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1.
20%唑菌酯悬浮剂对黄瓜霜霉病的作用方式 总被引：2，自引：0，他引：2
采用盆栽植株喷雾-叶碟法、叶碟喷雾法分别测定20%唑菌酯悬浮剂对黄瓜霜霉病的保护、治疗作用,采用离体叶片法、叶碟法测定其对黄瓜霜霉病的铲除作用。结果表明:在200 μg/mL浓度下,20%唑菌酯悬浮剂对黄瓜霜霉病的保护、治疗效果分别为77.99%、70.08%;20%唑菌酯悬浮剂对黄瓜霜霉病菌病斑扩展、产孢及再侵染的抑制率分别为74.37%、84.56%和72.22%,与黄瓜霜霉病菌孢子囊悬浮液混合接种能显著降低孢子囊的致病性。室内试验结果表明,20%唑菌酯悬浮剂对黄瓜霜霉病具有良好的保护、治疗作用,且效果均优于对照药剂25%嘧菌酯悬浮剂,20%唑菌酯悬浮剂对黄瓜霜霉病的铲除作用与25%嘧菌酯悬浮剂效果相当。 相似文献
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Occurrence and molecular characterization of strobilurin resistance in cucumber powdery mildew and downy mildew 总被引：1，自引：0，他引：1
Ishii H Fraaije BA Sugiyama T Noguchi K Nishimura K Takeda T Amano T Hollomon DW 《Phytopathology》2001,91(12):1166-1171
ABSTRACT Between 1998 and 1999, control failure of powdery mildew (Podosphaera fusca) and downy mildew (Pseudoperonospora cubensis) by the strobilurin fungicides azoxystrobin and kresoxim-methyl was observed in cucumber-growing areas of Japan. Results from inoculation tests carried out on intact cucumber plants and leaf disks clearly showed the distribution of pathogen isolates highly resistant to azoxystrobin and kresoximmethyl. Fragments of the fungicide-targeted mitochondrial cytochrome b gene were polymerase chain reaction amplified from total pathogen DNA and their sequences analyzed to elucidate the molecular mechanism of resistance. A single point mutation (GGT to GCT) in the cytochrome b gene, resulting in substitution of glycine by alanine at position 143, was found in resistant isolates of downy mildew. This substitution in cytochrome b seemed to result in high resistance to strobilurins in this pathogen. The same mutation was found in some but not all resistant isolates of powdery mildew. This study suggests that a mutation at position 143 in the target-encoding gene, resulting in an amino acid substitution, was probably a major cause of the rapid development of high strobilurin resistance in these two pathogens. 相似文献
4.
Relationship between Loci conferring downy mildew and powdery mildew resistance in melon assessed by quantitative trait Loci mapping 总被引：2，自引：0，他引：2
ABSTRACT Partial resistance to downy mildew (Pseudoperonospora cubensis) and complete resistance to powdery mildew (Podosphaera xanthii races 1, 2, 3, and 5 and Golovinomyces cichoracearum race 1) were studied using a recombinant inbred line population between 'PI 124112' (resistant to both diseases) and 'Védrantais' (susceptible line). A genetic map of melon was constructed to tag these resistances with DNA markers. Natural and artificial inoculations of Pseudoperonospora cubensis were performed and replicated in several locations. One major quantitative trait loci (QTL), pcXII.1, was consistently detected among the locations and explained between 12 to 38% of the phenotypic variation for Pseudoperonospora cubensis resistance. Eight other Pseudoperonospora cubensis resistance QTL were identified. Artificial inoculations were performed with several strains of four races of Podosphaera xanthii and one race of G. cichoracearum. Two independent major genes, PmV.1 and PmXII.1, were identified and shown to be involved in the simple resistance to powdery mildew. Three digenic epistatic interactions involving four loci were detected for two races of Podosphaera xanthii and one race of G. cichoracearum. Co-localization between PmV.1, resistance genes, and resistance genes homologues was observed. Linkage between the major resistance QTL to Pseudoperonospora cubensis, pcXII.1, and one of the two resistance genes to powdery mildew, PmXII.1, was demonstrated. 相似文献
5.
A. C. PAPPAS 《EPPO Bulletin》1985,15(4):411-418
Resistance to acylalanine fungicides in Pseudoperonospora cubensis, the downy mildew of cucurbits, is reviewed. Insensitive strains of the fungus predominated during the second year of metalaxyl application in cucumber glasshouses in Greece and Israel. Resistance was detected either on detached cucumber leaves floated on metalaxyl solutions or on potted plants treated (sprayed or drenched) with this fungicide. Metalaxyl-resistant strains of P. cubensis showed good pathogenicity and fitness, and competed favorably with the sensitive strains in the absence of the fungicide. A synergism between these two biotypes resulted in an increased virulence of the resistant forms on metalaxyl-treated plants. Metalaxyl-resistant strains of the pathogen exhibited cross resistance to other acylalanine fungicides. Strains resistant to acylalanines and to the chemically unrelated oomycete-fungicides fosetyl-Al and propamocarb were isolated in Israel, as well. In Greece, however, protective sprays with fosetyl-Al, cymoxanil and mancozeb gave good control of cucumber downy mildew when the pathogen was resistant to metalaxyl. P. cubensis is the first case of fungus which developed resistance to acylalanines in the field. 相似文献
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The downy mildew pathogen, Pseudoperonospora humuli, forms oospores abundantly in diseased hop tissue. Diverse monosporangial isolates of P. humuli derived from samples collected in Japan, Germany and the USA readily formed oospores within hop leaves when inoculated singly, suggesting homothallism. Single zoospore isolates also readily formed oospores within hop leaves, further supporting the homothallic nature of this oomycete. The majority of oospores were deemed viable based on cytoplasm characteristics and plasmolysis assays. However, disease symptoms failed to develop when hop leaves were inoculated with newly formed oospores, even when oospore conditioning was attempted with treatment with potassium permanganate or β‐glucuronidase/arylsulphatase, brief exposure to freezing temperature, or passage through an earthworm. Oospores derived from a monosporangial isolate of P. humuli that overwintered outdoors in infested leaves buried in soil also failed to cause downy mildew. Pseudoperonospora humuli is homothallic and oospores of the organism appear to require as yet unknown conditions to stimulate their germination and/or infection. 相似文献
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P. Sarris M. Abdelhalim M. Kitner N. Skandalis N. Panopoulos A. Doulis A. Lebeda 《Plant pathology》2009,58(5):933-943
Molecular genetic polymorphisms within Pseudoperonospora cubensis isolates of different geographic origins were investigated to establish their phylogenetic relationships and to assess genetic variability between two distant pathogen populations. Thirty isolates originating from Greece (Crete; 15), the Czech Republic (13), the Netherlands (one) and France (one) were analysed by AFLP fingerprinting and ITS 5·8S rDNA sequence analysis. All isolates were obtained from cucumber ( Cucumis sativus ) plants showing typical downy mildew symptoms. Four AFLP primer combinations produced a total of 288 high-quality bands of which 45% were polymorphic, allowing isolates to be grouped into two separate clusters: one including the Central European (Czech Republic) and Western European (the Netherlands and France) and the other the Cretan isolates. Within each AFLP cluster there was some variation, which could be accounted for by geographic origin or pathogenicity. The two populations (Cretan vs. Central and Western European) exhibited a high degree of genetic isolation. There was no clear AFLP grouping of isolates on the basis of pathotypes. No variability was detected in the ITS1 region; however, ITS2 sequences grouped P. cubensis isolates in two subclusters: one with all investigated European and the other with Asian isolates. The two subclusters formed a larger P. cubensis cluster which was differentiated from the cluster of the neighbouring species Pseudoperonospora humuli . Within P. cubensis , AFLP fingerprints could resolve genetically isolated populations, even on small or medium geographic scales, while ITS2 sequence showed differences on a global scale, being only suitable for phylogenetic analyses. 相似文献
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The most economically important plant pathogens in the genus Pseudoperonospora (family Peronosporaceae) are Pseudoperonospora cubensis and P. humuli, causal agents of downy mildew on cucurbits and hop, respectively. Recently, P. humuli was reduced to a taxonomic synonym of P. cubensis based on internal transcribed spacer (ITS) sequence data and morphological characteristics. Nomenclature has many practical implications for pathogen identification and regulatory considerations; therefore, further clarification of the genetic and pathogenic relatedness of these organisms is needed. Phylogenetic analyses were conducted considering two nuclear and three mitochondrial loci for 21 isolates of P. cubensis and 14 isolates of P. humuli, and all published ITS sequences of the pathogens in GenBank. There was a consistent separation of the majority of the P. humuli isolates and the P. cubensis isolates in nuclear, mitochondrial, and ITS phylogenetic analyses, with the exception of isolates of P. humuli from Humulus japonicus from Korea. The P. cubensis isolates appeared to contain the P. humuli cluster, which may indicate that P. humuli descended from P. cubensis. Host-specificity experiments were conducted with two reportedly universally susceptible hosts of P. cubensis and two hop cultivars highly susceptible to P. humuli. P. cubensis consistently infected the hop cultivars at very low rates, and sporangiophores invariably emerged from necrotic or chlorotic hypersensitive-like lesions. Only a single sporangiophore of P. humuli was observed on a cucurbit plant during the course of the studies. Together, molecular data and host specificity indicate that there are biologically relevant characteristics that differentiate P. cubensis and P. humuli that may be obfuscated if P. humuli were reduced to a taxonomic synonym of P. cubensis. Thus, we recommend retaining the two species names P. cubensis and P. humuli until the species boundaries can be resolved unambiguously. 相似文献
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Zhan-Bin Sun Xing-Fang Yuan Hui Zhang Lei-Fei Wu Chen Liang Yong-Jun Feng 《European journal of plant pathology / European Foundation for Plant Pathology》2013,137(4):847-857
Cucumber is a common vegetable all over the world; however, its production is seriously affected by cucumber downy mildew caused by Pseudoperonospora cubensis. Endophytes have great potential to control such fungal diseases. The aim of the study was to isolate, screen and identify endophytic bacteria, which show antagonistic activity to downy mildew, in cucumbers. Here, surface sterilized leaves were used for endophytic bacteria isolation. All the isolates were further screened for the antagonistic activities against P. cubensis by leaf discs assay, separate leaves assay and sporangia releasing inhibition assay. The control efficacies of the endophytic bacteria (screened above) were finally evaluated through field tests. In this study, a total of 81 endophytic bacteria were isolated from cucumber leaves sampled at blossoming and fruiting stages, respectively, among which, six (strains CE1, CE8, CE9, Y1, Y2 and Y22) were tested for their strong antagonistic activity in vitro. In the field test, strain CE8, identified as belonging to Bacillus sp. based on 16S rDNA phylogenetic analysis, showed a strong control efficacy of 42.1 %, a value almost two times as high as that using 69 % metalaxyl-mancozeb WG, a widely used antifungal chemical in China. Based on the results above, CE8 was finally screened out for its great potential in cucumber downy mildew control, implicating a powerful value of the strain in the production practice. 相似文献
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PopW蛋白对黄瓜霜霉病的防病促生作用 总被引：2，自引：0，他引：2
前期研究发现来源于青枯菌（Ralstonia solanacearum, ZJ3721）的Harpin蛋白PopW对多种作物有较好的诱导抗病作用。本文研究PopW蛋白在温室和田间条件下对黄瓜霜霉病的生防和促生效果。温室试验结果表明：人工接种霜霉病病原菌后15 d, 250 mg/L PopW蛋白水溶液对黄瓜霜霉病的防效最好（42.85%）,PopW蛋白（250 mg/L）处理的黄瓜苗与对照相比生物量增加26.92%,叶绿素含量显著提高。2010年,PopW蛋白（250 mg/L）间隔15 d喷雾1次,共使用3次。初次喷雾后8、25、35和48 d,对黄瓜霜霉病的生防效果分别为41.87%、48.36%、53.21%和50.85%; 2011年,等量的PopW蛋白间隔10 d使用1次,共使用3次。初次喷雾后的第8、15、22和27 d,生防效果分别为47.07%、48.17%、50.59%和54.48%。试验结果表明,250 mg/L PopW蛋白水溶液可作为黄瓜霜霉病的潜在生防因子,且其抗病作用有一定的持效期,可保持10~15 d,甚至更长时间。分析PopW蛋白处理对黄瓜的促生作用及其对黄瓜品质的影响,结果显示：PopW蛋白处理组黄瓜单株增产达33.01%。PopW蛋白处理的黄瓜果实可溶性蛋白、可溶性糖、游离氨基酸和维生素C含量分别为18.07 mg/g、6.80 mg/g、60.20 mg/100 g、68.27 μg/g,均显著高于对照（10.21 mg/g、5.30 mg/g、59.06 mg/100 g、49.55 μg/g）,结果表明PopW蛋白处理可显著提高黄瓜产量、改善黄瓜品质。 相似文献
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为明确黄瓜霜霉病菌对烯酰吗啉及双炔酰菌胺的抗性时空动态及这两种药剂对黄瓜霜霉病的田间防效,采用叶盘漂浮法检测了2011~2016年采自河北省和山东省黄瓜主产区的霜霉病菌1 821个菌株对烯酰吗啉及双炔酰菌胺的敏感性,并采用茎叶喷雾法对这两种药剂的田间防效进行评估。结果表明:黄瓜霜霉病菌1 821个菌株对烯酰吗啉和双炔酰菌胺抗性频率分别为88.5%和34.3%,供试菌株中对烯酰吗啉的低抗菌株及对双炔酰菌胺的敏感菌株占优势,平均抗性倍数分别为8.92和2.44,抗性指数分别为0.42和0.27。黄瓜霜霉病菌对这两种药剂的抗性频率、抗性倍数及抗性指数随着监测年限及地域的不同而波动。在河北定兴和山东寿光日光温室进行的田间药效试验中,按照药剂田间推荐剂量喷施4次,50%烯酰吗啉可湿性粉剂和250 g·L-1双炔酰菌胺悬浮剂对黄瓜霜霉病表现出良好的防效(85%以上),与两地黄瓜霜霉病菌对烯酰吗啉产生低抗、对双炔酰菌胺敏感的监测结果一致。由此推断,50%烯酰吗啉可湿性粉剂和250 g·L-1双炔酰菌胺悬浮剂可在对甲霜灵(或精甲霜灵)、噁霜灵及嘧菌酯普遍产生抗性的地区,作为58%甲霜灵·代森锰锌WP、68%精甲霜灵·代森锰锌WG、64%噁霜灵·代森锰锌WP 和250 g·L-1嘧菌酯SC的替代药剂单独使用或与不同作用机理的杀菌剂混用,防治黄瓜霜霉病。 相似文献
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S. S. Zhu X. L. Liu Y. Wang † X. H. Wu P. F. Liu J. Q. Li S. K. Yuan N. G. Si 《Plant pathology》2007,56(6):967-975
Plastic-house experiments were conducted over a 2-year period (2004–05) to estimate the effects of successive applications of flumorph or a mixture of flumorph with mancozeb to cucumber plants on selection for flumorph resistance in the downy mildew oomycete, Pseudoperonospora cubensis . Application of flumorph alone favoured the selection of resistant isolates of Ps. cubensis . Resistant populations were detected at a frequency of 2·5% after six successive applications of flumorph alone in a plastic house in 2004. Resistant isolates were also detected (4·8%) after eight successive applications of the mixture of flumorph and mancozeb in 2004, although the mixture gave significantly better disease control than flumorph alone and produced a slight delay in the development of resistance. In a second cucumber crop in the same plastic houses in 2004, the frequency of resistant isolates increased to 100% after three successive applications of flumorph or four of flumorph + mancozeb. Under laboratory conditions, most flumorph-resistant isolates showed high levels of resistance and their levels of pathogenicity and sporulation were as high as that of wild-type isolates. Flumorph showed cross-resistance with dimethomorph and iprovalicarb, but not with azoxystrobin, cyazofamid, cymoxanil or metalaxyl. These studies suggest a high risk for the occurrence of resistance to flumorph in Ps. cubensis in cucumber crops under plastic-house conditions. 相似文献
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不同湿润持续时间及叶片温度对温室黄瓜霜霉病发生的影响 总被引：1，自引：1，他引：0
为探明不同湿润持续时间及叶片温度与黄瓜霜霉病发生的关系,通过观察不同湿润条件下黄瓜霜霉病的初显症时间,计算逐日显症率及累积显症率,并利用热红外成像仪对显症后叶片温度进行连续监测。结果显示,不同湿润持续时间对黄瓜霜霉病的初显症时间、逐日显症率产生影响。叶片湿润持续4 h,黄瓜霜霉病在接种后7.00 d显症;叶片湿润持续12 h,黄瓜霜霉病初显症时间最早,仅为3.25 d。叶片湿润持续时间不同,黄瓜霜霉病初显症时的叶片温度存在显著差异。回归分析表明,初显症时间与最大温差呈显著正相关,与平均温度呈显著负相关。叶片湿润持续4、6 h的病斑出现高峰在显症后第2、3天,逐日显症率分别是37.50%和41.18%,比叶片湿润持续10、12 h的早。显症后期,湿润持续时间4、6、8、10、12 h的病斑累积显症率分别是87.94%、93.71%、90.25%、84.24%和88.36%,差异不显著。表明接种黄瓜霜霉菌Pseudoperonospora cubensis后叶片湿润持续时间越长,潜育期越短,叶片最大温差越小,叶片平均温度越大。 相似文献
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Downy mildew ( Pseudoperonospora cubensis ) is one of the most harmful diseases of cucumber in Ukraine. At high disease severity, the growing season is considerably shortened and yield is reduced. The most effective method of control is the development of resistant cultivars but, in the absence of absolutely resistant forms, control with fungicides remains very important. The effectiveness of such treatment depends on the dates of application, the number of sprays and the efficacy of the fungicides used. An improved scheme is presented, based on three components: use of cultivars with increased resistance; application of highly effective systemic + contact fungicides; and reliable short-term forecasting of disease appearance. The predictors for downy mildew forecasting are: sum of effective temperatures, weather index, duration of leaf wetness, concentration of sporangia in air and latent period of disease development. These conditions determine'critical days'for disease development. The first fungicide spray on less susceptible cultivars is recommended on the first critical day, and the next on the day of appearance of first disease symptoms. This scheme allows the fungicide load to be approximately halved, while ensuring higher yield. 相似文献
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A. Lebeda 《Phytoparasitica》1992,20(3):203-210
Under controlled inoculation, a set of 56 accessions belonging to 19 wild species of the genusCucumis was studied for resistance to seven isolates of cucurbit downy mildew (Pseudoperonospora cubensis (Berk. et Curt.) Rostow.) from cucumber. No resistance toP. cubensis was detected in theseCucumis accessions. In three host accession/pathogen isolate combinations, limited sporulation was observed. Nine newCucumis species are described as hosts forP. cubensis: C. africanus, C. ficifolius, C. figarei, C. meeusii, C. metuliferus, C. myriocarpus, C. leptodermis, C. sagittatus andC. zeyheri. Results are discussed in relation to the origin and evolution ofCucumis species. 相似文献
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Mostafa Hajji Erwin Dreyer Benoit Marçais 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(1):63-72
Oak powdery mildew, (Erysiphe alphitoides) causes one of the most common diseases of oaks. We assessed the impact of this pathogen on photosynthesis and water relations
of infected leaves using greenhouse-grown oak seedlings. Transpiration of seedlings infected by oak powdery mildew was also
investigated. Altogether, E. alphitoides had a low impact on host gas exchange whether at the leaf or whole plant scale. Maximal stomatal conductance of infected
leaves was reduced by 20–30% compared to healthy controls. Severely infected seedlings did not experience any detectable change
of whole plant transpiration. The reduction in net CO2 assimilation, An, was less than proportional to the fraction of leaf area infected. Powdery mildew reduced both the maximal light-driven electron
flux (Jmax) and the apparent maximal carboxylation velocity (Vcmax) although Vcmax was slightly more impacted than Jmax. No compensation for the infection occurred in healthy leaves of partly infected seedlings as the reduced photosynthesis
in the infected leaves was not paralleled by increased An levels in the healthy leaves of the seedlings. However, E. alphitoides had a strong impact on the leaf life-span of infected leaves. It is concluded that the moderate effect of E. alphitoides on oak might be related to the small impact on net CO2 assimilation rates and on tree transpiration; nevertheless, the severe reduction in leaf life-span of heavily infected leaves
may lead to decreased carbon uptake over the growth season. 相似文献
19.
两种候选甲氧基丙烯酸酯类杀菌剂对黄瓜霜霉病的作用方式 总被引：2，自引：0，他引：2
20%唑胺菌酯EC、20%SYP-3998 SC是甲氧基丙烯酸酯类候选杀菌剂,为探索两药剂对黄瓜霜霉病的作用方式,采用盆栽植株喷雾-叶碟法、叶碟喷雾法、盆栽植株喷雾-叶碟法分别测定两药剂对黄瓜霜霉病的保护、治疗及持效期,并采用离体叶片法、叶碟法测定二者对黄瓜霜霉病的铲除作用.结果表明:20%唑胺菌酯EC和20%SYP-3998 SC具有良好的保护、治疗及铲除作用.两药剂的铲除作用表现在能抑制黄瓜霜霉病菌病斑扩展、孢子囊产生及孢子囊再侵染,与孢子囊混合接种能显著降低孢子囊的致病性.此外,20%唑胺茵酯EC和20%SYP-3998 SC具有7～10天的持效期;20%唑胺茵酯EC预防、治疗、铲除效果及持效性均优于20%SYP-3998 SC及对照药剂25%嘧菌酯SC. 相似文献
20.
The development of plant diseases is associated with biophysical and biochemical changes in host plants. Various sensor methods have been used and assessed as alternative diagnostic tools under greenhouse conditions. Changes in photosynthetic activity, spectral reflectance and transpiration rate of diseased leaves, inoculated with Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV), and the powdery mildew fungus Sphaerotheca fuliginea were assessed by the use of non‐invasive sensors during disease development. Spatiotemporal changes in leaf temperature related to transpiration were visualized by digital infrared thermography. The maximum temperature difference within a leaf was an appropriate parameter to differentiate between healthy and diseased plants. The photosynthetic activity of healthy and diseased cucumber plants varied as measured by chlorophyll fluorescence and compared to the actual chlorophyll content. Hyperspectral imaging data were analysed using spectral vegetation indices. The results from this study confirm that each pathogen has a characteristic influence on the physiology and vitality of cucumber plants, which can be measured by a combination of non‐invasive sensors. Whereas thermography and chlorophyll fluorescence are unspecific indicators for plant diseases, hyperspectral imaging offers the potential for an identification of plant diseases. In a sensor data fusion approach, an early detection of each pathogen was possible by discriminant analysis. Although it still needs to be validated under real conditions, the combination of information from different sensors seems to be a promising tool. 相似文献