Persistence of grain protectants under silo conditions.
1987
Ong Seng Hock | Zulkifli Zainuddin M.
Paddy grain (unhusked rice) was treated with fenitrothion, diazinon and malathion at recommended dosages using controlled release (CR) and emulsion concentrate (EC) formulations. The persistence of these chemicals was studied in experimental metal silos kept under the shade. The trial was conducted in duplicate and will continue for a total storage period of 24 months. This paper reports on the progress that has taken place in the first six months. The breakdown of active ingredients was evident in the second month of storage and accelerated rapidly towards the third month. At the end of the six-month storage period, the levels of active ingredients had declined by 2-14 fold. The lower residue levels at the end of the third month of storage coincided well with the reduced efficacy of most of the treatments. In general, all formulations applied at the recommended dosages exhibited rapid degradation. Consequently, these formulations would only be useful as grain protectants for the first three months. The CR formulations appeared to be more persistent than the EC formulations, but the difference was not sufficiently marked for the CR formulations to be convincingly superior. Among the three active ingredients, fenitrothion appeared to be less persistent than malathion and diazinon for the period of six months under study.
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