriculture’s (USDA) Animal and Plant Health Inspection
Service’s (APHIS) Plant Protection and Quarantine (PPQ)
officials compiled a confidential list of potentially affected
nursery facilities. This list was then provided to the
corresponding State Department of Agriculture, who in
cooperation with Federal officials, contacted the affected
nurseries to schedule an investigation. During this
investigation, PPQ or State inspectors collected invoices and
shipping lists and recorded the location and number of suspect
plants. The purpose of the investigation was to assess the
extent of potential contamination of other plants in addition to
the three geranium varieties of concern, and whether wilt was
present in other geranium varieties as well.
Q.
Has any sampling been performed in the country of origin to
establish a link between the positive plants in New York and the
host country?
A.
PPQ scientists
have inspected the implicated Guatemalan facility and have
confirmed Ralstonia solanacearum race 3 biovar 2 in water collected
from one of the infected geranium varieties in Guatemala. The
tested water effluent and the New York positive plants were
collected from the same Guatemalan greenhouse. The basis for
APHIS’ control program is the positive test samples in New York.
Confirmatory testing in Guatemala was not necessary for APHIS to
initiate control actions.
APHIS Control Actions
Q.
Is there an available treatment for infected geraniums?
A.
No. There is no available treatment for plants infected with
Ralstonia solanacearum
race 3 biovar 2. Potentially infected geraniums must be
destroyed to prevent the spread of the disease.
Q.
Can greenhouse owners sell infected geraniums?
A.
No. Greenhouses that have received suspect geraniums will be
issued a “hold order,” which prohibits the movement of suspect
geraniums and other potentially infected plants from the
property until further evaluations can be made or control
actions taken.
Q.
Will potentially infected geraniums be destroyed?
A.
Yes. USDA has
ordered the destruction of all Americana Bright Red, Coral, and
Cherry Rose II, also marketed as Cherry Rose, shipped from a
geranium producer in Guatemala between August 2003 and January
2004. Additional plants may be potentially infected based on
watering and sanitary practices at the nursery. Destruction of
potentially infected geraniums should be witnessed, supervised,
and documented by a PPQ or State official.
Q. Is APHIS testing
plants prior to destruction?
A.
No tests are available for the large–scale nondestructive
sampling necessary to reliably determine if stock is free of
Ralstonia solanacearum
race 3 biovar 2. Available immunological tests require the
destruction of tested plants and can only identify the
Ralstonia solanacearum
bacterial group, not the targeted race and biovar. Based on the
lack of available testing methods and more precise data from the
geranium producer on potentially infected plants, APHIS must
conclude that all Americana Bright Red, Coral, and Cherry Rose
II cuttings produced in Guatemala between August 2003 and
January 2004 are potentially infected and should be destroyed.
Q.
Are asymptomatic (i.e., wilt-free) geraniums necessarily free of
Ralstonia
solanacearum
race
3 biovar 2?
A.
No. Geraniums that appear healthy and do not exhibit symptoms of
wilt may in fact be infected with
Ralstonia solanacearum
race 3 biovar 2. The only way to ensure a plant is not infected
with Ralstonia solanacearum race 3 biovar 2 is to destroy the
plant and perform laboratory testing. The number of asymptomatic
plants that would be required for testing to assure a group of
plants is free of the pathogen is not currently known.
Q.
What are the major differences between the 2003 and 2004
Ralstonia solanacearum
race 3 biovar 2 action plans?
A.
The February 2003 action plan developed to manage last year’s
Ralstonia introduction is not to be used to manage the current
introduction. The major changes from the 2003 action plan are:
- Definition of the basic
unit of control. In the February 2003 version, the shipment
was the basic level of control. In the current situation,
three geranium varieties (Americana Bright Red, Americana
Coral, and Americana Cherry Rose II [also marketed as
Americana Cherry Rose]) are the basic unit of control. These
plants, and other potentially infected plants as defined in
the action plan, are targeted for destruction.
- Elimination of the
destruction of all plants within 1–meter of an infected
shipment. There is little or no risk of
Ralstonia solanacearum
race 3 biovar 2 transmission through leaf contact or splashing
of water from leaf–to–leaf.
- Elimination of the
time/temperature model for holding plants. The model was an
attempt to predict when infected plants express wilt symptoms.
USDA based this on the idea that uninfected plants would not
express wilt while infected plants would wilt if subjected to
high enough temperatures for a long enough duration. USDA has
since learned through research that this model is unreliable
and cannot be used to accurately and consistently identify
infected plants. Studies indicate that some plants continue to
have latent infections, not showing wilt, even when high
temperatures are maintained for long periods of time.
Compensation
Q.
Will greenhouse owners be compensated for destroyed stock?
A.
USDA is not compensating owners for destroyed stock. For
additional information or guidance, growers may consult the USDA
Crop Disease Assistance services (i.e. Farm Service Agency, Risk
Management Agency) at http://disaster.usda.gov/crop_jump.htm, as
well as private insurers for crop insurance.
The U.S. Department of Agriculture (USDA)
prohibits discrimination in all its programs and activities on
the basis of race, color, national origin, sex, religion, age,
disability, political beliefs, sexual orientation, or marital or
family status. (Not all prohibited bases apply to all
programs.) Persons with disabilities who require alternative
means for communication of program information (Braille, large
print, audiotape, etc.) should contact USDAís TARGET Center at
(202) 720-2600 (voice and TDD).
To file a complaint of discrimination, write
USDA, Director, Office of Civil Rights, Room 326-W, Whitten
Building, 1400 Independence Avenue, SW, Washington, DC
20250-9410 or call (202)?720-5964 (voice and TDD). USDA is an
equal opportunity provider and employer.
PDF format
version:
http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/faq_phralstonia.pdf
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