Application of phosphine fumigant for controlling rice storage insect pests in foundation seeds

The development of phosphine resistance in storage insect pests is now problematic, so the increase of rate and frequency of phosphine fumigation in a storage room is needed. However, an adverse effect on seed germination, and human hazard needs to be tested. This experiment was aimed to find the most suitable methods used in combination with phosphine fumigation to reduce the risk of phosphine exposure. The treatments were (1) phosphine fumigation for 7 days and then open a plastic cloth (2) phosphine fumigation for 7 days and continue to cover a plastic cloth (3) phosphine fumigation for 7 days and spray pirimiphos methyl on sack (4) phosphine fumigation for 7 days and use a light trap (5) treat seeds with sweet flag powder before phosphine fumigation for 7 days (6) no phosphine fumigation with plastic cloth opening and (7) no phosphine fumigation with plastic cloth covering. In each treatment, seeds were sampled every month for 12 months to determine seed quality and insect populations. The results showed that seeds treated with sweet flag powder and fumed with phosphine for 7 days can significantly control storage rice insect pests in the first and the second year of experiments. The seed moisture content in each treatment changed in a similar pattern throughout 12 months storage in both years (13.4 – 13.7%). The seed germination showed similar results (more than 80% after 6 months storage), except the treatment of 7 days phosphine fumigation with plastic cloth covering which resulted in a slowly decline in germination. Seed weight losses and numbers of insect pests in the treatment with sweet flag powder were significantly less than the others.