黄板诱杀斑潜蝇技术研究

设置黄板诱集成虫是斑潜蝇测报和防治的重要手段.通过在茄果类及瓜类蔬菜田的对比试验,结果表明,柠檬黄色板在贵州诱杀斑潜蝇成虫量是橘黄色、淡黄色板的3倍以上;插板位置,黄板下端高于作物顶部20cm的诱虫量,分别是黄板下端和上端与作物顶部平齐的1.8倍、1.6倍;插板密度,每667m274块的每块诱虫量,分别比每667m245块、27块高31.8%、41.6%.试验为黄板诱杀斑潜蝇的设置技术提供了依据.     

水稻细菌性条斑病发生及流行因子分析

人工接种及病区调查研究结果表明，在种植感病品种情况下，气温决定了水稻细菌性条斑病的发生与否和潜育期的和短衣病斑长度；病害发生的最低温为１２℃，发病最适温度为２５－３０℃以上，而湿度决定此病发病率及严重度。结合主成分分析，该病在田间的流行取决于温度／湿度及降雨量。台风暴雨造成的伤口有利于病害的流行。     

生物间遗传学在防治河北省小麦叶锈病研究中的应用

作者应用生物间遗传学的观点和方法,对河北省的小麦品种与叶锈菌的相互作用进行了分析。供试的叶锈菌是来自河北省的177个标样,供试的28个小麦品种包括河北省的主要生产品种、区试品种(系)抗源和新鉴别寄主。用毒力频率法分析品种与叶锈菌群体的关系,有6个品种即鉴61、保麦2号、翼植88-5163、石86-2848、唐86-4043和百农3217表现较抗病。根据这6个品种对叶锈菌群体的反应、列出33种不同的毒性公式,在此基础上,根据若干品种对叶锈菌群体同时表现抵抗或感染计算抗性组合,为品种合理布局选择最佳组合,在小种鉴定方面,用新鉴别寄主对177个菌株的反应鉴定出频率在3.4%以上的小种8个,其中以V1,9-16和V1,9-12,14-16的频率较高,分别为13.6%和10.7%,也是近两年来北方冬麦区常出现的小种类型。在小种鉴定的基础上,根据28个品种与6个优势小种互作所出现的浸染型来推导品种和叶锈菌的基因型,共推导出7个抗性基因分散在不同的品种中。     

苹果砧木M26离体叶片愈伤组织发生及分类研究

对苹果砧木Ｍ２６ 离体叶片愈伤组织的发生研究表明,取继代后３０ ～３５ ｄ 的试管苗顶部１～４ 叶位的叶片,沿与主脉垂直方向横切后,以叶背面朝上方式置于愈伤组织诱导培养基上,经观察在叶片近柄端切口处愈伤组织发生较早,产生量较多。最适的愈伤组织诱导培养基为：ＭＳ＋２ ,４ － Ｄ０ ．２ ～２ ．０ ｍｇ·ｌ－ １ ＋ＩＡＡ０ ．２ ～２．０ ｍｇ·ｌ－ １ ＋ ＢＡ０ ．５ ～１．０ ｍｇ·ｌ－ １ ＋ 蔗糖３ ％ ＋ 琼脂０．６％ 。将诱导产生的愈伤组织按外部形态、细胞特点及生理生化指标等分为三类,其中表面干燥致密、细胞内含物丰富、淀粉、蛋白质及干物质含量均较高的Ⅲ类愈伤组织的芽再生频率最高,可达８３ ．３３ ％ ,是能利用的愈伤组织类型。     

Infection of Linseed by Alternaria linicola; Effects of Inoculum Density, Temperature, Leaf Wetness and Light Regime

Controlled environment studies were conducted to determine the effects of inoculum density, temperature, leaf wetness and light regime on the infection of linseed by Alternaria linicola. The % cotyledons and leaves with symptoms, and the disease severity (% leaf area with symptoms) increased linearly when the inoculum density increased from 1×10³ to 1×10⁵ conidiaml^–1. The first symptoms appeared on cotyledons and leaves 4 and 6 days after inoculation, respectively. Eight hours of leaf wetness were sufficient to initiate the disease at 25°C but not at 15°C, when 10-h periods of leaf wetness were required. % leaf area with symptoms was lower at 15°C than that at 25°C irrespective of the leaf wetness periods tested. Interruption of a continuous leaf wetness period by a 12-h dry period, occurring at any time between 1 and 18h after inoculation, decreased the % cotyledons with symptoms and the disease severity, with the greatest reductions (60% and 100%, respectively) being observed when the dry period began 6h after inoculation. A. linicola conidia were able to exploit successive 12-h periods of leaf wetness cumulatively to infect linseed plants. Disease incidence and severity were positively correlated with the dark period following inoculation, but they were negatively related to the length of the initial light period. Our findings suggest that infection of linseed by A. linicola and further development of symptoms can occur under unfavourable environmental conditions.     

叶露仪的研制和初步测试

植物叶面结露时间长短及露量与农作物病虫害,特别是真菌病害的发生有密切的关系。为监测叶露情况我们设计制作了叶露仪。该仪器适合在植物病虫害发生规律的科学研究和大田作物病害预测预报工作中使用。     

Quantitative PCR monitoring of the effect of azoxystrobin treatments on Mycosphaerella graminicola epidemics in the field

Quantitative PCR and visual monitoring of Mycosphaerella graminicola epidemics were performed to investigate the effect of curative and preventative applications of azoxystrobin in wheat field crops. A non-systemic protectant and a systemic curative fungicide, chlorothalonil and epoxiconazole, respectively, were used as references. PCR diagnosis detected leaf infection by M graminicola 3 weeks before symptom appearance, thereby allowing a clear distinction between curative and preventative treatments. When applied 1 week after the beginning of infection, azoxystrobin curative activity was intermediate between chlorothalonil (low effect) and epoxiconazole. When applied preventatively, none of the fungicides completely prevented leaf infection. There was some indication that azoxystrobin preventative treatments may delay fungal DNA increase more than epoxiconazole at the beginning of leaf infection. Both curative and preventative treatments increased the time lapse between the earliest PCR detection and the measurement of a 10% necrotic leaf area. Azoxystrobin only slightly decreased the speed of necrotic area increase compared with epoxiconazole. Hence, azoxystrobin activity toward M graminicola mainly resides in lengthening the time lapse between the earliest PCR detection and the measurement of a 10% necrotic leaf area. Information generated in this way is useful for optimal positioning of azoxystrobin treatments on M graminicola.     

抗噻枯唑和抗叶枯净的水稻白叶枯病菌株的适应度比较

将水稻白叶枯病噻枯唑抗性菌和叶枯净抗性菌的适应度特性进行了比较。当Ｓａ＾ｒ和Ｐ＾ｒ与敏感菌（Ｓ）的等量混合物在植株上繁殖时,Ｓａ＾ｒ和Ｐ＾ｒ竞争不过Ｓ,但Ｐ＾ｒ竞争能力较Ｓａ＾ｒ强。Ｓａ＾ｒ和Ｐ＾ｒ的致病力与Ｓ的无明显差异。但在离体保存时Ｓａ＾ｒ和Ｐ＾ｒ易于丧失致病力。这种致病力的丧失是由于被保原群体中低致病力的敏感菌比例上升所致,进一步说明Ｓａ＾ｒ和Ｐ＾ｒ的适应度不及Ｓ。结果表明,白叶枯病市民经     

Identification of Alternaria spp. on wheat by pathogenicity assays and sequencing

The pathogenicity of Alternaria spp. isolated from wheat leaves collected in regions where alternaria leaf blight has been reported was compared with that of IMI reference isolates of A. triticina and A. alternata using two durum and two bread wheat genotypes. To identify isolates putatively corresponding to A. triticina , morphological and DNA sequence analyses based on ribosomal DNA from the internal transcribed spacer (ITS) region (ITS1, 5·8S rRNA gene, ITS2) and toxicity bioassays of culture filtrate were combined. Glasshouse inoculations provided reliable information to assess the pathogenicity of A. triticina isolates on wheat. Alternaria leaf blight symptoms were produced by the A. triticina isolates only on durum wheat cv. Bansi, while A. alternata , A. tenuissima and A. arborescens isolates were found to be nonpathogenic on the wheat cultivars tested. Alternaria triticina isolates were distinguished from other Alternaria species by Simmons and Roberts' sporulation pattern 6 and two to three conidia per sporulation unit associated with primary conidia bearing long (> 7  µ m) apical secondary conidiophores. Phylogenetic analysis also proved effective at discriminating wheat-pathogenic A. triticina from other nonpathogenic Alternaria species. Alternaria triticina isolates yielded longer ITS sequences than A. alternata , A. tenuissima and A. arborescens isolates, leading to clear-cut differences as visualized with agarose gel electrophoresis. Additionally, only culture filtrates of A. triticina isolates caused nonspecific necrotic lesions on leaves of 3-week-old wheat plants.     

Structural Characterisation of the Interaction between Triticum aestivum and the Dothideomycete Pathogen Stagonospora nodorum

The interaction between Stagonospora nodorum and a susceptible wheat cultivar was investigated using a range of microscopic techniques. Germination of pycnidiospores occurred approximately 3 h after making contact with the leaf surface and was followed by attempted penetration 8–12 h later. Penetration was observed through stomata and also directly through periclinal and anticlinal epidermal cell walls. Penetration down the anticlinal cell walls appeared to occur without a differentiated penetrating structure whilst structures identified as either lateral appressoria or hyphopodia were typically present when penetrating over a periclinal cell wall. Once inside the leaf, the fungus continued to grow for the next 4–5 days colonising all parts of the leaf except the vascular bundles. Only in the later phase of the infection was total host cell collapse apparent. Evidence of polyphenolic compounds was observed. The infection cycle was completed within 7 days as indicated by sporulation on the leaf surface. These results have allowed us to understand how the fungus physically interacts with the leaf and will help the overall understanding of the infection process.