北京市区泡桐丛枝病发生特点研究

对北京市区泡桐丛枝病调查结果表明，２ａ以上树龄的泡桐树平均病株率为１９．２３％，病情指数达１０．２７，病害随树龄增大而加重。小片纯林受害最重，行道树次之，散植株最轻。周围高建筑物和稠密的植被可有效地阻止病害通过介体传播。在城市特殊生态环境中，种苗带毒是病害发生和发展的关键因子。在植株休眠期，病树丛枝的筛管中类菌原体（ＭＬＯ）浓度降低，但仍有一定数量的ＭＬＯ存活

Occurrence of Paulownia Witches' Broom Disease Caused by Mycoplasma Like Organism in the Urban Area of Beijing.

A survey on paulownia witches' broom disease caused by mycoplasma like organism (MLO) occurring in the urban areas of Beijing showed that the average disease incidence and index of two year old or more trees were 19.23% and 10.27, respectively. The disease rate increased with the ages of the trees. The disease severity from high to low was small paulownia woodland, shade trees along roads and sparse trees. The tall building and vegatation around paulownia trees blocked the spread of the disease significantly. The seedlings or saplings infected with MLOs could be a very important infection source when planted in those separated sites. MLO population decreased greatly in the witches' broom showing branches in the dormant stage of plant compared with growing seasons, but there still existed certain mumber of pathogenic MLOs in their functional phloems.