First detection of Neoscytalidium dimidiatum associated with canker disease in Egyptian Ficus trees

In September 2013, a canker disease of Ficus nitida and F. benjamina was reported for the first time in Assiut governorate, Egypt. Infected samples were collected from various locations. Pure cultures of a fungus were isolated on potato dextrose agar at 25°C from diseased plants. Morphological investigation and DNA sequencing showed that the causal agent was Neoscytalidium dimidiatum. A pathogenicity test conducted using 2‐year‐old plants of each host gave 70%–80% infection, and the pathogen was reisolated from the inoculated plants. A pure culture of N. dimidiatum was deposited in the culture collection of the Assiut University Mycological Centre (AUMC) under the code AUMC 9293 and the ITS sequence was placed in NCBI under accession number KX985929 .     

Genotypic diversity and distribution of Sphaeropsis sapinea within Pinus radiata trees from northern Spain

Sphaeropsis sapinea is an important latent pathogen of Pinus spp., outbreaks of which have a considerable impact on plantations. This study considers the population diversity and distribution of S. sapinea in northern Spain at different spatial scales from single plantations to a wide area covered by Pinus radiata trees. Estimation of genotypic diversity is an important component of the analysis of the genetic structure of plant pathogen populations. Ten simple sequence repeat (SSR) markers were used, together with vegetative compatibility tests, to study the genetic diversity among S. sapinea isolates. Polymorphism analysis at SSR loci is a simple and direct approach for estimating the genetic diversity of S. sapinea isolates. From a total of 86 isolates collected from four different areas, 14 microsatellite haplotypes and 13 vegetative compatibility groups (VCGs) were identified. The percentage of maximum genotypic diversity, based on Stoddart and Taylor's index, for microsatellites of the northern Spain population ranged from 14.6% to 38.1% and from 8.0% to 29.4% for VCGs. Analysis of these markers and vegetative compatibility groups confirmed that S. sapinea reproduces mainly asexually due to its reduced genotypic diversity in spatially close populations. Isolates of S. sapinea from northern Spain populations were predominantly monomorphic at the tested SSR loci. Vegetative compatibility groups also indicate a low level of genetic variability in these samples, which appear to be clonal.     

Host specificity of co‐infecting Botryosphaeriaceae on ornamental and forest trees in the Western Balkans

The Botryosphaeriaceae is a diverse family of endophytes and fungal pathogens of mainly woody plants. We considered the host range and distribution of these fungi by sampling diseased ornamental and forest trees and shrubs in Serbia, Montenegro, Bosnia and Herzegovina, spanning a Mediterranean and a Continental climatic region. In total, ten Botryosphaeriaceae species were identified in the Western Balkans and with the exception of Sphaeropsis visci and Phaeobotryon cupressi, which occurred on one host, all the species had a broader host range. Phaeobotryon cupressi was found only in the Mediterranean region and S. visci, Dothiorella sp., Dothiorella sarmentorum and Diplodia seriata were present only in the Continental region. Pathogenicity tests were conducted on a variety of hosts from which the Botryosphaeriaceae species were isolated. These included leaves and/or stems of seedlings of 21 hosts, and cut leaves and/or branches of six hosts. Moreover, stems of seedlings of Chamaecyparis lawsoniana, Cedrus deodara, Picea omorika, Pinus patula and Eucalyptus grandis were inoculated as hosts from which some or all of the Botryosphaeriaceae species used for inoculation were not isolated. Inoculations showed that the majority of these fungi could also co‐infect hosts other than those from which they were isolated. The results suggest that most of the species have broad host ranges and can potentially cause disease on a broad range of tree species under certain conditions.     

First record of Ektaphelenchoides pini associated with Ips sexdentatus on Pinus nigra laricio in Italy

In February 2015, an unexpected windstorm downed five hectares of a European black pine Pinus nigra subsp. laricio forest formation located close to Vallombrosa, Florence (Central Italy). In the following spring, an extensive survey was conducted in the area. Felled trees, stumps and all the suitable plant material were screened for the presence of the pinewood nematode (PWN), Bursaphelenchus xylophilus, by sampling wood and bark. Bark beetles were then collected from the gallery systems on the inner side of bark samples and observed in the laboratory. The following bark beetles were morphologically identified: Ips sexdentatus, Orthotomicus erosus, O. laricis and Pityogenes bidentatusa. The dissection of Ips sexdentatus allowed the extraction of numerous nematodes that were morphologically and molecularly identified as Ektaphelenchoides pini. Conversely, only few nematode specimens were isolated from either pine bark or wood. These individuals could be only molecularly identified and belonged to an undescribed nematode taxon. Even though no PWN was recorded in the investigated sites, our survey allowed the detection of a new association between E. pini and I. sexdentatus on P. nigra.     

Screening for host responses in Acacia to a canker and wilt pathogen,Ceratocystis manginecans

In Vietnam, the productivity of Acacia hybrid (Acacia mangium x A. auriculiformis) plantations is being threatened by an aggressive canker pathogen, Ceratocystis manginecans, and selection for tolerance is the main control strategy. A pot trial was established in Binh Duong province to screen for the host response of nine Acacia genotypes (six Acacia hybrid clones, two A. auriculiformis clones and mixed provenance seedlings of A. mangium) to artificial inoculation with three isolates of C. manginecans. Lesion lengths as measured on the inner bark suggested that the two A. auriculiformis clones were relatively more tolerant to C. manginecans than the A. mangium genotype. In contrast, the lesion lengths of all six Acacia hybrid clones fell between the A. auriculiformis and A. mangium genotypes. The results of this study indicate that among the Acacia hybrid clones, BV10 showed the most tolerance to C. manginecans. Chemical analysis of crude sapwood extracts sampled from the lesion provided some evidence that induced phenolic compounds, particularly tetrahydroxyflavanone and condensed tannins may have a defensive role in the Acacia—C. manginecans pathosystem. However, results were not consistent across individual Acacia hybrid clones and A. mangium genotypes.     

Assessment of molecular detection of Fusarium circinatum in insects and passive spore traps in Pinus radiata plantations

Fusarium circinatum is the causal agent of pitch canker, a destructive disease that threatens natural and planted pine forests around the world. Although pitch canker has caused problems in Spain and Portugal, concerning Europe as a whole, the fungus is not established across the pine distribution area. Its dispersion by wind and/or insect vectors could nevertheless play a role in the colonization of currently uninfected stands. It is therefore crucial to develop monitoring tools for its detection. To this end, we assessed the molecular detection of the pathogen in environmental samples of bark beetles and passive spore traps, collected in two infected Pinus radiata plantations in Basque country, Spain. The spread pattern of F. circinatum was assessed by an experimental design that included insect and spore traps installed at the centre, at the edge and outside the plots. Our results showed that F. circinatum was detected in both types of samples, at almost all collection dates. In both type of samples, positive detections were mainly found at the centre of the plots, a lower proportion at the edge, and very few outside. This suggests that long‐distance dispersion of Fusarium circinatum does not rely on wind spore dispersal neither on insect flight. Our study also shows that molecular methods are a powerful tool to monitor the pathogen in environmental samples.     

First molecular detection of Lecanosticta acicola from Poland on Pinus mugo

The presence of quarantine pathogen Lecanosticta acicola, the causal agent of brown spot needle blight, was confirmed using molecular methods for the first time in northern part of Poland on the coastal area adjacent to the Baltic Sea. This area includes sandy beaches, where Pinus mugo and P. sylvestris were planted. Symptomatic needles were collected in 2017 from 20 P. mugo trees growing in one stand in Ustka. Typical symptoms of brown spot needle blight infection, including dead needle tips and central zones with yellow or reddish brown, circular spots in green tissue, were observed on all samples. Only, the asexual stage of L. acicola was obtained during this work. The pathogen species identity was confirmed using classical morphological methods (microscopic examination of the infected needles), real‐time and species‐specific priming (SSPP) PCR, and ITS sequencing. Analysis of mating‐type (MAT) genes showed the presence of both mating types in northern Poland.     

Life cycle and in vitro sporulation dynamics of Corinectria constricta,the causal agent of Pinus radiata stem canker,in Chile

In 2008, a canker disease caused by the fungus Corinectria constricta was detected in southern Chile. The causal agent was previously identified as Neonectria fuckeliana (now Corinectria fuckeliana), which has been associated with stem cankers in Pinus radiata plantations in New Zealand since the 1990s. Many basic aspects of the life cycle of C. constricta remain unknown. The current study aimed to (a) document the periods during which C. constricta fruiting bodies are present in P. radiata plantations and associated factors; (b) determine the C. constricta life cycle in P. radiata plantations in southern Chile; and (c) evaluate, under in vitro conditions, the sporulation dynamics of ascospores. The first and second aims were carried out by evaluating affected plantations every 15 days, identifying asexual and sexual fungal structures, and recording the time periods when the structures were present. The third aim was achieved with in vitro tests in Petri dishes simulating humidity chambers. The life cycle was characterized by the presence of sporodochia from the Cylindrocarpon‐like (asexual form of C. constricta) morph during the autumn of 2012 (March–May). Subsequently, perithecia began to form on the sporodochia during April of 2012, taking approximately 3 months to mature (May–July), persisting for the rest of the year and providing inoculum to infect new trees. The development of perithecia in winter demonstrates that this is the most important period for dispersal and infection. In terms of sporulation dynamics, perithecia can release ascospores up to eight days following a wetting event; without this event, the spores are not released.     

Identification and characterization of bacterial strains associated with diseased oak trees in Northern Iran

Oak decline syndrome is characterized by periodic occurrences of decline and death of oaks over widespread areas. An outbreak of a new emerging disease on oak trees was reported in the Hyrcanian forest of Iran (Mazandaran and Golestan provinces) that showed stem bleeding and canker symptoms. Bacterial isolates were characterized through biochemical and physiological tests, protein electrophoresis, DNA fingerprinting (rep‐PCR, ERIC and BOX primers) and sequencing of 16S rRNA and MLSA (multilocus sequencing analysis) for housekeeping genes (gyrB, infB and atpD). A complex community of the genus Brenneria spp. (Brenneria goodwinii, Brenneria roseae subsp. roseae, Brenneria sp. and Brenneria nigrifluens) and a few isolates in the genus Gibbsiella were identified as major groups involved. Isolate differentiation was more accurate using concatenated partial gene sequences within the main groups. All bacterial isolates showed hypersensitivity reactions (HR) on Pelargonium leaves (Pelargonium × hortorum). Pathogenicity studies of different Brenneria and Gibbsiella strains revealed that they have potential to cause the disease in oak seedlings and devastating oak canker and stem bleeding symptoms in northern Iran. Due to the presence of several potentially pathogenic agent(s) associated with the oak decline, identification of the principal agent(s) is of major interest. To our knowledge, this is the first report of potentially pathogenic bacteria associated with oak bleeding and canker in Iran.     

江苏杨树烂皮病发生状况调查及化学防治试验

通过对江苏省杨树烂皮病发生状况调查发现,在新沂,六合和仪征3个地区有杨树烂皮病发生。在调查的4 417株杨树中,平均发病率占11.32%;杨树烂皮病的发生与树种、树龄、地形、土壤、坡向以及虫害的关系均较密切。苗圃内不同药剂、配比度对杨树苗刮皮后的涂药试验发现,吡唑醚菌酯500,1 000,1 500倍液3种配比度的防治效果均在88%以上,嘧菌酯500倍液的防治效果高于80%。说明在苗圃用吡唑醚菌酯1 000倍和1 500倍液防治杨树烂皮病,可以取得良好的防治效果。     

BACTERIAL SWOLLEN STEM CANKER ON POPLAR:THE DISEASE AND ITS CAUSES

The bacterial swollen stem canker of poplar is prevalent in planted poplars ofnortheast China.Serious damage occurs in the form of necrosis,putridity,cankers,swollen stemsand discolored wood of trunks and branches of young and mature trees.Tests of allergic reaction,pathogenicity,culture characteristic,Gram stain and anaerobic culture revealed that the pathogen isErwinia sp.Its occurrence depends mainly on the predisposing factors of the disease among whichthe susceptibility of poplars is the most important one.The disease becomes widespread in associa-tion with low-lying and high-humidity terrain,frost injury,node wounds,insect damage,and prun-ing and other mechanical wounds.Harmful factors promote the disease.     

樟树溃疡病病原菌再鉴定

樟树溃疡病是湖南新植樟树上发生的一种重要病害，导致植株大量死亡。经分离、接种、再分离试验确定致病茵。根据病原茵的形态特征、培养性状和致病性，该病茵鉴定为葡萄座腔菌(Botyasphaeria dothidena ces et de Not)，无性态为七叶树壳梭孢(Fusicoccum aesculi Corda)。     

洞庭湖区杨树苗木溃疡病调查研究

通过对洞庭湖区56块杨树苗圃地的两次实地调查,发现洞庭湖区杨树苗木溃疡病发生普遍,室内培养检测为水泡型溃疡病。两次调查发现第二次调查危害较第一次调查轻,一年生苗圃地较二、三年生苗圃地轻。分析了洞庭湖区杨树苗木溃疡病的危害情况及其原因,并为育苗和造林用苗选择提供依据和防治建议。     

8种杀菌剂对桉树溃疡病菌的室内毒力测定

对桉树溃疡病菌(Phoma eucalyptica)的杀菌剂室内毒力测定结果表明,多菌灵、根腐宁和宝宁对菌丝生长的抑制作用较大;代森锰锌、克露、宝宁和甲霜灵对分生孢子萌发的抑制作用较强。甲霜灵.锰锌和根腐宁对植株的保护效果较好,治疗效果以根腐宁为最佳,克露和百菌清次之。     

Anatomy of bacterial canker onMaackia amurensis var.buergeri

An anatomical study of the canker onMaackia amurensis var.buergeri was carried out. The initial symptoms appeared as a longitudinal series of swellings and slightly swollen bark. First, anatomical abnormalities appeared near the cambial zone. Xylem formation was suppressed and hyperplasia of irregular ray parenchyma cells occurred, then the swellings appeared. The irregular cells increased in number, then, the surface of swollen bark burst. The ruptured swellings coalesced to form long irregular cankers. A part of this paper was presented at the 106th Meeting of the Jpn. For. Soc. (1994).     

碳酸氢钠等药剂对水泡型杨树溃疡病的防治研究

对水泡型杨树溃疡病进行了碳酸氢钠和福美胂的室内抗菌活性测定和室外防治试验。当培养基中碳酸氢钠浓度为12 g/L时,溃疡病菌菌丝生长抑制率为96.71%;当培养基中福美胂含量为30 mg/L时,菌丝生长抑制率为100%。在野外40%福美胂150倍液和碳酸氢钠10倍液施药后2周防治效果分别为48.69%和67.74%。碳酸氢钠是一种价格低廉、效果理想、安全的无机化学药剂,对杨树溃疡病的防治有推广和应用价值。     

STUDY ON THE HOST BIOLOGICAL INDUCED RESISTANCE OF BACTERIAL CANKER OF POPLAR

ThefirstrePortabouttheprotectiveeffeetofless-aggrssivestrainswerethatSalamaninoculatedtheless-aggrssivcstrainsofI`tfnchingIobaccoontobaccoandIeaditob-tainpartresistance.ANerthen,thcexistofinducedresistancehavebeenrcPortonseveralkindsofplantssuchasPnIms,(*cstnut.Ma-hl.v.,1tcumis.lIlmus.lI'4'5'7.8.9.l().14.l5.16.I7.l8.1'J2lj.21=4.2s.2f'.=7.2x.3()IThei11ducedresistanceofplantsisassocl-atcdt`,iththeincrcaseofthelc17clofthepllellem*tl1eprocesscsofphellemaredcpcndonthcactivelevcloftheperoxidas…     

Occurrence and diversity of Phytophthora species in declining broadleaf forests in western Ukraine

In western Ukraine, forest decline and dieback of several broadleaved tree species have become increasingly evident during recent years, and surveys in some areas have shown symptoms indicative of Phytophthora infections. In this study, we aimed to determine the occurrence and diversity of Phytophthora species associated with several broadleaved tree species (Alnus glutinosa, Betula pendula, Castanea sativa, Fagus sylvatica and Quercus robur) from forest stands where dieback has been observed. Rhizosphere soil samples were collected from 14 forest stands during 2017 and 2018 and tested for the presence of Phytophthora species using morphological and molecular methods. Seven Phytophthora species (P. bilorbang, P. cactorum, P. gallica, P. gonapodyides, P. lacustris, P. plurivora and P. polonica), and two other clade six taxa were detected from the various forest types, several of which are probable agents responsible for decline. Four of the Phytophthora species (P. bilorbang, P. gallica, P. plurivora and P. polonica) have previously never been reported from broadleaf forests in Ukraine.