<正>通过野外调查、室内病菌的分离和室内外接种及田间化学药剂的防治试验，研究杨树红心病形成原因。结果表明，杨树红心病的产生是以杨树生理现象为主导，多种细菌、真菌共同作用引起的结果。只要杨树枝干上存在损伤，即可引起心材变色，在伤口上接种相关真菌、细菌则可使变色加重。此外，化学杀菌剂林间防治效果不明显。

Litters of the stands of Eucalyptus were obtained from different places and dates, in which microorganisms were isolated and purified and identified. The results showed that it was rich of microorganisms in quantities and species in the litters. And the quantities of bacteria were the highest. The second was fungi. The lowest was actinomycetes. The quantities of these microorganisms were less various in different dates. But it was higher in mixed forest than that in pure forest. 195 of strains were got. 129 of them were bacteria related to 10 genera like to Bacillus, Pseudomonas, Listeria and so on respectively. 23 of them belonged to Streptomyces, Nocardia, Micromonospora respectively. The rests were fungi subordinated to Fusarium, Cephalosporium, Rhizoctonia and so on respectively.