Host Range and Virulence of a Fungal Pathogen for Control of Giant Salvinia (<i>Salvinia molesta</i>)

A teleomorph of the fungus Botryosphaeria rhodina (Berkeley et Curtis) von Arx, (Br) was evaluated as a bioherbicide for control of giant salvinia (Salvinia molesta D.S. Mitchell) under greenhouse conditions and in small-scale field trials. We found that fungal mycelium was highly infective and could be rapidly produced (48+ h) in soy flour-cornmeal liquid media contained in shake flasks or fermenters. A dew period was not required to achieve infection and mortality of inoculated plants. A surfactant (Silwet L-77, a polyalkyleneoxide modified heptamethyl-trisiloxane) incorporated in the fungal formulation was required for Br to infect and kill plants. Infection and mortality occurred rapidly (within 48 h after treatment), and re-growth of treated plants did not occur. In replicated field trials, Br controlled giant salvinia ~95%. Br also infected other plants, such as common salvinia (S. minima Baker), and Azolla filiculoides Lam., as determined in ongoing host range research. However, no symptomatology was observed on several economically important crop species, such as rice (Oryza sativa L.), corn (Zea mays L.), and several woody species such as bald cypress (Taxodium distichum L.) and loblolly pine (Pinus taeda L.) occurring in areas where giant salvina occurs that would be subject to contact with releases of Br. These results suggest that this teleomorph of Botryosphaeria rhodina has potential as a bioherbicide for controlling this onerous aquatic weed.

速生槐叶蘋入侵风险评估及管理措施分析

【目的】速生槐叶蘋是一种原产于巴西东南部的多年生漂浮型水生植物,广泛引种至世界各地后逃逸,侵入湖泊、河流和稻田等各种水生生境。通过开展速生槐叶蘋入侵风险评估,进而提出其管理措施,可为其检疫决策及防治提供科学依据。【方法】通过查阅梳理文献,分别对速生槐叶蘋的国内外分布、传播方式及入侵扩散历史、防治方法、生态适应性和抗逆性、生物学和遗传特性、危害性及利用价值等方面进行定性分析。并基于外来植物风险指标体系和判断标准,对4个指标层的17个指标和32个问题进行量化赋值,完成速生槐叶蘋的定量分析。【结果】速生槐叶蘋通过自然和人为传播方式已经入侵全世界57个国家地区,可通过无性繁殖快速分裂生长建立种群,其环境适应性和抗逆性强、竞争能力强、检疫鉴定和根除难度大,对经济、生态和社会造成巨大负面影响。速生槐叶蘋的入侵性R_(1)为72,适应性R_(2)为53,扩散性R_(3)为82,危害性R_(4)为81,风险值R为73.4,应归为严格禁止引入的植物。【结论】尽管速生槐叶蘋在中国的分布范围有限,但属于高入侵风险物种,其潜在的逃逸扩散风险和危害性不可忽视,应严格禁止引入。考虑到该种已经传入我国且有作为观赏植物的市场需求,应制定相应的风险管理制度,定期开展检疫、监测和灭除,防止其逃逸至野外定殖于其他还未发生的地区。

多层静电植绒的空气层保持及亲水尖端仿生

植物人厌槐叶萍由于其表面特殊的"毛发"结构而具有水下保持空气层的能力,试验探讨多层植绒以及仿人厌槐叶萍的亲水尖端对水下空气层保持性能的影响。研究发现,双层植绒可减慢表面气泡流失,提高织物表面气液界面的稳定性;而三层植绒并无进一步减缓气泡流失的作用。在三层植绒样品上进行亲水尖端的仿生试验,发现采用沾取法亲水点施加,可以得到密度、面积比与人厌槐叶萍表面亲水端可比拟的点状亲水结构。试验证明,亲水尖端的存在有利于提高气液界面的稳定性。