Abstract

                                The insecticides viz., methyl parathion, quinalphos, malathion, carbaryl and 'HCH when used as dust to protect rice crop against rice oarhead bug during the flowering and grain forming stage, either left non-detectable level or residues well below the tolerance level in hand pounded rice, bran and straw. Even two rounds of dusting did not alter the situation. Therefore when the above mentioned chemicals were dusted once or twice 26 days before the harvest, the rice samples were devoid of any toxic residues of these chemicals. A safe waiting period of 3 weeks may be recommended between the application of these chemicals and the harvest of rice. The ND values or the low level of residues in all the treatment samples suggest that the waiting period suggested could still be reduced without any residue hazard.

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