BP Singh

Plant Quarnatine Treatments jor Salvaging Gennp/asm Infested with Insects and Mites 195Treatment vs. InfestationThe kind of treatment to be employed depends upon the typeof infestation to be taken care of. Germplasm to be quarantinedin National Bureau of Plant Genetic Resources comprises mainiyof seeds of various agri-horticultural crops while 2-3% of it is alsoin the form of vegetative propagules like bulbs, corms, cuttings,root stocks, tubers and seedlings, which harbour a variety ofinsects and mites of diverse habits. It is essential for a quarantinepersonnel to establish the systematic identity .of the interceptedpests to know their habits, so as to be able to employ a suitable/prescribed quarantine treatment schedule as the latter are specificto the pest as well as the material to be salvaged.Quarantine Treatments and their schedulesTreatments commonly used for the quarantine of germplasminclude X-ray radiography, fUmigation, pesticidal dip/spraytreatment, mechanical cleaning, tissue culture, cultural proceduresetc. Apart from these, quarantine treatments commonly used forfresh commodities are cold, heat, controlled atmosphere andcombination treatments. Although, limited for germplasm, theiruse is gaining popularity as environment friendly and alternatetreatments, specially to the use of chemicals, viz., methyl bromide,which has been designated as an ozone layer depletor and is likelyto be phased out in near future. Each of the above treatment isdiscussed below. .X-ray radiographyThis technique ~.hL.?Lal." 196'l~ is used against insectswhich live inside the seeds with no apparent external symptomsof their presence within. Over 300 plant genera have been listedfrom literature, seeds of which are reported to harbour such insectsand these are, therefore, essentially subjected to X-ray radiography.The seeds are spread in a single layer and are exposed to X-rays .at 22 kv, 3 rna for 10 seconds from 30 em distance. Infested seedsare clearly distinguishable from healthy ones on the X-ray plateafter development. Corresponding (infested) seeds are then handpicked from the original sample which is kept undisturbed. Thisis nondestructive and fool proof method of excluding insects' butis very cumbersome and is feasible only in small samples ofpreferably bold seeds.