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1.
ABSTRACT Rhizoctonia solani, the rice sheath blight pathogen, produces a toxin that reproduces all symptoms of the disease. The toxin has been partially purified and it was found to be a carbohydrate containing glucose, mannose, N-acetylgalactosamine, and N-acetylglucosamine. The toxin was also detected in infected leaves. Highly virulent isolates produced more toxin than less virulent isolates. Several R. solani isolates from rice and one each from cotton and tomato produced a similar toxin. All rice cultivars tested were susceptible to the pathogen and sensitive to the toxin. Host specificity of the toxin has been demonstrated using hosts and nonhosts of the pathogen.  相似文献   

2.
利用拮抗菌铜绿假单胞菌ZJ1999产生的粗提液进行防治水稻纹枯病研究的结果表明,抑制病菌侵染的活力随着粗提液浓度提高和处理时间的延长而增强。该菌株的定殖时间与最初引进时的浓度密切相关,其最低应用浓度为10^8cfu/ml,在接种纹枯病病菌后第一天的喷施防效最佳。拮抗菌ZJ1999在发病的秧苗、成株期植株茎杆和叶片上,14d后的菌量分别维持在10^2-10^3和10^3~10^4cfu/g。  相似文献   

3.
微生物杀菌剂及其混配剂防治水稻纹枯病的田间药效试验   总被引:4,自引:0,他引:4  
对微生物杀菌剂及其混配剂对水稻纹枯病进行田间防治试验,结果表明枯草芽孢杆菌10亿/g可湿性粉剂、井冈霉素·蜡质芽孢杆菌12.5%可湿性粉剂对水稻纹枯病有较好的防治效果。在发病初期施药,枯草芽孢杆菌10亿/g可湿性粉剂1500g/hm2防效为75.4%,产量增幅21.5%;井冈霉素·蜡质芽孢杆菌12.5%可湿性粉剂2880g/hm2防效为83.89%。可以作为井冈霉素的替代产品,进行推广应用。  相似文献   

4.
Fluxapyroxad,3-(difluoromethyl)-1-methyl-N-(3’,4’,5’-trifluorobiphenyl-2-yl) pyrazole-4-carboxamide (C18H12F5N3O, Fig. 1), is a SDHI fungicide, which is a new active ingredient that interferes with succinate ubiquinone reductase in the electron transport chain of fungi. Between 2008 and 2010, a total of 128 isolates of Rhizoctonia solani from Anhui Province of China were characterized for the baseline sensitivity to fluxapyroxad. The isolates collected between 2008 and 2010 all showed similar sensitivity to fluxapyroxad. Baseline sensitivity was distributed as unimodal curves with an average EC50 value of 0.054?±?0.014 μg ml?1. However, EC50 values of boscalid for inhibition of mycelial growth of R. solani isolates ranged from 1.89 to 2.68 μg/ml and the average (±SE) EC50 value was 2.212?±?0.228 μg/ml, indicating that the R. solani isolates were less sensitive to boscalid than that of fluxapyroxad. Fluxapyroxad exhibited excellent protective and curative activity against rice sheath blight and provided 82.6–94.2 % protective or curative control efficacy. In field trials, control efficacy of fluxapyroxad at 100 g a.i/ha 15 days and 30 day after second application was 83.4–88.0 %, suggesting excellent activity against sheath blight. Control efficacy of boscalid at a dosage of 600 g a.i/ha 15 days and 30 day after second application was about 51.7–57.0 %. There was a significant difference in the efficacy between fluxapyroxad and boscalid or jinggangmycin. These results suggested that fluxapyroxad is a good alternative fungicide to jinggangmycin for the control of rice sheath blight.  相似文献   

5.
采用先封泥于水稻基部叶鞘再人工接种水稻纹枯病菌,调查水稻纹枯病发生情况,同时测定水稻叶鞘过氧化物酶活性和可溶性糖含量变化。连续3年试验的调查结果表明:先封泥于水稻基部叶鞘再人工接种水稻纹枯病菌的发病率、病情指数明显低于井冈霉素处理和对照,其控病效果为72.80%~81.21%。先封泥再接病菌处理的过氧化物酶活性比对照高,但低于井冈霉素处理;先封泥再接病菌使可溶性糖含量降低,但不同处理之间差异不显著。  相似文献   

6.
我国水稻纹枯病拮抗细菌种类研究   总被引:13,自引:1,他引:13  
1996~2002年间从浙江、江苏、福建和云南等稻区采集稻种和稻株样本921份,从中分离出11635个细菌菌株,用平板对峙培养法进行了对水稻纹枯病菌的拮抗测试。经致病性测定、菌落形态及部分细菌学特征测定后,选出代表菌株631个连同26个对照菌株用Biolog及脂肪酸分析法进行测试。鉴定出假单胞菌属11个种或型,其中8个种内测到拮抗菌株,平均抑菌率为24.3%;其他非致病细菌14属的25种中13个种内存在拮抗菌,平均抑菌率为14.3%,明显低于假单胞菌属。  相似文献   

7.
Isolates ofRhizoctonia solani were adapted in vitro to grow on a medium amended with tolclofos-methyl at a concentration 500 times that which initially almost completely inhibited growth.Acquired resistance was retained after five transfers on a fungicide-free medium. Pathogenicity of resistant isolates was not reduced, but their growth rates on PDA were significantly lower than those of the original isolates. Recovery of the resistant isolates was not improved on a selective medium amended with tolclofos-methyl.Samenvatting Na overenting op een medium dat tolchlofos-methyl bevatte, raakten enkele isolaten vanRhizoctonia solani gewend aan 500 maal de dosis die oorspronkelijk bijna alle groei verhinderde.Resistente isolaten vanR. solani bleven minder gevoelig voor tolchlofos-methyl na vijf overentingen op een medium zonder het fungicide. De pathogeniteit van resistente isolaten was niet verminderd, maar hun groeisnelheid op PDA was significant vertraagd vergeleken bij die van de oorspronkelijke isolaten. Isolatie van de resistente stammen werd niet verbeterd op een selectief medium waaraan tolchlofos-methyl was toegevoegd.  相似文献   

8.
Water agar, artificially infested soil and leaf sheath inoculation methods were used to assess the suitable time of application, varietal host response and persistence of Rhv7, a hypovirulent, binucleate Rhizoctonia collected from soil in the Philippines, to effectively control virulent Rhizoctonia solani AG1-IA isolate RS35 on corn. With the water agar method, prior inoculation (2 to 3 days) with the biocontrol agent is essential to achieve maximum control of the pathogen. Disease protection was increased from 23 to 70% as the pre-incubation time of Rhv7 prior to the challenge inoculation with virulent isolate was lengthened from 0 to 3 days. Disease severity and incidence of banded leaf and sheath blight (BLSB) on the three corn hybrids were also suppressed in artificially infested soil. In leaf sheath inoculation, the suppressive ability of Rhv7 against BLSB on corn persisted during lesion expansion. This suppression was expressed as slower disease progress in plants with Rhv7 than in plants without Rhv7. Early and timely brace root formation that detached infected sheaths, also aided in reducing the number of diseased plants in Rhv7-treated plots at the final observation. Mycelial growth activity of RS35 was reduced when corn plants were pre-inoculated with Rhv7 before challenge even if there was no contact detected between Rhv7 and RS35, which suggests that Rhv7 protects corn against BLSB by induced resistance. The hypovirulent, binucleate Rhizoctonia Rhv7 strain effectively controlled R. solani AG1-IA isolate RS-35 in corn. Received 30 August 1990/ Accepted in revised form 25 October 1999  相似文献   

9.
从广西稻区74种水稻品种中采集了222个水稻标样,分离出1903株内生细菌。经形态和生理生化测定,确定这些菌株分属于芽孢杆菌属Bacillus、鞘胺醇单孢菌属Sphingomonas、土壤杆菌属Agrobacterium、伯克霍尔德氏菌属Burkholderia、肠杆菌属Enterobacter和成团泛菌属Pantoea。其中,Bacillus和Enterobacter为主要类群,Bacillus为优势类群。水稻内生细菌的类群随不同的水稻品种和栽培地区而变化。水稻内生细菌在植株器官中的分布以根部数量最多,其次是叶鞘和叶。内生细菌的总量在水稻生育期的变化趋势是从苗期到孕穗期上升,从灌浆期到乳熟期下降。分离到的1903株内生细菌中,有412个菌株对水稻纹枯病菌Rhizoctoniasolani有拮抗作用。  相似文献   

10.
枯草芽孢杆菌与井冈霉素混用防治稻曲病和纹枯病试验   总被引:1,自引:0,他引:1  
为了探讨枯草芽苞杆菌与井冈霉素混用对稻曲病和纹枯病的田间防治效果和应用技术,为今后大面积推广应用提供科学依据,现将试验结果总结如下:  相似文献   

11.
A new disease of Cymbopogon winterianus , characterized by symptoms of sheath rot and leaf blight, has been observed in the Tarai region of Uttar Pradesh (IN). The pathogen has been isolated and identified as Rhizoctonia solani.  相似文献   

12.
13.
Characterization of Rhizoctonia solani from potato in Great Britain   总被引:1,自引:1,他引:1  
One hundred and thirty five isolates of Rhizoctonia solani were obtained from British potato crops between 2001 and 2003. Isolates were assigned to anastomosis group (AG) using conventional PCR assays for AG2-1 or AG3 or through the observation of hyphal interactions, where appropriate. A previously published primer set was modified in this study to enhance specificity for AG3PT. Most of the isolates (92·6%) belonged to AG3PT whilst some (6·7%) belonged to AG2-1. Only one isolate recovered (0·7%) belonged to AG5. Isolates of AG2-1 were diverse, with variation in both the length of the rDNA intergenic spacer 1 (IGS1) region and the categories of hyphal interaction observed between pairings of AG2-1 isolates. No variation in the length of the rDNA IGS1 region was observed amongst the AG3 isolates collected. Tests carried out on potato stems with a sub-set of the isolates revealed a wide range of aggressiveness amongst AG2-1 isolates. Sequencing of the rDNA internal transcribed spacer (ITS) region of the AG2-1 isolates and construction of a neighbour joining tree with other AG2-1 sequences available indicated that AG2-1 isolates with the short IGS1 region were closely related. This is the first investigation which provides evidence of the relative AG composition of R. solani populations causing disease in potato crops in Great Britain.  相似文献   

14.
蜡质芽孢杆菌AR156防治水稻纹枯病机理初探   总被引:3,自引:0,他引:3  
蜡质芽孢杆菌AR156是一种防治多种土传病害的生物制剂,对水稻纹枯病具有较好的防治效果。本研究通过温室试验方面验证菌株 AR156的防病效果和促生作用,从细胞水平和基因水平初步揭示了菌株AR156防治水稻纹枯病的机理。结果表明,菌株AR156对水稻纹枯病的温室防效达73.06%,同时促进水稻生物量增加14.45%。菌株AR156处理提高了水稻植株SOD、PAL、POD和CAT等防御酶活性,增强了OsPR1b、OsPR10、OsNPR1和ZB8等防卫相关基因的表达。接种立枯丝核菌Rhizoctonia solani HNW-21之前用菌株AR156预处理的水稻植株,SOD和PAL分别提前4、2 d出现活性峰;防卫相关基因均提前表达,且表达时间延长,从而提高水稻对纹枯病的抗性。  相似文献   

15.
井岗霉素控制稻纹枯病效果的定量研究   总被引:2,自引:0,他引:2  
井岗霉素防治早稻纹枯病,其控病效果与施药时病情基数和控病时间有关,早稻纹枯病的防治以施药1~2次为宜,一次施药适期为孕穗至抽穗期,其控病效果为63%~74%,两次施药适期为孕穗至灌浆期,控病效果为86%~93%,不同施药措施对纹枯病控制效果与经济效益都有显著影响,用药次数一般不必超过两次。  相似文献   

16.
Real-time PCR protocols were developed to detect and discriminate 11 anastomosis groups (AGs) of Rhizoctonia solani using ribosomal internal transcribed spacer (ITS) regions (AG-1-IA, AG-1-IC, AG-2-1, AG-2-2, AG-4HGI+II, AG-4HGIII, AG-8) or β-tubulin (AG-3, AG-4HGII, AG-5 and AG-9) sequences. All real-time assays were target group specific, except AG-2-2, which showed a weak cross-reaction with AG-2tabac. In addition, methods were developed for the high throughput extraction of DNA from soil and compost samples. The DNA extraction method was used with the AG-2-1 assay and shown to be quantitative with a detection threshold of 10−7 g of R. solani per g of soil. A similar DNA extraction efficiency was observed for samples from three contrasting soil types. The developed methods were then used to investigate the spatial distribution of R. solani AG-2-1 in field soils. Soil from shallow depths of a field planted with Brassica oleracea tested positive for R. solani AG-2-1 more frequently than soil collected from greater depths. Quantification of R. solani inoculum in field samples proved challenging due to low levels of inoculum in naturally occurring soils. The potential uses of real-time PCR and DNA extraction protocols to investigate the epidemiology of R. solani are discussed.  相似文献   

17.
Rhizoctonia solani causes pre- and post-emergence damping-off, root and hypocotyl rot and foliar blight in soybean. Foliar blight has resulted in yield losses of 31–60% in north and northeast Brazil. The aim of this study was to characterize isolates of R. solani associated with soybean in Brazil. Among 73 Rhizoctonia isolates examined, six were binucleate and 67 were multinucleate. The multinucleate iso1ates were characterized according to hyphal anastomosis reaction, mycelial growth rate, thiamine requirement, sclerotia production, and RAPD molecular markers. Four isolates that caused hypocotyl rot belonged to AG-4 and using RAPD analysis they grouped together with the HGI subgroup. Another isolate that caused root and hypocotyl rots was thiamine auxotrophic, grew at 35°C, and belonged to AG-2-2 IIIB. All 62 isolates that caused foliar blight belonged to AG-1 IA. RAPD analysis of R. solani AG-1 IA soybean isolates showed high genetic similarity to a tester strain of AG-1 IA, confirming their classification. The teleomorph of R. solani, Thanatephorus cucumeris was produced in vitro by one AG-1 IA isolate from soybean. The AG-4 and AG-2-2 IIIB isolates caused damping-off and root and hypocotyl rots of soybean seedlings cv. FT-Cristalina, under greenhouse conditions. The AG-2-2 IIIB isolate caused large lesions on the cortex tissue, that was distinct from the symptoms caused by AG-4 isolates. The AG-1 IA isolates caused foliar blight in adult soybean plants cv. Xingu under the greenhouse and also in a detached-leaf assay.  相似文献   

18.
水稻纹枯病是辽宁省水稻的主要病害之一,每年均有不同程度的发生,各地防治该病多采用农药。但养蟹稻田应用哪些药剂防治纹枯病才不会影响河蟹生育,是当前生产上急需解决的问题。为此,我们应用井岗霉素、农抗120两种生物农药进行了药效和对河蟹生长影响的研究。1材...  相似文献   

19.
哈茨木霉在水稻体内的定殖及其对水稻纹枯病抗性的影响   总被引:3,自引:0,他引:3  
以具有抗腈菌唑标记哈茨木霉TUV-13菌株的分生孢子悬浮液对水稻种子分别进行浸种、蘸根、叶面接种,栽培至2叶1芯期,从秧苗各组织分离回收菌株TUV-13。对经菌液处理的秧苗进行显微及超微观察结果表明,浸种处理能使TUV-13菌株在水稻秧苗的根、茎、叶中稳定定殖;而蘸根处理、叶面接种,TUV-13菌株只能在处理的局部区域定殖。TUV-13菌株定殖后,水稻秧苗与抗病相关的酶活性显著提高,对水稻纹枯病防效达82.9%。  相似文献   

20.
A collection of 241 isolates of Rhizoctonia solani obtained from potato plants grown in different areas in France was characterized for anastomosis grouping, symptomatology on tubers of different cultivars and sensitivity to three fungicides. Most isolates collected belonged to (anastomosis groups (AGs)) AG 3, but 2% and 4% of the isolates were AG 5 and AG 2-1. AG 3 and AG 2-1 isolates were mostly obtained from sclerotia on tubers, but all AG 5, some AG 3 and some AG 2-1 isolates were recovered from superficial tuber alterations, like deformations, corky or scabby lesions. Sclerotia were formed on tubers produced by healthy stem cuttings grown in soil artificially infested with AG 3, but not on tubers grown in soil infested with either AG 5 or AG 2-1. No variation in susceptibility to sclerotial formation was observed among five potato cultivars. In all cases, a large proportion of tubers showed superficial corky lesions, often associated with deformations. The proportion of tubers with lesions and deformations was highest in soil infested with AG 2-1 and significantly lower on cv. Samba in all treatments. All isolates were highly sensitive to flutolanil, iprodione and pencycuron, except the AG 5 isolates, moderately sensitive to pencycuron. These results show that, although AG 3 is the most common R. solani group on potato in France, AG 5 and AG 2-1 may be present. Isolates differed for pathogenicity. In vitro sensitivity to fungicides varied among AGs.  相似文献   

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