从含杨树树皮浸提液的改良Ｆｒｉｅｓ３号培养基培养的杨树溃疡病菌（Ｄｏｔｈｉｏｒｅｌａｇｒｅｇａｒｉａ）代谢产物中分离出毒素粗提物。对不同抗病性杨树材料处理结果发现，该粗提物能使叶子出现黑斑和萎蔫，并使材料细胞膜透性增大、脯氨酸含量增加，且对感病品种北京杨（Ｐｏｐｕｌｕｓ×ｂｅｉｊｉｎｇｅｎｓｉｓ）的影响大于抗病品种毛白杨（Ｐ．ｔｏｍｅｎｔｏｓａ）。这表明，溃疡病菌在活体外培养的代谢产物中含有毒素，初步定为８０％丙酮沉淀物 Crude extract was isolated from the metabolites of Dothiorelagregaria cultured in modified Fries No. 3 medium containing poplar bark extract. The results showed that the crude extract could cause dark spots and wilting on the leaves, increase membrane permeability and increase proline content in poplar cultivars with different disease resistances. Populus × beijingensis is more affected than P.tomentosa. This shows that the canker bacterium contains toxins in the metabolites cultured in vitro initially set at 80% acetone precipitate