杨树冰核细菌溃疡病发病的主导因素

The Dominant Factors Caused by Poplar INA Bacterial Canker

在我国东北地区、杨树上普遍存在的冰核活性（ＩＮＡ）细菌。能在温度－４℃以下产生冰核活性。主要种类为：成团泛氏菌［Ｐａｎｔｏｅａ ａｇｇｌｏｍｅｒａｎｓ Ｇａｖｉｎｉ ｅｔ ａｌ＝Ｅｒｗｉｎｉａ ｈｅｒｂｉｃｏｌａ］、菠萝泛氏菌［Ｐａｎｔｏｅａａｎａｎａｓ（Ｓｅｒｒａｎｏ） Ｍｅｒｇａｅｒｔ ｅｔ ａｌ＝Ｅ． ａｎａｎａｓ］、大黄欧文氏菌［Ｅｒｗｉｎｉａ ｒｈａｐｏｎｔｉｃｉ（Ｍｉｌｌａｒｄ） Ｂｕｒｋｈｏｌｄｅｒ］噬夏孢欧文氏菌［Ｅｒｗｉｎｉａ ｕｒｅｄｏｖａｒａ（Ｐｏｎ．ｅｔ ａｌ）Ｄｙｅ］和丁香假单胞菌［Ｐｓｅｕｄｏｍｏｎａｓ ｓｙｒｉｎｇａｅ ｐｖ．ｓｙｒｉｎｇａｅＶａｎ Ｈａｌｌ］。它们主要分布于感病寄主的冻枝、冻死芽、枝干肿包、溃疡瘤、病枝、真菌溃疡病斑等部位。春秋两季为活动期和侵染期．出现频率最高．占细菌分离数的５０％以上．泛氏菌占优势．在病部内外均有分布、内部较多。杨树冰核活性细菌在春秋季节霜冻条件下能造成杨树冻害．并引起肿茎型细菌溃疡病、是病害发生的主导因素。研究还证明．杨树冰核活性细菌能增强真菌溃疡病菌的侵染、促进真菌溃疡病的发生。

INA bacteria lie in poplar widely in Northeast China. they can produce ice nucleation activity at -4 ℃. They belong to p(lntoea sp.. Ervinia sp. and Pseudomonas sp.. the main strains are Pantoea agglomerans Gavini et al=Erwinia herbicola. Pantoea ananas (Serrano) Mergaert et al=E. ananas. Erwinia rhapontici (Millard) Burkholder. Erwinia uredovara (Pon. et al) Dye and Pseudomonas syringae pv. syringae Van Hall. They mostly lie in diseased hosts frozen branches. buds frozen to death. branch swelling. canker tumour. diseased branch. fungi canker spot. Spring and autumn are active and invading periods for INA bacteria. their occuring frequency is the highest and can reach 50 percent. Pantoea and Erwinia species are dominant. they exist both inside and outside diseased spot. but more exist inside. Through inside and outside inoculation and reisolation test in different seasons. the results show that INA bacteria cause poplar freeze injury under frozen condition. then induce INA bacterial canker disease. this is the main factor to cause the disease. At the same time. mix INA active bacteria and Coryneum populimum Bresad. or Dothiorella gragaris Sacc. to make inoculation test, this call strengthen invading capacity of fungi canker germs and increase fungi canker disease.