杀菌剂对昆虫病原真菌块耳霉孢子萌发的影响

研究了10种杀真菌剂在田间使用浓度的中间浓度及其10倍稀释液下,对昆虫病原真菌块耳霉孢子萌发的影响。结果表明各杀菌剂对块耳霉孢子萌发有不同程度的抑制,浓度愈高,抑制作用愈大。多菌灵、普力克对孢子的抑制作用最小,与块耳霉表现出良好的相容性,是与块耳霉实施菌药合用的候选药剂。施保功、大生、达科宁3种杀菌剂对块耳霉孢子的杀伤力最大,在两种浓度下孢子萌发率均为0。施佳乐、速克灵和敌力脱在低浓度下,与块耳霉的相容性良好,处理后24～48 h与对照无显著性差异;但在中间浓度水平下,处理后48 h孢子萌发率分别为12.45％,0,0。其余药剂随处理时间和浓度不同,对块耳霉孢子萌发有不同程度的抑制。     

4种植物提取物对茶炭疽病菌的体外抑制作用

以丙酮作溶剂对芦柑皮、艾蒿、香樟叶和侧柏叶进行浸提;采用菌丝生长速率法测定各提取物对茶炭疽病菌菌丝的抑制作用,采用水琼脂培养法测定提取物对分生孢子萌发的抑制效果。结果表明:1 500μg/mL浓度下,各提取物对茶炭疽病菌菌丝均有抑制作用,其中芦柑皮96h的抑制率达到93.32%,艾蒿、香樟叶和侧柏叶96h的抑制率分别为61.10%、55.64%和48.20%,EC50分别为8.981、839.575、1 058.682μg/mL和1 429.094μg/mL;芦柑皮、艾蒿、香樟叶和侧柏叶提取物对分生孢子的抑制率分别为34.85%、85.54%、55.40%和59.68%,EC50分别为5 764.142、281.121、1 502.49μg/mL和969.369μg/mL。芦柑皮、艾蒿丙酮提取物具有开发植物源杀菌剂的潜力。     

A one-hit model for the infection of clubroot-susceptible cabbage (Brassica oleracea var.capitata) byPlasmodiophora brassicae at various inoculum densities

In two glasshouse and three phytotron experiments, clubroot-susceptible cabbage (Brassica oleracea varcapitata) cv Septa was inoculated with clubroot resting spores at inoculum densities ranging from 0 to 2·10⁷ spores-plant^–1. At densities of 10⁵ spores·plant^–1 and higher all plants developed clubroot symptoms, except in one glasshouse experiment conducted in winter. The proportion of plants developing symptoms plotted against inoculum density showed a sigmoid curve. Although the shape of the curve was similar in all experiments, the inoculum densities required to induce 50% disease incidence varied from 10³ to 10⁵ resting spores·plant^–1. The data of all five experiments could be well described by a generalized one-hit model which involves variation between plants with regard to the probability of infection.Abbreviations cv cultivar - ECD European Clubroot Differential set     

大豆茎溃疡病菌子囊壳诱导及孢子萌发方法探索

大豆茎溃疡病是为害大豆的重要病害,世界上十大大豆生产国中已有7个国家发现大豆茎溃疡病菌的分布,对当地农业造成严重威胁[1]。该病是我国进境植物检疫性有害生物[2],目前没有发生为害的报道。大豆茎溃疡病菌以菌丝和子囊壳在大豆植株及其残体上越冬,子囊壳在干燥35 d     

Suppression of clubroot disease under neutral pH caused by inhibition of spore germination of Plasmodiophora brassicae in the rhizosphere

To elucidate the mechanism of clubroot suppression under neutral soil pH, a highly reproducible germination assay system under soil culture conditions was designed based on the hypothesis that germinated spores of Plasmodiophora brassicae could be identified by the absence of a nucleus (i.e. having released a zoospore to infect a root hair of the host plant). Brassica rapa var. perviridis seedlings were inoculated with a spore suspension of P. brassicae at a rate of 2·0 × 10⁶ spores g⁻¹ soil and grown in a growth chamber for 7 days. The spores were recovered from rhizosphere and non-rhizosphere soils and stained with both Fluorescent Brightener 28 (cell-wall-specific) and SYTO 82 orange fluorescent nucleic-acid stain (nucleus-specific stain). Total numbers of spores were counted under UV-excitation, and spores with a nucleus that fluoresced orange under G-excitation were counted. The significant increase in the percentage of spores without a nucleus (germinated spores) in the rhizosphere after 7 days' cultivation and the correlation with root-hair infections validated the assay system. Applications of calcium-rich compost or calcium carbonate to neutralize the soil significantly reduced the percentage of germinated spores in the rhizosphere, as well as the number of root-hair infections. The present study provides direct evidence that the inhibition of spore germination is the primary cause of disease suppression under neutral soil pH.     

解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌的抗生作用

为明确解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌的抗生作用, 采用平板对峙法和菌丝生长速率法以及孢子萌发法测定了解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌菌落生长和孢子萌发的抑制作用?结果表明:菌株TS-1203对苹果炭疽叶枯病菌具有显著的抑制作用, 其菌液对病菌的抑制率高达70.4%; 其发酵液对苹果炭疽叶枯病菌的抑制率随着发酵液浓度的增加而升高, 尤其当发酵液浓度为15%时, 其抑菌率为 59.0%; 发酵液处理苹果炭疽叶枯病菌孢子24 h后, 其萌发抑制率与芽管生长抑制率分别为78.2%与64.3%, 且芽管出现畸形; 利用TS-1203发酵液处理苹果离体叶片后接种炭疽叶枯病菌, 其防效为70.1%?综合分析表明, 解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌具有良好的抑制作用?     

康氏木霉抑菌物质的抑菌效果

康氏木霉抑菌物质的抑菌效果与培养时间呈直线回归关系,即在培养５７天以内,随着培养时间的延长,抑菌效果在不断增强。康氏木霉抑菌物质对丝核菌属、镰孢属,、刺盘孢属、核菌属等致病菌都有较强的抑制作用。     

采用孢子萌发法测定化合物对黄瓜白粉病菌的生物活性

接种黄瓜白粉菌后16 h的黄瓜叶片用透明胶带在子叶表面粘孢子取样的平均发芽率与用台盼蓝染色后在光学显微镜下调查的发芽率分别为83.7%和85.0%,t测验无显著差异,表明透明胶带取样的发芽率可以代表黄瓜叶片上白粉病菌孢子的发芽率。采用孢子萌发法和叶碟法分别测定了醚菌酯、植物源活性组分大黄素甲醚(P3D)对8个黄瓜白粉菌菌株的EC₅₀。统计结果表明:采用两种方法测定醚菌酯P、3D对黄瓜白粉菌的EC₅₀的相关系数的平方值分别为0.880、.99,表明两种方法的测定结果有很强的相关性;采用该孢子萌发法可评价化合物对植物专性寄生病菌如白粉菌孢子萌发的生物活性。     

Usefulness of nonhost plants in managing Plasmodiophora brassicae

Germination of resting spores of Plasmodiophora brassicae , causal agent of clubroot in crucifers, may be stimulated by certain nonhost plants. Without a host plant to infect, such germination would lead to a reduced persistence of resting spores in the soil. The effect of four nonhost plants on P. brassicae was investigated in a 3-year field experiment and a 14-month glasshouse experiment. Three of the plant species used, leek ( Allium porrum ), winter rye ( Secale cereale ) and perennial ryegrass ( Lolium perenne ), have been reported to stimulate resting spore germination, while the fourth, red clover ( Trifolium pratense ), does not. In the field experiment, none of the plant species reduced the concentration of P. brassicae in soils when tested with bioassay plants (Chinese cabbage, Brassica rapa var. pekinensis ). In the glasshouse experiment, there was a lower disease level in all plant treatments compared with the plant-free control following incorporation and decomposition of plant roots. At this time, pH in the soils with plant treatments was higher than that in the control soil. There were no indications of a species-specific interaction between any of the nonhost plants investigated and P. brassicae , and it cannot be concluded that any of them would be useful in the sanitation of P. brassicae -infested soils within short time periods.     

十种藓类植物孢子萌发与原丝体发育的初步研究

对10种藓类植物（红蒴立碗藓、无疣墙藓、钟帽藓、短尖叶墙藓、中华细枝藓、柳叶藓、多褶青藓、狭叶绢藓、东亚绢藓）的成熟孢子在光照培养箱中进行人工培养,培养液为Knodson C培养液,对照组为自来水。在光学显微镜下描绘和照相记录了这10种藓类孢子萌发与原丝体发育的基本过程,并对孢子的萌发能力和时间,原丝体系统发育的类型、特点进行了分析和讨论。     

球孢白僵菌与一些常用市售复合肥料的相容性

为了解5种常用市售复合肥料对球孢白僵菌孢子萌发的影响,调查混有不同浓度肥料的平板培养基上的菌落形成单位和摇瓶培养中的孢子发芽率。结果表明,在2种培养条件下“大洋生态有机肥”（F2）在高、中、低3种剂量下与对照的差异均不显著,“绿营高”（F3）仅在低剂量下与对照无显著差异,而其余剂量都极显著地抑制孢子萌发。其他3种肥料在3种剂量下对孢子萌发都有显著抑制作用。这表明只有F2及低剂量的F3可以与白僵菌分生孢子制剂混合使用。     

石楠叶锈病菌 Aecidium wenshanense 锈孢子萌发的生物学特性

为了解由文山春孢锈菌Aecidium wenshanense引起的石楠叶锈病的发生发展及流行规律,为病害的防治提供依据,本文以椭圆叶石楠Photinia beckii发病植株叶上的新鲜锈孢子为试验材料,采用水琼脂平板孢子萌发法对温度、湿度、光照、酸碱度及寄主汁液等条件对该锈孢子萌发的影响进行了研究。结果表明,该锈菌锈孢子在温度5～30℃和pH3～10的范围内都能萌发,最适温度为20～25℃;最适pH为6～8;相对湿度大于或等于90%时孢子才能萌发,最适湿度为100%+水;连续光照抑制孢子萌发,而连续黑暗条件下孢子萌发率最高。寄主(椭圆叶石楠)老叶的新鲜汁液对锈孢子的萌发有一定抑制作用。     

串珠镰刀菌细胞壁多糖激活寄生菌纤细齿梗孢的孢子萌发

 利用碱抽提法从串珠镰刀菌(Fusarium moniliforme)菌丝细胞壁得到多糖粗提物。该多糖提取物可以激活寄生于串珠镰刀菌上的活体寄生真菌纤细齿梗孢(Olpitrichum tenellum)的孢子萌发,多糖浓度为0.2 mg/m L时,萌发率达80.5%。纤细齿梗孢的孢子仅在存在该多糖提取物的条件下才能萌发,在马铃薯-葡萄糖或葡萄糖-酵母液体培养基上不能萌发,一些糖、氨基酸、无机盐、维生素不能促使其萌发,光也不影响萌发。纤细齿梗孢孢子萌发最适p H是7.0,最适温度25℃。结果表明,串珠镰刀菌菌丝细胞壁多糖可能在激活纤细齿梗孢孢子萌发中起重要作用。     

油类和糖类对绿僵菌孢子萌发的影响

在２３－２４℃及保湿条件下培养２４小时，绿僵菌分生孢子在７种植物油油滴上的萌发率在９６％以上。在４种矿物油中，石蜡油、煤油、柴油萌发率达８６％－９９％，但在润滑油中不能发芽。对１５种碳源上观察结果，赤癣糖、麦芽糖、Ｄ－甘露糖、葡萄糖有促进孢子萌发的作用。     

农药对虫生真菌粉虱座壳孢孢子萌发和菌丝生长的影响

虫生真菌粉虱座壳孢Aschersonia aleyrodis是大有前途的粉虱和介壳虫杀虫剂。用6种大田常用农药在推荐浓度下,研究其在25℃下对座壳孢菌孢子萌发和菌丝生长的影响,发现甲氰菊酯和克螨特抑制其孢子萌发和菌丝生长,表明二者与本菌极不相容。吡虫啉、水胺硫磷和双甲脒能促进孢子萌发且后两者亦可加速菌丝生长,多菌灵对其孢子萌发起暂时促进作用然而抑制其菌丝生长。     

5种链格孢属植物病原真菌对10种杀菌剂的敏感性比较

离体条件下测定并比较了10种杀菌剂对番茄早疫病菌、苹果斑点落叶病菌、梨黑斑病菌、烟草赤星病菌和甘蓝黑斑病菌等5种链格孢属植物病原真菌的抗菌活性。结果表明,不同种的链格孢属病菌对同一药荆的敏感性相近;咪鲜胺、啶菌恶唑、苯醚甲环唑、异菌脲、腐霉利等5种杀菌剂对供试病菌菌丝生长的抑制活性最好,其EC50在0．01～1．28μg／mL之间;百菌清对病菌分生孢子萌发的抑制活性最高,其次是醚菌酯和嘧菌酯。