石榴枯萎病发生危害与防治初步研究

2004-2005年对蒙自县石榴枯萎病的症状、病原和影响病害发生的因素进行了田间调查。研究了病害的分级标准,设计和实施了以多种药剂树体茎干输液和刮皮涂抹包茎两种施药方式的防治试验,同时结合该病害系统相关因素的分析,提出了相应的防治对策和后续研究重点。     

云南发现石榴枯萎病

 石榴枯萎病是云南省石榴生产中近年发生的一种毁灭性病害,并有逐渐加重的趋势,对云南石榴种植业威胁极大。     

Genetic variation in populations of the cacao wilt pathogen, Ceratocystis cacaofunesta

Ceratocystis cacaofunesta (=  Ceratocystis fimbriata ) causes a lethal wilt disease of cacao ( Theobroma cacao ) in Latin America. Polymorphic microsatellite markers, (CAT)₅ nuclear DNA fingerprints and Hae III mitochondrial DNA fingerprints were used to compare genetic diversity among isolates of C. cacaofunesta collected from populations in western Ecuador, Costa Rica, Colombia, and Rondônia and Bahia in Brazil. Microsatellite markers and nuclear DNA fingerprints separated Ecuadorian isolates from isolates of the other four populations, and these two major groups correspond to genetic lineages already identified from ITS-rDNA sequences and intersterility groupings. Mitochondrial DNA fingerprints also demonstrated substantial diversity and split the Ecuadorian isolates into two groups. All marker types showed limited variation in the Colombian, Costa Rican and Bahian populations, as might be expected for introduced populations that have gone through recent genetic bottlenecks. In contrast, the Rondonian and western Ecuadorian populations showed gene diversity values similar to natural populations of other Ceratocystis species. The Rondonian population was the only sampled population in the native range of T. cacao (the Upper Amazon), and the putatively introduced populations were more closely related to the Rondonian population than to the western Ecuadorian population. The Ecuadorian population is in an area with other native Theobroma species, which may serve as natural hosts.     

Gummosis and wilt of Acacia mearnsii in South Africa caused by Ceratocystis fimbriata

A dieback of Acacia mearnsii trees was observed in the Mkomasi river valley, Natal Province, South Africa. A fungus, tentatively identified as Ceratocystis fimbriata , was consistently isolated from affected twigs and branches. Reinoculation of the pathogen resulted in the development of typical wilt and dieback of A. mearnsii seedlings and saplings and in a dieback of Protea cynaroides plants. This is the first report of this disease in South Africa.     

Comparison of populations of the wilt pathogen Ceratocystis albifundus in South Africa and Uganda

Ceratocystis albifundus is an important fungal pathogen of Acacia mearnsii trees in South Africa. In a previous study, a high level of gene diversity was demonstrated in a South African population of C. albifundus . This, together with the occurrence of the pathogen on native Protea species and its exclusive occurrence in South Africa, led to the hypothesis that C. albifundus is probably native to that country. More recently, C. albifundus has been reported from A. mearnsii in south-western Uganda. The aim of this study was to compare the populations of C. albifundus from Uganda and South Africa based on genetic diversity, population structure and possible gene flow. This was achieved using codominant microsatellite markers developed for the closely related species Ceratocystis fimbriata . Available isolates for comparison were from six different areas of South Africa and six jungle stands in Uganda. Eight of the 11 available markers amplified loci in C. albifundus . Gene diversity was higher in the Ugandan population, but genotypic diversity was greater for the South African isolates. There were no common genotypes between the two populations and they shared only 22% of the total alleles. The populations were genetically isolated from each other and highly substructured within. There was no association between isolates collected from the same geographic locations, and gene flow between the two populations was low. Results suggest that C. albifundus was probably not introduced into Uganda from South Africa but rather that an ancestral population, yet to be discovered, is the source of both populations.     

The increasing importance of herbicides in worldwide crop production

Herbicide use is increasingly being adopted around the world. Many developing countries (India, China, Bangladesh) are facing shortages of workers to hand weed fields as millions of people move from rural to urban areas. In these countries, herbicides are far cheaper and more readily available than labor for hand weeding. History shows that in industrializing countries in the past, including the United States, Germany, Japan and South Korea, the same phenomenon has occurred—as workers have left agriculture, herbicides have been adopted. It is inevitable that herbicide use will increase in sub‐Saharan Africa, not only because millions of people are leaving rural areas, creating shortages of hand weeders, but also because of the need to increase crop yields. Hand weeding has never been a very efficient method of weed control—often performed too late and not frequently enough. Uncontrolled weeds have been a major cause of low crop yields in sub‐Saharan Africa for a long time. In many parts of the world, herbicides are being increasingly used to replace tillage in order to improve environmental conditions. In comparison with tillage, herbicide use reduces erosion, fuel use, greenhouse gas emissions and nutrient run‐off and conserves water. © 2013 Society of Chemical Industry     

甘蓝枯萎病病原菌的鉴定

 采用温室接种致病性测定、形态学观察和分子鉴定方法对甘蓝枯萎病病原进行了研究。从北京市延庆县9个甘蓝生产基地采集甘蓝枯萎病病样96份,分离获得来自甘蓝病株根、短缩茎、叶片等器官的30个真菌分离物。经过致病性试验证实,分离物GLW3和GLW8为甘蓝枯萎病病原菌。经形态学鉴定,GLW3为尖孢镰刀菌(Fusarium oxysporum),GLW8为轮枝样镰刀菌(Fusarium verticillioides)。利用镰刀菌的核糖体DNA(rDNA)内转录间隔区(internal transcribed spacer,ITS)的保守性和变异性,分别采用真菌通用引物和镰刀菌属及轮枝样镰刀菌特异性引物对GLW3和GLW8进行PCR扩增,并将测序结果在GenBank中进行同源性比对分析,分子鉴定与形态学鉴定结果一致。轮枝样镰刀菌作为甘蓝枯萎病的病原菌系首次报道。     

Verticillium wilt of olive in Turkey: a survey on disease importance,pathogen diversity and susceptibility of relevant olive cultivars

A comprehensive survey on the prevalence and incidence of Verticillium wilt of olive in Turkey has been conducted over 6 years (2003–2008). Vegetative compatibility group (VCG) assessment and PCR-based molecular pathotyping were used to evaluate the distribution of the defoliating (D) and nondefoliating (ND) pathotypes of Verticillium dahliae in surveyed areas. Pathogen prevalence was 35% of all olive orchards inspected and incidence of the disease reached 3.1%. VCG1A was predominant (29.3%) and infected all major cultivars grown in Turkey. The other two VCGs detected (2A and 4B) were of minor relevance (4.9% and 0.9%, respectively). Disease incidence caused by VCG1A infections was higher (ranging from 1.1% to 6.9%) than that caused by VCG2A and VCG4B in 10 provinces (Manisa, Aydin, Kahramanmaras, Izmir, Mugla, Kilis, Denizli, Gaziantep, Mardin and Balikesir). However, VCG2A and 4B were more prevalent (and responsible for higher disease incidence) than VCG1A in three provinces (Hatay, Osmaniye and Bursa). Finally, VCG1A isolates were found in all provinces except Canakkale, and simultaneous presence of the three VCGs was only verified in Hatay province. An artificial inoculation bioassay (19 representative V. dahliae isolates included) revealed that VCG1A (13) isolates as a group were more aggressive and caused defoliation, whereas VCG2A (5) and VCG4B (1) isolates induced milder symptoms. Within a VCG group, virulence varied among isolates infecting the same olive cultivar and this virulence was also related to the differential susceptibility of the cultivars (‘Manzanilla’, ‘Ayvalik’ and ‘Gemlik’) tested. Molecular pathotyping allowed the identification of D (VCG1A) and ND (VCG2A/4B) pathotypes, which correlated with results from pathogenicity tests. Remarkably, the V. dahliae VCG1A/D pathotype population infecting olive in Turkey was molecularly different from that one previously identified in Spain.     

瓜类枯萎病防治研究进展

瓜类枯萎病是国内外重要的土传病害 ,本文就抗病育种、农业防治、生物防治及化学防治等方面介绍了该病的防治研究进展。目前各种防治方法对该病均具局限性 ,因地制宜地开展综合防治才是行之有效的防治方法     

杨梅凋萎病综合防治技术试验

杨梅凋萎病传染性强,发病快,给杨梅生产带来了巨大损失。木质素基材料因来源广泛、价格便宜、且活性官能团较多,已广泛应用于纳米药物递送领域。为寻求具有缓释功能的药剂,以便更好地防控杨梅凋萎病,以苯醚甲环唑 (difenoconazole,以下简称Di) 为供试药剂,用苯甲酸酐对木质素磺酸钠 (LS) 进行疏水性改性后,负载Di制备了纳米颗粒Di@BLS,通过核磁共振氢谱 (¹H NMR)、傅里叶红外光谱 (FT-IR)、扫描电子显微镜 (SEM) 及动态光散射激光粒度仪 (DLS) 等对其结构进行了表征,通过Turbiscan稳定性分析仪 (TSI) 对样品稳定性进行了分析;采用QuEChERs方法提取叶片中的Di,研究Di@BLS在杨梅中的吸收转运情况;最后对收集的杨梅病枝进行致病菌的分离鉴定,并分别采用菌丝生长速率法和盆栽试验法研究了Di@BLS对杨梅凋萎病菌的抑制效果。结果表明：在BLS载体浓度为1%、料药比为5 : 1、质量浓度为0.2%的SDS用量条件下制备的Di@BLS平均粒径为135.2 nm,该配方在大量减少表面活性剂用量的同时,可以保持与苯醚甲环唑微乳剂 (Di ME) 相近的制剂稳定性;吸收转运和田间试验均证实Di@BLS能延缓Di的降解,比Di ME在杨梅体内持留时间更久;菌丝生长速率法测定结果显示,Di@BLS对杨梅凋萎病菌可可毛色二孢菌Lasiodiplodia的EC₅₀值为0.643 μg/mL,与Di ME的接近;盆栽试验结果表明,在200 μg/mL质量浓度下,相比Di ME,Di@BLS可降低杨梅凋萎病发病率2.3%。研究结果表明,所制备的纳米颗粒Di@BLS在杨梅体内具有较长的持效期和较好的抑菌效果,可为杨梅凋萎病的防控提供理论依据。     

西瓜种传枯萎病病原菌鉴定及其防控方法

为明确西瓜生产中一种幼苗新病害的病原菌种类,分离纯化获得菌株XG1601,并测定其致病性,利用形态学特征和rDNA ITS序列分析技术明确了该病原菌的分类地位,研究了不同杀菌剂及干热处理西瓜种子对该病害的防治效果。结果显示,结合形态特征及rDNA ITS序列技术分析最终确定菌株XG1601为尖孢镰刀菌Fusarium oxysporum f. sp. niveum。该病原菌为种子传带,引起西瓜种传枯萎病,西瓜种子种皮和种胚的带菌率分别为5.4%和1.7%,在温室中播种30 d左右,幼苗的发病率可达35.7%～41.1%。种子处理对该病害的防治试验结果显示,6.25%精甲霜灵?咯菌腈悬浮种衣剂和2.5%咯菌腈悬浮种衣剂包衣种子对病害的防治效果分别为67.0%和68.6%,80℃干热处理种子72～96 h的防治效果均为100.0%,且对处理种子的发芽势、出苗率和鲜重均无不利影响。说明80℃干热处理种子72～96 h对西瓜种传枯萎病的防治效果最好。     

中国番木瓜枯萎病病原菌的首次鉴定

从发病的番木瓜茎基部组织分离培养得到纯分离物,采用形态学和分子生物学方法进行分离物鉴定。经过致病性测定证实,分离物确定为番木瓜枯萎病的病原菌;通过形态学观察表明,与茄腐镰刀菌(Fusarium solani)形态一致。根据真菌的核糖体DNA(rDNA)内转录间隔区(ITS)的保守性和变异性,采用通用引物ITS1和ITS4进行PCR扩增,然后将PCR产物纯化后直接测序,对测试菌株与10株来自GenBank中的菌株ITS序列进行聚类分析,结果表明,测试菌株与GenBank上注册的茄腐镰刀菌GU134886、GQ451337、EU625405、EF534183和GQ376115聚在同一分枝上,分子鉴定结果与形态学观察结果一致,此为国内首次报道。     

MgO-induced defence against bacterial wilt disease in Arabidopsis thaliana

Bacterial wilt, caused by Ralstonia solanacearum, is a devastating soilborne disease in plants that limits the production of many crops worldwide. Although management of bacterial wilt has so far been unsuccessful, enhancing host resistance to the pathogen may be an effective control strategy. Recently, magnesium oxide (MgO) was found to induce defence responses against R. solanacearum in tomato plants. Here, the mechanisms underlying MgO-induced defence responses against R. solanacearum (MgO-i DARS) were investigated using Arabidopsis thaliana as a host plant. MgO-i DARS was confirmed in A. thaliana mutants deficient in jasmonic acid or ethylene signalling pathways as well as in the wildtype (Col-0) plants. In contrast, no MgO-i DARS was found in A. thaliana mutants deficient in the salicylic acid (SA) production (sid2-2) and signalling pathways (tga1-1 and npr-1). MgO treatment led to significant accumulation of SA in both roots and shoots of Col-0. The SA biosynthesis gene isochorismate synthase 1 (ICS1) was induced in roots and shoots of A. thaliana treated with MgO. An NADPH oxidase gene respiratory burst oxidase homolog D (AtRbohD) was up-regulated in both roots and shoots of Col-0 treated with MgO. No MgO-i DARS was observed in A. thaliana mutants deficient in AtRbohD. These results suggest that SA and RBOHD-mediated ROS are pivotal for MgO-i DARS in A. thaliana.     

枇杷叶尖焦枯病的发生及防治

黔东南州枇杷种植面积发展迅速,现在大部分已进入结果初期。但是,枇杷叶尖焦枯病发生较普遍,严重影响了树势、产量及品质。目前对该病的报道不多,病原性质尚未明确。为探索有效的防治技术,笔者从2000年以来对该病的发生情况做了调查研究。     

Variation in growth rates and aggressiveness of naturally occurring self‐fertile and self‐sterile isolates of the wilt pathogen Ceratocystis albifundus

Ceratocystis albifundus is the most important fungal pathogen of black wattle (Acacia mearnsii) grown in plantations in southern and eastern Africa. It is a homothallic fungus but also undergoes unidirectional mating type switching. As a result, the ascospore progeny can be either self‐fertile or self‐sterile. The only apparent difference between these mating types is the deletion of the MAT1‐2‐1 gene in self‐sterile isolates. There is some evidence suggesting that self‐sterile isolates grow more slowly than self‐fertile isolates, but this has not been tested rigorously. The aim of this study was to determine whether self‐sterile isolates are less fit by examining growth rate, relative germination rate and pathogenicity. Five self‐sterile isolates were generated from each of five self‐fertile isolates of C. albifundus and these 30 isolates were compared. The results showed that the self‐sterile isolates grew consistently slower and were less pathogenic than the self‐fertile isolates. The germination ratio of self‐fertile to self‐sterile isolates from single ascospores collected from the ascomata of five self‐fertile isolates was on average 7:3. This could be a consequence of the self‐sterile isolates having a lower germination rate. This observation, and the lower growth and pathogenicity levels, suggests that self‐sterile isolates are not likely to compete effectively in nature, raising intriguing questions regarding their role and value to C. albifundus and other fungi having a similar mating system.     

草地早熟禾对腐霉枯萎病的抗性评价

研究了温室条件下45份草地早熟禾材料对腐霉枯萎病的抗病性差异.结果表明,不同接种条件下草地早熟禾的发病率存在显著差异:传统的土壤接种法造成草地早熟禾的发病率最高,可达39.2％;改进的土壤接种法测定的发病率明显低于传统的土壤接种法.相同试验条件下品种间抗病性差异显著,不同的试验条件下同一品种表现出的抗病性不一致,具有相对稳定的特征.温室效果评价获得的高抗品种有:‘公园’、‘午夜’、‘肯塔基,、‘开鲁坦,、‘纳苏’和‘特拉内尔’等,高感品种有:‘莫桑斯克’、‘菲尔京’、‘雪狼’等.     

Silicon application enhances resistance to xanthomonas wilt disease in banana

Silicon (Si) has been reported to be a beneficial element and shown to enhance disease resistance in many crops, although it is not regarded to be critical for plant growth and development. In this study, the potential effect of Si supplementation on resistance to banana xanthomonas wilt (BXW) disease was evaluated using various banana cultivars. Si application at a concentration of 200 mg per plant per week was found to be optimal in enhancing resistance to BXW without any detrimental effects on plant growth. The effect of varying the duration of Si application showed continuous supply of Si before and after pathogen inoculation led to a significantly higher level of resistance to BXW in all the banana cultivars tested in comparison to non‐Si‐treated inoculated plants. Banana plants treated with Si before pathogen inoculation only, also exhibited high protection against BXW similar to plants treated continuously with Si. The total Si content in leaves increased significantly in Si‐treated plants in comparison to non‐Si‐treated control plants. The amount of Si accumulation was directly correlated to the duration of application; plants treated with Si continuously showed significantly higher amounts of Si accumulation in leaves than plants where Si application was terminated following bacterial inoculation or when Si application started immediately after pathogen inoculation. The Si‐treated plants also showed higher activity of the peroxidase enzyme in comparison to non‐Si‐treated control plants. This study confirms that application of Si enhances resistance to BXW and may provide an alternative disease management strategy.