水稻白叶枯病和条斑病的田间诊断和鉴别

白叶枯病(Xanthomonas oryzae)和条斑病(Xanthomonas oryzicola)是水稻上的两种重要细菌病害。这两种细菌性病害都可以由稻种传播。稻种非但可以带菌,并且可以传病。为了防止病区的扩大和新病区的出现,加强检疫工作是非常重要的。 检验水稻白叶枯病和条斑病,可分室内检验和田间检验。室内检验主要是确定稻种是否带菌和带菌的程度,可以采用种植检验和噬菌体检验的方法,以噬菌体检验更为可靠。室内检验需要一定的设备,工作量较大,同时目前所用的室内检验方法是否适用于带菌量极低的稻种,还有待在生产实践中考验。田间检验就是通过病害的普查,了解病害发生情况,确定无病田和无病区。这样非但可以解决当地的留种和换种的问题,并且为无病稻种的调运提供依     

用茎枯病芦笋茎秆饲喂奶牛的牛粪传病试验研究

芦笋鳞茎盘残存的病残体及其散落在田间的病株残体,是导致芦笋茎枯病发生的最初侵染来源。试验表明,食用带茎枯病芦笋茎秆的牛产生的粪便,能引起芦笋感病,是值得注意的芦笋茎枯病的一个新的最初侵染源。     

药剂处理种子防治水稻叶尖枯病

应用５种药剂进行种子处理防治水稻叶尖枯病,结果表明,多菌灵和禾枯灵杀菌效果最好,速保利和粉锈宁效果很差,盐水没有作用。４０％多菌灵２５０倍液浸种２４～４８ｈ时,或４０％禾枯灵２５０倍液浸种２４ｈ,杀菌效果达１００％,对稻种发芽率和幼苗生长无任何影响,但延长禾枯灵浸种时间或加大浓度,对稻苗生长有明显的抑制作用。     

广东水稻橙叶病病原(MLO)的越冬

研究结果表明,广东水稻橙叶病病原(MLO)的传染介体和越冬介体昆虫只有电光叶蝉(Recilia dorsalis)一种,但其卵不传递该病原到子代若虫,越冬寄主植物只有水稻的再生稻株和落粒自生稻株。在茂名病区的冬、春期间电光叶蝉的带菌虫和带菌再生稻及感病落粒自生稻始终存在,其带菌率分别为2.33％—35.11％、2.37％—17.78％和1.95％—16.67％。在茂名地区由于冬、春气温不甚低,电光叶蝉仍能继续繁殖越冬,并能不断获菌和传病,所以说该病原是动态越冬的。室内试验表明,带菌电光叶蝉的寿命可长达105—125天,而在茂名的秋收期至翌年春播期一般105天,据此推测有些带菌虫可从秋收后直接存活和传病原到春播稻苗。看麦娘(Alopecurus aequalis)用电光叶蝉人工接种并回接水稻成功。但在病区田间调查从未发现病株。以下植物人工接种不成功:野生稻(Oryzea rufipogon)、小麦(Triticum aestivum)、玉米(Zea mays)、李氏禾(Leersia hexandra)、稗草(Echinochloa crus-gallis)。     

细辛叶枯病侵染循环、流行规律及其防治对策研究

细辛叶枯病（Ｍｙｃｏｃｅｎｔｒｏｓｐｏｒａ ａｃｅｒｉｎａ（Ｈａｒｔｉｇ）Ｄｅｉｇｈｔｏｎ）是一种毁灭性新病害。病原菌主要以分生孢子和菌丝体在田间病残体上越冬，早春可再生大量次生孢子，成为发病的初侵染来源。该病是一种典型的多循环病害。气流和雨滴飞溅是田间病害传播的主要方式，种苗带菌可进行远距离传播。低温、高湿、强光有利病害流行，其中温度是影响田间流行动态的主导因素。周年发病动态可分为春季始发期、初     

直播稻田杂草发生特点及综合防除技术研究

水稻直播具有省工、省力、省本的效果,但杂草危害影响直播稻的稳产、高产。为解决直播稻田的草害问题,从１９９５年到１９９８年,我们开展了直播稻田杂草发生规律调查和综合防除技术的研究,现将结果报道于下,供参考。一、直播稻田杂草发生的特点（一）杂草种类多、数量大由于直播稻田稻种量少、生育期长、田间长期干湿交替,使得杂草发生种类多、数量大。全市直播田主要杂草共约１８种,分别是禾本科的稗草、千金子,双穗雀稗、游草;莎草科的异型莎草、扁杆蔗草、水莎草、日照飘拂草、牛毛毡;阔叶类的矮慈菇,节节菜、鸭舌草、四叶萍…     

水稻白叶枯病杂草带菌和传病的研究

水稻白叶枯病自发现到现在已有90年的历史。由于发生地区广泛,为害严重,各国对此病曾做了大量研究。日本对它已研究了半个多世纪,我国也有二十多年的研究经历。但对其侵染来源和传播途径,仍有不同看法。我国最初认为种子传病是首要的。但在病区单抓种子处理还不能收到预期效果,又认为病稻草是病区次年的主要菌源。近年来,又发现在严格处理病革、病种子的情况下,仍然发病,故怀疑除上述两种传播途径外,还有其它传播途径。关于杂草传病问题,日本已进行了多年的研究,但和我国国内一样,对杂草带菌传病问题,意见很不一致。我们认为对这一传播途径有彻底弄清的必要,它不仅关系到一个病的侵染循环问题,而且直接关系到对白叶枯病的彻底防治。如果这一传播途径确实存在,我们若不承认它,在防治上就会出现大的漏洞。如果白叶枯病确与杂草无关,盲目地采用相应的措施,也是多余而毫无意义的。这次试验是采用较直接的“离心浓缩针刺接种法”,其结果:第一年证实有马唐等六种杂草、黄豆和水稻根部能够带菌;第二年证实有车前等三种杂草和水稻根不仅带菌,而且可越冬并存活到次年五月;第三年又证实在不同地区有马唐,狗牙根等四种杂草能够带菌越冬,并存活到次年五月中旬。另外,用病区杂草和水稻健苗混栽,结果稻苗上发病,而对照的不发病。通过三年来的试验研究,证实有数种杂草的根茎部不仅带菌,而且能传病。     

噁唑酰草胺WP对水稻直播田禾本科杂草的防效

为明确10%噁唑酰草胺WP在湖北省水稻直播田的应用前景,建立水稻直播田的杂草管理体系,研究了其对水稻直播田稗草和千金子的防除效果,并研究了杂草防除对杂草养分含量变化和水稻增产效果的影响。结果表明,施用10%噁唑酰草胺WP对直播稻田中杂草的防除效果显著,对稗草、千金子的综合密度防除效果和综合鲜重防除效果分别保持在91.79%～99.44%和96.42%～99.90%,极显著优于人工除草的防除效果。施用10%噁唑酰草胺WP防除田间杂草,降低了杂草对田间养分的吸收,从而显著提高了水稻的产量,增产效果显著。     

水稻细菌性褐斑病的研究 Ⅲ、病原细菌的寄主范围

水稻细菌性褐斑病病原细菌 Pseudomonas oryzicola Klement 的寄主范围较广,除为害水稻外,尚能侵染陆稻、小麦、谷子、高粱等四种禾本科作物及30余种禾本科野生杂草。在自然条件下被 P.oryzicola 侵染的野生禾本科植物有:无芒野稗、野稗、钿画眉草、水稗草、稻稗、菵草、狗尾草、东北鹅冠草、雀麦一种、偃麦草、拂子茅草、匐茎剪股颖、披礆草、垂披礆草、无芒雀麦草及荻草等16种。经人工接种而感病的禾本科植物有:知风草、沼早熟禾、看麦娘一种、老芒麦、雀麦、早熟禾、长芒野稗、紫羊茅、短穗看麦娘、稗子、长叶草、萎酸草及小糖草等13种。在稻田周围的大多数禾本科杂草,都轻重不同的感染了水稻细菌性褐斑病。而且发病早于水稻,这些野生杂草寄主上的病原是水稻初次侵染来源之一。试验结果证明,血清玻片凝聚反应是鉴定永稻细菌性褐斑病寄主范围简便而准确的方法。     

稻白叶枯病与稻叶尖枯病田间症状的识别

白叶枯病（ＸａｎｔｈｏｍｏｎａｓｃａｍｐｅｓｔｒｉｓＰＶ．Ｏｒｙｚａｅ）与叶尖枯病（ＰｈｙｌｌｏｓｔｉｃｔａＯｒｙｚａｅｃｏｌａ）都是籼稻上的常见病害 ,且其症状（尤其是后期症状）与发病盛期均相似 ,故二者常被混淆。２０世纪７０年代在江苏省稻区叶尖枯病已有发生 ,但因白叶枯病发生普遍且流行频率高 ,叶尖枯病多被误认为白叶枯病 ;２０世纪９０年代以来 ,江苏省境内白叶枯病有所减轻 ,叶尖枯病有所上升 ,于是又出现了相反情况 ,把白叶枯病误认为叶尖枯病。近几年在农村考察水稻病害时发现 ,不少基层农技人员还是把这两个病害…     

水稻叶尖枯病病原种类研究

 从江苏13个县市采集病叶标本,经分离、纯化后获280株菌。据鉴定结果和接种试验,稻生叶点霉(Phyllosticta oryzicola Hara)为主要致病菌,占74.6%。此外,还分离到稻盘多毛孢(Pestalotia oryzae Hara)、链格孢(Alternaria alternata(Fr.) Keissl.)、稻喙孢(Rhynchosporium oryzae Hash.et York.)、苍白弯孢(Curvularia pallescens Boed.)、新月弯孢(C.lunata(Walk.) Boed.)、膝曲弯孢(C.geniculata(Tracy et Earle) Boed.)、镰刀菌(Fusarium spp.)、平脐蠕孢(Bipolaris spp.)、稻黑孢(Nigrospora oryzae(Berk.et Br.) Perch)、球黑孢(N.sphaerica(Sacc.) Mason)等真菌。首次以透射电镜观察表明,稻生叶点霉产孢方式为全壁芽生单体式(hb-sol)。     

白芷黑斑病病原菌鉴定及病害发生规律研究

对四川白芷黑斑病的症状、病原菌致病性和形态特征等进行了研究,确定病原菌为当归叶点霉(PhyllostictaangelicaeSaccardo)。经两年的田间病害发生动态调查,该病在四川始发期为3月上旬,高峰期为6月份,病株率达100%,病叶率达74.51%。病害的初侵染源主要是留种株的病叶和田间病残体。病菌分生孢子借雨滴飞溅的方式传播,并在白芷生长期中不断引起再侵染。     

Overwintering of <Emphasis Type="Italic">Pyricularia oryzae</Emphasis> in wild infected foxtails

The rice blast fungus Pyricularia oryzae mainly overwinters in infested rice organs stored indoors, whereas it is difficult or impossible for the pathogen to overwinter outdoors. By contrast, blast pathogens infecting weed grasses must overwinter outdoors every winter to continue their life cycle. In this study, we investigated the overwintering location of P. oryzae infecting wild, green, and giant foxtails to identify the mechanism that enables them to overwinter. Recovery of P. oryzae was tested in seeds of wild foxtail collected from the soil surface from December to April over three winters. No P. oryzae was recovered from the seed samples of any wild foxtail collected at the ends of the three experimental periods in April. Recovery was also tested from blast lesions on leaves and seeds sampled from withered green foxtail in the experimental field of Saga University from November to April during two winters. In contrast to seeds on the soil surface, P. oryzae survived in lesions and seeds at the ends of the two experimental periods during April, suggesting that withered host plants could be the overwintering site of the pathogen. Rice plants are reaped and removed from paddy fields after harvesting. Thus, withered, standing plants may be available solely to blast pathogens infecting wild grasses, possibly explaining the higher winter survival frequency of weed pathogens than that of rice blast pathogens outdoors.     

水稻细菌性条斑病菌拮抗细菌的筛选、评价与应用研究

从江苏省南京、泰州、扬州和宿迁等地区水稻田采集水稻病叶、健叶、根围土等样品90份,分离纯化得到1173个细菌分离物,对其进行水稻细菌性条斑病菌Xanthomonasoryzaepv．oryzicola皿内抑制试验,共获得12株拮抗能力较强的细菌,其中4株拮抗细菌抑菌圈直径大于27mm。盆栽试验结果表明,12株拮抗能力较强的细菌中有4株对水稻细菌性条斑病菌防效大于50％,其中菌株Lx-1l盆栽防效达62．5％。大面积示范试验结果表明菌株Lx．11田间防效达60．2％,显著高于化学药剂20％叶枯唑的防效（51．2％和45．8％）。形态特征、理化特性和分子鉴定分析确定菌株Lx．11为解淀粉芽孢杆菌Bacillusamyloliquefaciens。     

广东新发生流行的水稻橙叶病的鉴定

 1991~1992年广东茂名市的水稻约2万公顷发黄。用电光叶蝉Reclia dorsalis(Motsch)接种3叶龄稻苗,在平均气温28℃下,潜育期为8~36天;主要症状为病株矮,叶片竖直、橙黄至金黄色;部分病叶纵卷干枯;多数病苗早枯死。四环素液浸病稻根可明显延迟死亡。介体昆虫为电光叶蝉。而黑尾蝉Nephotettix cincticeps(Uhler)、二条(大斑)叶蝉N.apicalis(Motsch)和二点叶蝉N.virescence(Distant)以及虱Nilaparvata lugens(Stal)等均不传病。电光叶蝉最短获毒和最短传毒饲育期分别为<2min和<5min.期在室温25~30℃下,约为7~26天,保毒虫能终生传毒,但有间歇传病现象。在病叶脉韧皮筛管细胞毒叶蝉唾腺切片中均可见大量多形态的类菌原体,大小为75~639nm。据此认为本病与1980年云南十年代在东南亚报道的水稻橙叶病基本相同。     

水稻稻曲病室内人工接种技术

为提高稻曲病人工接种的发病效果和稳定性,在温棚条件下采用水稻孕穗期注射接种法分别研究了稻曲病菌不同接种体、培养时间、接种浓度和接种时期的接种效果。采用病菌马铃薯蔗糖液体培养基（potato sucrose broth,PSB）作为接种体,其穗发病率为100%,明显好于病菌米糠培养液（23.33%）。病菌在PSB中培养5～7天接种效果较好,随病菌培养天数的延长,接种效果明显下降。接种的分生孢子浓度越低水稻病穗率和病粒数也越低。在水稻品种两优培九孕穗中后期,采用含分生孢子浓度为4×106个/mL的病菌PSB培养液注射接种,穗发病率达100%,平均病粒数35.1粒,最高达87粒。研究表明,温棚条件下建立的稻曲病人工接种技术能获得稳定的发病效果,并可区别水稻品种间的抗性差异。     

Induction of systemic resistance byPseudomonas fluorescens Pf1 againstXanthomonas oryzae pv.Oryzae in rice leaves

When lower leaves of rice plants were inoculated with powder formulation of a saprophytic strain ofPseudomonas fluorescens, Pfl, upper leaves, in addition to the inoculated lower leaves, showed resistance to the rice bacterial blight pathogenXanthomonas oryzae pv.oryzae. When the leaves were challenge-inoculated withX. oryzae pv.oryzae 4 days afterP. fluorescens application on lower leaves, the disease intensity in upper leaves decreased from 6.7 to 1.1. When rice seeds were treated with the formulation ofP. fluorescens Pfl and sown, 30-day-old seedlings showed resistance toX. oryzae pv.oryzae and the disease intensity decreased from 6.8 to 1.2. The induced resistance was transient; leaves sprayed withP. fluorescens Pfl at 30 days after treatment and leaves of 60-day-old seedlings fromP. fluorescens-treated seeds did not show resistance to the pathogen. In field trials, seed treatment followed by foliar application of the powder formulation ofP. fluorescens Pfl effectively controlled rice bacterial blight and increased the yield. In the induced resistant leaves a sharp increase in lignification and activities of peroxidase, phenylalanine ammonia-lyase and 4-coumarate: CoA ligase was observed when the leaves were challenge-inoculated withX. oryzae pv.oryzae. An approximately threefold increase in lignin content, peroxidase activity and phenylalanine ammonia-lyase activity and a fivefold increase in 4-coumarate: CoA ligase activity were observed 5 days after challenge inoculation withX. oryzae pv.oryzae in rice leaves pretreated withP. fluorescens for 5 days. A similar increase in defense-related activities was not observed in susceptible interactions or inP. fluorescens-treated plants at later stages of interactions when no resistance to the pathogen was observed.     

水稻不育系稻粒黑粉病病穗率与病粒率间的关系研究

 经田间调查分析,稻粒黑粉病在水稻不育系D汕A和珍汕97A上的病穗率与病粒率之间的关系(简称P-S关系)均可用指数函数描述,分别建立了两个育系上的P-S关系模型。协方差分析表明两回归方程的截距间有显著差异,并建立了两个不育系的P-S关系综合模型。     

Effects of salt stress on ion accumulation and antioxidative enzyme activities of Oryza sativa L. and Echinochloa oryzicola Vasing

The effects of salt stress on physiological factors, such as inorganic ion absorption and antioxidative enzyme activities, of rice ( Oryza sativa L. cv. Anapurna) and Echinochloa oryzicola Vasing were investigated. Although having similar morphology, rice and E. oryzicola possessed considerably different salt-tolerance mechanisms. Echinochloa oryzicola was more salt-tolerant than rice. When exposed to salt stress (100 mmol L⁻¹ sodium chloride, NaCl; six days), E. oryzicola had the ability to limit the accumulation of sodium ions (Na⁺), maintained high potassium ion (K⁺) content and had a constantly higher K⁺/Na⁺ ratio than rice. Rice was not effective in limiting Na⁺ absorption but had a higher antioxidative capacity than E. oryzicola . The constitutive activities of superoxide dismutase (SOD) and catalase of rice were three and five times higher than that of E. oryzicola, respectively. Induced activities of SOD, ascorbate peroxidase and glutathione reductase were also higher in rice than in E. oryzicola . The high antioxidative capacity was one of the tolerance mechanisms used by rice to cope with salt stress. Therefore, the salt tolerant-mechanisms are different between the two plants.     

Relative Contribution of Seed-Transmitted Inoculum to Foliar Populations of Phaeosphaeria nodorum

ABSTRACT A marked-isolate, release-recapture experiment was conducted to assess the relative contributions of seed-transmitted (released isolates) versus all other inocula to foliar and grain populations of Phaeosphaeria nodorum in winter wheat rotated with nonsusceptible crops in New York and Georgia, United States. Seed infected with two distinct groups of marked isolates of P. nodorum containing rare alleles (identified by amplified fragment length polymorphisms [AFLPs]) and balanced for mating type were planted in experimental field plots in two locations in each state. Recapture was done by isolating P. nodorum from leaves showing necrotic lesions at spring tillering and flowering stages, and mature grains from spikes showing glume blotch. Isolates from these samples were genotyped by AFLPs and categorized as released or nonreleased to infer sources of inoculum. Both infected seed and other sources of the pathogen contributed significant primary inocula to populations recovered from leaves and harvested grain. Seed-transmitted genotypes accounted for a total of 57% of all isolates recovered from inoculated plots, with a range of 15 to 90% of the populations of P. nodorum collected over the season in individual, inoculated plots at the four locations. Plants in the noninoculated control plots also became diseased and 95% or more of the isolates recovered from these plots were nonreleased genotypes. Although other potential sources of P. nodorum within and adjacent to experimental plots were not ruled out, nonreleased genotypes likely were derived from immigrant ascospores potentially from sources at a considerable distance from the plots. Our results suggest that, although reduction of seedborne inoculum of P. nodorum may delay foliar epidemics, this strategy by itself is unlikely to result in high levels of control in eastern North America because of the additional contribution from alternative sources of inoculum.