CHEMICAL CONTROL

Chemical substances intended for controlling postharvest diseases may be fungicides and bactericides, or fungistats and bacteristats. To serve its purpose, the chemical should come into contact with the pathogen; the minimal effective concentration is pathogen dependent. Chemical treatments can be applied under various strategies and with various timings: preharvest application to prevent infection in the field, sanitation procedure to reduce the level of inoculum in the environment to which injured fruits or vegetable are liable to be exposed, and postharvest application to prevent infection through wounds and to eradicate or attenuate established infections to prevent their development and spread during storage. In order to choose the appropriate strategy for decay control, one has to understand the mode of infection of the pathogen, its time of infection, and the environmental factors that may affect disease development.