网室栽培对柑橘生长及病虫害的影响

柑橘黄龙病（Citrus Huanglongbing,HLB）是柑橘生产上的毁灭性病害,在田间主要通过柑橘木虱（Diaphorina citri Kuwayama）传播,目前尚未有有效防治柑橘黄龙病的药剂。通过搭建防虫网室种植柑橘是目前国内多个黄龙病高发区用以防控柑橘木虱及黄龙病的新型种植方式,但有关网室栽培技术在柑橘木虱及黄龙病等主要柑橘病虫害上的防控效果并未有系统评估。本研究以黄龙病流行区（广东惠州）的柑橘果园为实验地进行防虫网覆盖,通过对网室栽培区与露天区柑橘的树势、柑橘木虱与黄龙病的流行状况及其他害虫发生情况进行系统比较,分析其差异。本研究发现,搭建防虫网室种植柑橘有利于增长其树势,一定程度上能够减少柑橘害虫的种类和数量,特别是柑橘木虱,同时黄龙病的病情也有所减轻。但网室内的相对湿度会在秋季降低,进而引起柑橘红蜘蛛（Panonychus citri McGregor）的爆发。搭建防虫网室的种植方式对柑橘生长及黄龙病的防控有重要的作用,但也会引起部分柑橘红蜘蛛和粉虱的泛滥。     

热水处理对柠檬接穗中黄龙病菌脱除效果研究

采集感染黄龙病的尤力克柠檬接穗,分别用不同温度和不同时间长度的热水处理,结果显示预先用45℃温水预处理30min,然后用47℃温水处理20min,嫁接前接穗无褐化,且发芽率在96.67%以上。该方法处理后的接穗嫁接160天后,PCR检测为阴性,网室种植3年后也没有植株表现黄龙病症状。说明该处理可以有效消除柠檬接穗上的黄龙病菌。     

桂北地区柑橘木虱携带黄龙病菌量及其种群动态变化

柑橘木虱是柑橘新梢期的重要害虫,也是传播柑橘黄龙病的主要自然虫媒,其种群数量越大,越有利于黄龙病的扩散,因此是一种重要的柑橘经济害虫。本研究采用五点调查法,监测了2018年4月至12月桂北地区失管果园柑橘木虱种群发生动态,并利用实时荧光定量PCR方法明确了感病果园柑橘木虱含黄龙病菌量的动态规律。结果表明,2018年桂北地区失管果园柑橘木虱种群发生动态具有3个高峰期,分别出现在6月、9月和11月。柑橘木虱携带黄龙病菌量在4 ~ 7月处于较低水平,随后逐步上升并于10月达最高值,其动态变化为单峰型。此外,柑橘木虱年均含菌量可能与性别有关,且雌性含菌量高于雄性。     

柑橘黄龙病菌的重组酶聚合酶扩增(RPA)检测

【目的】本研究旨在建立黄龙病菌的重组酶聚合酶扩增(Recombinase Polymerase Amplification,RPA)快速检测体系,丰富柑橘黄龙病的高效简便检测方法。【方法】以黄龙病菌株psy62的保守基因序列设计并筛选特异性引物,经灵敏度比较和检测特异性验证,建立该病的RPA检测体系。经PCR、RPA和实时荧光PCR对87份柑橘样品的黄龙病菌检测,验证RPA检测体系的适用性。【结果】建立了黄龙病菌的RPA检测方法。(1)特异性：能特异性检测柑橘黄龙病。(2)灵敏度：RPA是PCR的100倍,与实时荧光PCR相当。(3)检测体系：只需20min,大幅提高检测效率。(4)适用性：RPA与实时荧光PCR检出率均为35.63%,比PCR的31.03%略高。【结论】建立了黄龙病菌的RPA检测方法,具有特异性强、灵敏度高、检测快速、无需特殊仪器设备和操作简便等特点,为柑橘黄龙病提供了高效简便的快速检测手段。     

柑橘黄龙病植株显症差异叶片内生细菌群落结构分析

【目 的】从同株柑橘黄龙病罹病植株的不同显症部位内直接检测植物内生菌群落分布情况,为筛选出对柑橘黄龙病原菌（Ca. L. asiaticus）有相互作用的伴生菌奠定理论基础。【方 法】通过 QPCR方法对脐橙和蜜柚中Clas进行验证,并利用 16S rRNA 基因高通量测序技术对同一颗树上显症和不显症枝条叶片内生菌微生物群落的结构进行研究。【结 果】显症叶与不显症叶之间无特有的内生菌,黄龙病菌是决定植物组织是否显症的关键性因素。显症叶片与不显症叶片内生菌差异显著,显症叶片多样性降低。共有18个内生菌属是不显叶片的共同优势菌群,显症叶中较弱。其中,芽孢杆菌Bacillus与黄龙病菌CLas呈负相关,芽孢杆菌属鉴定出科氏芽孢杆菌 Bacillus cohnii,贝莱斯芽胞杆菌Bacillus_velezensis和大量未培养细菌。【结 论】同一罹病5年以上的柑橘黄龙病病株中,各部位所带病菌量不均匀,是否显症与组织内柑橘黄龙病菌CLas的量呈正相关,芽孢杆菌与黄龙病菌的量呈显著负相关。在韧皮部细胞内增殖过程中的相互作用具有深入研究的价值,下步实验可进行分离柑橘黄龙病植株内生芽孢杆菌,鉴定未培养的其他芽孢杆菌种类。     

江西省吉水县柑橘黄龙病菌检测

为了确切诊断江西省吉安市吉水县近年出现的疑似柑橘黄龙病,从该县6个果园共采集12份(株)病叶样品,采用PCR和序列测定技术对病样进行黄龙病菌检测,结果从6份样品中检测到柑橘黄龙病菌即亚洲韧皮部杆菌(Candidatus Liberibacter asiaticus, CLas),结果表明吉水县已有柑橘黄龙病发生。检测结果同时还表明,依据叶片不对称斑驳症状进行柑橘黄龙病田间诊断具有可靠性。     

柑橘黄龙病菌浓度对琼中绿橙果实品质的影响

为了定量衡量黄龙病菌量对琼中绿橙果实品质的影响,本实验以采自海南琼中橘园中感染了柑橘黄龙病的琼中绿橙为实验材料,用实时荧光定量PCR相对定量的方法测定果实中柑橘黄龙病菌的浓度,同时对果实品质的8个外在指标（果实纵经、横径、果形指数、单果重、果皮率、残渣率、种子数量、种子重量）和5个内在指标（果汁率、可食率、可溶性固形物含量、可滴定酸含量、固酸比）进行测定,研究黄龙病菌浓度对琼中绿橙果实品质的影响。结果表明：随着琼中绿橙果实中柑橘黄龙病菌浓度的增大,果实外观品质变化明显的指标包括果实纵经、果形指数、单果重（p<0.05）,其中果实纵经呈现明显下降趋势,从64.97mm下降到57.44mm,相对较少11.59%;果形指数呈现明显上升趋势,从0.83上升到0.94,相对增多13.25%;单果重呈现下降趋势,从166.35g下降到109.66g,相对较少34.08%;果实横径、果皮率、残渣率、种子数量、种子重量等指标变化不明显。随着琼中绿橙果实中柑橘黄龙病菌浓度的增大,果实内在品质变化明显的指标为可溶性固形物含量,可溶性固形物含量呈现明显下降趋势（P<0.05）,从9.65%下降到8.19%,相对减少15.13%;果汁率、可食率、可滴定酸含量和TSS/TA没有明显变化。结论：在黄龙病菌浓度增加的情况下,琼中绿橙在果实外观、内在品质等多个指标呈现下降趋势。研究结果为定量评价黄龙病对柑橘果实的影响提供参考。     

贵州省柑橘黄龙病发生历史回顾及现状调查

为掌握柑橘黄龙病在贵州省的发生及控制情况,本文回顾了病害在贵州省的发生历史,并对田间的疑似样品进行了。结果表明：贵州省柑橘黄龙病在经过近些年大力防控后,目前在黔东南柑桔主产区黄龙病病情得到一定控制,为零星发生。而在黔西南及黔南一些失管产区,病害发生较为严重。从病原菌序列比对的结果来看,此次收集的样品均为柑橘黄龙病菌亚洲种。此外,在本次田间调查中没有发现柑橘木虱。     

广西-湖南地区柑橘黄龙病综合防控技术模式集成及实践

广西-湖南地区通过试验,研究集成了“以种植无病苗木为基础,以统一放控梢、大型植保机械喷施低毒高效药剂、果园悬挂黄板和冬季清园防治木虱为重点,以常态化普查清理病树为保障的柑橘黄龙病综合防控技术模式”,并在技术模式的应用上,因果园类型及黄龙病发病程度不同,不同果园采取分类防控策略;在柑橘黄龙病片区联防联控上,构建了政府责任制、宣传培训和村规民约为核心的柑橘黄龙病片区联防联控的“荔浦模式”,并取得了显著成效。本文对上述技术模式进行了介绍,以期为其它片区防控柑橘黄龙病提供技术和经验借鉴。     

赣南地区柑橘黄龙病菌遗传多样性分析

为探究赣南地区柑橘黄龙病菌的遗传多样性。从赣南16个县市区采集32个具典型柑橘黄龙病症状的脐橙样品,运用PCR-RFLP(聚合酶链式反应-限制性长度多态性分析)技术研究了柑橘黄龙病菌16S rDNA序列、16S/23S rDNA间隔区序列和核糖体蛋白基因的遗传多态性;并对三个基因片段进行测序,分析其序列的碱基含量、转换与颠换、同源性、核苷酸遗传距离和系统进化特征。RFLP结果表明：赣南16个县市区柑橘黄龙病菌XbaⅠ酶切图谱均与亚洲韧皮部杆菌（Candidatus Liberibacter asiaticus, CLas）的一致;进一步分析显示,三个基因片段各自之间的RFLP指纹图谱一致,并未表现多态性。序列分析结果表明：32个分离物三个基因片段各自的同源性均在98%~100%,与CLas的同源性最大,且与CLas的遗传距离最小。系统进化树展示赣南地区柑橘黄龙病菌与CLas处于同一分支,结合酶切图谱、序列同源性及系统进化分析结果表明： 赣南地区柑橘黄龙病菌均为CLas。结论：赣南地区柑橘黄龙病菌的16S rDNA序列、16S/23S rDNA间隔区序列和核糖体蛋白基因未表现遗传多样性,表明赣南地区柑橘黄龙病菌间遗传多样性不显著。 关键词：柑橘黄龙病;16S rDNA序列;核糖体蛋白基因;16S/23S rDNA间隔区;RFLP;序列分析     

The control of heartwater by means of tick control

Two main methods are currently being used by farmers in the heartwater regions to control this disease in cattle and other stock, namely strategic control of ticks and total control of ticks. Some farmers make successful use of the latter method, particularly in areas which are marginal for the disease. Total tick control requires top managerial skills, which includes continual expert supervision, a relatively rare asset. The majority of farmers, often unintentionally, apply strategic control of ticks to control heartwater, either without or with vaccination against the disease. In this case the objective of tick control is to minimize "tick worry" without interfering too drastically with natural transmission of the disease. This method would make provision for natural immunization of young animals (a more uncertain method than vaccination) and the maintenance of immunity. In practice these methods appear to diminish deaths from heartwater appreciably, but do not protect all animals from the disease. Furthermore, they appear to be more effective in cattle than other stock. Although strategic control has an evolutionary background and considerable merit under African conditions, it is being applied in an empirical way because of paucity of information on the epidemiology of heartwater. More information on the infection rate in and infectivity of ticks (percentage of infected ticks) offer challenging research possibilities.     

禽病预防与环境控制技术

温度的好坏直接影响鸡的健康生长和饲料利用。温度过高,鸡只采食量减少,饮水量增多,生长缓慢;温度过低,雏鸡卵黄吸收不良,易引起消化不良等疾病,增加饲料消耗量。温度过高,过低都会降低饲料报酬,从而降低经济效益。     

Disease control through fertility control: Secondary benefits of animal birth control in Indian street dogs

We sought to (1) survey sexually intact street dogs for a wide range of diseases in three cities in Rajasthan, India and (2) evaluate links between the health of non-treated dogs and both the presence and duration of animal birth control (ABC) programs. ABC regimes sterilize and vaccinate stray dogs in an attempt to control their population and the spread of rabies. They are commonly suggested to improve the health of those dogs they serve, but here we provide evidence that these benefits also extend to untreated dogs in the community.     

Infection control and biosecurity in equine disease control

Infectious diseases are an important cause of morbidity and mortality in horses, along with economic costs and broader impacts associated with the loss of members of a species that generates income, acts as a working animal and is a companion. Endemic diseases continue to challenge, emerging diseases are an ever‐present threat and outbreaks can be both destructive and disruptive. While infectious diseases can never be completely prevented, measures can be introduced to restrict the entry of pathogens into a population or limit the implications of the presence of a pathogen. Objective research regarding infection control and biosecurity in horses is limited, yet a variety of practical infection prevention and control measures can be used. Unfortunately, infection control can be challenging, because of the nature of the equine industry (e.g. frequent horse movement) and endemic pathogens, but also because of lack of understanding or motivation to try to improve practices. Recognition of the basic concepts of infection control and biosecurity, and indeed the need for measures to control infectious diseases, is the foundation for successful infection prevention and control.     

Mastitis control

Extract

Sir,—There are two unrelated measures in mastitis control which are worth mention.     

"养鸡生产中沙门氏菌病的预防与控制策略"专栏(二)出栏前沙门氏菌控制策略

美国肉鸡生产行业应该制定一套可行的策略,以解决肠炎沙门氏菌(Salmonella Enteritidis,SE)问题,从而避免美国农业部食品安全检验署(The Food Safety and Inspection Service,FSIS)的严厉处罚措施.     

品质管理的再认识

<正>品质管理是企业管理的重要内容之一,因为品质代表着利润、代表生产力、代表客户的忠诚度,换句话说,代表着市场的占有率,它是企业生存与发展的基础。