• 作者： 彭武康
• 作者服務機構： 國立臺灣大學植物病蟲害學系
• 中文摘要： 木實驗採用直徑25公分，高4.1公尺之圓形鐵製筒倉作穀倉模型試驗，探討好達勝（Phos-toxin）施於各種深度後，PH3在積穀中之分散情形及殺蟲效果，以決定施藥於何種深度，最能發揮其效果。 試驗資料顯示，在積穀中有往下沉的趨勢，且易被穀物吸收，結果濃度逐漸減低。在空的密閉空間，PH3分佈在底層之濃度顯著地較上層為高，而在水平方向，則可達成均勻擴散。 以每公噸5片好達勝單獨均勻施於積穀表面至以下2公尺間，均可達到防治效果。但單獨施於4公尺處，PH3大部份沉於底層，而上昇至表層之濃度無法達到預期防蟲效果。若分為兩層施用，一半施於表層，另一半施於自表面起1, 2, 3或4公尺深處，其防治效果均可達到100%。 由生物檢定結果顯示，處理時間加長，可增進防治效果。故在密閉條件良好之穀倉中，保持有效濃度達較長久的時間，可提高其防治效果。 在穀倉中，自積穀表面至屋頂均有一空間。此處之空氣對PH3有稀釋之作用，使PH3下沉速度減緩，並影響其擴散量。故建議於實際施藥時，在積穀表面覆以大型不逐氣之敷蓋物在塑膠布等，可增進防治效果。
• 英文摘要： While reacting with water or moisture inthe air, phostoxin releases the toxic gas-, PH3.From its distribution behavior, it showed slightlyheavier than air. It has a tendency to go downto the bottom either among rice or in closedempty space. However, it distributed homoge-neously in horizontal directions in the lattercase. Several methods are being adapted for ricestorage in Taiwan. The common one is to pilethe rice in the storehouse up to a height of 4meters. To use phostoxin to control the pestsin the storehouse it may treat the tablets atdifferent depths in the rice pile. In an attemptto evaluate which ways contributed the bestcontrol efficacy, 25 cm in diameter and 410 cmheight experimental bins were used to investi-gate both the PH3 distritions and insect morta-lities following its application. Phostoxin at the dose rate of 5 tablets perton of rice was treated at the depths of 0, 1, or2 m below the surface, the results revealed 100%control. While it treated at 4 M, most PH3stayed at the bottom and could not go up tothe surface, hence the control efficacy was verypoor. As the dose divided into two parts, onetreated at the surface and the other at 1, 2, 3,or 4m, it also showed 100% control. The bioassay data showed that long expo-sures at low concentrations were far more effec-tive than short exposures at high concentrations.Practically, for minimizing the dilution by theair in the space from the rice surface to theroof of storehouse, it is suggested to cover aplastic coverage on the rice surface after phos-toxin application
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