白枸杞瘤螨的虫瘿特点、分布及对枸杞的危害

本文调查了内蒙古托克托县白枸杞瘤螨为害引起的虫瘿在枸杞植株不同方向枝条,不同相对位置枝条,同一枝条上不同部位叶片上的分布,及螨虫对枸杞叶片和果实造成的为害。结果表明,白枸杞瘤螨有较重为害西北方向枝条的倾向。枸杞生长中后期,虫瘿的分布多集中在植株的上、中部和枝条端部的嫩叶上。白枸杞瘤螨为害形成的虫瘿直径在1~7.5mm之间,不同大小虫瘿出现的频率呈正态分布,直径2~4mm的虫瘿占绝大多数。虫瘿直径与其内活螨数量有一定的相关性,虫瘿直径小于4mm时,直径与其内活螨数量呈正相关趋势;直径大于4mm时,呈负相关。受害叶的叶长、叶宽、叶面积及果实的纵径、横径、重量均显著减小,受害叶的叶长、叶宽约为正常叶的3/4,叶面积约为正常叶面积的1/2,干果重量减少11.5%。     

环境因素对芸苔链格孢生长发育的影响

研究结果表明,芸苔链格孢(Alternaria brassicae)在0—35℃下均可萌发,最适温度15—20℃。菌丝在0—30℃下均能生长,最适温度20—25℃;孢子及菌丝的致死温度为50℃,10分钟。该菌对湿度要求较严格,相对湿度在90％以上时孢子才能萌发,最适相对湿度为98％;病菌在相对湿度达93％时可以侵染,98％以上最适。脱落后孢子曝露在室内(相对湿度约63％)经1小时萌发率下降32.4％,4小时下降80％。耐旱能力较差。一般情况下紫外光能促进该菌产孢,但是对某些菌系的促进作用不明显。过长的紫外光照射对该菌产孢不利,照射160分钟孢子萌发率下降近80％。麦芽糖、蔗糖为该菌的最佳碳源;硝态氮、有机氮是该菌的良好氮源。pH值为4—6时有利于分生孢子萌发,强酸、强碱对分生孢子萌发有抑制作用。     

小菜蛾高致病力绿僵菌的筛选、鉴定及培养特性研究

为开发蔬菜害虫小菜蛾Plutella xylostella的高致病力真菌生物农药,以3龄小菜蛾幼虫为供试虫源,测定了25株虫生真菌菌株对小菜蛾的致病力,从中筛选出1株对小菜蛾幼虫有较高致病力的菌株CQM125。生测结果显示,在20℃、1.0×108孢子mL 1菌株CQM125菌液处理小菜蛾幼虫的LT50为3.97 d;25℃、5.0×107孢子mL 1菌液的LT50为2.44 d;在25℃下,第7 d的LC50为2.31×104孢子mL 1;接种处理后,20℃、8 d的小菜蛾死亡率为84.22%,对小菜蛾表现出良好的控制效果。依据菌株的形态特征、培养性状和rDNA ITS序列分析将菌株CQM125鉴定为金龟子绿僵菌Metarhizium anisopliae。对该菌株的培养基和培养条件进行了优化,优化后的产孢培养基为PPDA,其中葡萄糖2%,蛋白胨0.5%;最适产孢温度30℃,最适产孢pH值为6.0;最适光照条件为前6 d黑暗,后8 d光照。     

温度、湿度和光照对苹果炭疽叶枯病菌(Glomerella cingulata)产孢的影响

苹果炭疽叶枯病(Glomerella cingulata)是我国苹果上新发现的一种病害,为了了解病原菌的产孢条件和产孢动态,为病害的预测预报与防控提供依据。本研究在人工控制条件下,测试了温度、湿度和光照对苹果炭疽叶枯病菌产生分生孢子和子囊孢子的影响。结果表明,苹果炭疽叶枯病新形成的病叶润湿后,在15℃~30℃下保湿培养2~6 d后可产生大量橘黄色的分生孢子堆,其中30℃下产孢量最大,产孢速度最快,仅需2 d时间。炭疽叶枯病菌在新形成的病叶上于15℃~30℃下培养20~30 d可形成子囊孢子,最适温度为25℃,子囊孢子的形成需要高湿环境或叶片润湿。炭疽叶枯病菌的单孢分离菌株于15℃~25℃下,在马铃薯葡萄糖琼脂培养基(PDA)上培养20~30 d也可形成子囊孢子,最适产孢温度25℃。紫外光、黑光和日光都能促进子囊孢子的形成。     

绿僵菌的培养及其防治白蚁的效果

在平板上测定了不同温度、pH值、碳氮源、微量元素及生长因子(维生素)对绿僵茵茵丝生长及产孢量的影响.结果表明:pH值7.0、温度28℃时最适合绿僵茵的生长;以玉米粉为碳源、酵母膏为氮源时茵丝生长最好、产孢量最高;加入适量的微量元素及维生素有利于茵丝生长及产孢量的提高,其中以加入微量元素Mn和维生素C的效果最佳.绿僵茵对黑翅土白蚁具有强烈的毒杀效果.     

金龟子绿僵菌的液固双相发酵研究

金龟子绿僵菌是重要的害虫致病真菌,采用液固双相发酵方法对MA4-37菌株进行发酵,研究液体培养基、固体培养基及其厚度、浅盘固体发酵、袋装固体发酵对金龟子绿僵菌生长及产孢量的影响,优化控制发酵过程。结果表明,液体发酵较适合的培养基为发酵液B(大豆1%、蔗糖1%、NaCl0.5%、MnSO40.5%,用KH2PO4-K2HPO4缓冲液调节pH值为6.0～7.0),采用该培养基时液生分生孢子产量和菌丝生长量均最高,分别达到4.3×109个/L、5.99g/L。固体发酵时,浅盘发酵方法优于袋装发酵,其中采用配方F的固体培养基(碎米600g、大米300g、H2O 50%、KH2PO4-K2HPO4缓冲液0.05%、蔗糖0.5%),厚度在1.3cm时,浅盘培养7d的产粉量可达16.1mg/g。     

三种杀真菌剂对金龟子绿僵菌产孢及生长的影响

三种杀真菌剂在一定浓度范围为（氯硝胺在１００×１０￣（－６），孟加拉红在５００×１０￣（－６）和柯赛得在２０００×１０￣（－６）内）对金龟子绿僵菌的菌落形成没有明显影响，而柯赛得（含５０％氢氧化铜）和孟加拉红分别在１００×１０￣（－６）和５００×１０￣（－６）浓度时显著地增加金龟子绿僵菌的产孢量，柯赛得还具有缩短产孢时间的作用。氯硝胺在１～１００×１０￣（－６）浓度范围内，随着浓度增加，对产孢能力和菌落大小的抑制作用加强。柯赛得和孟加拉红随浓度的增加对菌落的抑制作用也有所加强，但没有像氯硝胺的抑制作用那么强。     

Components of resistance to late blight (Phytophthora infestans) in eight South AmericanSolanum species

Four components of partial resistance toPhytophthora infestans were measured after inoculation in the greenhouse and in the field ofSolanum arnezii x hondelmannii, S. berthaultii, S. circaeifolium, S. leptophyes, S. microdontum, S. sparsipilum, S. sucrense andS. vernei, and four hybrid progenies ofS. microdontum withS. tuberosum. The four components were infection efficiency, lesion growth rate, generation time and sporulation capacity. The results were compared with resistance ratings derived from field experiments, and with observations made on the potato cultivars Bintje, Bildstar, Libertas and Pimpernel. Genetic variation for all components was found, while the relative importance of the components of partial resistance appeared to vary between the species. InS. microdontum, generation time, infection efficiency and lesion growth rate, and inS. tuberosum infection efficiency, lesion growth rate and sporulation capacity appeared positively associated, but in other species no such association was found. A strong hypersensitive reaction, the expression of which appeared to depend on environmental conditions, was found inS. microdontum. ForS. berthaultii, infection efficiency appeared to be the main resistance component.Abbreviations ADPC area under the disease progress curve - IE infection efficiency - LGR lesion growth rate - GT generation time - SC sporulation capacity     

Biotin Induces Sporulation of Mulberry Anthracnose Fungus, Colletotrichum dematium

Compounds in mulberry leaves inducing sporulation of C. dematium, mulberry anthracnose fungus, were detected. Dissolved or suspended aqueous solutions (1%) of 16 amino acids and 10 vitamins occurring in mulberry leaves were applied individually at the margin of the fungal colony growing on PSA plate. Sporulation was induced only where a biotin solution was applied on the mycelium at a concentration of at least 0.01 ppm. This result suggests that biotin, which occurs in mulberry leaves (ca. 0.6 mg/kg of dried leaves), has a role in inducing sporulation of C. dematium. Received 20 August 1999/ Accepted in revised form 16 November 1999     

番茄叶霉病重要流行环节初步研究Ⅱ.病斑产孢、孢子飞散

对番茄叶霉病病斑产孢规律的研究表明:在保湿24h内,随着保湿时间的延长,病斑相对产孢量也随之增加;黑暗条件有利于病斑产孢;病斑产孢适宜温度为10～28℃。其中,在23℃时产孢量最大,4℃和35℃时病斑几乎不产孢;在80%～100%的相对湿度范围内病斑均可产孢,病斑产孢量随湿度的增加而增大;另外,病斑相对产孢量随氮肥使用量的增加而增加,却随着磷钾肥使用量的增加而减少;6～9龄的病斑产孢能力最强。叶霉病菌分生孢子主要在夜间飞散;在番茄植株株高30～100cm范围内,60cm株高处分生孢子数量最多。