辽宁玉米弯孢菌叶斑病发生原因及防治对策

玉米弯孢菌叶斑病是辽宁玉米上的新病害，其流行速度快、发生范围广、为害严重。主栽品种严重感病、气象条件适宜、菌源量大是病害流行的主要原因。本文针对病害的发生特点、成因，提出了相应的对策     

我国玉米病害发生现状及防治措施

当前我国玉米大、小斑病已得到控制，但玉米茎腐病、灰斑病、弯孢菌叶斑病、纹枯病及病毒病等病害仍发生普遍，且日趋严重，成为玉米生产上的主要病害。对上述病害生产上应采取以选用抗病品种和提高栽培管理水平为主，结合药剂防治的综合防治措施     

玉米大斑病发病原因及防治方法

玉米大斑病是玉米的重要病害之一。大斑病的发生和流行程度受品种的抗病性、轮作制度、气候条件和栽培措施等因素的综合影响。根据多年的生产实践经验,总结玉米大斑病的发病原因及预防措施,以减少玉米的损失。     

玉米黑束病发病原因与防治对策

玉米黑束病是苗期根部侵染,系统性发生的病害。由土壤、病残体、种子带菌传播。大面积种植感病品种是病害发生严重的主要原因。采取种植抗病品种为主,辅以减少氮肥用量,增施磷、钾肥,合理灌溉,清除病株根、茎残体等保健栽培措施可取得持续地防治效果。     

2012年玉米大斑病重发原因和控制对策

玉米大斑病是由真菌引起的世界性玉米病害,常给生产造成严重损失。2012年玉米大斑病在东北、华北地区大流行,本文归纳了玉米大斑病全国发生概况、区域分布和各地病情。总结了2012年玉米大斑病发病时间早,流行速度快,品种间和地区间发病程度差异大等发生特点,分析了适宜天气条件、主栽品种不抗病、栽培管理措施不合理是导致大斑病重发的主要原因。并针对性地提出了重视玉米病害的预测预报、推荐种植抗病品种、加强病害综合防治的对策建议,旨在对今后进一步做好玉米大斑病测报工作,指导玉米病害防治、有效控制其危害、保障玉米生产有所裨益。     

南繁玉米茎腐病发生危害情况调查

海南省南繁基地玉米茎腐病发生普遍,损失率达20.8％—42.7％,造成减产的原因是千粒重下降,籽粒出产率降低。该病害流行与玉米生育期、品种抗病性、降雨量和施肥水平等环境因素密切相关。建议采用抗病品种为主,加强栽培管理的综合防治措施控制其危害。     

玉米纹枯病调查研究初报

1995－1996年调查研究玉米纹枯病的发生发展规律，菌核、病残体和病土是该病的初次侵染源；无论是春玉米或晚玉米，及不同玉米品种，其病害始发期均在8－11张叶期，以10－11张叶期出现的频率最高；病斑激增期从玉米抽雄期到灌浆期，且病情发展很快。该病除了多晴少雨天外，无明显的停滞期；不同玉米品种发病程度也有差异；同一品种在栽培环境不同时，其发病程度也不一样。     

荔波县不同优质玉米品种大小斑病发生规律初探及防治措施

大小斑病是荔波县玉米上的主要病害，近年其危害程度上有上升趋势，特别是优质玉米营养丰富，易遭受大小斑病危害，为掌握大小斑病在不同优质玉米品种上的发生发展规律，选出优质，高产，抗大小斑病的品种，也为今后大面积推广提供决策性依据，结合县种子分司筛选品比试验，对其进行系统监测，初步掌握不同优质玉米的品种大小斑病发生发展规律及防治措施。     

玉米丝黑穗病的发生与综合防治

近年来玉米丝黑穗病不断加重发生,特别是在北方春播玉米区和冷凉丘陵山地春播玉米受害比较严重．该病主要通过土壤带菌传染,到穗期才出现典型症状,种植感病品种和连作是发病的主要原因。可通过选育种植抗病品种、减少田间菌源、改进栽培管理措施、种衣剂或药剂拌种等措施进行防治。     

玉米丝黑穗病发病症状及防控技术

近年来,随着玉米感病品种的增多和玉米连年栽培,玉米丝黑穗病不断蔓延、加重,局部地区已成为当前玉米生产上的严重病害,给部分农户生产带来很大损失。介绍玉米丝黑穗病在田间的发病症状,并提出栽培抗病品种、减少田间菌量、改进栽培管理和种子药剂处理的防治措施。     

Modelling effects of vector acquisition threshold on disease progression in a perennial crop following deployment of a partially resistant variety

Deployment of resistant varieties is a key strategy to mitigating economic losses due to arthropod‐transmitted plant pathogens of perennial crops. In many cases, the best available resistant traits for introgression confer only partial resistance. Plants displaying partial resistance have lower pathogen titres than susceptible counterparts, but remain hosts for the pathogen. As partially resistant varieties maintain yield after infection, infected plants are unlikely to be rogued (i.e. removed). Accordingly, there is a risk that partially resistant plants could serve as a source of inoculum for pathogen spread to susceptible plants. Here, a mathematical model that tracked spread of an arthropod‐transmitted pathogen in a plant population consisting of susceptible and partially resistant plants was used to identify a threshold acquisition rate from partially resistant plants that resulted in limited spread of the pathogen from partially resistant plants to susceptible plants. The acquisition threshold from partially resistant plants varied with parameters influenced by disease management decisions such as number of vectors per plant, vector turnover, replacement of susceptible plants, and proportion of plants that were partially resistant. In model simulations, effects of deploying a partially resistant variety on disease incidence in a susceptible variety depended on the extent to which pathogen spread among susceptible plants was suppressed and acquisition rates from partially resistant plants. Collectively, the results indicate that risk of partially resistant plants serving as inoculum sources could be assessed prior to deployment, thereby enabling design of complementary disease management tactics to minimize economic losses in susceptible varieties following deployment.     

内蒙古燕麦叶斑病的发生及其影响因素

为探究内蒙古田间影响燕麦叶斑病的因素，采用正交试验设计对燕麦品种、播期、种植密度、施氮量、施磷量和灌水量6个因素及其组合于2009—2011年进行连续3年的重复试验，运用逐步回归法对3年试验数据进行分析，探讨不同因素及其组合对燕麦叶斑病的影响。正交方差和分析表明，播期和品种是影响燕麦叶斑病的主要因素，方差贡献率分别为78.69%和12.20%；而施氮量、施磷量和灌水量对燕麦叶斑病发生程度均无显著影响。拟合分析获得燕麦叶斑病发生程度与播期(x₂)、品种(x₁)和种植密度(x₃)之间的非线性回归方程为y=51.99-6.45x2-0.39x₁x₃，表明适当推迟播期、选择抗性较高的燕麦品种且相对密植可减轻燕麦叶斑病的发生程度。     

A general model of plant-virus disease infection incorporating vector aggregation

In plant-virus disease epidemiology, dynamical models have invariably incorporated a bilinear inoculation rate that is directly proportional to both the abundance of healthy (susceptible) hosts and the abundance of infective vectors. Similarly, the acquisition rate is usually assumed to be directly proportional to the abundance of nonviruliferous vectors and that of infectious hosts. These bilinear assumptions have been questioned for certain human diseases, and infection rates that incorporate power parameters of the variables have been proposed. Here, infection rates for plant-virus diseases that are of a more general form than the familiar bilinear terms are examined. For such diseases, the power parameter can be regarded as a measure of the spatial aggregation of the vectors or as a coefficient of interference between them, depending on the context.
Field data of cassava mosaic virus disease (CMD) incidence were examined. When vector population density and disease incidence were high, disease progress curves over the first 6 months from planting could not be explained using models with bilinear infection rates. Incorporation of the new infection terms allowed the range of observed disease progress curve types to be described. New evidence of a mutually beneficial interaction between the viruses causing CMD and the whitefly vector, Bemisia tabaci , has shown that spatial aggregation of the vectors is an inevitable consequence of infection, particularly with a severe virus strain or a sensitive host. Virus infection increases both vector fecundity and the density of vectors on diseased plants. It is postulated that this enhances disease spread by causing an increased emigration rate of infective vectors to other crops. Paradoxically, within the infected crop, vector aggregation reduces the effective contact rate between vector and host and therefore the predicted disease incidence is less than when a bilinear contact rate is used.     

影响南方水稻黑条矮缩病发生流行的因子分析

南方水稻黑条矮缩病是近年来在我国南方稻区新发生的一种重要病毒性病害。本文通过大田调查、田间试验并结合气象资料分析,表明品种抗性、种植方式、播种期、播种地段和气象因子等是影响该病发生的主要因素。不同类型水稻的发病率存在显著性差异。杂交稻发病最重,糯稻发病次之,常规稻发病最轻。同一类型的杂交稻不同品种对南方水稻黑条矮缩病的抗(耐)病性存在较大差异。‘特优161’最感病,‘华优638’最抗病。抛栽田比移栽田和直播田发病轻。不同播种期显著影响南方水稻黑条矮缩病的发病率。在化州稻区,播种早的发病重于播种迟的。晚稻秧田靠近早稻本田的田块,南方水稻黑条矮缩病发病重,秧田远离早稻本田的田块发病较轻。6月中旬-7月上旬降水日数、6月下旬-7月上旬相对湿度和8月上旬平均最高气温等气象因子与南方水稻黑条矮缩病发病率关系最密切。     

Cassava brown streak disease and the sustainability of a clean seed system

One method of reducing disease in crops is the dissemination of disease‐free planting material from a multiplication site to growers. This study assesses the validity and sustainability of this method for cassava brown streak disease, a threat to cassava crops across East Africa. Using mathematical modelling, the effects of different environmental and control conditions on pathogen spread were determined in a single‐field multiplication site. High disease pressure, through large vector populations and disease in the surrounding area, combined with poor roguing practice, resulted in unsuccessful disease suppression. However, fields may produce sufficiently clean material for replanting if these factors can be overcome. Assessing the sustainability of a low‐pressure system over multiple harvests, well‐managed fields were found to maintain low disease levels, although producing sufficient cuttings may prove challenging. Replanting fields from the previous harvest does not lead to degeneration of planting material, only cutting numbers, and the importation of new clean material is not necessarily required. It is recommended that multiplication sites are only established in areas of low disease pressure and vector population density, and the importance of training in field management is emphasized. Cultivars displaying strong foliar symptoms are to be encouraged, as these allow for effective roguing, resulting in negative selection against the disease and reducing its spread. Finally, efforts to increase plant multiplication rates, the number of cuttings that can be obtained from each plant, have a significant impact on the sustainability of sites, as this represents the primary limiting factor to success.     

陕西玉米病毒病及流行因素研究

 研究结果表明:陕西玉米病毒病毒原主要有玉米矮花叶病毒B株系(MDMV-B)、玉米粗缩病毒(MRDV)和大麦黄矮病毒(BYDV)。用血清鉴定225份病株样品中,MDMV-B、MRDV和BYDV侵染分别占40%、23%、4.5%。MDMV-B和MRDV复合侵染占23.5%。在田间自然条件下,MDMV-B主要通过玉米蚜和禾谷缢管蚜以非持久性传播,MRDV则由灰飞虱以持久传播。MDMV-B、MRDV和BYDV的粒子大小分别为735~755 nm×17 nm、70~75 nm和23~30 nm。随着玉米生育成熟,侵染逐渐降低,为害亦趋减轻。研究认为,玉米品种、播种期、播量、田间传毒介体数量及发生早晚和地膜覆盖等是影响玉米病毒病流行的主要因素。     

沿黄稻区水稻品种对水稻条纹叶枯病抗性评价

2007年和2008年在田间自然发病条件下, 鉴定了河南省沿黄稻区25个主要推广品种、育种高代品系对水稻条纹叶枯病的抗性。结果表明,在两个年份均表现为抗病的有5个粳稻（5/17）、3个籼稻（3/3）和2个旱稻（2/5）品种;但有4个品种（4/25）表现不一致。2007年17个粳稻品种中的11个表现为感病或中感（64.70%）,5个旱稻品种中2个表现感病或中感（40％）。2008年17个品种中有10个表现为感病或中感（58.80%）,5个旱稻品种中3个表现为感病或中感（60％）。 2008年对25个品种的病情变化和田间灰飞虱种群动态的调查结果表明,抗、感品种间的病情变化具有明显的差异,不同水稻品种间灰飞虱的虫口数量也具有显著的差异,但品种对水稻条纹叶枯病的抗性程度和灰飞虱的虫口数量并不完全一致。     

棉花抗枯萎病品种连作防病效果的研究

1978～1982年,在人工病圃试验调查了抗病品种连作1～5年的田间发病情况及生育产量。结果表明,抗病品种连作3年以上换种1～2年感病品种,比感病品种连作或只种1～2年抗病品种后换种感病品种,发病显著减轻,前者病害对棉花生育产量影响甚微。土壤病原菌菌量消长及土壤、病株中病原菌致病力测定,看出土壤病原菌量随抗病品种连作年限增加而减少,土壤病原菌致病力也有随抗病品种连作年限增加而减弱的趋势。抗病品种连作4年以上与只种1～2年抗病品种即改种感病品种或与感病品种连作相比,土壤病原菌量差异达极显著平准。土壤病原菌致病力差异达显著平准。     

甘肃省马铃薯主要病毒病发生情况调查

2015年-2016年,在甘肃省10个地市24个马铃薯主栽县(区)146个生态区域(乡镇)采集了757份具有典型症状的马铃薯样品,应用DAS-ELISA法进行检测,筛查6种主要病毒(PVX、PVY、PLRV、PVA、PVS和PVM)。结果表明:631份样品检测到病毒,PVS的检出率最高,达47.03%,PVY次之,为33.82%,PVA最低,只有0.63%;发生复合侵染的病毒主要为PVY+PVS,复合侵染率达到10.13%,三种病毒复合侵染主要是PVY+PVS+PVM;病毒种类和感病程度与品种、地域有关。     

Plant community diversity influences vector behaviour and Barley yellow dwarf virus population structure

The species composition of a plant community can affect the distribution and abundance of other organisms including plant pathogens. The goal of this study was to understand the role of host diversity in the transmission of two Barley yellow dwarf virus (BYDV) species that share insect vectors and hosts. Greenhouse experiments measured the transmission rate of BYDV species PAV and PAS from infected oat plants to healthy agricultural and wild grasses and from these species back to healthy oat seedlings. In the field component of the study, the rate of spread of PAV and PAS was measured in monoculture plots planted with agricultural grasses. In greenhouse experiments, the aphid vector more readily transmitted PAV from agricultural grasses and more readily inoculated PAS to the wild grass species assayed. In the field experiment, disease prevalence was greater in wheat, but there was no difference in the rate of spread of PAV and PAS. These results indicate an interaction between vector and host genotype that selects for greater PAV transmission in grain crops, contributes to differences in disease prevalence between grass types, and maintains pathogen diversity within the larger plant community (i.e. agricultural and non‐agricultural hosts).