9种杀菌剂对苹果斑点落叶病菌和轮纹病菌的毒力比较

在室内比较测定了己唑醇等9种杀菌剂对苹果斑点落叶病菌和苹果轮纹病菌的抑菌毒力。结果表明:苹果斑点落叶病菌对三唑类杀菌剂己唑醇、戊唑醇、腈菌唑、氟硅唑和苯醚甲环唑的敏感性依次下降,EC50值均在1μg/mL以下,EC90值均低于10μg/mL;上述药剂与异菌脲的毒力相当,高于多氧霉素。苹果轮纹病菌对供试5种三唑类杀菌剂的敏感性略低于斑点落叶病菌,其中仍以己唑醇毒力最高,其次是戊唑醇、氟硅唑、腈菌唑、苯醚甲环唑,异菌脲与苯醚甲环唑的毒力水平相当,表明上述药剂对轮纹病有兼治作用,而多氧霉素对该病菌的毒力相对较低。2种病菌对甲氧基丙烯酸酯类的醚菌酯敏感性均较低,而硫酸铜的抑菌毒力最低。     

山东省草莓枯萎病菌对四种三唑类杀菌剂的敏感性检测

为了明确山东省草莓枯萎病菌对三唑类杀菌剂的敏感性现状,从有代表性的草莓种植区采集、分离了12个草莓枯萎病菌菌株,采用菌落直径法测定其对四种三唑类杀菌剂的敏感性.结果显示,戊唑醇、烯唑醇、苯醚甲环唑和腈菌唑对12个菌株的EC50值分别在0.1107～1.1670、0.1446～2.2586、0.1307～9.0317和1.1969～60.9270μg·mL-1之间.其中菌株LY002对苯醚甲环唑和腈菌唑的敏感性较低;ZY002对苯醚甲环唑最敏感,其毒力倍数是LY002的69.10倍;TA005对腈菌唑最敏感,其毒力倍数是LY002的50.90倍;TA002对烯唑醇和TZ004对戊唑醇的敏感性均较低,而LY001对这两种药剂最敏感.结果表明,不同菌株之间对三唑类杀菌剂的敏感性差异较大.     

中国河南省小麦纹枯病菌对苯醚甲环唑及戊唑醇的敏感性

为明确中国河南省小麦纹枯病菌对苯醚甲环唑及戊唑醇的敏感性,采用菌丝生长速率法测定了2种药剂对采自河南省15个地市分离的95株病菌的毒力。结果显示:供试菌株对苯醚甲环唑和戊唑醇的EC50值分别在0.014~1.609和0.002~0.064 μg/mL之间。敏感性频率分布图显示:在小麦纹枯病菌群体中已出现对苯醚甲环唑敏感性下降的亚群体,而对戊唑醇则不明显;可将其中呈连续单峰频次分布的大多数菌株群体的平均EC50值（0.165±0.101）和（0.019±0.008）μg/mL分别作为小麦纹枯病菌对苯醚甲环唑和戊唑醇的相对敏感基线。苯醚甲环唑的平均EC50值是戊唑醇的26倍,表明该病原菌对戊唑醇更为敏感。不同地区病原菌群体间对苯醚甲环唑和戊唑醇的敏感性均存在显著性差异。小麦纹枯病菌对2种杀菌剂的敏感性之间存在着微弱的正相关性。本研究结果可为河南省小麦纹枯病防控杀菌剂的合理使用提供理论依据。     

辽宁省黄瓜靶斑病菌对苯醚甲环唑和戊唑醇的敏感性

采用菌丝生长速率法,测定了2013年采集分离自辽宁省8个地区的101株黄瓜靶斑病病原菌群体对三唑类杀菌剂苯醚甲环唑和戊唑醇的敏感性。结果表明:苯醚甲环唑对101株黄瓜靶斑病菌的EC50值范围为1.062~18.918μg/mL,相差16.814倍,平均EC50值为(7.109±4.578)μg/mL;戊唑醇对上述菌株的EC50值范围为1.624~21.708μg/mL,相差12.367倍,平均EC50值为(9.398±4.944)μg/mL。田间尚未出现对2种杀菌剂产生抗药性的菌株。不同地区间黄瓜靶斑病菌对苯醚甲环唑和戊唑醇的敏感性无显著差异。     

苹果轮纹病菌对苯醚甲环唑和氟硅唑的敏感性及其交互抗性

 为明确苹果轮纹病菌对苯醚甲环唑和氟硅唑的敏感性状况,本研究采用菌丝生长速率法检测了90个采自山东省各地区的苹果轮纹病菌对苯醚甲环唑和氟硅唑的敏感性。实验结果表明,苯醚甲环唑和氟硅唑对轮纹病菌的EC₅₀平均值分别为0.198 1±0.247 1 μg·mL^-1和0.117 4±0.121 8 μg·mL^-1。频次分布图显示,苹果轮纹病菌群体中出现了敏感性降低的亚群体。三唑类杀菌剂苯醚甲环唑、氟硅唑和戊唑醇之间具有交互抗性;而三唑类杀菌剂苯醚甲环唑、氟硅唑、戊唑醇与代森锰锌之间不存在交互抗性。田间试验结果表明,苯醚甲环唑和氟硅唑对高敏感性和低敏感性病菌引起的枝干轮纹病具有同等的防治效果。本研究结果为田间防控苹果轮纹病的杀菌剂合理轮换使用提供了理论依据。     

9种三唑类杀菌剂对苹果轮纹病菌的毒力及田间防效

为筛选得到防治苹果轮纹病的高效药剂,采用生长速率法测定9种三唑类杀菌剂对苹果轮纹病菌菌丝生长的毒力,评价其对苹果生长的安全性及对轮纹病的田间防治效果.结果 表明,苯醚甲环唑和氟硅唑对苹果轮纹病菌的室内毒力较高,EC50分别为0.107 μg/mL和0.140 μg/mL;其次为氟环唑、丙环唑和己唑醇,EC50分别为0....     

河北省梨树褐斑病菌对苯醚甲环唑的敏感性

 为明确河北省梨树褐斑病菌(Septoria piricola Desm) 对苯醚甲环唑的敏感性,采用菌丝生长速率法测定了苯醚甲环唑对从该省11个地市分离的133 株菌株的毒力,通过方差及聚类分析法对测定结果进行了分析,并分别研究了苯醚甲环唑与双胍三辛烷基苯磺酸盐、吡唑醚菌酯、戊唑醇敏感性的相关性。结果显示:梨树褐斑病菌对苯醚甲环唑菌丝生长的最低抑制浓度为3 μg·mL^-1;供试133株菌株对苯醚甲环唑的EC₅₀范围在0.032 2~1.882 2 μg·mL^-1 之间,平均EC₅₀为(0.488 8 ±0.003 9) μg·mL^-1;敏感性频率分布图显示,病菌群体中存在着对苯醚甲环唑敏感性较低的亚群体,但 81.95% 供试菌株敏感性频率呈正态分布,将此部分菌株的 EC₅₀平均值为(0.319 3±0.001 8) μg·mL^-1 作为梨树褐斑病菌对苯醚甲环唑的敏感性基线。方差分析及聚类结果均显示,不同县市内的菌株对苯醚甲环唑EC₅₀的最大值和最小值之比为1.7~7.5;各县市的菌株对苯醚甲环唑敏感性不同,苯醚甲环唑EC₅₀平均值变化范围在0.207 4~0.961 2 g·mL^-1 之间,最大值是最小值的4.6倍;梨树褐斑病菌对苯醚甲环唑的敏感性与其对双胍三辛烷基苯磺酸盐、吡唑醚菌酯的敏感性之间无明显相关性,与戊唑醇的敏感性之间存在相关性,苯醚甲环唑与双胍三辛烷基苯磺酸盐、苯醚甲环唑与吡唑醚菌酯可以复配使用。表明河北省梨树褐斑病菌群体中尽管存在着敏感性较低的亚群体,但可通过药剂复配进行防控。     

河北省梨树褐斑病菌对苯醚甲环唑的敏感性

 为明确河北省梨树褐斑病菌(Septoria piricola Desm) 对苯醚甲环唑的敏感性,采用菌丝生长速率法测定了苯醚甲环唑对从该省11个地市分离的133 株菌株的毒力,通过方差及聚类分析法对测定结果进行了分析,并分别研究了苯醚甲环唑与双胍三辛烷基苯磺酸盐、吡唑醚菌酯、戊唑醇敏感性的相关性。结果显示:梨树褐斑病菌对苯醚甲环唑菌丝生长的最低抑制浓度为3 μg·mL^-1;供试133株菌株对苯醚甲环唑的EC₅₀范围在0.032 2~1.882 2 μg·mL^-1 之间,平均EC₅₀为(0.488 8 ±0.003 9) μg·mL^-1;敏感性频率分布图显示,病菌群体中存在着对苯醚甲环唑敏感性较低的亚群体,但 81.95% 供试菌株敏感性频率呈正态分布,将此部分菌株的 EC₅₀平均值为(0.319 3±0.001 8) μg·mL^-1 作为梨树褐斑病菌对苯醚甲环唑的敏感性基线。方差分析及聚类结果均显示,不同县市内的菌株对苯醚甲环唑EC₅₀的最大值和最小值之比为1.7~7.5;各县市的菌株对苯醚甲环唑敏感性不同,苯醚甲环唑EC₅₀平均值变化范围在0.207 4~0.961 2 g·mL^-1 之间,最大值是最小值的4.6倍;梨树褐斑病菌对苯醚甲环唑的敏感性与其对双胍三辛烷基苯磺酸盐、吡唑醚菌酯的敏感性之间无明显相关性,与戊唑醇的敏感性之间存在相关性,苯醚甲环唑与双胍三辛烷基苯磺酸盐、苯醚甲环唑与吡唑醚菌酯可以复配使用。表明河北省梨树褐斑病菌群体中尽管存在着敏感性较低的亚群体,但可通过药剂复配进行防控。     

烟草赤星病菌对苯醚甲环唑和氟环唑敏感性测定及田间防效试验

为明确山东省主要烟草产区烟草赤星病菌Alternaria alternata对苯醚甲环唑和氟环唑的敏感性,采用菌丝生长速率法检测苯醚甲环唑和氟环唑对86株烟草赤星病菌菌株的EC_(50),用Spearman’s秩相关系数法分析供试菌株对2种杀菌剂敏感性的相关性,并评价其对烟草赤星病的田间防效。结果表明,苯醚甲环唑对烟草赤星病菌菌丝生长EC_(50)值介于5.3883～8.0316 mg/L之间,平均值为6.9594 mg/L,敏感性频率分布呈连续性偏正态分布,田间烟草赤星病菌对苯醚甲环唑仍然较为敏感,可建立田间烟草赤星病菌对苯醚甲环唑的敏感基线。氟环唑对烟草赤星病菌菌丝生长的EC_(50)值介于0.1253～0.2517 mg/L,平均值为0.1773 mg/L,敏感性频率分布呈连续性偏正态分布,可建立田间烟草赤星病菌对氟环唑的敏感基线。相关性分析结果表明,烟草赤星病菌对苯醚甲环唑和氟环唑敏感性之间不存在明显的相关性。田间试验结果表明,30%苯醚甲环唑悬浮剂对烟草赤星病具有较好的防效,其有效成分150 g/hm~2处理的防效最高,为73.99%;12.5%氟环唑悬浮剂对烟草赤星病的最高防效为70.57%。表明2种三唑类杀菌剂对烟草赤星病防效较好。     

甘肃省枸杞炭疽病菌对4种甾醇脱甲基抑制剂的敏感性

为明确甘肃省枸杞炭疽病菌对甾醇脱甲基抑制剂类药剂 (DMIs) 的敏感性,采用菌丝生长速率法测定了采自甘肃省靖远县3个地区及景泰县3个地区共102株枸杞炭疽病菌对苯醚甲环唑、戊唑醇、丙环唑及氟硅唑的敏感性,分别就不同年份、不同地区间胶孢炭疽复合种和尖孢炭疽复合种对4 种 DMIs 杀菌剂的敏感性差异进行了分析。结果表明:供试46 株枸杞胶孢炭疽复合种整体上对苯醚甲环唑、戊唑醇、丙环唑和氟硅唑仍表现为敏感,EC₅₀值分别在0.28~1.20、0.11~2.98、0.32~2.84和0.35~3.85 μg/mL之间;而56株尖孢炭疽复合种对4种药剂的敏感性则出现了不同程度分化,部分菌株疑似已出现敏感性下降现象,其中,对苯醚甲环唑、戊唑醇、丙环唑和氟硅唑敏感性最低的菌株EC₅₀值分别为1.63、3.80、6.21和4.74 μg/mL。不同年份间采集的枸杞胶孢炭疽复合种和尖孢炭疽复合种对4种杀菌剂的敏感性均存在显著差异,2017年采集的菌株敏感性相对更低,4种杀菌剂对胶孢炭疽复合种的平均EC₅₀值分别为 (0.84 ± 0.03)、(1.23 ± 0.13)、(1.19 ± 0.09) 和 (1.69 ± 0.17) μg/mL,对尖孢炭疽复合种的平均EC₅₀值分别为 (1.06 ± 0.03)、(2.25 ± 0.15)、(2.43 ± 0.20) 和 (2.85 ± 0.19) μg/mL。不同地区枸杞炭疽病菌对4种杀菌剂的敏感性表现不同,其中靖远县五合镇的胶孢炭疽复合种对4种杀菌剂敏感性最低,平均EC₅₀值分别为 (0.79 ± 0.12)、(1.28 ± 0.87)、(1.39 ± 1.05) 和 (1.74 ± 1.04) μg/mL,景泰县草窝滩镇的胶孢炭疽复合种对苯醚甲环唑和丙环唑敏感性最高,平均EC₅₀值为 (0.28 ± 0.10) 和 (0.46 ± 0.10) μg/mL,对戊唑醇和氟硅唑敏感性最高的胶孢炭疽复合种来自景泰县寺滩乡,平均EC₅₀值为 (0.42 ± 0.16) 和 (0.65 ± 0.09) μg/mL;不同地区间采集的尖孢炭疽复合种对4种杀菌剂的敏感性则不存在显著差异。研究结果可为甘肃省枸杞炭疽病防治中杀菌剂的合理使用及延缓抗药性发展提供依据。     

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.