桃树主要病害的防治

<正>在桃树生产中,常受到多种病害的为害,对桃造成减产。为了有效防治病害,提高桃的产量,笔者现介绍兴义市马岭镇桃树主要病害的发生和防治措施,以供参考。1桃炭疽病     

桃树桔始叶螨抗药性测定

桔始叶螨可为害多种果树,以刺吸式口器吸食叶片汁液,对桃树等果树的生长、结果影响很大.近年来,由于不合理的使用化学药剂,致使该螨产生严重抗性,为了解西昌地区桃树桔始叶螨的抗药性问题,有效地抑制其抗性发展和升级,我们于去年4月对桃树桔始叶螨进行了室内抗药性测定,为果园合理使用化学药剂防治害螨提供依据 .     

桃细菌性穿孔病及防治研究进展

树生黄单胞菌李致病变种Xanthomonas arboricola pv.pruni(Xap)是一种危害桃树的植物病原细菌,会导致桃树发生细菌性穿孔病。本文主要对该细菌性穿孔病菌的分布、命名、遗传多样性、致病机理和防治技术的研究进展进行了总结,重点阐述了桃细菌性穿孔病的不同防治方法,以期能提供新的防治思路,提升防治水平,保障桃果的安全生产。     

平塘县桃树病虫害绿色防控技术

在桃树病虫害防治适期,采取农业防治、物理防治、生物防治等绿色防控综合配套技术,有效控制桃树病虫害的发生与为害,确保桃产品质量与环境安全,实现桃产业的可持续发展。     

桃褐腐病的发生与防治

<正>近年来,随着秀美乡村建设和农业供给侧改革的推进,桃树作为景观点建设还是名特优果树产业的发展需要,我县桃树种植面积不断扩大,桃树种植面积达到3.2万亩。为保障桃树丰产和景观建设,我们密切调查关注桃树病虫害的发生情况,特别是桃树褐腐病的发生和防治。桃树褐腐病是我县上的主要病害,主要为害桃树的花、叶、枝干和果实,以为害果实为主,遇天气适宜发病的年份,若防治不力,桃果采摘前后大量烂果,造成重大损失。2014年~2017年桃     

桃树高效栽培技术要点

桃树是当前我国广泛种植的重要经济果树。本文从科学建园、肥水管理、整形修剪、病虫害防治等方面总结了桃树的栽培技术,为提升桃树栽培管理技术水平提供参考。     

桃树日灼病的发生特征及防治措施

日灼病也称日烧病,是高温烈日暴晒引起的生理病害。此病在其它果树上的表现和防治措施的报告较多,而在桃树上的表现和防治措施还没有人作详细报告。经调查,日灼病对桃树中、晚熟品种的果实为害较严重,病果率一般在8%~30%,严重的高达36%以上;对枝干的危害则较普遍,尤以夏季干旱、高温年份发生严重。此病对桃树的丰产、稳产和生长寿命带来极大影响,应引起足够重视。     

桃树蚜虫的危害及防治

危害桃树的蚜虫主要有桃蚜、桃粉蚜、桃瘤蚜３种 ,均属同翅目 ,蚜科。这３种蚜虫除主要危害桃树外 ,还危害杏、李、樱桃等多种核果类果树。桃蚜又是传播病毒的重要害虫。这３种蚜虫寄主广泛 ,夏秋寄主有大豆、烟草、瓜类、白菜等多种作物。冬季较温暖 ,若早春雨水适宜 ,将为蚜虫大发生提供了条件。一、危害症状桃树蚜虫一年发生多代 ,且主要危害幼嫩部位。集中在嫩梢和叶片上吮吸汁液 ,被害桃叶叶绿素含量低 ,苍白卷缩 ,不能展叶 ,光合作用下降 ,最后脱落 ,影响桃果产量及花芽形成 ,严重削弱树势。二、防治的最佳时期由于蚜虫危害造成卷叶 ,…     

加纳根除可可肿枝病运动

在许多国家,曾广泛采用根除措施来防治或至少是遏制多种作物的病虫害。如北欧各地对李痘病(Plum pox),以色列对柑桔速衰病(Citrus tristeza),澳大利亚昆士兰对甘蔗菲济病和新南威尔士对香蕉束顶病,美国对桃树花叶病、加拿大对樱桃小果病(lit-tle cherry)和菲律宾对椰子败生病(Coco-nut cadang cadang)等都是用根除法防治多年生作物上病毒病或类病毒病的例子,     

桂南桃树桑白盾蚧的发生与防治

桑白盾蚧(Pseudaulacaspis pentagona Targioni)又名桑白蚧、桑盾蚧、桃介壳虫,是一种危害桃、李、梨、杏、梅、枇杷、板粟、桑、茶等多种果树和园林植物的害虫.广西桂南桃园近几年危害呈上升趋势,2003年广西职业技术学院桃园90%的桃树受害.该虫在桂南地区桃树上发生危害及防治的研究报道甚少,本人在校桃园对桑白盾蚧的发生危害及防治进行了调查研究.     

VirE1-Mediated Resistance to Crown Gall in Transgenic Arabidopsis thaliana

ABSTRACT Crown gall disease, caused by Agrobacterium tumefaciens, remains a serious agricultural problem despite current biocontrol methods. Agrobacterium tumefaciens transfers single-stranded DNA (T-strands) into plant cells along with several virulence proteins, including a single-stranded DNA-binding protein (VirE2). In plant cells, T-strands are protected from nucleases and targeted to the nucleus by VirE2, which is essential for efficient transmission (transfer and integration) of T-strands. VirE1 is the secretory chaperone for VirE2; it prevents VirE2 from forming aggregates and from binding the T-strands in bacterial cells. Therefore, we hypothesized that sufficient quantities of VirE1 expressed in plant cells might block T-DNA transmission by preventing VirE2 from binding T-strands. Here we show that root explants from Arabidopsis thaliana plants that expressed virE1 formed 3.5-fold fewer tumors than roots from plants without virE1. Also, this resistance was specific for VirE2-mediated Agrobacterium transformation. Plants that have been genetically altered to resist crown gall may prove more effective than biological control.     

Evidence of Migration and Endophytic Presence of Agrobacterium tumefaciens in Rose Plants

Agrobacterium tumefaciens was isolated from stem tumors of several rose cultivars showing that the bacterium is the causal agent of aerial galls in rose plants. No differences were observed in the characteristics of the Agrobacterium isolates from crown or aerial galls. Stem inoculation of ten rose cultivars showed that all of them were susceptible to A. tumefaciens but differences in the size of the resulting tumors were observed. The movement of A. tumefaciens in rose plants was demonstrated using two wild type strains and two antibiotic resistant mutants. Three months after inoculation, the inoculated strains were recovered in the roots, crown and below and above the inoculation site but low numbers of pathogenic Agrobacterium cells were isolated. New tumors appeared in 5% of the noninoculated wounds. A. tumefaciens was isolated from the stem at different distances from the tumor in naturally infected plants. In symptomless commercial plants, the isolation from the roots, crown and at different stem levels demonstrated the existence of systemic and latent infections in rose. Direct isolation using a nonselective and selective media with or without a previous enrichment step were efficient methods for isolating tumorigenic Agrobacterium from the different parts of rose plants.     

Crown gall of hop caused by Agrobacterium tumefaciens biovar 1 in South Africa

Crown gall of hop caused by Agrobacterium tumefaciens biovar 1 is reported for the first time from South Africa. The causal organism was inhibited in vitro by the agrocin of A. radiobacter strain D286 but not by that of the control strain K84. Nevertheless, control was achieved on hop stems in glasshouse inoculations by both biological control strains.     

Effect of antibiosis on antagonist dose-plant disease response relationships for the biological control of crown gall of tomato and cherry

ABSTRACT The crown gall pathosystem was used to evaluate a model that describes the dose-response relationship between biological control agents and plant pathogens. The model predicts that this relationship can become asymptotic, such that increased antagonist doses cannot compensate for deficiencies in disease suppression. Wounded roots of tomato (Lycopersicon esculentum) and cherry (Prunus mahaleb) plants were dipped into different concentrations of the biological control organism Agrobacterium radiobacter strain K84 prior to inoculation with the pathogen A. tumefaciens. Pathogen strains sensitive or resistant to the antibiotic agrocin 84 were used, and for tomato experiments, a derivative of A. radiobacter strain K84 that does not produce agrocin 84 also was included as an experimental treatment. As predicted by the dose-response model, the amount of disease suppression per unit of antagonist decreased with increasing antagonist dose and became asymptotic at high antagonist densities. Control of crown gall of tomato was nearly complete with the combination of A. radiobacter K84 and an agrocin 84-sensitive strain of A. tumefaciens. Pathogen resistance to agrocin 84 or lack of agrocin 84 production by A. radiobacter resulted in antagonist dose-crown gall incidence relationships that were apparently asymptotic at levels of control significantly less than 100%. For field-grown cherry, similar dose-response relationships were observed with higher asymptotic levels of disease suppression obtained when trees were inoculated with an agrocin 84-sensitive A. tumefaciens strain compared with an agrocin 84-resistant pathogen strain. The differences among bacterial strain combinations in the magnitude of the asymptote defined by the dose-response relationships suggest that A. radiobacter impacts a smaller proportion of the pathogen population when the activity of agrocin 84 is muted.     

放射土壤杆菌MI15菌株生物防治葡萄根癌病的研究

 从内蒙古玫瑰香葡萄冠瘿中分离到一株无致病力的土壤杆菌MI15菌株,经鉴定为放射土壤杆菌(Agrobacterium radiobacter),属生物Ⅰ型。在平皿培养产生的土壤杆菌素,能抑制葡萄根癌土壤杆菌生物Ⅲ型菌株的生长,在温室向日葵幼苗和葡萄嫩枝上接种,MI15菌株能显著地抑制多株不同类型葡萄根癌土壤杆菌诱导形成冠瘿瘤。在琼脂糖凝胶电泳图谱上,MI15菌株有一条质粒带,与生物Ⅰ型根癌士壤杆菌C58菌株的质粒情况基本相同。研究还表明该菌株能在葡萄上存活定殖。     

农杆菌介导的哈茨木霉T-DNA转化系统优化及拮抗能力突变子的性质分析

采用单因子试验方法研究了农杆菌EHA105介导的哈茨木霉Th-33转化过程中,各主要因素对转化效率的影响,建立了高效的转化系统,使农杆菌转化哈茨木霉的效率达到60～150个转化子/10^6个木霉孢子,利用该转化系统构建了含有8000多个转化子的T-DNA插入突变库。通过转化子与立枯丝核菌的对峙试验,从1260株转化子中筛选到23株拮抗能力发生变化的突变子。随机挑选5株突变子对其遗传稳定性进行分析,表明5株突变子都具有稳定性,聚合酶链式反应（PCR）表明上述突变子均有T-DNA片段的插入。     

Chromosomal and Ti plasmid characterization of tumorigenic strains of three Agrobacterium species isolated from grapevine tumours

Fifty-six tumorigenic Spanish grapevine strains of Agrobacterium spp. were tested for biovar classification, pathogenicity on several hosts, opine utilization, 16S rRNA gene sequencing and PCR amplifications using five primer sets targeting chromosomal and Ti plasmid genes. Fifty of them belonged to A. vitis (biovar 3), three to A. tumefaciens (biovar 1) and three to A. rhizogenes (biovar 2). All strains were tumorigenic on grapevines. Most A. vitis strains were also pathogenic on tomato and tobacco plants, while the three A. tumefaciens strains were only pathogenic on grapevine. Although most A. vitis strains used octopine, 12 utilized neither octopine nor nopaline. 16S rRNA gene sequencing clearly distinguished between strains belonging to the three species. Those of A. vitis could be further divided into three chromosomal backgrounds according to their 16S ribosomal RNA gene sequences. No universal primer pair was found for the detection of all three Agrobacterium species isolated from grapevine. DNA from all A. vitis strains was amplified with the chromosomally-encoded pehA primer pair. In both A. vitis and A. tumefaciens a correlation was observed between the amplifications obtained using the tmr and the virA Ti-plasmid-targeting primer pairs. Three types of Ti plasmid were found in A. vitis strains according to their PCR amplifications and opine utilization profiles. A given chromosomal background harboured only one type of Ti plasmid within the strains from each analysed sample, showing a strong association between chromosomal backgrounds and Ti plasmids in A. vitis .     

Biological control of crown gall of grapevine, rose, and tomato by nonpathogenic Agrobacterium vitis strain VAR03-1

A nonpathogenic strain of Agrobacterium vitis VAR03-1 was tested as a biological control agent for crown gall of grapevine (Vitis vinifera). When roots of grapevine, rose (Rose multiflora), and tomato (Lycopersicon esculentum) were soaked in a cell suspension of antagonists before planting in soil infested with tumorigenic A. vitis, A. rhizogenes, and A. tumefaciens, respectively, treatment with VAR03-1 significantly reduced the number of plants with tumors and disease severity in the three plant species. The inhibitory effects of treatment with VAR03-1 and the nonpathogenic A. rhizogenes strain K84 on crown gall of rose and tomato were almost identical, and the inhibitory effect of VAR03-1 on grapevine was superior to that of K84. Moreover, VAR03-1 greatly controlled crown gall of grapevine due to tumorigenic A. vitis in the field. VAR03-1 established populations averaging 10(6) colony forming units (CFU)/g of root in the rhizosphere of grapevine and persisted on roots for 2 years. VAR03-1 was bacteriocinogenic, producing a halo of inhibition against those three species of Agrobacterium. This is the first report that a nonpathogenic strain, VAR03-1, can effectively control crown gall caused by tumorigenic A. vitis, A. rhizogenes, and A. tumefaciens.     

Agrobacterium-Mediated Transformation of Fusarium oxysporum: An Efficient Tool for Insertional Mutagenesis and Gene Transfer

ABSTRACT Agrobacterium tumefaciens-mediated transformation (ATMT) has long been used to transfer genes to a wide variety of plants and has also served as an efficient tool for insertional mutagenesis. In this paper, we report the construction of four novel binary vectors for fungal transformation and the optimization of an ATMT protocol for insertional mutagenesis, which permits an efficient genetic manipulation of Fusarium oxysporum and other phytopathogenic fungi to be achieved. Employing the binary vectors, carrying the bacterial hygromycin B phosphotrans-ferase gene (hph) under the control of the Aspergillus nidulans trpC promoter as a selectable marker, led to the production of 300 to 500 hygromycin B resistant transformants per 1 x 10(6) conidia of F. oxysporum, which is at least an order of magnitude higher than that previously accomplished. Transformation efficiency correlated strongly with the duration of cocultivation of fungal spores with Agrobacterium tumefaciens cells and significantly with the number of Agrobacteruium tumefaciens cells present during the cocultivation period (r = 0.996; n = 3; P < 0.01). All transformants tested remained mitotically stable, maintaining their hygromycin B resistance. Growing Agrobacterium tumefaciens cells in the presence of acetosyringone (AS) prior to cocultivation shortened the time required for the formation of transformants but decreased to 53% the percentage of transformants containing a single T-DNA insert per genome. This increased to over 80% when Agrobacterium tumefaciens cells grown in the absence of AS were used. There was no correlation between the average copy number of T-DNA per genome and the colony diameter of the transformants, the period of cocultivation or the quantity of Agrobacterium tumefaciens cells present during cocultivation. To isolate the host sequences flanking the inserted T-DNA, we employed a modified thermal asymmetric interlaced PCR (TAIL-PCR) technique. Utilizing just one arbitrary primer resulted in the successful amplification of desired products in 90% of those transformants analyzed. The insertion event appeared to be a random process with truncation of the inserted T-DNA, ranging from 1 to 14 bp in size, occurring on both the right and left border sequences. Considering the size and design of the vectors described here, coupled with the efficiency and flexibility of this ATMT protocol, it is suggested that ATMT should be regarded as a highly efficient alternative to other DNA transfer procedures in characterizing those genes important for the pathogenicity of F. oxysporum and potentially those of other fungal pathogens.     

Application of alginate gel for protection of wounds against crown gall (Agrobacterium tumefaciens)

In glasshouse and laboratory experiments, calcium alginate gel, produced in situ on wounds by successive dipping in solutions of sodium alginate and CaCl₂ gave significant protection against infection by pathogenic isolates of Agrobacterium tumefaciens on carrot discs, tomato cuttings and chrysanthemum cuttings. Gel protection was sometimes equal to that given by strain K84 of A. radiobacter and also operated against a pathogenic isolate insensitive to control by strain K84. Sodium alginate or CaCl₂ alone gave little or no protection, suggesting that calcium alginate acted by physically excluding the pathogen from wound surfaces. The use of the method described is discussed for delivery of biological or chemical control agents to plant surfaces whilst also providing protection in its own right.