新疆MEAM1烟粉虱隐种对吡虫啉的抗性遗传力分析及交互抗性测定

采用Tabashnik的域性状指标分析了新疆MEAM1(Middle-East-Asia-Minor l)烟粉虱隐种对吡虫啉的抗性现实遗传力(h2)和不同致死率下的抗性发展速率,同时测定了抗性种群对不同类型杀虫剂的交互抗性。结果表明,在30%~50%较低的选择压力下,新疆MEAM1烟粉虱隐种连续汰选8代后,对吡虫啉的抗性上升28.01倍,抗性现实遗传力h2为0.429 7。假设田间种群现实遗传力为实验室筛选估算值的1/2,即h2=0.214 9,对新疆MEAM1烟粉虱隐种对吡虫啉的抗性发展速率估算结果表明:在药剂选择压力为50%~60%下,若使其对吡虫啉的抗性增长10倍,则需要生长10~8代;而在药剂选择压力为70%~90%下,若使其抗性增长10倍,则仅需要生长6~4代。表明新疆MEAM1烟粉虱隐种对吡虫啉产生抗性的风险很大。交互抗性测定结果显示:抗性种群对同类型的杀虫剂吡虫清和噻虫嗪分别产生了10.78倍和4.75倍的中等至低水平交互抗性;对多杀菌素、毒死蜱、吡丙醚和高效氯氰菊酯的敏感性有所降低;对阿维菌素、氟啶虫胺腈和乙基多杀菌素等杀虫剂则无交互抗性。     

7种杀虫剂对北京地区烟粉虱成虫毒力的比较研究

本试验比较测定了7种杀虫剂对北京地区烟粉虱成虫的毒力,以期为北京地区高毒农药淘汰提供参考。结果表明:氟虫腈对烟粉虱成虫的毒力最强,其LC50值为2.98(g/mL;新烟碱类杀虫剂啶虫脒、吡虫啉对烟粉虱成虫的生物活性较好,LC50值分别为8.04(g/mL、7.49(g/mL,噻虫嗪对烟粉虱成虫毒力相对较差,LC50值仅为95.03(g/mL;烟粉虱成虫对马拉硫磷、异丙威和噻嗪酮3种杀虫剂不敏感。在北京地区,采用噻虫嗪、马拉硫磷、异丙威和噻嗪酮等杀虫剂,不能有效防治烟粉虱的成虫;氟虫腈、吡虫啉和啶虫脒可以用来防治烟粉虱成虫。     

山东省不同地区棉蚜对新烟碱类杀虫剂的抗药性检测及酶抑制剂的增效作用研究

为明确山东省棉蚜对新烟碱类杀虫剂的抗性水平,采用毛细管微量点滴法测定了泰安、聊城和东营3个田间种群及1个敏感种群对吡虫啉、烯啶虫胺、啶虫脒、噻虫嗪、噻虫啉、噻虫胺6种新烟碱类杀虫剂的敏感性,同时测定了磷酸三苯酯(TPP)、顺丁烯二酸二乙酯(DEM)和增效醚(PBO)3种酶抑制剂的增效作用。结果表明:泰安棉蚜种群对烯啶虫胺的抗性倍数为16.95,处于中等抗性水平,对吡虫啉和啶虫脒的抗性倍数分别为5.69和9.57,已产生低水平抗性,对噻虫胺、噻虫嗪和噻虫啉的抗性倍数均小于3.0,仍较敏感;聊城棉蚜种群对吡虫啉、啶虫脒和噻虫嗪的抗性倍数分别为28.51、25.88和18.16,属中等抗性水平,对噻虫啉和噻虫胺的抗性倍数分别为6.01和6.37,已产生低水平抗性,对烯啶虫胺仍处于敏感阶段;东营棉蚜种群对吡虫啉、啶虫脒和噻虫胺的抗性倍数分别为37.95、21.52和12.95,已产生中等水平抗性,对噻虫啉、烯啶虫胺和噻虫嗪的抗性倍数分别为7.07、6.38和4.75,处于低水平抗性阶段。多功能氧化酶抑制剂PBO和羧酸酯酶抑制剂TPP对6种供试新烟碱类杀虫剂的增效作用明显,谷胱甘肽-S-转移酶抑制剂DEM对这6种药剂也具有一定的增效作用。研究表明,山东省泰安等3地区棉蚜种群对6种新烟碱类杀虫剂均产生了不同程度的抗药性,多功能氧化酶和羧酸酯酶可能在棉蚜对该类杀虫剂的抗性中起主要作用,谷胱甘肽-S-转移酶可能也具有一定的作用。     

5种杀虫剂灌根施药对黄瓜烟粉虱的防治效果研究

以盆栽黄瓜为供试植物,利用灌根法,研究了5种杀虫剂对黄瓜烟粉虱的防治效果。结果表明:阿维菌素对黄瓜烟粉虱最高防效不足30%,吡虫啉、噻虫嗪、啶虫脒和烯啶虫胺灌根施药后7d,防效均在60%以上,10d防效达最高,其中吡虫啉130mg/L处理防效最高为94.3%,持效期长达20d。本研究为黄瓜烟粉虱防治药剂的合理使用提供了科学依据。     

北京地区蔬菜烟粉虱种群动态及其对烟碱类杀虫剂的抗药性监测

为了明确北京地区蔬菜烟粉虱的种群发展动态及对常用烟碱类杀虫剂的抗药性,为烟粉虱防治适期的确定及高效杀虫剂的选择提供基础资料及科学指导,2009年调查了北京地区春茬和秋茬蔬菜烟粉虱的种群动态,并监测了该地区2009-2011年度烟粉虱种群对3种烟碱类杀虫剂的抗药性。结果表明,春茬蔬菜烟粉虱在5月中旬种群快速上升,持续到春茬拉秧;秋茬蔬菜烟粉虱在塑料棚内9月上旬种群数量即开始上升,露地出现时间较晚,10月中旬后种群数量下降;塑料棚内种群数量明显高于露地蔬菜烟粉虱数量。烟粉虱2009年对吡虫啉和噻虫嗪的抗药性很高,2010年和2011年抗性程度显著下降,LC50处于133.94～251.16mg/L,属中等抗性水平;而对新型杀虫剂烯啶虫胺的抗药性在近3年内持续升高,抗性倍数由6.68倍升至83.62倍,即由低抗性水平升至高抗性水平。上述调查结果表明,北京地区蔬菜烟粉虱的防治应掌握春季5月中旬前、秋季9月中旬前种群处于低密度时进行。烟粉虱对新型杀虫剂烯啶虫胺的抗药性在近三年内快速上升,生产中应注意药剂的轮换使用。     

Q型烟粉虱细胞色素P450 CYP6DV5基因克隆及其在烟粉虱对噻虫嗪抗性中的作用

烟粉虱Bemisia tabaci已严重危害农作物的正常生长,而新烟碱类杀虫剂噻虫嗪已被广泛用于烟粉虱的防治,但由于常年应用,致使烟粉虱对噻虫嗪产生了严重的抗性,而目前其抗药性分子机制尚不明确.本研究通过荧光定量PCR比较分析烟粉虱噻虫嗪抗性及敏感种群,发现细胞色素P450基因CYP6DV5在噻虫嗪抗性品系中的表达量为...     

新疆北疆马铃薯甲虫成虫对新烟碱类杀虫剂的敏感性变化

采用点滴法于2009和2010年监测了新疆维吾尔自治区北疆马铃薯甲虫Leptinotarsa decemlineata 9个田间种群成虫对新烟碱类杀虫剂吡虫啉、啶虫脒、噻虫嗪和噻虫啉的敏感性变化,发现其对吡虫啉和噻虫嗪的敏感性逐年降低。2009年监测的6个种群中有3个对啶虫脒和噻虫嗪低抗(抗性倍数5.0~10.0);2010年监测的6个种群全部对噻虫嗪产生了抗性,其中中抗(抗性倍数10.1~40.0)和低抗种群各3个。噻虫嗪与高效氯氟氰菊酯可能存在交互抗性。     

灰飞虱对杀虫剂抗药性的研究进展

灰飞虱对杀虫剂产生抗药性是其近年来暴发频繁的重要原因。本文综述了国内外关于灰飞虱抗药性的研究成果,包括灰飞虱抗药性的发展、交互抗性、抗性机理、抗性遗传及生物适合度等。田间灰飞虱种群对多种药剂产生了不同程度的抗药性,其中对新烟碱类药剂吡虫啉和昆虫生长调节剂噻嗪酮产生了高水平到极高水平抗性(抗药性倍数分别为44.6～108.8倍和超过200倍),对有机磷类药剂毒死蜱和乙酰甲胺磷(抗药性倍数分别为10～12.6倍和9～13倍)、氨基甲酸酯类药剂甲萘威和残杀威(抗药性倍数分别为29.8～45.3倍和40.1～131.5倍)和拟除虫菊酯类药剂高效氯氰菊酯和溴氰菊酯(抗药性倍数分别为7.8～108.8倍和12～21倍)产生了中等水平到高水平的抗药性,对氟虫腈、阿维菌素和噻虫嗪没有产生抗药性(抗性倍数5倍)。长期大面积使用化学药剂是灰飞虱产生抗药性的重要原因。因此,必须加强灰飞虱的抗性治理,以延缓其抗药性进一步发展。     

3种杀虫剂对柑橘木虱的田间防效

为有效防控柑橘木虱,阻止柑橘黄龙病扩散蔓延,2017年采用田间试验探索了新烟碱类杀虫剂25%噻虫嗪水分散粒剂、昆虫生长调节剂类杀虫剂100 g/L吡丙醚乳油、微生物杀虫剂80亿孢子/mL绿僵菌油悬浮剂对柑橘木虱的防治效果。结果表明,25%噻虫嗪水分散粒剂对柑橘木虱的速效性和持效性均表现较好,药后3 d防效达85%以上,药后14 d防效达90%以上;其次是80亿孢子/mL绿僵菌油悬浮剂,药后14 d防效达80%以上;100 g/L吡丙醚乳油防效相对较差,药后3~14 d防效均未达到70%。     

烟粉虱抗、感杀虫剂品系内生菌群落的差异分析

本研究对B型和Q型烟粉虱的吡虫啉或吡丙醚的抗、感品系进行16SrRNA细菌多样性测序分析,以明确内共生菌的种类和数量与烟粉虱生物型和抗性的关系。结果表明Candidatus Nitrososphaera、Bacillus、Sphingobium只在Q型烟粉虱中存在,而Candidatus Hamiltonella、Lactobacillus、Helicobacter等只在B型烟粉虱中存在,说明这些内共生菌可能与烟粉虱B、Q两种生物型的分化有关;内共生菌Rickettsia、Candidatus Portiera、Candidatus Hamiltonella、S24-7、Prevotella等在烟粉虱的新烟碱类杀虫剂吡虫啉抗性品系中明显多于敏感品系,其可能与烟粉虱对吡虫啉的抗性有关;在对保幼激素类似物杀虫剂吡丙醚的抗性品系中,Candidatus Hamiltonella-OTU7、Candidatus Portiera-OTU5、Candidatus Portiera-OTU190、Rickettsia-OTU4、Rickettsia-OTU2的数量明显多于敏感品系,说明这些内共生菌可能与烟粉虱对该类药物的抗性有关。     

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.