BP Singh

Plant Quarnatine Treatments for Salvaging Gerrnplasm Infested with Insects and Mites 199for tissue culture under aseptic conditions to produce healthyplants.AerosolsInsecticide particles dispensed through gas are mainly used. as space sprays in plant quarantine to disinfest, cargoes andinspection sites. These are effective against flying/ exposed insects.Hot water treatment (HWT)This is primarily used against pathogens, but various fruitflies have also been controlled by this method. For examplemediterranean fruit fly -15 minutes immession at 50°C (Armstrong,1989).Vapour heat treatment (VHT)Air, heated and saturated with moisture is used to raise thetemperature of commodity to the reqUired point. Specificallydesigned airtight, insulated chambers with a false floor, ducts,thermocouples and temperature'recording system are required toundertake VHT against various fruit flies. The schedule prescribesan approach period during which a commodity is heated upto therequired temperature and held at that during treatment period.Commodity is then cooled immediately and air dried. Forexample, VHT for oriental fruit-fly llh approach period from23.3°C to 44.4°C to be held 'for 8&3/4 h (Sec et al., 1974).Microwave HeatingShort exposures of 100-130 seconds to raise the temperatureupto 53°C-57°C have been found effective against tobacco leafinsects (Herose et al., 1975).Controlled Atmosphere TreatmentsThe use of manipulated natural atmosphere in terms of CO 2,02 and N z content to treat a commodity is called controlled ormodified atmosphere treatment. This involves removing of lifesupporting O 2by adding CO/N 2• These treatments are quitesimilar to fumigation in respect of their requirements, i.e., airtightchambers and gas dispensing units etc. In fact these can be anappropriate substitute for fumigation because gases involved donot leave any harmful residue and prov~de superior conditions to