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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
Chemical Control 157
decaying fruit. The compound has some activity against stem-end rot but
has no effect on Geotrichum, Alternaria or Phytophthora. Since
sec-butylamine has low phytotoxicity and toxicity to mammals, the fruit
does not have to be rinsed after treatment (Eckert and Ogawa, 1985).
Sec-butylamine can be applied to the harvested fruit as a salt solution
to protect oranges during the period of ethylene degreening; or it can be
added to wax formulations applied to lemons before storage. The
fungicide may also be volatilized and applied as a fumigation treatment
which inhibits the development of Penicillium after the injuries on the
surface of the fruit become alkaline by absorption of the amine vapor. In
addition, residues of neutral sec-butylamine salts persist in the injuries
following the fumigation treatment (Eckert and Kolbezen, 1970).
Captan N-trichloromethylmercapto-4-cyclohexene-l,2-dicarboximide),
which is a bicarboximide fungicide, has been proven effective as a
postharvest dip against decay development in various fruits and
vegetables, such as strawberries, peaches, cherries, pears, figs and
potatoes (Eckert and Sommer, 1967). However, captan is not well suited
to postharvest treatment because, when applied as a wettable powder
suspension at effective concentrations, it may leave visible residues of
powder on the surface of the fruit.
Dicloran (2,6-dichloro-4-nitroaniline, DCNA, botran) is effective
against several postharvest fungi. It is particularly efficient in
controlling soft-watery rot caused by Rhizopus stolonifer in stone fruits
and sweet potatoes, for which Rhizopus is the main postharvest
pathogen. The capability of dicloran to penetrate to a depth of 11 mm
into peaches (Ravetto and Ogawa, 1972) explains the inhibitory action of
dicloran treatment against established lesions of Rhizopus on peaches.
However, this treatment is less effective against other decays of stone
fruits, such as the brown rot caused by Monilinia fructicola, and the blue
mold caused by Penicillium expansum (Daines, 1970), and
dicloran-resistant strains of R. stolonifer have also been reported
(Webster et al., 1968). The effectiveness of dicloran against postharvest
pathogens depends on the level of the fungicide persisting on the fruit
after treatment, and the optimum deposit of dicloran for brown rot
control is much greater than that required for adequate control of
Rhizopus rot.
The effect of dicloran against M fructicola can be greatly improved by
heating the fungicide suspension or combining it with another fungicide.
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