草间小黑蛛实验种群参数

作者在不同温度条件下,观察草间小黑蛛实验种群的发育历期、存活率、繁殖动态和捕食效应,组建 Logistic 发育速度模型和繁殖特征生命表。在建立实验种群生命表的基础上,测定草间小黑蛛实验种群的生命表参数、生殖指标参数和稳定年龄组配。通过草间小黑蛛对白背稻虱捕食量的观察,建立 Holling 功能反应模型和 Hassell-Varley 干扰反应模型。同时测定瞬时攻击率、处理时间、最大理论捕食量、干扰常数、搜寻常数。     

斜纹猫蛛对草地贪夜蛾幼虫的捕食作用

为明确斜纹猫蛛Oxyopes sertatus对草地贪夜蛾Spodoptera frugiperda幼虫的控害能力，在实验室条件下评估斜纹猫蛛亚成蛛和雌、雄成蛛对草地贪夜蛾2龄和3龄幼虫的捕食能力以及斜纹猫蛛自身密度对捕食效能的影响。结果显示，斜纹猫蛛对草地贪夜蛾幼虫的日均捕食量随着猎物密度的增大呈上升趋势，达到某一阈值后趋于稳定，其对2龄幼虫的日均捕食量显著高于对3龄幼虫的日均捕食量。斜纹猫蛛对草地贪夜蛾2个龄期幼虫的捕食功能反应既符合Holling Ⅱ功能反应模型，又符合Holling Ⅲ功能反应模型。斜纹猫蛛对草地贪夜蛾2龄幼虫的瞬时攻击率均大于对3龄幼虫的瞬时攻击率，雌成蛛对草地贪夜蛾2龄和3龄幼虫的瞬时攻击率最大，分别为0.664和0.558；斜纹猫蛛对草地贪夜蛾2龄幼虫的处理时间总体上短于对3龄幼虫的处理时间，亚成蛛对草地贪夜蛾2龄和3龄幼虫的处理时间最短，分别为0.011 d和0.009 d；斜纹猫蛛对草地贪夜蛾2龄幼虫的最佳寻找密度均高于对3龄幼虫的最佳寻找密度。随着猎物密度的增长，斜纹猫蛛的搜寻效应呈下降趋势。斜纹猫蛛的捕食作用率与其自身密度呈负相关，随着自身密度的增...     

叉角厉蝽的饲养

室内饲养叉角厉蝽时,成虫的饲养温度控制在不低于25℃为宜,以利于成虫交配、产卵。以菜青虫5龄幼虫饲养叉角厉蝽,平均1.95头菜青虫可使一头叉角厉蝽完成若虫期的发育,此时叉角厉蝽的繁殖增长率为108.37。菜青虫和斜纹夜蛾是大量繁殖叉角厉蝽的较好饲料。     

黄带犀猎蝽对斜纹夜蛾3、4龄幼虫的捕食功能反应

为明确黄带犀猎蝽Sycanus croceovittatus对斜纹夜蛾Spodoptera litura的控害潜能,在实验室条件下对黄带犀猎蝽3~5龄若虫和雌雄成虫对斜纹夜蛾3、4龄幼虫的捕食功能反应、搜寻效应和自身密度干扰反应进行研究。结果表明,黄带犀猎蝽对斜纹夜蛾幼虫的捕食功能反应均符合Hol-ling II型和Holling III型2种模型;在拟合Holling II模型中,黄带犀猎蝽3~5龄若虫和雌雄成虫对斜纹夜蛾3龄幼虫的日均最大捕食量分别为2.78、4.17、4.35、12.50和8.33头,控害效能分别为5.53、6.54、8.78、14.75和10.42;对斜纹夜蛾4龄幼虫的日均最大捕食量分别为2.56、2.86、3.85、3.57和4.35头,控害效能分别为2.23、3.94、4.54、11.32和5.70,其中雌成虫的控害效能最大。在拟合Hol-ling III模型中,对斜纹夜蛾3龄幼虫的日均最大捕食量分别为2.75、4.10、4.32、10.76和7.41头,最佳寻找密度分别为1.19、2.03、1.73、5.28和3.88头/盒;对斜纹夜蛾4龄幼虫的日均最大捕食量分别为2.38、2.78、3.55、3.58和4.00头,最佳寻找密度分别为1.83、1.50、2.06、0.95和2.10头/盒。搜寻效应与害虫密度呈负相关;种内干扰效应与天敌密度呈正相关。表明黄带犀猎蝽成虫对斜纹夜蛾3、4龄幼虫的捕食能力优于黄带犀猎蝽若虫。     

叉角厉蝽低温贮藏最适虫态和条件

叉角厉蝽是一种能够有效控制草地贪夜蛾等鳞翅目农业害虫的捕食性天敌昆虫，低温贮藏是天敌昆虫开展大规模生产与释放的重要环节之一。本研究对叉角厉蝽适合低温贮藏的虫态进行了筛选，探究了不同低温与食物条件组合的贮藏方式对叉角厉蝽雌雄成虫寿命、存活率和致死中时间的影响。结果表明叉角厉蝽最佳贮藏虫态为成虫期，该时期低温贮藏效果优于若虫期和卵期；在低温贮藏成虫时，供水组、供水与食物组的效果要好于供食物组和饥饿组。在同时提供食物与水的条件下雌成虫在16 ℃、雄成虫在10 ℃或13 ℃下各项指标较优，平均寿命分别为49.78 d、39.41 d和44.00 d，存活率达80%的冷藏时间为22.00 d、25.33 d和21.00 d，LT₅₀分别为49.32 d、38.98 d和43.62 d；综合考虑存活率、寿命等适合度因素，叉角厉蝽的低温贮藏可选择雌成虫在16 ℃、雄成虫在10～13 ℃，同时提供食物与水的条件下进行。     

东亚小花蝽对草地贪夜蛾1龄幼虫的捕食作用

为明确天敌昆虫东亚小花蝽Orius sauteri对草地贪夜蛾Spodoptera frugiperda幼虫的捕食潜力,在室内测定东亚小花蝽5龄若虫和成虫对草地贪夜蛾1龄幼虫的日捕食量,并对其捕食功能、搜寻效应和干扰效应进行分析。结果表明:东亚小花蝽5龄若虫和成虫对草地贪夜蛾1龄幼虫的捕食功能反应符合Holling II模型;东亚小花蝽5龄若虫对草地贪夜蛾1龄幼虫的日最大捕食量、瞬时攻击率和处理单头猎物的时间分别为20.833头、0.747和0.048 d;东亚小花蝽成虫对草地贪夜蛾1龄幼虫的日最大捕食量、瞬时攻击率和处理单头猎物的时间分别为11.236头、1.355和0.089 d。东亚小花蝽的日捕食量与草地贪夜蛾密度呈正相关,搜寻效应与草地贪夜蛾密度呈负相关。东亚小花蝽自身密度对其捕食作用的干扰符合Hassell模型,对草地贪夜蛾1龄幼虫的捕食作用率随自身密度的增加而降低。     

大红犀猎蝽对草地贪夜蛾3龄幼虫捕食功能反应

为探明天敌昆虫大红犀猎蝽Sycanus falleni对草地贪夜蛾Spodoptera frugiperda幼虫的捕食潜力,在室内条件下测定大红犀猎蝽3龄若虫和成虫对草地贪夜蛾3龄幼虫的捕食功能反应、搜寻效应,以及不同自身密度对捕食草地贪夜蛾的干扰反应。结果表明:大红犀猎蝽3龄若虫和成虫对草地贪夜蛾3龄幼虫的捕食功能反应符合Holling II模型;其中大红犀猎蝽3龄若虫对草地贪夜蛾3龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为4.049头、1.198和0.247 d;大红犀猎蝽雌成虫对草地贪夜蛾3龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为47.619头、0.717和0.021 d;大红犀猎蝽雄成虫对草地贪夜蛾3龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为43.478头、0.650和0.023 d;大红犀猎蝽的捕食量与害虫密度正相关,搜寻效应与害虫密度负相关。大红犀猎蝽自身密度对捕食作用的干扰效应符合Hassell模型,对草地贪夜蛾3龄幼虫的捕食作用率随自身密度的增加而降低。表明大红犀猎蝽3龄若虫和成虫对草地贪夜蛾3龄幼虫均有一定的捕食能力,大红犀猎蝽成虫的捕食作用大于3龄若虫。     

基于MaxEnt模型预测叉角厉蝽在全球的潜在地理分布

为明确草地贪夜蛾Spodoptera frugiperda的捕食性天敌——叉角厉蝽Eocanthecona furcellata在全球的潜在地理分布,基于叉角厉蝽在全球已有的历史分布记录,结合环境数据,采用MaxEnt生态位模型结合GIS技术对其在全球范围的适生区进行分析。结果显示,最暖季降水和最冷季平均温度是影响叉角厉蝽分布的主要环境因素。预测的叉角厉蝽在各个洲均可能发生,适生区集中分布在亚洲东部、东南亚大部、印度半岛东部、非洲南部东西沿海岸地区、南美洲中部地区及澳洲北部沿海岸地区。表明叉角厉蝽适生性较强,可以充分利用其捕食性释放到田间用于生物防治。     

叉角厉蝽对草地贪夜蛾的捕食特性研究

采用捕食行为观察、多种猎物共存、功能反应测定和干扰反应测定试验研究了叉角厉蝽对草地贪夜蛾的捕食特性.结果 显示,叉角厉蝽主要在上午时段搜寻猎物,能捕食草地贪夜蛾2～6龄期幼虫和预蛹,对6龄期幼虫和预蛹具有喜好性;其雌成虫和5龄若虫对草地贪夜蛾3龄幼虫捕食反应符合Holling-Ⅱ型方程,分别为Na=0.9819N0 和...     

叉角厉蝽人工饲养技术及其防治草地贪夜蛾的初步研究

为研究叉角厉蝽人工大量繁殖技术和其在草地贪夜蛾防治中的应用,笔者测定了室内饲养条件下叉角厉蝽的平均发育历期和存活率,分析了饲养密度和饥饿处理对叉角厉蝽存活率的影响,并初步研究了叉角厉蝽田间释放密度和时期对防治玉米田草地贪夜蛾的影响。结果表明,室温25～32℃、相对空气湿度60%～80%、光照周期L∶D=14∶10的条件下,饲养叉角厉蝽一个世代需要41.40 d。饲养密度过高或过低都显著降低总产卵数。雌虫平均产卵量和存活率随饲养密度升高而降低,室内饲养叉角厉蝽成虫的最佳密度为4头/L。饥饿处理对不同龄期的叉角厉蝽存活时间的影响有显著差异。雌虫耐饥饿能力最强。在田间玉米虫量约为20头/百株时,按照0.24头/m2释放叉角厉蝽5龄若虫,7 d后草地贪夜蛾虫口减退率达72.41%;玉米拔节期释放叉角厉蝽效果好于喇叭口期和抽穗期,7 d后草地贪夜蛾虫口减退率达68.75%,对草地贪夜蛾幼虫具有较好的防治效果。     

Dermestid beetles in ‘evolution Canyon’, lower Nahal Oren, Mt. Carmel, including new records for Israel

Fifteen species of dermestid beetles were recorded at ‘Evolution Canyon’ (EC), Lower Nahal Oren, Mt. Carmel, Israel. They represent ~35% of known Israeli dermestid species. The following three species were recorded for the first time in Israel:Trogoderma svriaca Dalla Torre, 1911;Ctesias svriaca Ganglbauer, 1904; andAnthrenus (s.str.) jordaniens Pic, 1934. Adults of 13 species were collected on the more solar radiated, warmer and climatically more fluctuating south-facing slope (SFS); ten species were collected on the opposite, north-facing slope (NFS), which was cooler and climatically more stable. The abundance of adult dermestid beetles was 1.9 times higher on the SFS than on the NFS (86 and 47, respectively). Species richness and abundance distribution at EC (three collecting stations on each slope and one at the valley bottom) were significantly negatively correlated with the plant cover that consisted of trees and bushes (Spearmanr _s ,P=0.007 and 0.039, respectively) and perennials (Spearmanr _s ,P=0.039 and 0.077, respectively), indicating that non-woody plants were preferred by adult dermestid beetles.     

Epidemiology of Toxigenic Fungi and their Associated Mycotoxins for Some Mediterranean Crops

Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.     

A survey of the genera of<Emphasis Type="Italic">Microgaster</Emphasis> latreille and<Emphasis Type="Italic">Hygroplitis</Emphasis> thomson (Hymenoptera: Braconidae: Microgastrinae) from China

The genera ofMicrogaster Latreille 1804 andHygroplitis Thomson 1895 from China are presented systematically in this paper. Thirty-two species ofMicrogaster and three species ofHygroplitis are known in China. Diagnosis, character variation, distribution and host of each species among the two genera are presented, including its host and distribution. Keys to the species ofMicrogaster andHygroplitis are given. http://www.phytoparasitica.org posting Dec. 19, 2006.     

Plant Viruses Transmitted by Whiteflies

One-hundred and fourteen virus species are transmitted by whiteflies (family Aleyrodidae). Bemisia tabaci transmits 111 of these species while Trialeurodes vaporariorum and T. abutilonia transmit three species each. B. tabaci and T. vaporariorum are present in the European–Mediterranean region, though the former is restricted in its distribution. Of the whitefly-transmitted virus species, 90% belong to the Begomovirus genus, 6% to the Crinivirus genus and the remaining 4% are in the Closterovirus, Ipomovirus or Carlavirus genera. Other named, whitefly-transmitted viruses that have not yet been ranked as species are also documented. The names, abbreviations and synonyms of the whitefly-transmitted viruses are presented in tabulated form together with details of their whitefly vectors, natural hosts and distribution. Entries are also annotated with references. Whitefly-transmitted viruses affecting plants in the European–Mediterranean region have been highlighted in the text.     

Broad bean mottle virus in Morocco; curculionid vectors,and natural occurrence in food legumes other than faba bean (Vicia faba)

Broad bean mottle virus (BBMV) was transmitted from infected to healthy faba-bean plants by the curculionid weevilsApion radiolus Kirby,Hypera variabilis Herbst,Pachytychius strumarius Gyll,Smicronyx cyaneus Gyll, andSitona lineatus L. The latter appeared to be an efficient vector: acquisition and inoculation occurred at the first bite, the rate of transmission was c. 41%, and virus retention lasted for at least seven days.S. lineatus transmitted the virus from faba bean to lentil and pea, but not to the three genotypes of chickpea tested. This is the first report on the generaHypera, Pachytychius, andSmicronyx as virus vectors, and onA. radiolus, H. variabilis, P. strumarius, andS. cyaneus as vectors of BBMV.Out of 351 samples of food legumes with symptoms suggestive of virus infection, 16, 11, 19, and 17% of the samples of chickpea, lentil, pea, and common bean, respectively, were found infected when tested for BBMV in DAS-ELISA. This is the first report on the natural occurrence of BBMV in chickpea, lentil, pea, and common bean. The virus should be regarded as a food-legume virus rather than a faba-bean virus solely, and is considered an actual threat to food legume improvement programmes.     

Characterization of potato potyvirus Y (PVY) isolates from seed potato batches. Situation of the NTN, Wilga and Z isolates

A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVY^N strain and six to the PVY^O strain. No PVY^C was found. Two other isolates reacted serologically like PVY^O, but were unable to elicit a hypersensitive response from the Ny_tbr gene and probably represent the PVY^Z group. At the molecular level, these two isolates showed a combination of both PVY^O and PVY^N and could be recombinants of these strains. Another isolate reacted serologically like PVY^O, but induced vein necrosis in tobacco, like PVY^N-Wilga. Some PVY^N isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVY^NTN group. The PVY^NTN, PVY^N-Wilga and PVY^Z groups probably represent pathotypes within strains PVY^N and PVY^O, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.     

The autumn leafroller: Phenology,damage and parasitoids in a Dutch apple orchard

The phenology of the autumn leafroller,Syndemis musculana, a local pest of apple, was studied in order to forecast larval emergence. From 1983–1986, peak flight as determined with sexpheromone traps was always between 13–18 May. The duration of embryonic development was determined at various constant temperatures and used to estimate the periods of egg hatch in these four years. Each year, most eggs should have hatched in the second decade of June.Differences in attack rates between apple cultivars seem to be explained largely by the variation in picking time. Larvae are only half grown at the beginning of harvest (cv. James Grieve), and have gone into hibernation when the latest variety (cv. Golden Delicious) is picked. Moreover, the varieties Cox's Orange Pippin and Belle de Boskoop, picked about half time, are liable to receive additional damage by caterpillars brought with the picked fruits into storage.Various hymenopterous parasites were reared from caterpillars. As the only leafroller in the orchard which hibernates as mature larva,S. musculana may promote winter survival of some parasitoids, like the eulophidColpyclypeus florus.Samenvatting De fenologie van de herfstbladroller (Syndemis musculana Hübner), een incidentele plaag op appel, werd nader bepaald met het doel het uitkomen van de eieren te kunnen voorspellen. In 1983–1986 viel de piekvlucht, bepaald met behulp van feromoonvallen, steeds tussen 13 en 18 mei.De ontwikkelingsduur van de eieren bij verschillende constante temperaturen werd gebruikt om de periode van uitkomen te schatten. De meeste eieren zullen ieder jaar in de eerste helft van juni uitkomen.Geconstateerde verschillen in schade tussen appelrassen blijken goeddeels terug te voeren op verschillen in pluktijdstip. De rupsen van de herfstbladroller zijn pas half-was als de eerste appels eind augustus geplukt worden, terwijl tegen het einde van de oogst begin oktober de meeste al in winterslaap zijn. Met name tussentijdse rassen, als Cox's Orange Pippin and Schone van Boskoop, lopen extra schade op doordat grotere rupsen met de geplukte vruchten in de kist terecht komen.Uit de rupsen werden negen, al van andere boomgaardbladrollers bekende, sluipwespen gekweekt, Omdat deze bladrollersoort, als enige in de boomgaard, als volgroeide rups overwintert, lijkt zij bij uitstek geschikt als winterwaard.This study was carried out at the Experimental Orchard De Schuilenburg, Schuilenburg 3, 4041 BK Kesteren, the Netherlands, to which address correspondence should be addressed.     

Characterization of Sclerotinia minor populations in Texas peanut fields

In the summer of 2004 an epidemic of sclerotinia blight of peanut, a disease caused by Sclerotinia minor, occurred in Texas in fields where the disease was never previously detected. The disease was observed on many plants within one of the fields (>3000 disease foci), although most foci were <1 m. It is hypothesized that these observations were inconsistent with the recent introduction of a monocyclic pathogen, even if disease developed under conducive environmental conditions. The pattern of disease is most suggestive of the presence of foliar (ascospore) infections, although air temperature was above the known limits for apothecia development if the pathogen had arrived in the field in 2004 peanut seed. To further examine this epidemic, 232 isolates were collected, across a variety of spatial scales spanning this field and other Texas peanut fields, and evaluated for aggressiveness, fungicide sensitivity and genotypic diversity. There was wide variation among isolates for the phenotypic characteristics measured, but there was no evidence that a genotypically unique, highly aggressive, and fungicide resistant isolate had been introduced or evolved. The predominant genotype, TX1, which contained 154 isolates, was found in every county and field population.     

Eyespot of Cereals Revisited: ITS phylogeny Reveals New Species Relationships

Four species so far classified in Pseudocercosporella or Ramulispora (hyphomycetes) are associated with eyespot disease symptoms of cereals. Two of these have been linked to teleomorphs that were described in Tapesia. Sequence data derived from the Internal Transcribed Spacer region (ITS1, 5.8S and ITS2) of the rDNA operon showed, however, that the eyespot fungi associated with Tapesia are not congeneric with Ramulispora sorghi, the type of Ramulispora. The genus name Tapesia is now rejected in favour of the conserved name Mollisia, which appears to comprise heterogeneous fungi. Tapesia yallundae is not closely related to the type of Mollisia, M. cinerea, but clusters separately, being more closely allied to species with Cadophora anamorphs. A new holomorph genus, Oculimacula, is therefore proposed for teleomorphs of the eyespot fungi, while the anamorphs are accommodated in Helgardia gen. nov.     

Tumours of Begonia and some other ornamentals,induced by Corynebacterium fascians

In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten.