草地贪夜蛾卵块在玉米植株上的空间分布

本研究调查了草地贪夜蛾卵块在田间玉米植株上的空间分布,发现草地贪夜蛾卵块主要分布于植株中部,即玉米小喇叭口期倒3叶与倒4叶、吐丝期倒5叶与倒6叶上卵块最多,在小喇叭口期主要分布在叶正面,吐丝期主要分布于叶背面,距叶尖平均距离分别为23.4 cm和35.2 cm。为玉米上草地贪夜蛾卵的调查和防治提供了参考。     

草地贪夜蛾在安徽地区越冬能力初探

草地贪夜蛾的生长发育、繁殖和分布与环境温度密切相关,为探明该虫在安徽地区的越冬能力,本研究利用人工接虫的方式模拟草地贪夜蛾冬季的田间存活状态,调查幼虫存活率、龄期、植株被害率,并利用线性模型预测草地贪夜蛾田间发育历期。结果表明:草地贪夜蛾在田间平均气温低于10℃并持续8~10 d时死亡率达到100%;10月15日接入的草地贪夜蛾幼虫无法完成完整世代周期,但仍能为害玉米幼苗,接虫后30 d玉米植株的被害率均达100%;根据模型公式,采用10月15日至11月18日期间的温度预测发育历期,得到卵、幼虫、蛹以及整个世代的发育历期分别为9.23、46.86、40.70、69.38 d。本研究初步探明了草地贪夜蛾在安徽地区的越冬规律,研究结果为虫情监测和防控提供科学依据。     

越南北部草地贪夜蛾发生情况调查

越南是草地贪夜蛾的重要虫源地,其发生情况对我国草地贪夜蛾的动态有明显影响。2019年9月15-21日,在越南山罗省安州县对草地贪夜蛾田间发生和为害情况进行了调查。结果表明,调查区域均发生草地贪夜蛾为害,玉米田间虫株率为50.7%,百株虫量为110.7头;不同玉米生长期(苗期和穗期)的虫株率和百株虫量差异显著,苗期大喇叭口期虫株率和百株虫量(84.9%和201.1头),显著高于苗期小喇叭口初期(53.2%和114.7头)和抽雄期(14.2%和16.2头);田间虫株率和百株虫量之间的幂函数模型为y=0.842 8x~(1.212 5)。因此,要进一步加强与越南相关部门的合作,掌握越南草地贪夜蛾发生和为害动态,为我国草地贪夜蛾的监测与防控提供依据。     

草地贪夜蛾在云南德宏为害生姜初报

草地贪夜蛾于2019年1月入侵云南江城县,随后逐步向国内扩散传播,同时为害作物种类也陆续增多。1月份入侵德宏主要为害玉米,4月份为害甘蔗,至2019年9月11日,发现草地贪夜蛾和斜纹夜蛾幼虫混合发生为害生姜。本文介绍草地贪夜蛾幼虫的为害程度和生姜的受害症状。草地贪夜蛾为害株率及百株虫量分别为58.4%和42.2头,发生量比斜纹夜蛾高,形成田间相对优势种群。建议准确区分草地贪夜蛾和斜纹夜蛾的田间为害情况,有效提供预测预报信息。     

甜玉米生长后期草地贪夜蛾的为害情况调查

玉米是草地贪夜蛾最嗜好的寄主,然而草地贪夜蛾对玉米生长后期的为害程度和在玉米植株上的分布位置及虫龄结构未见报道.本文采用五点取样法,调查了广西横县甜玉米抽雄期草地贪夜蛾的分布及为害情况.结果表明,玉米生长后期被害株率达(90.60±3.57)％,有虫株率为(51.00±4.97)％,幼虫虫口密度为(68.80±8.85...     

草地贪夜蛾测报调查技术初探

2019年1月,联合国粮农组织全球预警的重大害虫草地贪夜蛾侵入我国云南并为害冬玉米。本文基于我国云南草地贪夜蛾发生分布现状和田间为害特征,提出了草地贪夜蛾成虫、卵、幼虫、蛹等不同虫态的种群监测方法,系统介绍了田间调查技术。同时,建议深入研究草地贪夜蛾区域性发生规律、推广自动化和智能化种群监测技术、制定草地贪夜蛾测报技术规范,旨在提高对草地贪夜蛾的监测预报水平。     

2019年江苏省草地贪夜蛾发生及为害情况调查

为掌握草地贪夜蛾在江苏省的发生及为害情况,在开展系统监测和田间调查的基础上,对2019年草地贪夜蛾在江苏省的发生动态及玉米受害情况进行了总结.结果表明,2019年5月入侵江苏苏南地区后,逐步向北扩散,6-7月是其主要扩散期.2019年江苏省玉米受草地贪夜蛾为害面积约3 440.3 hm2.其中,夏玉米发生面积最大、占7...     

大麦田草地贪夜蛾的发生为害及抽样技术

草地贪夜蛾在中国可取食为害玉米、高粱、小麦等禾本科作物,但其在大麦田的发生为害情况尚不清楚。我们对云南省曲靖市马龙区处于苗期至分蘖期大麦田的调查结果表明,草地贪夜蛾的虫田率高达62.5%、大麦受害株率为9.33%~100%、虫口密度为1~46头/m2,其中1~3龄幼虫比例达98.6%,受害株率与虫口密度呈显著正相关。大多数草地贪夜蛾幼虫藏匿于大麦心叶为害,取食后叶片形成半透明薄膜窗孔,幼虫在大麦田呈聚集分布。基于空间分布型的研究结果,我们提出了大麦田草地贪夜蛾幼虫理论抽样模型。本研究表明草地贪夜蛾可对大麦生产构成严重威胁。研发的幼虫抽样方法为大麦田草地贪夜蛾幼虫种群调查提供了技术支撑。     

广西浦北草地贪夜蛾周年发生为害动态

为掌握草地贪夜蛾在广西浦北县的发生为害情况,于2019—2021年开展系统调查、大田普查、灯光诱集。结果表明,浦北县已成为草地贪夜蛾的周年繁殖区,全县17个乡镇（街道）玉米种植区四季玉米均受到草地贪夜蛾为害,纬度较低的、玉米种植面积大的区域发生较重;春玉米、秋玉米受害重;玉米各主要生育期均可受害,以喇叭口期虫量高、受害重;灯下成虫盛发期在5—8月、高峰期在7月中旬至8月中旬。在生产上应做好玉米全年全生育期的监测与防治。     

草地贪夜蛾对夏玉米的为害及产量影响因素研究

川东北夏玉米草地贪夜蛾发生为害严重,亟需明确其对玉米产量的主要影响因素和损失情况.2019-2020年,笔者通过对草地贪夜蛾在夏玉米苗期至喇叭口期发生为害田的受害株与未受害株的同田抽样对比测产的调查分析,明确幼虫在苗期至喇叭口期的自然为害损失随生育期的早晚相应增减,在苗期7～8叶、小喇叭8～9叶、大嗽叭10～11叶被害...     

Pathogenic fungi involved in root rot of peas in the Netherlands and their physiological specialization

Research on root rot pathogens of peas in the Netherlands has confirmed the prevalence ofFusarium solani, F. oxysporum, Pythium spp.,Mycosphaerella pinodes andPhoma medicaginis var.pinodella. Aphanomyces euteiches andThielaviopsis basicola were identified for the first time as pea pathogens in the Netherlands. Other pathogens such asRhizoctonia solani andCylindrocarpon destructans were also found on diseased parts of roots. F. solani existed in different degrees of pathogenicity, and was sometimes highly specific to pea, dwarf bean of field bean, depending on the cropping history of the field.A. euteiches was specific to peas, whereasT. basicola showed some degree of physiological specialization.     

Occurrence of pepper yellow vein in the Netherlands

Samenvatting Het verschijnsel van geelnervigheid bij paprika (Capsicum annuum) kon door verenting en met de schimmelOlpidium brassicae worden overgebracht. Hierdoor bleek de ziekte identiek te zijn met een eerder in Engeland gemelde ziekte. Door inoculatie met zoösporen of rustsporen vanO. brassicae werden ook symptomen verkregen inC. baccatum, C. chacoense enC. frutescens. S. villosum bleek een waardplant te zijn voor het geelnervigheidsagens, waarbij zwakke nerfchlorosen werden waargenomen.Seconded to the Glasshouse Crops Research Station, P.O. Box 8, 2670 AA Naaldwijk, the Netherlands.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Tobacco rattle virus serotypes and associated nematode vector species of Trichodoridae in the bulb-growing areas in the Netherlands

Soil samples from the coastal bulb-growing areas in the provinces of North- and South-Holland and the North-East Polder in the Netherlands were examined for trichodorid nematodes and tobacco rattle virus (TRV) serotypes. At least one of a total of eight species of Trichodoridae, of whichParatrichodorus pachydermus was most prevalent, was found in 93% of the samples from the provinces of North- and South-Holland and TRV, including four serotypes, was obtained from 49% of these samples. In the North-East Polder one of three species of trichodorids, of whichP. teres occurred most frequently, was present in 72% of the samples, and TRV of one serotype was obtained from 28% of these samples. The TRV isolates recovered from these samples reacted serologically with one of four antisera to strains of TRV. Virus transmitted byP. pachydermus reacted to the PRN-, byTrichodorus viruliferus to the RQ-, byP. teres to the N5- and byT. similis, to the TS-antiserum, respectively.     

Monitoring of the winter populations of cereal aphids near Wageningen,the Netherlands,in 1982/1983

Cereal aphids on a wheat crop were sampled through the winter of 1982/1983 using both fixed and random quadrats.Sitobion avenae overwintered successfully anholocyclically although there was a substantial decline in the population of this species. No evidence for successful anholocyclic overwintering in other aphid species was found, althoughRhopalosiphum padi was seen to colonise the crop in early winter and was found until the end of December.Eggs ofR. padi onPrunus padus were observed through the winter. A steady decline in their numbers occurred. The overall survival rate of the 5385 eggs was c.30%.Eggs ofMetopolophium dirhodum onRosa spp. were also monitored. They also showed a steady decline in numbers through the winter. The overall survival rate of the 1360 eggs was c.34%.Egg hatch in bothR. padi andM. dirhodum was closely synchronised with bud burst of their host plant. For the latter species this resulted in egg hatch starting in January.Samenvatting In de winter van 1982/1983 werden de graanluizen in een tarwegewas regelmatig geteld in willekeurig en in van tevoren gekozen monstereenheden. Hoewel er een aanmerkelijke afname van de populatie vanSitobion avenae werd waargenomen, overwinterde deze soort toch anholocyclish. Er werden geen aanwijzingen gevonden dat de andere bladluissoorten anholocyclish overwinterden hoewel kolonies vanRhopalosiphum padi tot eind december werden waargenomen.De gehele winter werden eieren vanR. padi opPrunus padi aangetroffen, de aantallen ervan namen geleidelijk af; van de 5385 getelde eieren overleefde ongeveer 30%. Ook de aantallen eieren vanMetopolophium dirhodum opRosa spp. werden reglematig vastgesteld; ook hier werd een geleidelijke afname geconstateerd. Van de oorspronkelijk getelde 1360 eieren overleefde ongeveer 34%.Het uitkomen van de eieren vanR. padi enM. dirhodum viel nauw samen met het uitlopen van de knoppen van hun waardplant. VoorM. dirhodum betekende dit dat de eerste eieren al begin januari uitkwamen.     

Characterisation of the fungal population in citrus packing houses

The aim of this work was the characterisation of the environmental and superficial mycoflora of equipment and facilities of two citrus packing houses in Sao Paulo State, Brazil, in 2004 and 2005. One of the packing houses packed fruit for the export market (municipality of Matao), the other for the domestic market (municipality of Engenheiro Coelho). The study also identified the presence of isolates of Penicillium spp. resistant to thiabendazole and imazalil fungicides in packing houses. The environmental mycoflora was sampled according to the gravimetric method, using Petri dishes containing potato dextrose agar medium opened for 2 min. The superficial mycoflora on equipment and facilities was sampled with Rodac plates. The mycoflora in the environment and on surfaces of the packing houses in Matao were 12.3 and 52.3 cfu/plate, respectively, while these populations for the Engenheiro Coelho packing house were 46.3 and 68.2 cfu/plate, respectively. Cladosporium and Penicillium were the most prevalent genera of fungi. The contamination levels of clean zones in the packing houses (washing of fruits, packing table, boxes and containers) was not substantially lower than the contamination in dirty zones (reception of fruits and first selection). The percentage of P. digitatum isolates in Matao that was resistant to thiabendazole and imazalil was 25.9 and 1.5 in the environment and 30.1 and 16.0 on packing house surfaces, respectively. In Engenheiro Coelho, percentage of resistance to these fungicides was 51.9 and 0.1 in the environment and 39.2 and 0.9 on packing house surfaces, respectively.     

Genetic Analysis of the Role of Trichothecene and Fumonisin Mycotoxins in the Virulence of Fusarium

The phytotoxicity of the Fusarium trichothecene and fumonisin mycotoxins has led to speculation that both toxins are involved in plant pathogenesis. This subject has been addressed by examining virulence of trichothecene and fumonisin-nonproducing mutants of Fusarium in field tests. Mutants were generated by transformation-mediated disruption of genes encoding enzymes that catalyze early steps in the biosynthesis of each toxin. Two economically important species of Fusarium were selected for these studies: the trichothecene-producing species Fusarium graminearum, which causes wheat head blight and maize ear rot, and the fumonisin-producing species F. verticillioides, which causes maize ear rot. Trichothecene-non-producing mutants of F. graminearum caused less disease than the wild-type strain from which they were derived on both wheat and maize, although differences in virulence on maize were not observed under hot and dry environmental conditions. Genetic analyses of the mutants demonstrated that the reduced virulence on wheat was caused by the loss of trichothecene production rather than by a non-target mutation induced by the gene disruption procedure. Although the analyses of virulence of fumonisin-non-producing mutants of F. verticillioides are not complete, to date, the mutants have been as virulent on maize ears as their wild-type progenitor strains. The finding that trichothecene production contributes to the virulence of F. graminearum suggests that it may be possible to generate plants that are resistant to this fungus by increasing their resistance to trichothecenes. As a result, several researchers are trying to identify trichothecene resistance genes and transfer them to crop species.     

Detection of the phytotoxin coronatine by ELISA and localization in infected plant tissue

Several pathovars of Pseudomonas syringae produce the phytotoxin coronatine (COR)in vitro, and the availability of purified toxin has facilitated development of immunological detection methods. A modified, indirect competitive ELISA using the COR-specific monoclonal antibody 11B8 was developed to detect COR in various host plants infected by P. syringae. The estimated detection limit for COR was 50 pg per well, and COR could be reliably quantified from 5 to 40 ng ml⁻¹. The subcellular localization of COR within infected tomato tissue was investigated using the COR-specific antibody MAb 8H3G2. Immunofluorescence microscopy and immunogold labelling showed that COR was present inside tomato cells and was associated with chloroplasts and particles of proteinase inhibitor I. Localization studies indicated that COR is mobile in infected plant tissue and can be detected in healthy tissue adjacent to the bacterial lesions.     

Aetiology and causal agents of mango sudden decline disease in the Sultanate of Oman

Mango sudden decline is a recently introduced, economically serious disease in Oman. Affected mango trees have wilting symptoms that usually begin on one side and later spread to involve the entire tree. Trees exude amber-coloured gum from the bark of their trunks or branches and vascular tissues are discoloured. Having entered Oman in the recent past, survey data is presented that shows the disease to have spread throughout the northern part of the country. Evidence is presented that the vascular wilt pathogen Ceratocystis fimbriata causes mango sudden decline disease in Oman, possibly in concert with Lasiodiplodia theobromae and the recently described Ceratocystis omanensis. Isolates of these fungi from affected trees, cause infection and can be recovered from inoculated seedlings. Bark beetles (Hypocryphalus mangiferae) are shown to carry C. fimbriata and L. theobromae and are presumably responsible for transmitting both pathogens to healthy mango trees. Acting as a wounding agent and vector, the bark beetle is likely to have assisted the rapid spread of the disease across Oman.     

Benomyl-resistant Fusarium-isolates in ecological studies on the biological control of fusarium wilt in carnation

Ecological properties and stability of benomyl resistance of three benomyl-resistant mutants of nonpathogenicFusarium-isolates antagonistic to fusarium wilt in carnation, and three benomyl-resistant mutants of a pathogenic isolate ofFusarium oxysporum f.sp.dianthi were evaluatedin vitro and in glasshouse experiments. The benomyl resistance of the nonpathogenic mutants was stable under all conditions tested, also after a 1000-fold increase of the population in sterilized soil. Mutants of the pathogen were stable during allin vitro tests, but after proliferation in carnation stems only part of the population was benomyl resistant.Compared to the wild type, mutants of the pathogen were less pathogenic, also if thein vitro propeties were similar. Colonization of carnation by benomyl-resistant nonpathogenicFusarium in the presence of the pathogen showed that the antagonistic effect correlated with the presence of the nonpathogenic isolates within the carnation stem. The wild types and two of the mutant nonpathogenicFusarium-isolates controlled fusarium wilt in the susceptible cultivar Lena for 50% or more.UV-induced benomyl resistance appeared to be a valuable marker to distinguish between differentFusarium isolates and to study the population dynamics, but intensive screening of the mutants is a prerequisite since alterations in antagonism and pathogenicity can occur.