阳春砂仁(Amomum villosum lour.)叶枯病病原菌研究

砂仁叶枯病是一种发生普遍而严重的病害。该病有四种症状类型:叶枯型、斑枯型、星斑型和叶鞘病斑。以前者为主。根据病原菌的形态、培养性状、致病性及寄主范围鉴定为围小丛壳菌(Clomerella cingulata(Stonem.)Spauld.et Schrenk),分生孢子阶段为盘长孢状刺盘孢(Co-lletotrichum gleosporioides(Penz.)Sacc.)。病菌生长量和产孢量依培养和光照条件而异。寄主范围广,在参试的23科39种植物中,有9科15种植物发病。     

江苏水稻旱育秧“黄枯”病原鉴定及致病力研究

 从江苏13个市采集肥床旱育秧"黄枯"标本1030份,分离后获784株菌。经鉴定和致病性测定,752株为致病菌,分属4属11种真菌:(1)镰孢属(Fusarium),占74.0%,有6个种,分别为禾谷镰孢(F.graminearum Schw.)、尖孢镰孢(F.oxysporum Schlecht.)、木贼镰孢[F.equiseti (Corda) Sacc.]、串珠镰孢(F.moniliforme Sheld.)、半裸镰孢(F.semitectum Berk.et Rav.)和雪腐镰孢[F.nivale (Fr.) Ces.],其中禾谷镰孢最多,占病菌总数的25.3%;其次是尖孢镰孢、木贼镰孢和串珠镰孢,分别占16.2%、13.3%和10.2%;而雪腐镰孢仅占1.1%。(2)丝核属(Rhizoctonia),有立枯丝核(R.solaniKühn),占14.6%。(3)平脐蠕孢属(Bipolaris),占7.4%,主要是麦根腐平脐蠕孢[B.sorokiniana (Sacc.) Shoem.],占7.0%,而稻平脐蠕孢[B.oryzae (Breda.de Haan) Shoem.]仅为0.4%。(4)腐霉属(Pythium),占4.0%,有瓜果腐霉[P.aphanidermatum (Eds.) Fitzp.]和链状腐霉(P.catenulatum Matth.)。病菌种类及其比例因地区和苗床土类型的不同存在一定差异。接种试验表明,不同病菌致病力和引起的症状类型差异较大。腐霉、禾谷镰孢、串珠镰孢和麦根腐平脐蠕孢引起的发病率均为100%,而半裸镰孢和雪腐镰孢仅40%左右。多数病菌能够引致稻苗的"黄枯",并且茎基部有褐色病斑。引起死苗的主要是腐霉、麦根腐平脐蠕孢和禾谷镰孢,而串珠镰孢往往引起稻苗的徒长或矮化。     

浙江省梨孢属(Pyricularia Sacc.)真菌的寄主植物

 在浙江省梨孢菌(Pyricularia)除感染水稻引起稻瘟病外,在蟋蟀草(Eleusine indica Gaertn.)、狗尾草(Setaria viridis Beauv.)、法氏狗尾草(S.faberri Herrm.)、马唐(Digitaria sanguinalis Scop.)、毛马唐(D.sanguinalis var.ciliaris Parl.)、稗(Echinochola crusgallis Beauv.)、茭白(Zizania caduciflora Hand.-Mazz.)和碎米莎草(Ceperus iria L.)等植物上均发现梨孢菌的自然感染。除茭白和碎米莎草外,其他植物的感染症状基本与稻叶瘟相似,典型病斑为梭形或纺缍形,最外层为黄色的中毒部,内层为褐色的坏死部,中央为灰白的崩溃部,病斑两端有褐色的坏死线向外延伸成长条状,在幼嫩的叶片上也会出现急性型病斑,病斑表面有一层灰褐色的霉层,即梨抱菌的分生袍子梗和分生抱子;菱白上的病斑近圆形,病斑结构与稻叶瘟相同,但坏死线不如稻叶瘟明显;碎米莎草上的病斑为椭圆形,只有灰白色的崩溃和褐色的坏死部,没有中毒部和坏死线。     

甘肃省药用植物上链格孢属（Alternaria）的种类及分布（Ⅱ）

对2004年以来甘肃省百合科、苋科、木犀科、大戟科、桔梗科药用植物链格孢属引起的病害进行了鉴定,结果如下:芍药叶斑病病原为细链格孢[Alternaria alternata (Fr.:Fr.)Keissler],青葙叶斑病病原为青葙链格孢[A.ce-losiae (Tassi)O.Sǎvul],连翘灰斑病病原为A.forsythiae Harter,引起连翘灰斑病、甘遂褐斑病病原为甘遂链格孢(A.kansuiae T.Y.Zhang&.Z.Zhang),沙参黑斑病的病原为茄链格孢[A.solani(Ellis et Martin)Sorauer].     

河北省苹果果实黑点病的症状与病原研究初报

 为明确河北省苹果果实黑点病的症状类型及其对应的病原菌,本研究对河北省6个市的果园进行了病害调查和样品采集,并对引起不同症状类型的病果进行了病原菌的分离和鉴定。结果表明,河北省的套袋苹果黑点病可以分为四大类型,分别是萼洼黑点型、果面黑点型、果面晕斑型和梗洼褐斑型。除了果面晕斑型为单一病原侵染之外,其他类型的病斑均分离获得3种或3种以上的病原菌。通过形态学分析以及系统发育分析发现,分离的菌株主要为5个不同属的真菌,分别是粉红聚端孢(Trichothecium roseum)、细极链格孢(Alternaria tenuissima)、产菌核枝顶孢(Acremonium sclerotigenum)、尾孢菌(Cercospora sp.)和镰刀菌(Fusarium sp.)。致病性检测表明,粉红聚端孢和细极链格孢的致病力较强,为引起该病害的主要致病菌。而产菌核枝顶孢在河北省造成的症状比之前的报道更加多样化。本研究明确了河北省苹果果实黑点病的主要症状类型及其对应的病原菌,为该病害的流行规律以及综合防控研究奠定了基础。     

梨果生刺盘孢子囊孢子单孢菌系的生物学特性及致病性研究

 梨果生刺盘孢的2种致病型菌株FJ-85(产生黑点症状)和菌株FJ-11-2(产生坏死斑症状)的子囊孢子单孢培养均可产生正、负2种类型的单孢菌系。正型单孢菌系菌落浅白色,其上形成的子囊孢子再培养,可形成正、负2种类型的单孢菌系;负型单孢菌系菌落深灰色,其上形成的子囊孢子再培养,只形成负型一种单孢菌系。2个菌株的单孢菌系中,负型的比例明显多于正型。2种类型的单孢菌系对峙培养,在菌落内及菌落交界处均可形成子囊壳,而同种类型的单孢菌系对峙培养仅在菌落内产生子囊壳。结果表明同种类型的单孢菌系可同宗配合,而正、负2种类型的单孢菌系还可异宗配合。正型单孢菌系的致病力与原始菌株相近,而负型单孢菌系较原始菌株弱。2个菌株的单孢菌系在翠冠梨上引起的症状差异与其原始菌株相同。研究结果为解析梨果生刺盘孢的有性生殖与致病的关系提供了新的有用信息。     

猕猴桃储藏期病原真菌的分离与鉴定

为明确猕猴桃采后病害的病原种类,本研究对猕猴桃储藏期病果进行了病原真菌的分离培养,观察了病原的培养性状和形态特征,并进行了分子生物学鉴定及其致病性测定。结果表明,引起猕猴桃储藏期病害的病原真菌有7种(类),分别是链格孢菌(Alternaria spp.)、葡萄座腔菌(Botryosphaeria dothidea)、间座壳菌(Diaporthe spp.),无性态为拟茎点霉菌(Phomopsis spp.)、拟盘多毛孢菌(Pestalotiopsis sp.)、假尾孢菌(Pseudocercospora sp.)、刺盘孢(Colletotrichum sp.)、灰葡萄孢(Botrytis cinerea),研究结果可为后期猕猴桃采后病害的防控提供科学依据。     

广东省裁培药用植物上弯孢类型炭疽菌的鉴定

 作者按照Sutton的分类系统,把标准培养特性、致病力和寄主范围等作为分种的主要特征,对广东省15种栽培药用植物上的弯孢型炭疽菌进行研究,共鉴定出3个种,即辣椒刺盘孢(Colletoptrichum capsici)、百合刺盘孢(C.liliacearum)和束状刺盘孢(C.dematium]报道了辣椒刺盘孢的7种新寄主,即:良姜(Alpinia officinarum Hance)何首乌(Polygo-hum multiflorum Thunb.)五叶参[Pentapanax leschenaultii (Wight&Arn.) Seem].龙利叶(Sauropus spatulifolius Beille)、穿心莲[Andrographis paniculata (Burmf).Nee.]佛手(Citrus medica L.)、山柰(Kaempferia galanga L.)辣椒刺盘孢在广东分布普遍,致使淮山、何首乌和佛手等遭受重大损失。     

淡紫拟青霉研究概况与展望

淡紫拟青霉Paecilomyces lilacinus(Thom.)Samson属半知菌纲、丝孢菌目、丝孢菌科、拟青霉属。此菌广泛分布于世界各地,具有功效高、寄主广、易培养等优点,特别在控制植物病原线虫方面功效卓著。半个多世纪以来,国内外许多专家学者对此菌进行了广泛而深入的研究,在生物学、生态学、大量培养、控害效能与田间应用等方面取得了一系列研究成果。笔者对有关淡紫拟青霉研究进行综述。     

观赏百合叶枯病症状类型与病原菌鉴定

引起甘肃省百合叶枯病的主要致病菌为椭圆葡萄孢[Botrytis elliptica(Berk.)Cooker],分离率为70.5%;其次是灰葡萄孢(Botrytis cinerea Peers),分离率为23.0%。该病原菌在不同品种百合叶片上造成的症状有4种类型。不同症状类型病斑分离的病原菌种类不同,其中紫缘黄褐斑型、褐色环纹型和黄缘褐斑型主要致病菌为椭圆葡萄孢,平均分离率为82.5%;叶缘干枯型的主要致病菌为灰葡萄孢,分离率达93.7%。温度为15℃时,易产生菌核;菌核萌发最适温度为15~20℃。     

南瓜叶枯病病原菌生物学特性研究

本文对南瓜叶枯病病原菌瓜链格孢（Alternaria cucumerina）进行了生物学特性研究,结果表明：温度、pH、光照对其生长和产孢都有一定的影响。该病原菌菌丝生长、产孢和萌发的适宜温度为28 ℃,pH为7时菌丝生长最快,pH为8时最易产孢。25 ℃下连续黑暗培养产孢最多。碳、氮源对菌丝生长和产孢量有一定的影响,碳源中甘露醇组菌丝生长最快,山梨醇处理产孢量最多。氮源中牛肉浸膏最适宜菌丝生长和产孢,硫酸铵最差。该菌致死温度为50 ℃。     

Anthracnose of centipede grass caused by Colletotrichum caudatum

Anthracnose disease was found on centipede grass [Eremochloa ophiuroides (Munro) Hack.] planted as a ground cover on paddy field levees in Shiga Prefecture in 2004. The symptoms were ear blight, stalk blight, and leaf spots. The causal fungus was morphologically identified as Colletotrichum caudatum (Sacc.) Peck. This is the first report of centipede grass anthracnose caused by C. caudatum.     

Gnomonia fragariae, a Cause of Strawberry Root Rot and Petiole Blight

Gnomonia fragariae has been occasionally listed among the fungi associated with diseased strawberry plants. However its pathogenicity has not been established. During the investigation on strawberry decline in Latvia and Sweden, a fungus was repeatedly recovered from discoloured root and crown tissues of severely stunted plants. Attempts to induce sporulation of the isolates grown on several agar media resulted in the formation of mature ascomata only on potato carrot agar and oatmeal agar. On morphological grounds and comparisons with reference herbarium specimens these isolates were identified as Gnomonia fragariae. The pathogenicity of the fungus was evaluated initially in the detached leaf assay and subsequently in three bioassays on strawberry plants. All the bioassays showed that G. fragariae was pathogenic on strawberry and capable of causing severe root rot and petiole blight. The symptoms that developed in the greenhouse experiments closely resembled those observed in the fields. The fungus did not cause rapid plant death but growth and development of inoculated strawberry plants was severely affected. To our knowledge this is the first time when pathogenicity of G. fragariae as a root rot pathogen has been clearly established. Our study shows that G. fragariae is one of the serious pathogens involved in the root rot complex of strawberry in Latvia and Sweden.     

Epidemiology of Northern leaf blight on sweet corn

The epidemiology of northern leaf blight of corn, caused byExserohilum turcicum (Pass.) Leonard and Suggs, is reviewed. The minimal dew period required for infection is temperature-dependent. At 25°C, 1 h of dew is sufficient to cause infection and at this temperature the minimal dew period for sporulation is 14 h. Under natural conditions when one dew night is not long enough for conidia to develop, the dew period on the following night enables the completion of conidial formation. The amount of conidia formed is dependent on temperature, light, plant age, leaf position and plant susceptibility. Both qualitative and quantitative types of resistance were identified in several hybrids. Subsequently, there developed additional biotypes ofE. turcicum which are aggressive to plants containing qualitative monogenic resistance. Within the same physiological race, a significant variation in aggressiveness between isolates from various locations is observed. The pathogen overwinters as mycelia and conidia in infected leaves, husks and other plant parts, or onSorghum halepense L. Reduction in yield due to northern leaf blight is associated with the level of resistance of the host plant, with disease severity, plant age during infection, and position of infected leaves.     

山楂花腐病的研究Ⅱ.山楂花腐病的症状

 山桂花腐病菌为害叶片、新梢和幼果。叶片上,展叶后4~5天即可出现褐色小班,经6~7天后病斑可扩展到病叶的1/2~2/3。天气潮湿时,在病斑上生出灰白色霉层,即病菌的分生孢子。在新梢上,初生褐色至红褐色病斑,当病斑环绕新梢一周时,新梢上部萎蔫枯死。在幼果上,落花后10天左右幼果果面出现褐色病斑,逐渐扩大,直至整个果实变成暗褐色脱落。     

五味子叶枯病病原菌鉴定

 The pathogen causing leaf blight on Schisandra chinensis (Turcz.) Baill. was isolated from diseased leaf. Based on morphological characteristics and pathogenicity test, the pathogen was identified as Alternaria tenuissima (Fr.) Wiltshire. This is the first report of this fungus infecting S. chinensis.     

Pathogenicity and toxigenicity of <Emphasis Type="Italic">Fusarium verticillioides</Emphasis> isolates collected from maize roots,stems and ears in South Africa

Sunflower (Helianthus annuus L.) is an important oilseed crop in South Africa, and is grown in rotation with maize in some parts of North West, Limpopo, Free State, Mpumalanga and Gauteng provinces. Alternaria leaf blight is currently one of the major potential disease threats of sunflower and is capable of causing yield losses in all production regions. Alternaria helianthi was reported as the main cause of Alternaria leaf blight of sunflower in South Africa; however small-spored Alternaria species have been consistently isolated from leaf blight symptoms during recent surveys. The aim of this study was to use morphological and molecular techniques to identify the causal agent(s) of Alternaria blight isolated from South African sunflower production areas. Alternaria helianthi was not recovered from any of the sunflower lesions or seeds, with only Alternaria alternata retrieved from the symptomatic tissue. Molecular identification based on a combined phylogenetic dataset using the partial internal transcribed spacer regions, RNA polymerase second largest subunit, glyceraldehyde-3-phosphate dehydrogenase, translation elongation factor and Alternaria allergen gene regions was done to support the morphological identification based on the three-dimensional sporulation patterns of Alternaria. Furthermore, this study aimed at evaluating the pathogenicity of the recovered Alternaria isolates and their potential as causal agents of Alternaria leaf blight of sunflower. Pathogenicity tests showed that all the Alternaria alternata isolates tested were capable of causing Alternaria leaf blight of sunflower as seen in the field. This is the first report of A. alternata causing leaf blight of sunflower in South Africa.     

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.     

Effects of inoculum concentration, wetness duration and plant age on development of early blight (Alternaria solani) and on shedding of leaves in tomato plants

Effects of inoculum concentration, wetness duration and plant age on the development of tomato early blight were evaluated in relation to host susceptibility under controlled environmental conditions. The main effect of early blight was premature defoliation, which was linearly related to the percentage of leaf area showing symptoms. As ln(inoculum concentration, conidia mL⁻¹) increased from 6·2 to 11·5, the percentages of leaf area affected and of defoliation increased linearly. Four h of leaf wetness after inoculation were sufficient to initiate the disease on plants of hybrid Skala RZ but not on those of cv. Rio Rojo, for which at least 6 h leaf wetness were needed. As wetness duration increased up to 24 h, there was an increase in the percentage leaf area showing symptoms and in the percentage of defoliation, but thereafter there was no significant increase in either parameter. Tomato plants were susceptible to Alternaria solani at all growth stages, but susceptibility increased as plants matured. There were no significant differences in susceptibility between tomato cultivars and hybrids.     

Circular Leaf Spot of Sweet Basil Caused by <Emphasis Type="Italic">Cercospora guatemalensis </Emphasis>New to Japan

A leaf spot disease on sweet basil (Ocimum basilicum L.) was observed in Chiba Prefecture in 1997. The lesions were amphigenous, circular to irregular, hygrophanous, dark brown. Stromata were amphigenous, composed of a few brown cells. Conidia with a thickened truncate base, filiform to cylindrical, hyaline, were produced from conidiophores with thickened conidial scars. These morphological characteristics agreed with those of Cercospora guatemalensis Mueller et Chupp. This species was new to Japan. The symptoms appeared 10 days after inoculation and the inoculated fungus was re-isolated. Artificial sporulation and detection from commercial seeds were not successful. Received 7 May 2001/ Accepted in revised form 7 August 2001