草莓丝核菌根腐病病原菌鉴定及7种杀菌剂的抑菌作用测定

为了解草莓丝核菌根腐病的病原种类及筛选防治丝核菌根腐病的有效杀菌剂,本研究基于形态学特征、细胞核荧光染色、菌丝融合群测定以及rDNA-ITS的序列分析,对北京和河北承德地区的草莓丝核菌根腐病的病原菌进行了鉴定,并利用菌丝生长速率法测定了7种杀菌剂对丝核菌的抑菌作用。结果发现,北京地区的丝核菌为双核丝核菌(binucleate Rhizoctonia,BNR),属于融合群AG-A;河北的丝核菌为立枯丝核菌Rhizoctonia solani,属于融合群AG-4。氟啶胺、吡唑醚菌酯、噻呋酰胺、戊唑醇、咯菌腈、氟硅唑对2种丝核菌均有很强的抑制作用,EC_(50)值为0.063 9～2.485 7μg/mL,抑霉唑的抑制作用较差,EC_(50)值为9.966 8～11.236 8μg/mL。同一种杀菌剂对不同丝核菌的抑制作用存在差异,噻呋酰胺、戊唑醇、氟硅唑、咯菌腈和抑霉唑对立枯丝核菌的抑制作用强于对双核丝核菌。试验结果为生产上合理选用杀菌剂防治草莓丝核菌根腐病提供了科学依据。     

甘薯软腐病病原的rDNA-ITS分子鉴定及其对11种杀菌剂的敏感性测定

采用rDNA-ITS通用引物PCR扩增的分子检测方法对甘薯软腐病病原物进行了鉴定,并采用室内生长速率法测定了该病原菌对11种杀菌剂的毒力。rDNA-ITS分子鉴定结果表明,该病害的病原为匍枝根霉菌(Rhizopus stolonifer)。毒力测定结果显示,其病原菌已对多菌灵产生了抗药性(EC50100μg/mL);其他10种杀菌剂对甘薯软腐病病菌均具有较高的活性,EC50分布在0.011～0.145μg/mL之间。不同杀菌剂对其活性高低顺序依次为咯菌腈吡唑醚菌酯氟啶胺腐霉利啶酰菌胺苯醚甲环唑嘧菌环胺氟吡菌酰胺菌核净戊唑醇。     

五种杀菌剂对烟草立枯病菌的生物活性

由立枯病丝核菌引起的烟草立枯病是我国烟草苗床上危害最严重的病害之一。本研究评价了5种杀菌剂 (嘧菌酯、啶酰菌胺、氟啶胺、丙环唑和嘧霉胺) 对立枯丝核菌菌丝生长、菌核形成和萌发的影响,以及其对烟草立枯病的防治效果。结果表明:立枯丝核菌菌丝对氟啶胺和嘧菌酯的敏感性高于丙环唑和啶酰菌胺,而对嘧霉胺的敏感性较低;嘧菌酯对菌核形成的抑制作用强于丙环唑、氟啶胺、啶酰菌胺和嘧霉胺;5种杀菌剂对立枯丝核菌菌核萌发均无抑制作用。在离体烟叶的保护活性方面,12.5和50 mg/L的嘧菌酯和啶酰菌胺对立枯病的保护作用优于氟啶胺、丙环唑和嘧霉胺;在治疗活性方面,50和200 mg/L的嘧菌酯的治疗作用优于其他4种杀菌剂。因此,供试的5种杀菌剂中嘧菌酯最适合用于烟草立枯病的防治。     

戊唑醇等9种农药对螟黄赤眼蜂的毒性评价

为明确生产中9种常用农药 (戊唑醇、咪鲜胺、丙硫菌唑、苯醚甲环唑、噻呋酰胺、嘧菌酯、氯虫苯甲酰胺、茚虫威和甲氨基阿维菌素苯甲酸盐) 对天敌昆虫螟黄赤眼蜂Trichogramma chilonis的影响,采用药膜法测定了上述9种农药对螟黄赤眼蜂的毒性以及其中不同杀菌剂混合使用对该赤眼蜂存活的影响。结果表明:丙硫菌唑、苯醚甲环唑、噻呋酰胺和嘧菌酯对螟黄赤眼蜂的半致死用量 (LR₅₀) 大于1832 g/hm2,致死中时间 (LT₅₀) 大于4 d,均属低风险性药剂;茚虫威和氯虫苯甲酰胺也属低风险性药剂,两者LR₅₀值均大于916 g/hm2,LT₅₀值分别为2.94和0.86 d;咪鲜胺和戊唑醇的LR₅₀值分别为106和207 g/hm2,LT₅₀值分别为0.27和0.35 d,属中等风险性药剂;甲氨基阿维菌素苯甲酸盐属高风险性药剂,其LR₅₀和LT₅₀值分别为0.53 g/hm2和0.16 d。咪鲜胺和戊唑醇分别与丙硫菌唑和噻呋酰胺混合,以及戊唑醇与嘧菌酯混合,在一定时间范围内与咪鲜胺和戊唑醇单剂相比,混剂处理组螟黄赤眼蜂的死亡率均显著下降,且与丙酮空白对照组无显著性差异。研究表明,氯虫苯甲酰胺和茚虫威对螟黄赤眼蜂毒性较低,同时不同杀菌剂混用能一定程度上降低单剂对螟黄赤眼蜂的毒性,研究结果可为放蜂期合理使用杀虫剂和杀菌剂提供指导。     

江苏省葡萄炭疽病菌群体对4种杀菌剂的敏感性

为明确江苏省葡萄炭疽病菌Colletotrichum gloeosporioides群体对苯醚甲环唑、吡唑醚菌酯、咯菌腈和戊唑醇4种杀菌剂的敏感性和抗性水平,本研究采用菌丝生长速率法测定了来自江苏省7个地区的68株葡萄炭疽病菌对上述4种药剂的敏感性,建立敏感基线,并分析菌株抗性水平和抗性频率。结果表明：苯醚甲环唑、吡唑醚菌酯、咯菌腈和戊唑醇对供试68株葡萄炭疽病菌的EC₅₀范围分别为0.03～1.20、0.05～3.48、0.14～1.20 mg/L和0.50～12.30 mg/L;对苯醚甲环唑、吡唑醚菌酯和咯菌腈的敏感基线分别为(0.53±0.032)(1.00±0.15) mg/L和(0.38±0.024) mg/L。68株菌株对戊唑醇的EC₅₀平均值为3.61 mg/L,因敏感性频率分布不符合建立敏感性基线要求,故未建立敏感性基线。供试菌株对苯醚甲环唑均表现为敏感,对吡唑醚菌酯和咯菌腈呈现一定的低抗水平,抗性频率分别为4.41%和3.03%;对戊唑醇呈低抗和中抗水平,抗性频率分别为16.18%和5.88%。该研究为防控江苏省葡萄炭疽病提...     

不同药剂对蓝莓枝干溃疡病病菌抑制作用初报

采用菌丝生长速率法比较6种杀菌剂对蓝莓枝干溃疡病病菌(Botryosphaeria dothidea)的抑制作用。综合各药剂不同稀释倍数处理的抑菌表现,药剂抑制菌丝生长作用由高到低为吡唑嘧菌酯苯甲·丙环唑咯菌腈腈苯唑氟啶胺嘧菌酯;抑制中浓度以吡唑嘧菌酯最低,为0.008 1 mg/L。     

福建省草莓炭疽病菌对吡唑醚菌酯的敏感性及与其他药剂的交互抗性

为明确吡唑醚菌酯对福建省草莓炭疽病菌Colletotrichum gloeosporioides的防治潜力和应用前景,采用室内生测法测定草莓炭疽病菌对该菌剂的敏感性及其与6种不同杀菌剂之间的交互抗性。结果显示,吡唑醚菌酯对福建省5个地区分离的62株草莓炭疽菌菌株的EC₅₀介于0.086～0.879μg/mL之间,总变异系数为10.24,且符合正态分布,以其平均值0.363μg/mL为敏感基线的菌株抗性比值均低于5;此外,吡唑醚菌酯EC₅₀与多菌灵、戊唑醇、苯醚甲环唑、咪酰胺、咯菌腈、甲基硫菌灵的EC₅₀间不存在显著相关性。表明福建省不同地区草莓炭疽病菌群体对吡唑醚菌酯的敏感性虽存在一定变异,但仍均较敏感;吡唑醚菌酯与其他6种杀菌剂间不存在交互抗性,可用于防控草莓炭疽病。     

不同种类杀菌剂对辣椒炭疽病的田间防效

为筛选出对辣椒炭疽病具有较好防效的杀菌剂,选用10种不同杀菌剂于2021年进行田间药效试验。结果表明：3次药后7 d, 32.5%苯醚甲环唑·嘧菌酯悬浮剂、50%咪鲜胺锰盐可湿性粉剂和43%氟吡菌酰胺·肟菌酯悬浮剂的防效分别为85.1%、82.7%和81.9%;25%吡唑醚菌酯乳油、24%烯肟菌胺·苯醚甲环唑悬浮剂和10%苯醚甲环唑水分散粒剂三者的防效在75.8%～77.8%之间;80%甲基硫菌灵水分散粒剂、22.5%啶氧菌酯悬浮剂和25%溴菌腈乳油等处理的防效在69.2%～74.6%之间;50%克菌丹可湿性粉剂的防效相对较差。32.5%苯醚甲环唑·嘧菌酯悬浮剂、50%咪鲜胺锰盐可湿性粉剂及43%氟吡菌酰胺·肟菌酯悬浮剂可作为福建地区防治辣椒炭疽病的较优选择。     

油茶炭疽病病原鉴定及绿色防治药剂筛选

油茶炭疽病是我国油茶重要病害,为筛选出有效的防治药剂,本研究从我国油茶主产区采集具有典型症状的炭疽病病叶分离病原菌,结合病原菌形态特征和多基因系统发育分析对其进行了系统鉴定,并采用菌丝生长速率法测定病原菌对化学杀菌剂敏感性。结果表明,本研究分离出的17株油茶炭疽病菌均属于刺盘孢属胶孢复合群(Gloeosporioides complex)真菌,包括山茶刺盘孢Colletotrichum camelllae、果生刺盘孢Colletotrichum fructicola、暹罗刺盘孢Colletotrichum siamense、胶孢刺盘孢Colletotrichum gloeosporioides、卡瓦刺盘孢Colletotrichum kahawae、哈锐刺盘孢Colletotrichum horri等。测试的13种杀菌剂中,油茶炭疽病菌对咪鲜胺药剂最敏感,平均EC₅₀值为0.035 μg/mL;其次为氟啶胺、多菌灵、咯菌腈、吡唑醚菌酯、苯醚甲环唑、氟环唑、苯并烯氟菌唑和戊唑醇,平均EC₅₀依次为0.076、0.169、0.202、0.243、0.342、0.490、0.534和1.401 μg/mL;此外,测试的油茶炭疽病菌对嘧菌酯、啶酰菌胺、氟醚菌酰胺和氟吡菌酰胺四种药剂均不敏感,平均EC₅₀值大于100 μg/mL。     

咯菌腈与苯醚甲环唑等三种药剂复配对马铃薯早疫病菌（Alternaria solani）的联合毒力

采用菌丝生长速率法测定咯菌腈分别与丁香菌酯、吡唑醚菌酯或苯醚甲环唑3种药剂复配对马铃薯早疫病菌(Alternaria solani)的联合毒力,以Wadley公式评价咯菌腈与其他3种药剂复配对抑制早疫病菌菌丝生长是否有增效作用。通过田间试验验证咯菌腈与其他药剂有增效作用的桶混产品对马铃薯早疫病的防治效果。结果表明,咯菌腈与上述3种药剂按9种配比混合均无拮抗作用(增效系数均大于0.5),咯菌腈与苯醚甲环唑以5∶1复配有明显的增效作用(增效系数SR 2.02),与丁香菌酯或吡唑醚菌酯的9种配比混合物有加和作用(SR介于0.5与1.5之间)。在田间咯菌腈与苯醚甲环唑以5∶1桶混,并以105g/hm2的剂量施用,防效可达85%以上、增产率40%以上,显著高于同浓度单剂的防效和增产率。     

土传大豆、南瓜疫病化学防治

本文介绍了土传大豆和南瓜疫病的发病特点及化学防治现状，评述了两种疫病化学防治存在的问题，提出了未来化学防治发展途径。     

Plectosporium blight of pumpkin and ranunculus caused by Plectosporium tabacinum

Based on inoculation experiments and morphological studies on the pathogenic isolates of Plectosporium spp., Microdochium blight (Hakuhan-byo in Japanese) of pumpkin (Cucurbita maxima Duch.) occurring in Japan was reconfirmed to be caused by Plectosporium tabacinum, and seedling blight (Kabugare-byo in Japanese) of ranunculus (Ranunculus asiaticus L.) was demonstrated to be caused by P. tabacinum. Both diseases are renamed Plectosporium blight in this article. Some isolates of the fungus appeared to have host specificity, whereas the others had either weak or no pathogenicity to pumpkin and ranunculus.     

Effect of temperature and duration of wetness during initial infection periods on disease development, fungal biomass and mycotoxin concentrations on wheat inoculated with single, or combinations of, Fusarium species

Experiments were conducted under controlled environment conditions to study the relationship between environmental conditions, development of fusarium head blight (FHB) and mycotoxin production. A single isolate from each of four Fusarium species ( F. avenaceum , F. culmorum , F. graminearum and F. poae ) was used to inoculate wheat ears separately. Combinations of two or three isolates were also used to inoculate ears simultaneously. Inoculated ears were subjected to various combinations of duration of wetness (6–48 h) and temperature (10–30°C). For all inoculations, both incidence of spikelets with FHB symptoms and concentration of mycotoxins generally increased with increasing length of wetness period and temperature. There were significant positive correlations among disease incidence, fungal biomass (quantified as total amount of fungal DNA) and mycotoxins. Mycotoxin production was also greatly enhanced by high temperatures (≥ 20°C) during initial infection periods. In single-isolate inoculations, F. poae was the least aggressive. There was no evidence to support synergetic interactions between fungal isolates in causing visual symptoms; rather the results suggest, in most cases, the presence of competitive interactions. Furthermore, the competition led to large reductions in fungal biomass compared to single-isolate inoculations, often > 90% reduction for the weaker isolate(s). In contrast, mycotoxin productivity increased dramatically in the co-inoculations, by as much as 1000 times, suggesting that competition resulted in greater production of trichothecene mycotoxins. The F. graminearum isolate was most competitive and isolates of the other three species were similar in their competitiveness.     

Oospore formation by Phytophthora infestans in host tissue after inoculation with isolates of opposite mating type found in the Netherlands

Samenvatting Uit combinaties van A1- en A2-paringstypen vanPhytophthora infestans werden zowel bij tomaat als bij aardappel oösporen verkregen in de plant. Oösporen werden niet in de bladeren gevormd, maar werden veelvuldig aangetroffen in de epidermis van de stengels. De proeven werden uitgevoerd in de klimaatkamer; de veldsituatie moet nog onderzocht worden.     

Stability of partial resistance in potato cultivars exposed to aggressive strains of Phytophthora infestans

Potato cultivars were evaluated for their resistance responses to aggressive strains of Phytophthora infestans in field and laboratory experiments. Analysis of variance revealed differential cultivar-by-isolate interactions for both foliar and tuber blight resistance. Differential responses occur as revealed by specific susceptibilities of cultivars to certain pathogen genotypes and changing rank order. In general, severity of late blight epidemics as observed in the haulms did not correlate well with foliar blight resistance ratings as presented in the National List of Recommended Potato Varieties. No significant correlation was found between tuber blight incidence under field conditions and the tuber blight rating in the National List. Also, there was no relation between the field and laboratory tuber blight resistance assessments. A significant association was demonstrated between late blight infection in the foliage and tuber blight incidence under field conditions. The presence of differential interaction, independent of R-gene-based resistance, indicates some adaptation of P. infestans to partial resistance and consequently adverse effects on the stability and durability of partial resistance to potato late blight.     

水稻纹枯病的"后效应"观察

通过单独或混合施用不同浓度的两种药剂,造成水稻纹枯病不同发生程度,继而观察接茬小麦纹枯病病情,结果进一步证明,水稻纹枯病与接茬小麦纹枯病极显著正相关,其后效应明显。指出在实行水稻—小麦种植方式地区,要注意水稻与小麦纹枯病的交叉感染。     

Rapd Pcr-based differentiation of Xanthomonas campestris pv. phaseoli and Xanthomonas campestris pv. phaseoli var. fuscans

A RAPD PCR-based method was used to differentiate between isolates of Xanthomonas campestris pv. phaseoli and Xanthomonas campestris pv. phaseoli var. fuscans. Using random primer OP-G11, a single, high intensity band of 820 bp was amplified from DNAs of all X. c. pv. phaseoli var. fuscans isolates, while multiple amplification products of varying sizes were generated from X. c. pv. phaseoli DNAs. Whereas RAPD PCR differentiation gave an unambiguous result in under 4 h, standard differentiation by recording the production of a brown pigment by X. c. pv. phaseoli var. fuscans isolates took up to 7 days and showed variation both between isolates and between media. The unequivocal nature of the RAPD PCR method was demonstrated when isolate 408, originally classified as X. c. pv. phaseoli var. fuscans, failed to produce the 820 bp band typical of X. c. pv. phaseoli var. fuscans isolates, and after also failing to produce a brown pigment, was re-classified as X. c. pv. phaseoli.     

过表达嗜热毛壳菌Cu/Zn-SOD基因提高转基因水稻对3种病害的抗性

超氧化物歧化酶(Superoxide dismutase,SOD,EC1.15.1.1)是生物体中清除氧自由基、保护细胞免受氧化损害的关键保护酶之一,SOD活性的提高可以增加植物对各种不良环境的适应和耐受能力。本研究将一个源自嗜热毛壳菌(Chaetomium thermophilum,Ct)的Cu/Zn-SOD基因Ct SOD通过农杆菌介导的遗传转化方法转入水稻,转基因植株的SOD活性均得到显著提高。对转基因植株分别接种水稻白叶枯病、细菌性条斑病以及纹枯病的病原,发现过量表达Ct SOD能够显著提高转基因植株对3种病害的抗性。这种对多种病害具有抗性的单个基因在植物抗病育种中具有重要应用价值。     

Distribution of Mating Types and Diversity in Virulence of <Emphasis Type="Italic">Didymella rabiei</Emphasis> in Israel

The distribution of mating types and diversity in virulence of Didymella rabiei populations were studied in Israel from 1997 to 1999. Forty-one monoconidial D. rabiei isolates from 18 commercial fields distributed among all the chickpea production areas of the country were paired with MAT1-1 and MAT1-2 mating type tester isolates of D. rabiei. Both mating types were found in all chickpea production areas of the country. Of the 18 fields sampled, MAT1-1 was observed in 44%, and MAT1-2 in 88% of the sites. In some sites both mating types were present in close proximity, suggesting that sexual reproduction of the pathogen was feasible. The contribution of sexual reproduction of the fungus to virulence diversity was tested on detached leaves of six differential chickpea cultivars. Nine isolates were derived from different well separated foci (derived from ascospores as inoculum) and eight isolates were derived from a single, well defined infection focus (derived from sister conidia). In the analyses of variance the cultivar × isolate interaction showed no significant (P of F>0.09) effect on disease incidence; the chickpea cultivars differed significantly (P of F<0.0001) in their response to D. rabiei; and the isolate effect was highly significant (P of F = 0.0007) for the conidial population, but not significant (P of F>0.1) among isolates of the ascosporic population. Nevertheless, when comparing a cultivar at a time, the ascosporic and conidial populations did not differ significantly (P of F>0.1) in their virulence diversity. Virulence of 41 isolates collected from the different chickpea fields was tested on detached leaves of four Israeli cultivars that differ in their field response to D. rabiei. The cultivar × isolate interaction showed no significant effect (P of F = 0.95) on disease incidence. The main effects of cultivar and isolate on disease incidence were highly significant (P of F<0.0001). Accordingly, our data do not support the hypothesis that there is pathogenic specialization in the D. rabiei–C. arietinum pathosystem in Israel.     

Identification of Alternaria spp. on wheat by pathogenicity assays and sequencing

The pathogenicity of Alternaria spp. isolated from wheat leaves collected in regions where alternaria leaf blight has been reported was compared with that of IMI reference isolates of A. triticina and A. alternata using two durum and two bread wheat genotypes. To identify isolates putatively corresponding to A. triticina , morphological and DNA sequence analyses based on ribosomal DNA from the internal transcribed spacer (ITS) region (ITS1, 5·8S rRNA gene, ITS2) and toxicity bioassays of culture filtrate were combined. Glasshouse inoculations provided reliable information to assess the pathogenicity of A. triticina isolates on wheat. Alternaria leaf blight symptoms were produced by the A. triticina isolates only on durum wheat cv. Bansi, while A. alternata , A. tenuissima and A. arborescens isolates were found to be nonpathogenic on the wheat cultivars tested. Alternaria triticina isolates were distinguished from other Alternaria species by Simmons and Roberts' sporulation pattern 6 and two to three conidia per sporulation unit associated with primary conidia bearing long (> 7  µ m) apical secondary conidiophores. Phylogenetic analysis also proved effective at discriminating wheat-pathogenic A. triticina from other nonpathogenic Alternaria species. Alternaria triticina isolates yielded longer ITS sequences than A. alternata , A. tenuissima and A. arborescens isolates, leading to clear-cut differences as visualized with agarose gel electrophoresis. Additionally, only culture filtrates of A. triticina isolates caused nonspecific necrotic lesions on leaves of 3-week-old wheat plants.