Differenzierung der beiden Erscheinungsformen der Spitzendürre (Monilinia laxa) an Sauerkirschen ermöglicht eine Reduktion des Fungizideinsatzes zur Blüte

Since the early nineties control of twig blight on sour cherries in Rheinhessen/Germany caused by Monilinia laxa has become more and more difficult. Severe twig blight incidence even occured during cold and dry periods despite several hours of wetness are necessary for flower infecions by M. laxa conidia. Also repeated fungicide applications during bloom did not provide reliable control of twig blight. Field and laboratory studies have been carried out from 2002–2005 to find the reasons for control failures and the infection process under cold and dry conditions. On the basis of field observations frost damage of flowers and inoculum transport from untreated old cherry trees could be excluded. Monitoring studies revealed that only M. laxa caused twig blight and not M. fructicola as assumed before. The reason for the severe twig blight damage is the fact that M. laxa causes 2 different forms of twig blight. Besides the well known and often described twig blight after flower infection during rainy periods a second form of twig blight exists also caused by M. laxa but starting from “latent” infections inside the twig. These “latent” or “early” twig blight symptoms already occur at full bloom even during dry weather periods. Fungicide applications at the flowering stage do not control this form of twig blight because M. laxa is already present inside the twig. A diagnostic system is described allowing a clear differentiation of the two forms of twig blight what will lead to a reduced number of fungicide applications. Only the “true” flower infections can be controlled by fungicide treatments.     

楠木枝枯病病原菌鉴定

<正>楠木为我国传统名贵树种,其木质紧密、耐腐蚀性强,能够驱虫美化环境,是建筑、家具、雕刻的首选木料;同时具有净化空气、吸烟滞尘、涵养水源、固土防沙等功能,有着巨大的经济及生态价值。楠木主要包括润楠属(Machilus Nees)以及楠属(Phoebe Nees)植株,均属于濒危树种,在我国境内     

楠木枝枯病病原菌鉴定

Phoebe is a traditional precious tree species in China, which has great economic and ecological value. A new disease twig blight was found in the Phoebe planting area of Zhejiang province. Symptoms usually appear on the base or fork of branches with black swollen epidermis and gradually get worse resulting branch wilting or whole plant death when longitudinal epidermis cracking. The diseased samples were collected in 2017-2018 and the fungal isolate was identified as Lasiodiplodia pseudotheobromae based on morphological characteristics of colony and spore and sequence analysis of ITS region and EF1-α gene. The pathogenicity tests on Phoebe showed that L. pseudotheobromae caused the typical symptoms of twig blight. Koch′s postulates were satisfied following reisolation and identification of the isolate from the infected tissues using the methods described above. This is the first report of Phoebe twig blight caused by L. pseudotheobromae in China.     

蓝莓枝枯病拮抗细菌HMQAU140045的鉴定和抑真菌活性

以蓝莓毛色二胞枝枯病菌假可可毛色二胞Lasiodiplodia pseudotheobromae为靶标菌,通过稀释平板法从山东青岛的蓝莓种植园根际土壤中分离出20株细菌,采用对峙平板法和菌丝生长速率法筛选得到一株对靶标菌具有明显抑制效果的拮抗菌株HMQAU140045,采用凹玻片法和菌丝生长速率法测定该菌株发酵滤液对靶标菌孢子萌发和菌丝生长的影响。结果表明,稀释50倍的发酵滤液的抑制率可达100%。离体枝条试验结果表明,发酵液不同组分对蓝莓毛色二胞枝枯病的防治效果均可达90%以上。菌丝生长速率法测定结果表明,该菌株抑真菌谱广,对包括4种蓝莓枝枯病菌在内的15种植物病原真菌具有良好的拮抗作用。通过形态观察、生理生化特性以及gyrB的序列分析,确定该菌株为解淀粉芽孢杆菌Bacillus amyloliquefaciens。试验结果表明,解淀粉芽孢杆菌菌株HMQAU140045具有较好的抑真菌活性。     

黑老虎枝枯病病原鉴定及其生物学特性

<正>黑老虎[Kadsura coccinea (Lem.) A. C. Smith]又名冷饭团、布福娜,果实含丰富的Vc、Ve及多种微量元素,是山区野果珍品[1]。上世纪末,人们从野外引种试栽,目前在黔东南地区实现了规模化栽培。笔者于2017和2018年调查发现,黑老虎枝枯病在黔东南州各种植基地普遍发生,造成严重损失,但关于黑老虎病害的报道甚少[2,3]。本研究对黑老虎枝枯病的病原菌进行了分离培养、柯赫氏法则验证、形态学特征观察及多基因序列     

黑老虎枝枯病病原鉴定及其生物学特性

Kadsura coccinea (Lem.) A. C. Smith has been wildly cultivated in Southeast of Guizhou province, bearing fruit as an excellent nutrition source being rich in vitamin C, vitamin E, and a variety of trace elements. In 2017-2018, we found twig blight on Kadsura coccinea with small black dot-like structure in the late stage on lesion, a very common disease causing significant economic losses. The fungal isolates were recovered from the symptomatic stem tissues and small black dot (pycnidium) which contained transparent, unicellular and spindle-shaped conidia of (17.4±1.2) μm×(6.5±0.7) μm. The purified culture with the grayish white to dark grayish-green as well as partial straight hyphae on PDA plate was consistent with Neofusicoccum parvum, supported by the aliment and phylogenetic analyses of ITS, Ef1 α and Tub2 gene sequences (GenBank no: MK563984、MK563986 and MK563987).The pathogenicity test on leaves and stems with needle-punching method matched the symptoms described above and re-isolated the fungus confirming the Koch’s postulate. The lethal temperature for mycelial growth was 54℃ for 10 min; The strain could grow normally in most carbon and nitrogen sources except ammonium carbonate. This is the first report of Neofusicoccum parvum causing twig blight on Kadsura coccinea in China.     

Biological control of peach twig blight (Monilinia laxa) with Penicillium frequentans

In 1986 and 1988 various preparations of spores and or mycelium of the antagonist Penicillium frequentans , alone or in alternation with captan were applied to field-grown peach trees inoculated with Monilinia laxa , the cause of twig blight. Some preparations of P. frequentans containing nutrients gave significant reductions in severity of disease (from 38 to 80%) over control, comparable to that given by captan. Combinations of P. frequentans and captan gave a level of control similar to or less than that given by the antagonist or chemical alone. Populations of P. frequentans on shoots were monitored after application in 1986. When applied with nutrients, levels of P. frequentans on shoots remained higher than when the fungus was applied in the absence of nutrients. In a glasshouse experiment the effect of P. frequentans treatments on twig blight was influenced by the type and amount of M. laxa inoculum applied.     

Dravya,a product of seaweed extract (<Emphasis Type="Italic">Sargassum wightii</Emphasis>), induces resistance in cotton against<Emphasis Type="Italic">Xanthomonas campestris</Emphasis> pv.<Emphasis Type="Italic">malsvacearum</Emphasis>

Dravya, a commercially developed aqueous seaweed extract, was evaluated for its effect on the expression of symptoms of bacterial blight caused byXanthomonas campestris pv.malvacearum (E.F. Smith) Dye in cotton. Seed soaking with Dravya (1:500) followed by foliar spray thrice at intervals of 10 days (10, 20, 30 days after sowing) resulted in a reduction in blight incidence on plants by 66%, 70% and 74% as determined 40, 60 and 80 days, respectively, after sowing. Induction of systemic resistance was associated with increases in plant height, total number of bolls formed, boll weight, stem girth, chlorophyll content, total phenols and peroxidase activity, which intimates that Dravya could be used as an ecofriendly potential input in the integrated management of bacterial-blight of cotton.     

Identification and characterization of Pestalotiopsis spp. causing twig blight disease of bayberry (Myrica rubra Sieb. & Zucc) in China

Bayberry (Myrica rubra) is a fruit tree native to the subtropical regions of China. It produces fruit with a unique taste and pharmacological characteristics, thus making it a widely cultivated tree commercially in many regions of China, including Zhejiang, Fujian, Guizhou, Sichuan and Yunnan Provinces. Recently, a twig blight disease occurred on the fruit tree and caused destructive damage of plantings in the Zhejiang Province. However, the etiology of the disease was unclear. This study was carried out to identify the causal agent(s) of the blight disease on bayberry. Fungal isolates were obtained from blighted twig samples collected from bayberry fields in Xianju, Rui’an, and Huangyan of Zhejiang Province. The majority (87.9 %) of the 257 fungal isolates were identified as Pestalotiopsis spp. based on their conidial morphology. DNA sequences of the internal transcribed spacer (ITS) region of the ribosomal RNA gene and the β-tubulin gene were obtained from six representative strains (XJ27, XJ42, RA2-1, YS26, YS44 and RA1-2) of the Pestalotiopsis spp. Phylogenetic analysis showed that three of the strains (XJ27, XJ42, and RA2-1) grouped with P. versicolor (Speg.) Steyaert while the other three strains (YS26, YS44 and RA1-2) grouped with P. microspora (Speg.) Batista & Peres. Pathogenicity tests in the greenhouse showed that all these six isolates of Pestalotiopsis spp. caused twig blight disease symptoms on bayberry plants, which were the same as observed in naturally infected plants in the field. Our results clearly indicated that P. versicolor and P. microspora were the major pathogens causing the twig blight disease on bayberry in southern China.     

华北棉铃疫病菌及蓖麻疫病菌的鉴定

 近年在华北地区普遍发生棉铃疫病和蓖麻叶果疫病。对于这两种疫病菌的形态和生理特性,按标准方法分剧进行了详细观察。把棉铃疫病菌鉴定为Phytophthora boehmeriae Sawada的一个株系,并对它的寄主范围作了补充,在温度关系和有性生殖习性上它不同于已往西印度报导的棉铃上的P.palmivora Bulter和P.parasitica Dastur。蓖麻疫病菌的性状与印度的典型P.parasitica Dastur相符合,与泽田兼吉在台湾描述的P.ricini Sawada和P.formosana Sawada两个新种只在寄主范围和孢子囊长宽比倒上稍有差异。     

禾谷类作物纹枯病研究Ⅰ:水稻、玉米、小麦纹枯病和棉花立枯病四者之间的关系

 为澄清水稻、玉米、小麦纹枯病和棉花立枯病之间的关系,1980~1982年以水稻、玉米、小麦纹枯病为对象,以能代表Rhizoctonia solani Kühn的棉花立枯病为对照,从病菌无性时期的形态、培养性状、生长发育温度范围和交互接种等方面进行了比较研究。     

Diversity and pathogenicity of pestalotioid fungi associated with blueberry plants in Portugal,with description of three novel species of Neopestalotiopsis

European Journal of Plant Pathology - Blueberries (Vaccinium corymbosum) have been increasingly cultivated in Portugal. Although blueberry is known to be susceptible to twig blight and dieback...     

棉花烂铃病的发生、品种抗病性及主要病原菌致病力分析

2011~2013年,调查了我国黄河和长江流域6省70县(市)200块棉田和不同栽培模式下棉花烂铃病发生情况,田间试验评价了棉花品种对烂铃病的抗性,采用离体棉铃人工接种方法分析了棉铃烂铃主要病原菌的致病力分化情况。结果表明:(1)所有调查的棉田均有棉花烂铃病发生,其中,棉铃疫病在各地发生最为普遍而且严重,仍属于我国黄河和长江流域棉区的最主要的棉花烂铃病,其病原菌为苎麻疫霉(Phytophthora boehmeriae)。(2)与春棉直播模式相比,3种套种模式均能显著减少棉花烂铃病的发生,其中麦-棉-西瓜12∶2∶1种植模式的防效最好,减少烂铃72.96%。(3)河北、山东和河南3省审定的50个棉花品种对棉花烂铃病的抗性存在显著差异,其中邯7860、邯棉103、锦科178、百棉1号和郑农棉4号5个品种对棉花烂铃病表现了较好的抗性,单株烂铃低于3.0个。(4)苎麻疫霉在棉铃上的致病力存在显著分化。     

棉铃疫病生防细菌筛选、鉴定及制剂防治效果

为有效防治由苎麻疫霉Phytophthora boehmeriae引起的棉铃疫病,采用平板对峙培养法、离体试验和田间小区试验对棉花、玉米、番茄、黄瓜等作物根围细菌进行筛选,结合形态学观察、16S rDNA序列分析及Biolog微生物自动鉴定系统对筛选出的生防细菌进行分类鉴定,并通过离体试验对优秀生防菌2种制剂的防治效果进行评价。拮抗细菌初筛试验结果表明,在供试的1 250株作物根围细菌中,399株细菌菌株有良好的抑菌能力,其中40株拮抗细菌菌株抑菌率在80.00%以上,菌株HMB22922抑菌能力突出,对棉铃疫病菌的抑菌率为85.71%,抑菌带宽10.0 mm。室内筛选试验结果表明,菌株HMB22922、HMB23917和HMB21405的病情指数显著低于空白对照,与化学药剂对照间差异不显著,人工接种苎麻疫霉5 d和7 d后,3株菌株对棉铃疫病的防治效果分别为73.92%、69.58%、56.54%和81.34%、66.67%、64.60%。田间筛选试验结果表明,菌株HMB22922培养液对棉铃疫病的田间防治效果为47.12%～58.64%,优于其它2株供试菌株,与化学药剂的防治效果相当且防治效果稳定。生防菌株HMB22922经形态学观察、序列分析和和微生物鉴定系统被鉴定为萎缩芽胞杆菌Bacillus atrophaeus。人工接种苎麻疫霉5、7和12 d时,以菌株HMB22922为有效成分的2.5′109 CFU/mL萎缩芽胞杆菌悬浮剂的防治效果分别为86.33%、78.66%和64.44%,均优于其相同菌量培养液的防治效果。     

扁秆荆三棱种群密度对棉花形态指标､产量和品质的影响

为明确扁秆荆三棱不同种群密度对棉花形态指标?产量和品质的影响?本试验将扁秆荆三棱种群密度设为0?20?40?60?80?100株/m 26个梯度, 在棉花整个生长期每10 d测一次株高?茎粗和主茎节数, 采收期测棉花单株结铃数?单铃重?产量和纤维品质?扁秆荆三棱对棉花株高?茎粗和主茎节数影响随扁秆荆三棱种群密度的增大而增加?扁秆荆三棱种群密度为80株/m 2时对棉花第6节果枝以上结铃数和单铃重影响最大, 结铃数和单铃重相对于对照分别减少了2.86个和1.82 g?棉花的产量随扁秆荆三棱种群密度的增加而降低, 其中扁秆荆三棱种群密度为20株/m 2时影响不大?对棉花纤维品质的影响主要表现在对棉纤维马克隆值的影响和成熟度的影响?扁秆荆三棱种群密度能显著影响棉花株高?茎粗和主茎节数, 进而对棉花产量产生极大影响?扁秆荆三棱种群密度为20株/m 2时对棉花产量和品质影响不大, 因此应将扁秆荆三棱种群密度控制在20株/m 2以下?     

Effects of pyroquilon on the infection process of Monilinia laxa causing peach twig blight

The capacity of Monilinia laxa (Aderh. et Ruhl.) Honey to induce peach twig blight was lost in an albino mutant and in a wild-type strain of the pathogen treated with pyroquilon, a melanin biosynthesis inhibitor. Pyroquilon (10 ù ml^?1) inhibited melanin biosynthesis but did not inhibit mycelial growth of the pathogen or the albino mutant in vitro. These observations indicate that the compound interferes in some manner with the infection process of host cells.     

Moisture Sources in Relation to Conidial Dissemination and Infection by Cladosporium carpophilum Within Peach Canopies

ABSTRACT Cladosporium carpophilum, the causal agent of peach scab, overwinters in lesions on 1-year-old twigs, from which conidia infect the developing fruit during spring and early summer. Twig lesions constitute the sole source of initial inoculum; therefore, the mode of dissemination of conidia from such lesions to the fruit is of considerable interest. In a 4-year study, we determined the relative importance of air- versus water-borne conidia and their interaction with different fruit wetness sources (splash, twig runoff, and dew) in a peach orchard with areas that had been treated or not treated with fungicide the previous year. The rareness of scab twig lesions in the previously sprayed trees implied that fruit infection in these trees would occur primarily by airborne conidia from unsprayed trees nearby (located within the same tree row or the adjacent row). In the unsprayed areas, additional infections could occur by short-distance waterborne dissemination of conidia from locally abundant twig lesions via splashing or runoff. Beginning at calyx fall, individual fruit were protected from splash by rain shields, protected from runoff by cotton wicks placed proximal to the peduncle, or left untreated. Rain shields were adjustable, allowing rain or dew to be excluded selectively. Various combinations of the shield and wick treatments were implemented in the previously sprayed and unsprayed areas, and statistical comparison of fruit scab severity between individual treatments by linear contrasts allowed us to untangle the relative contributions of the various sources of inoculum and fruit wetness. Results showed that aerial dissemination of conidia contributed little to fruit scab development, even in the presence of fruit surface wetness caused by splashing, runoff, or dew. In contrast, waterborne conidia contributed considerably and significantly (P < 0.0001) to disease development. This was due primarily to the importance of splash in disseminating conidia from twig lesions to the fruit, given that exclusion of splashing via rain shields decreased disease severity by >90%. Runoff water from the twig to the fruit via the peduncle also contributed to scab development, as evidenced by the fact that exclusion of runoff by cotton wicks reduced disease severity by 31.6 to 44.9%; however, this effect was not always statistically significant. The exclusion of dew did not reduce scab severity (P > 0.4), suggesting that it played a limited role in infection in the presence of other fruit wetness sources.     

荆芥茎枯病病原菌的分离与鉴定

 The pathogen causing stem blight was isolated from diseased stem of Schizonepeta tenuifolia Briq.. Based on rDNA-ITS analysis, morphological characteristic and pathogenicity test, the pathogen was identified as Phytophthora nicotianae.     

辣椒溶杆菌NF87-2防治瓜类蔬菜蔓枯病的研究

由黑腐球壳菌Didymella bryoniae引起的瓜类蔬菜蔓枯病是一种重要真菌土传病害,造成瓜类蔬菜生产上重大的经济损失。本研究以蔓枯病菌DB-20为靶标菌,采用平板对峙培养法,测定了拮抗细菌及其代谢产物对蔓枯病菌菌丝生长和孢子萌发的的室内抑制作用,拮抗细菌和蔓枯病菌同时接种后,测定西瓜种子的发芽率和出苗率,采用盆栽试验研究拮抗细菌对黄瓜蔓枯病的防治效果。结果表明,辣椒溶杆菌Lysobacter capsici NF87-2对蔓枯病菌菌丝生长的室内抑制率为81.6%,菌株NF87-2及其次生代谢物对蔓枯病菌孢子萌发的抑制率分别为59.4%和67.2%。蔓枯病菌DB-20处理的京欣一号西瓜种子发芽率和出苗率分别为48%和38%,菌株NF87-2＋DB-20同时接种处理组的西瓜种子发芽率和出苗率分别为83%和82%。菌株NF87-2发酵液及其代谢产物对黄瓜蔓枯病的盆栽防治效果分别为81.6%和66.5%。辣椒溶杆菌NF87-2是一株具有较好生防应用潜力的拮抗菌株,有望开发成防治瓜类蔬菜蔓枯病的生物杀菌剂。     

Characterization of pathotypes among isolates of Xanthomonas axonopodis pv. manihotis in Colombia

Cassava bacterial blight, caused by Xanthomonas axonopodis pv. manihotis ( Xam ) is a destructive disease occurring in most cassava growing-areas. Although Colombian isolates of Xam differ in DNA polymorphism and pathogenicity, no suitable host differentials have been identified to demonstrate physiological specialization. A set of 26 Xam isolates from three edaphoclimatic zones (ECZs) in Colombia was selected for inoculation on a set of 17 potential cassava differentials. Leaf inoculation and stem puncture were used in order to detect possible specific interactions between cultivars and isolates. Cultivar × isolate interaction was highly significant ( P  < 0·001) after stem inoculation, but not after leaf inoculation. The stem inoculation technique was selected as a method for resistance screening of cassava cultivars for bacterial blight resistance. A highly significant interaction was also detected when cultivar behaviour was rated as area under the disease progress curve (AUDPC) after stem inoculation. Different pathotypes were defined among the 26 isolates and differential cultivars were proposed to define the pathotypic composition of Xam populations in three ECZs in Colombia. The results should help to improve selection of sources of resistance to cassava bacterial blight.