桉树青枯病发生规律与控制技术

桉树青枯病的病原为世界范围内广泛分布的茄拉氏菌[Ralstonia Solanacearum(Smith)Yabuuchi etal.],主要以生理小种1号、生化变种3菌系侵染为害。近10多年来由于桉树造林以无性系为主,在具备发病条件时,感病无性系的发病率可达30%~90%以上。由于茄拉氏菌生理小种1号为高温型菌系,在高温高湿和大风气候条件下易爆发成灾;桉树青枯病是单年流行病,有一定数量病原,气候因素有利于发病,桉树青枯病就大发生;易感病的树种1~3年生期间,青枯病可连年流行,随树龄增大病害流行逐渐缓慢,其中以1年生林发病率最高,4年生后基本不发病。桉树青枯病发生危害的程度具有明显区域差异,根据区域气候特点可以将桉树栽培区划分为高风险发生区、中风险发生区和低风险发生区。桉树青枯病的初侵染源为带菌土壤、带菌苗木和农家肥。在桉树青枯病高风险发生区,感病品系在沙土、壤土和粘土造林地均可严重发病,但在前作为易感农作物或以农家肥为基肥时,抗病品系也可严重发病;在中风险发生区,感病品系主要在坡下低洼积水处发病,在前作为易感农作物、以农家肥为基肥或以带病苗木造林的林地严重发病;在低风险发生区,感病品系主要在前作为易感农作物、以农家肥为基肥或以带病苗木造林的林地发生。目前,国内外对桉树青枯病仍没有有效的防治措施。根据桉树青枯病发生与流行规律,提出桉树青枯病可持续控制策略:实行植物检疫,培育无病苗木,减少病原菌初侵染源;采取科学营林技术,减少病原菌的种群数量,降低发病率;合理布局桉树品种(系),充分利用桉树良种资源;培育多类型抗病品种(系),以多品系混合造林减缓病原菌进化,形成专化型新菌系。并提出具体技术措施。     

桉树无性系抗青枯病性能的测选初报

用WFT接种技术对47个桉树无性系进行了对青枯病的抗性测定 ,通过青枯病株率计算和逐步聚类分析 ,认为31个无性系是抗病品系 ,10个无性系是感病品系 ,6个无性系是高感品系。在31个无性系抗病品系中 ,经生产实践证明 ,其中MLA、ZU6、W5、LH1、LH2、LH3、SH1、M1等8个无性系显示出很强的抗病性 ,至今未发生青枯病株。大面积推广应用优良抗病无性系造林 ,防治桉树青枯病的大面积发生 ,目前已取得初步成效。     

安树无性系抗青枯病性能的测选初报

用WFT接种技术对47个桉树无性系进行了对青枯病的抗性测定，通过青枯病株率计算和逐步聚类分析，认为31个无性系是抗病品系，10个无性系是感病品系，6个无性系是高感品系。在31个无性系抗病品系中，经生产实践证明，其中MLA、ZU6、W5、LHl、LH2、LH3、SHl、M1等8个无性系显示出很强的抗病性，至今未发生青枯病株。大面积推广应用优良抗病无性系造林，防治桉树青枯病的大面积发生，目前已取得初步成效。     

普通木麻黄对青枯病的抗性及其生理生化机制的初步研究

对选自平潭县青枯病严重发病区的普通木麻黄(Casuarina equisetifoliaForst)优树子代不同无性系的幼苗经青枯假单胞菌(Pseudomonas solanacearum E.F.Smith)人工二次接种后,发病症状大致可以划分为青枯、萎蔫、部分枝枯和正常生长四个类型,其对青枯病的抗性有差异。我们选择经二次人工接种后表现出典型的不同抗病性的4个普通木麻黄无性系和华南农学院梁子超教授经多年筛选的1个普通木麻黄抗病无性系,对其一年生幼苗的根、主茎和小枝进行含水量、pH值、细胞相对渗透性及多酚类物质含量的测定,并对各无性系小枝的组织结构进行观察。结果表明,不同抗病性普通木麻黄5个无性系在含水量、pH值、细胞相对渗透性及多酚类物质含量等均存在差异;其小枝的组织结构无明显差异。这些差异初步阐明了普通木麻黄5个无性系抗病性的机理,可作为早期测定普通木麻黄对青枯病抗性的参考指标。     

桉树品系对青枯病抗性及其稳定性的研究

通过剪顶包扎菌液接种、伤根淋灌菌液接种、 WFT培养接种测定结果与桉树当年新造林分青枯病自然发生率调查结果对比 ,青枯病菌对桉苗的致病力因接种方法不同而异 ,经模糊聚类分析表明 ,WFT接菌培养技术测出的结果更接近自然实际发病情况。试验表明 ,桉树不同品种、同一品种的不同种源、不同无性系 ,对青枯病菌的抗性不同。课题组通过 8年研究 ,在生产单位提供的 10 1个桉树品系中 ,已筛选出高抗品系 12个、抗病品系 14个、低感品系 2 6个。自 1994年起在粤、桂、琼三省区 ,生产上大面积推广这些高抗和抗病品 (种 )系 ,已直接造林 2万多 hm2 ,扩散面积更大 ,造林效果跟踪检查表明 ,这些林分的青枯病株率均在 1‰以下 ,受到生产者和经营者欢迎。试验和应用中发现部分抗病无性系随着在林木组培苗工厂连续繁殖使用年份增加其抗病性逐年出现下降 ,有些抗病无性系使用 3年以后 ,其抗病性就明显下降 ,值得引起重视     

杉木45个无性系在种子园抗炭疽病的调查

本文是对靖县排牙山林场杉木嫁接种子园炭疽病自然发病情况的调查报告。用1977—1982年的调查结果,按各无性系的平均感染指数大小分类,将杉木45个无性系划分为抗病(X)。属于抗病的有5个无性系,占45个无性系的11.11%;中庸的22个,占48.89%;感病的18个,占40%。以10、Ⅲ和20号无性系最抗病,即使进行人工接种也不发病。尤其是20号无性系,是属于生长快(>X S)的一类,但结实少(<(?))。20号家系的子代也表现较好,其速生抗病的优良性状较稳定,可作为建立高一级种子园和杂交组合的材料。     

桉树抗青枯病的鉴定技术

采用菌液浸泡法、顶尖接种法对不同的桉树无性系盆栽苗和生根组培苗进行抗青枯病性能测定,并结合林间调查筛选桉树抗青枯病树种和无性系,并从根系分泌物和组织研磨液的角度研究其对桉树青枯病菌生长的抑制作用,探索不同抗性桉树无性系抗病性强弱与其根系分泌物和组织研磨液之间的关系。结果表明:供试的18个桉树无性系中,bd1、bd2、赤桉和南宁巨尾桉为抗病无性系;U6、南宁尾叶桉、雷9、钦32-29为中抗无性系;DH32-27、钦9、南宁广9、钦8、邓恩桉、钦32-22、雷2、巨桉、尾叶桉和钦广9为感病无性系。不同抗性桉树无性系根系分泌物和组织研磨液对青枯菌没有直接拮抗作用,但随着接种时间的延长,青枯病菌在抗病性强的无性系的根系分泌物及组织液中的增殖显著低于感病无性系,验证通过茎段浸泡接种筛选出的桉树无性系的准确性,同时表明根系分泌物和组织研磨液可以反映桉树不同无性系的抗病性强弱。     

广西林业科学研究院林业生物技术研究所

通过广西区林业局林木良种审定委员会认定的广西尾叶桉4号（GLU4）、广林巨尾桉5号（GLGU5）、广林巨尾桉9号（GLGU9），不但速生丰产，还具有高抗青枯病、焦枯病的特性、5～6年即可主伐，     

广西林业科学研究院林业生物技术研究所

通过广西区林业局林木良种审定委员会认定的广林尾叶桉4号（GLU），广林巨尾桉5号（GLGU），广林巨尾桉9号（GLGU），不但速生丰产，还具有高抗青枯病，焦枯病的特性，5-6年即可主伐，     

广西林业科学研究院林业生物技术研究所

通过广西区林业局林木良种审定委员会认定的广林尾叶桉4号（GLU4）、广林巨尾桉5号（GLGU5）、广林巨尾桉9号（GLGU9），不但速生丰产，还具有高抗青枯病，焦枯病的特性，5-6年即可主伐，年蓄积量每公顷达45m^3以上，比实生苗造林的遗传增益高20%-30%。     

First report of bacterial wilt caused by Ralstonia solanacearum on eucalypts in South Africa

Ralstonia solanacearum, the causal agent of bacterial wilt, has one of the widest host ranges of all phytopathogenic bacteria. This pathogen was first reported on Eucalyptus spp. in the late 1980s in Brazil. Since then, there have been reports of its occurrence on this host in Australia, China and Venezuela. Early in 1997, an 18‐month‐old clonally propagated Eucalyptus grandis × Eucalyptus camaldulensis (GC) hybrid in Zululand, KwaZulu/Natal, showed signs of wilting. The vascular tissue of infected trees was dicoloured and bacterial exudation was produced from cut surfaces. The bacterium was consistently isolated from diseased tissue, purified and identified as R. solanacearum biovar 3 race 1, using the BioLog bacterial identification system. Inoculation trials were conducted on three E. grandis × E. camaldulensis clones (GC515, GC550 and GC505). Clone GC550 displayed wilting after 3 days and all cuttings subsequently died. Clones GC515 and GC505 appeared to be less susceptible with cuttings not showing signs of disease until 7 days after inoculation. After 14 days, 90 and 80%, respectively, of cuttings of these two clones had died. This is the first report of bacterial wilt on Eucalyptus in South Africa.     

抗松材线虫病赤松组培再生植株田间生长表现

为了评价从日本引进的抗松材线虫病赤松通过无性快繁获得的再生植株在我国的生长状况.本研究对田间试种的抗病赤松6个家系12个无性系共688株再生植株进行跟踪监测.结果表明,抗病赤松0.5年生再生植株试种成活率明显低于2.5年、2年、1.5年及1年生再生植株;不同无性系间抗病赤松再生植株生长状况存在明显差异.其中,1#-A和5#-5无性系再生植株生长较好.菌根化造林试验表明,两种外生菌根菌美味牛肝菌(Be)和黄色须腹菌(R1)对抗病赤松1#-A5代、8代再生植株具有明显促生效果.此研究为今后抗病赤松再生植株造林育种提供了参考依据.     

Methods of inoculation and evaluation of Erwinia psidii in eucalypt

The dieback and wilting caused by Erwinia psidii are emerging eucalypt diseases that have been observed since 2014 in the south and central‐south regions of Brazil. Field observations have shown variability in disease severity resistance among Eucalyptus spp. clones and species. It is hypothesized that this variability is due to genetic resistance. To confirm this hypothesis, inoculations in genetically distinct eucalypt plants are necessary. However, lack of an inoculation method and disease assessment makes difficult to select resistant genotypes for use in commercial plantations or genetic breeding programmes. Three inoculation methods were tested on eight clones of Eucalyptus spp. Among them, inoculum deposition with bacteria‐impregnated toothpick on the axillary buds was the simplest and most effective, capable to reproduce the disease symptoms observed under conditions of natural infection. We also developed a rating scale for disease assessment. Among eight clones tested, only Clone 1 (Eucalyptus saligna) and Clone 2 (Eucalyptus urophylla) were resistant.     

我国桉树青枯病控制技术研究进展

阐述了桉树青枯病控制技术研究及应用所取得的进展。包括化学防治技术的研究应用情况;生物防治如拮抗细菌、菌根真菌、植物诱导抗病性以及抗病基因转导技术的研究进展;桉树抗病育种的研究与应用进展;控制桉树青枯病的营林技术措施。     

Individual resistance of Fraxinus angustifolia clones to ash dieback

The presumed resistance of individual ash trees to ash dieback caused by invasive pathogen Hymenoscyphus fraxineus is an important issue for the maintenance of ash in European forests. All known studies regarding the resistance of ash trees to ash dieback were conducted in plantations and stands of F. excelsior; however, no such data exist for F. angustifolia. Crown damage assessments were performed over four consecutive years between 2009 and 2012 at a F. angustifolia clonal plantation in Hra??ica, Slovenia. Inoculation of H. fraxineus into the branches of the most and least damaged clones of F. angustifolia and leaf phenology assessments was performed to verify the presence of defence mechanisms that limit fungal growth or promote disease escape. Additionally, root collars of selected clones were inspected for fungal infections. The crown damage assessments showed considerable differences among F. angustifolia clones, indicating genetic variability in susceptibility to ash dieback. Crown dieback progressed significantly over the 4‐year time period; the mean crown damage of individual clones in 2012 varied between 16.7% and 83.8%. Significant differences among F. angustifolia clones were found in the inoculation trials and leaf phenology assessments. However, defence mechanisms such as early leaf flushing, early leaf shedding and the ability to inhibit pathogen growth in host tissues were not confirmed. High frequency of Armillaria spp. and H. fraxineus root collar infection demonstrated the need for whole tree inspection to determine causal agent of damages on individual ash trees. Armillaria spp. may be highly associated with ash decline epidemiology.     

Incidence of dieback disease following fungal inoculations of sexually and asexually propagated shisham (Dalbergia sissoo)

Shisham (Dalbergia sissoo) is an important multipurpose tree with great economic importance, but this tree has been devastated by dieback disease. Seedlings and asexually propagated (cuttings) plants were artificially inoculated with four fungi (Fusarium solani, Botryodiplodia theobromae, Curvularia lunata and Ganoderma lucidum) to evaluate the potential role of these fungi in shisham dieback disease. Results at 2 years revealed that highest disease was caused by inoculation of F. solani (31.39%), followed by B. theobromae (19.042%) and C. lunata (12.22%), but no dieback disease was caused by G. lucidum. During both years, seedlings exhibited greater susceptibility to disease (17.24%) compared to cuttings (7.83%). In particular, F. solani caused more disease in seedlings (46.18%) compared to cuttings (16.61%). With the F. solani inoculations, maximum disease rate was observed at 8 weeks post‐inoculation both in seedlings (77%) and in cuttings (31%), but the maximum disease increase was observed at 4–5 weeks post‐inoculation. Analysis of variance showed significant differences among the different fungi and also between seedlings and cuttings. F. solani can be considered as a major fungal pathogen contributing to dieback disease of shisham, and asexual propagation can reduce the severity of dieback.     

多粘类芽孢杆菌对木麻黄青枯病的抑菌防病作用

室内测定了商品化生物农药多粘类芽孢杆菌可湿性粉剂对木麻黄青枯病病原菌的毒力。采用打孔法结果表明,多粘类芽孢杆菌对木麻黄青枯病病原菌具有良好的拮抗作用,其抑菌圈的平均直径达到9.4 mm。采集4个品系的木麻黄小枝水培生根后进行温室盆栽,采用改进的伤根淋菌法进行接种,以只施多粘类芽孢杆菌可湿性粉剂(CK1)和只接种青枯菌(CK2)为对照,施用多粘类芽孢杆菌可湿性粉剂后接种青枯菌为处理进行实验。结果表明,在两个时间点,湛江-3的防效达到了60.8%和51.6%;湛江-2的防效达到了41.5%和40.3%;广东A14的防效达到了28.8%和23.3%,差异均显著(α=0.05);广东701-3的防效为16.3%和26.8%,差异不显著,出现此原因是广东701-3抗性强于其他3个品系。综上所述,在盆栽试验中,多粘类芽孢杆菌可湿性粉剂对木麻黄青枯病有显著的防治效果,品系本身越感病,防效越高。     

Xyleborus glabratus attacks and systemic colonization by Raffaelea lauricola associated with dieback of Cinnamomum camphora in the southeastern United States

Laurel wilt, caused by Raffaelea lauricola, is responsible for extensive mortality of redbay and other American members of the Lauraceae in the southeastern United States. Raffaelea lauricola is a mycangial symbiont of the redbay ambrosia beetle (Xyleborus glabratus), and the beetle and fungus were accidentally introduced from Asia. Branch dieback of camphortree (Cinnamomum camphora), an Asian member of the Lauraceae, has been occasionally observed in areas where laurel wilt has decimated redbay populations, and R. lauricola was isolated from such camphortrees. However, the role of X. glabratus and R. lauricola in this branch dieback remains unclear. Examination of camphortrees on Jekyll Island, Georgia showed that healthy‐appearing trees and those with branch dieback had been attacked by X. glabratus, but the trees with branch dieback had four times as many beetle attacks. Raffaelea lauricola was routinely isolated from discoloured xylem near beetle tunnels in healthy trees and those with dieback. Single‐point inoculations with R. lauricola on stems of mature, healthy camphortree trees failed to induce wilt‐like symptoms or branch dieback, although areas of discoloration were scattered throughout the xylem, and R. lauricola was reisolated irregularly at various heights in some inoculated trees. In growth chamber experiments, single‐point inoculations with R. lauricola resulted in systemic colonization but no wilt symptoms or branch dieback in camphortree saplings. In contrast, inoculations at multiple points along the stem (simulating multiple attacks by the vector) caused branch dieback and wilt‐like symptoms, including a brownish, diffuse discoloration of the xylem. Camphortree appears to be more resistant than American species of Lauraceae to the vascular wilt caused by R. lauricola. The fungus does colonize camphortrees systemically, however, and can apparently cause branch dieback. This suggests that the fungus may provide brood material for X. glabratus in Asia as it does in the southeastern United States.     

桉树伞房属4个树种在广西的早期病害调查

本文调查分析了引自澳大利亚的桉树伞房属4个树种23个种源209个家系在广西柳州试验点遭受桉树Quambalaria顶梢与白叶枯萎病病害情况.4个引进树种中斑皮桉和大叶斑皮桉受害最为严重,感染率分别达99.2%和97.9%;柠檬桉和斑皮柠檬桉总体抗性表现较好,感病率为63.2%和72.4%.4个树种易感病的特性和适宜的降雨环境,是病害集中爆发的主要原因.对伞房属4个树种的下一步研究应注重于抗病种源、家系的选育.