本研究主要探討臺灣難防治雜草—雙穗雀稗(Paspalum distichum L.)於田間春、秋作氣候下之生長與繁殖特性，以及數種化學除草劑之藥效試驗，作為研擬防治策略之參考。結果於溫度發芽試驗中發現，雙穗雀稗之種子發芽率僅為0至2%，顯見本雜草於田間成為難防治雜草之因不在於種子之數量及發芽率。於春、秋兩季之生長勢調查結果顯示，雙穗雀稗之秋季生長勢無論於最長枝條長度、葉片數、節間數及鮮重都顯著大於春季生長勢，另秋季節間數/最長枝條長度之比值較春季大 2.85 倍，可見其於溫暖季節之傳佈潛力較高。藥劑試驗之結果顯示西殺草對於雙穗雀稗無防治效力，而甲基合氯氟、伏寄普、嘉磷塞、固殺草依登記用量使用可有效防治剛扦插之雙穗雀稗，而嘉磷塞與固殺草即使施用登記用量之一半亦有效力；另僅嘉磷塞與固殺草兩藥劑可針對扦插四個月大之植株有防治效果。綜合上述結論，本雜草在防治上須注意營養器官田間散布之狀況，若有防治須求則建議耕作者先搭配田區整地後，盡速於整地後三週內施用上述之推薦藥劑，並輪替使用，才可達到防治與避免抗藥性發生之效力。

Knotgrass (Paspalum distichum L.) is considered to be a difficult control weed on Taiwan. This study calculated growth and propagation property between spring and fall, at the same time observed the effect of different chemical herbicides for formulating control strategies. The result of temperature germination test showed germinated rate of knotgrass just 0-2%, being hard to invade field. Growth calculation test showed that no matter the length of longest shoot, leaf numbers, internode numbers and fresh weight of fall season are significantly larger than spring season. The ratio of internode numbers/ length of longest shoot in fall was 2.85 times than spring, showing the higher spreading ability in warm season. Chemical herbicide treatment test showed that sethoxydim was no effect to knotgrass but haloxyfop, fluazifop, glyphosate and glufosinate were effective when using registered dose to the grass while cutting in few days. Glyphosate and glufosinate were effective when using half of registered dose. On the other hand, there just these two herbicides were effective to the grass after cutting on the ground for four months. The weed has to be warning the spreading condition of vegetative organ. If the weed is necessary to control that can alternatively use following herbicides within three weeks after soil preparation for attaining the goal and preventing pesticide resistance.