Expurgo de sementes de milho com brometo de metila em diferentes doses e tempos de exposição

Bacchi, Oswaldo; Zink, Eduardo

doi:10.1590/S0006-87051962000100078

Oswaldo Bacchi; Eduardo Zink

SUMMARY

Corn seeds of the Hybrid Hd 6999 and of the Azteca variety with about 12.5% of moisture content were vacuum fumigated with methyl bromide, using 18, 28 and 38 g of the gas per cubic meter and exposition times of two, four and six hours.

Same kinds of seeds were also treated with malatox (5%) and DDT (5%) in the proportion of 1%.

Both fumigated and chemical treated seeds were stored in open containers for period of 12 months and periodically compared with untreated seeds for germination capacity and insect damage.

The results obtained permitted the following conclusions:

1) fumigations made with 18g of methyl bromide during 2, 4 and 6 hours, and 28g for 2 hours were not immediately effective against adult insect of Sitophilus oryzae L.;

2) even the highest dose of methyl bromide and exposition time used did not show to be harmfull to the vitality of both kinds of seed;

3) no insect reinfestation ocurred with the chemical treated seeds during the 12 months of storage, while the fumigated seeds were reinfested after 5 months, and untreated ones after 3 and l months for the hybrid and Azteca seeds, respectively;

4) the longevity of both kinds of seed during the storage period was inversely proportional to their percentages of insect infestation.

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Recebida para publicação em 13 de junho de 1962.