紫茎泽兰根系释放的化感物质是导致其土壤环境发生变化的重要因素，可为其成功入侵提供有利条件.以空白土样为对照，提取健康和感染棉蚜的紫茎泽兰根区土壤酚酸类化感物质，采用GC-MS分析其组分和相对含量.结果表明：不同处理根区土壤酚酸类化感物质的种类没有变化，但相对含量发生了改变.其中，虫害处理土样中苯甲酸和对羟基苯甲酸的相对含量均显著高于对照，但对羟基肉桂酸的相对含量显著低于对照，且苯甲酸、对羟基苯甲酸和对羟基肉桂酸的相对含量在3种处理土样中的比例存在差异.用上述3种物质单体及它们在3个处理土样的比例复配进行抑菌试验发现：在较低浓度（50～150 mg·L-1）下，3种化感物质对5种土传性病菌有显著的抑制作用，但复配后对5种病菌的抑制作用各不相同，虫害处理的复配对其中3种病原菌的抑制作用均低于对照和健康植株.
The allelochemicals released by Eupatorium adenophorum roots is an important factor inducing the changes of the weed soil environment, which provides favorable conditions for the successful invasion of the weed. By using GC/MS technique, the components and their relative contents of phenolic allelochemicals in aphid-infested and non-infested E. adenophorum root zone soils were analyzed, with unplanted soil as the control. Less difference was observed in the components of phenolic allelochemicals among the test soils, but their relative contents differed significantly. The relative contents of benzoic acid and 4-hydroxybenzoic acid in aphid-infested E. adenophorum root zone soil were significantly higher than the control; whereas that of 4-hydroxylcinnamic acid was in reverse. In the test three soils, the proportions of benzoic acid, 4-hydroxybenzoic acid, and 4-hydroxylcinnamic acid were different. The bacteriostatic test with the three acids and their combinations based on their proportions in test soils showed that at lower concentrations (50-150 mg·L-1), the three acids had significant inhibitory effects on five kinds of soil-borne pathogens, but their combinations had different inhibitory effects on the five pathogens, with the effects being significantly higher for the combinations with the proportions in non-infested E. adenophorum root zone soil and the control.