Post harvest diseases fruits and vegetables - Xavier University ...

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
154 Postharvest Diseases of Fruits and Vegetables
disinfection of the atmosphere and the equipment in the packinghouse
and storage rooms.
Removal of pathogen sources may be achieved through the immediate
disposal of every rotted fruit or vegetable, or by immersing it in a
disinfectant solution in a special container, which would eradicate fungal
spores and prevent their dispersion. For disinfecting packinghouses or
store rooms, including their equipment, it is possible to use one of the
following disinfectants: formaldehyde, isopropyl alcohol, quadronic
ammonium compounds, captan or other chemicals. A standard
commercial practice in fruit packinghouses is to disinfect the atmosphere
with formaldehyde, boxes and other equipment with quaternary
ammonium compounds and the surface of the fruit with a solution of
active chlorine (Eckert, 1990). Steam may also be used to sanitize citrus
boxes (Klotz and DeWolfe, 1952).
C. POSTHARVEST CHEMICAL TREATMENTS
Since open wounds, created during harvesting, handling and
packaging, are the major sites of invasion by postharvest wound
pathogens, the protection of wounds by chemicals will considerably
decrease decay in storage. Among the various types of 'wounds' we
should also include injuries created in severing the crop from the plant or
cuts created deliberately during handling procedures, such as stem cuts
in banana hands or petiole cuts in celery intended for export. Other
potential sites of infection are the natural openings in the host surface,
such as lenticels and stomata, whose sensitivity to infection is increased
by wounding or after washing the commodity in water. An efficient
disinfection process should reach the pathogenic microorganisms
accumulated in all these sites.
Disinfection should be applied as close as possible to the time of
exposure to infection, since a fungal spore located in the wound may,
under appropriate conditions, germinate in several hours and initiate its
establishment in the tissue. The allowable time between inoculation
(harvesting) and the chemical application, if the treatment is not to lose
its effectiveness, depends on several factors: the rate of spore
germination and mycelial growth of the pathogen, the level of host
resistance, the prevailing environmental conditions, and the
penetrability of the tissue to the chemical.
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