可克达拉市白蜡树蛀干害虫发生为害情况调查

白蜡树是可克达拉市园林绿化主要树种之一,在行道树中具有较高的占比,但近年来饱受蛀干害虫的不断侵扰。为明确可克达拉市白蜡树蛀干害虫为害情况,对白蜡树蛀干害虫进行了调查研究。经过调查共发现4种蛀干害虫,分别是小线角木蠹蛾Streltzoviella insularis(Staudinger)、白蜡窄吉丁Agrilus planipennis Fairmaire、咖啡脊虎天牛Xylotrechus grayii White和白蜡外齿茎蜂Stenocephus fraxini Wei。其中小线角木蠹蛾、白蜡外齿茎蜂和咖啡脊虎天牛均是新疆新记录种。白蜡窄吉丁和小线角木蠹蛾发生相对普遍且为害严重;白蜡外齿茎蜂在多数白蜡树都有观察到,主要为害上部枝梢;咖啡脊虎天牛仅在2株白蜡树上发现。     

应用排除法分析两种天敌对桔全爪螨的控制作用

采用排除法，分析桔园中两种主要天敌对桔全爪螨的控制作用。试验表明，在一定益害数量比例条件下，尼氏钝绥螨或深点食螨瓢虫，均可在短期内发挥控制作用，将桔全爪螨种群数量控制在较低的密度。当尼氏钝绥螨：桔全爪螨为１：２０时，１个月后猎物密度从２６头／叶降至１头／叶以下，而对照中则保持在２０头／叶。当深点食螨瓢虫：桔全爪螨为１：２５时，１个月后猎物数量从２９头／叶下降至９．５头／叶。两种天敌共同作用时，猎物     

Stem rot of jewel orchids caused by a new forma specialis,Fusarium oxysporum f. sp. anoectochili in Taiwan

Stem rot of Anoectochilus formosanus (Af) caused by Fusarium oxysporum (Fo) is a major limiting factor to jewel orchid production in Taiwan. Fo causes discoloration in vascular tissues. However, some newly collected Fo isolates from Af stem rot do not cause vascular discoloration, suggesting changes may have occurred in the pathogen. Among recent Fo isolates from Af there are two colony types, the cottony alba (CA) and the sporodochial (S). In order to confirm that both colony types cause Af stem rot, 200 isolates were obtained from diseased stems in Nantou County and characterized by colony type and whether or not the infected plants had vascular discoloration. Isolates of both the CA and S types caused stem rot of Af; some isolates in each colony type caused vascular discoloration whilst others did not. Pathogenicity tests with 22 isolates resulted in stem rot disease severity ratings on Af of 3·1–4·0 and 2·1–4·0 with CA and S type colonies, respectively. The same isolates failed to cause disease on Cattleya, Dendrobium or Phalaenopsis plants. Phylogenetic analysis of partial intergenic spacer sequences showed that these isolates were distinguishable from other formae speciales of Fo and could be separated into two groups correlated with the CA or S type colonies with high bootstrap. Based on pathogenic, morphological and molecular characterizations, the Fo that causes stem rot of Af is proposed to be a new forma specialis, F. oxysporum f. sp. anoectochili, with different pathotypes.