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21.3.2 Phytosanitary Treatments
G. J. Hallman
Phytosanitary treatments are done directly to the commodity at some point
before it is released to the market in the importing country or region to
reduce the risk of infestation of that commodity by invasive species to acceptable
levels. Virtually any physical, chemical, or biological technique that can
be used to kill an organism or prevent its reproduction could theoretically be
used as a phytosanitary treatment (Table 21.2). Commercially used treatments
are limited by several concerns:
1. The controlling factor must reach the organism, which may be inside the
commodity with no easy access from the outside. For example, tephritid
fruit fly and weevil (Curculionidae) larvae mine deep inside fruit and other
plant parts with no opening to the outside of the plant, making their control
more difficult than surface-infesting organisms.
2. The level of control must be near 100 %. The risk of an imported commodity
resulting in the establishment of an invasive species depends on, among
other things, the infestation rate of the species in the commodity, shipment
size, and level of treatment efficacy. Because it takes only one mating pair
or one parthenogenic organism to start an infestation, the level of control
should ensure that this does not occur within an appropriate margin of
error. Landolt et al. (1984) were among the first to consider using pest risk
to determine the necessary level of treatment efficacy, rather than setting
the level arbitrarily high. Follett and McQuate (2001) review the intervening
literature on this topic, and give citations for calculating pest risk associated
with treatments, along with real-world examples.
3. The treatment cannot harm the commodity significantly, or pose a health
or environmental hazard.Virtually any physical treatment designed to kill
organisms on fresh commodities, which are also alive, could harm or kill
that commodity or accelerate decomposition and shorten shelf life. Biocidal
chemical treatments may harm a live vegetative commodity, and are
limited by health and environmental concerns. Many approved phytosanitary
treatments cause some recognizable, albeit tolerable, damage to the
commodity, and commercial interests should check tolerance of the items
they wish to treat before investing in the treatment technology. More treatment
options are available for durable commodities, such as bulk grain,
lumber, hay, and tobacco, which are harder to damage than fresh produce.
4. The treatment must be commercially viable from the standpoint of price
and logistics. This criterion may not keep a phytosanitary treatment out of
the regulations, but it will keep it from being used commercially for very
long.
Quarantine treatments are presented below in approximate chronological
order of their development and commercial application.