通过对籼粳杂交稻甬优12在6个不同生育期防治稻曲病的防效进行比较，发现在全田10%～20%植株剑叶完全抽出（即破口前16 d）时施药对稻曲病的预防效果最佳，校正防效达95.54%，如推迟至破口前12 d、破口前5 d和破口期进行防治，防效逐步下降，而提前到破口前21 d，防效也没达到理想效果。因此认为，预防籼粳杂交稻稻曲病应在全田10%～20%植株剑叶完全抽出（即破口前16 d）时进行防治最为适宜，药剂可采用30%苯甲·丙环唑EC。

We conducted a comparative experiment on the control efficiency of different agents on rice false smut of Yongyou 12 in 6 different growth periods in 2017. The results showed that the best control period was 16 days before the rupturing stage, when 10% to 20% flag leaves of the plants were fully expanded, the correction control effect was 95.54%. If the time was put off, the control effect would be gradually declined. If the time was advanced to 21 days before rupturing stage, the control effect was not ideal, too. Thus, it is preferable to control rice false smut of indica and japonica hybrid rice on the 16 day before rupturing stage, when 10% to 20% flag leaves of the plants were fully expanded, and 30% difenoconazole propiconazole EC has better control effect.