Plants and Plant Products
Mitigating Risk
Approaches for mitigating risk (achieving quarantine or phytosanitary
security in commodities)Most approved commodities are enterable with
inspection alone. The PPQ has several options regarding the approaches
to recommend for mitigating risk (achieving quarantine or phytosanitary
security) for pests in commodities when the risk assessment indicated
that inspection alone would not be adequate.
Approaches for mitigating risk include:
- Post harvest treatments
- Pest-free areas
- Systems approaches
- A variety of specially designed inspection schemes.
We will focus primarily in this module on post harvest treatments,
pest-free areas, and systems approaches because they are the ones
used most widely at this point.
Post harvest treatments:
This approach to quarantine security has as its objective mortality,
sterility, or prevention of maturation of pest organisms. An example
of a non-chemical treatment is the hot water dip treatment developed
to establish quarantine security for fruit flies in mangoes.
Post harvest treatments may inflict enough damage on some commodities
as to make them unmarketable. Other approaches for achieving quarantine
or phytosanitary security may then be preferable.
Circumstances for use in post-harvest situations:
- the host is suitable;
- the infestation rate is high;
- the host is easily infested;
- distribution of pests is uneven; and
- the pest is internal or difficult to detect.
Typical post harvest treatment methods:
- Cold or high temperature
- Hot water
- Irradiation
- Fumigation
Pest Free Areas: A viable alternative for exporting countries
to address quarantine requirements for the entry of fresh
agricultural products in lieu of commodity treatment is to
establish and maintain specifically defined areas or regions
free of certain pests for a given commodity or group of commodities.
The pest free area (PFA) concept is a risk management option
based on a sound pest risk assessment coupled with satisfactory
evidence of effective, on-going surveillance and exclusion measures
to maintain such areas pest free.
Pest Free Area (PFA) applies where an area:
- has been found completely free of a pest
- is made free through specific actions
- is protected from infestation or re-infestation
The PFA concept applies to situations where a specific area or district
of a country has been found completely free of a pest or is made free
through specific actions, and is then protected from infestation or
re-infestation.
PFA does not imply an absolute absence of all pests,
but is aimed at designated commodities from specific geographic
areas based on the absence of a specific pest or group of pests.
Pest Free Area Example: The Mossoro area of Brazil (a portion of
the state of Ceara) honeydew melons are an approved commodity and
therefore has PFA status in relation to a South American fruit fly,
Anastropha grandis. Quarantine stations operated by the Government
of Brazil are located on the principal roads to restrict the movement
of commercial hosts into the fruit fly free area. USDA periodically
monitors the fruit fly surveillance and regulatory actions to verify
the integrity of PFA status.
In the state of Sonora, Mexico,
eleven municipalities are approved for eight types of approved
commodities. This area is free of several species of fruit flies
and the entry of fruits from other parts of Mexico are required
to have a post harvest treatment for those pests.
Systems Approaches:
A systems approach is a set of safeguards
and mitigation measures which individually and cumulatively provide
a reduction in plant pest risk. These measure can occur in the
growing area, at the packinghouse, or during the shipment and
distribution of the commodity. Commonly the components of a
systems approach include pest survey, trapping and sampling,
field treatment, cultural practices, host resistance, post-harvest
safeguards, limited harvest period, limited sales distribution,
and restrictions on maturity at harvest.
In general, a systems approach has two or more components that are
independent, thus creating redundancy. So if one mitigating measure
fails, other safeguards exist which still reduce the risk to a
negligible level.
An example is the application of a systems approach to achieve
a pest free glasshouse. One measure to make sure the host plant
within the glasshouse remains uninfested is the selection of screen
vents and double doors. However those two safeguards do not provide
redundant or independent safeguards. Therefore another independent
measure is needed such as pest survey (trapping) in the glasshouse
environs. Either the glasshouse safeguards or the pest trapping could
fail, but if the other component works the host plant within the
glasshouse remains uninfested.
Systems Approach Examples:
Unshu oranges from Japan. This systems
approach, designed to prevent citrus canker from entering the United
States, requires an established growing area with surrounding buffer
zones, field survey, surface treatment, resistant varieties, inspection
and limited United States distribution.
Bell peppers from Israel. This systems approach, designed to prevent
the introduction of Mediterranean fruit fly, includes growing the peppers
within a fly-proof glasshouse, location of the glasshouse in areas where
the pest is absent or rare, trapping of the environs, and fly-proof
packaging.
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