在室内用蔬菜叶片浸渍苏云金杆菌药液测定对小菜蛾的ＬＣ５０试验结果指出，供试蔬菜的生长期对测试结果有明显的影响。用营养生长旺盛期的菜叶，所得的ＬＣ５０值比营养生长末期的菜叶高出４倍左右，差异显著。因此，用叶片浸渍法测定药液毒力，提供生长期标准一致的植物是保证试验准确性的必要条件 The results of LC50 test on Plutella xylostella by immersing Bacillus thuringiensis in laboratory show that the growth period of tested vegetables has a significant effect on the test results. The vegetative growth vigor of the leaves, the resulting LC50 value than vegetative late leafy 4 times higher, the difference was significant. Therefore, the leaf dipping method to determine the toxicity of liquid chemicals to provide the same growth stage of the plant is to ensure the accuracy of the test conditions necessary