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草坪腐霉疫病是禾本科草坪的重要病害,其中主要为瓜果腐霉Pythium aphanidermatum（Eds）．Fitzp,禾谷腐霉P．graminicola Subram和终极腐霉P．ultimum Trow等。草坪腐霉疫病的防治是草坪护养工作的关键。 相似文献
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草坪腐霉枯萎病也叫绵腐病、油斑病等。该病病原菌较多,如禾草腐霉、终极腐霉和瓜果腐霉等20余种腐霉菌都能引发这种病害。气温高、雨水多、湿度大、土壤含氮量高或碱 相似文献
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腐霉对甲霜灵抗性测定及其生物防治 总被引：8，自引：3，他引：8
测定了腐霉属的8个种209个菌株对甲霜灵在浓度为0.5和50ug/ml时的抗性，从实验中观察到不同菌株对甲霜灵抗性变化的范围非常大，有95株在0.5ug/ml时，菌丝即停止生长，在20株在50ug/ml时，菌丝生长速度与对照几乎一样。经鉴定，这209株菌中，优势种为终极腐霉(Pythium ultimum）和刺腐霉(P.spinosum)。20株高抗菌中,P.ultimum占16株，P.irregulare占2株，P.spinosum和P.graminicola各占1株。盆栽试验表明：假单胞菌株Pseudomonas sp.CR56对高抗菌株P.ultimum ONCUR01引起黄瓜苗期猝倒病具有显著的防效，防效与甲霜灵和五氯硝基苯相比，达到极显著差异。 相似文献
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大白菜黑腐病的病因、传染及防治王秀芬（河北农业大学农学院保定０７１００１）大白菜黑腐病是由细菌引起的病害。主要症状是从叶缘开始，先叶脉变黑，而后病部向两侧和内部扩展，最后形成“Ｖ”字形黄褐色枯斑。病斑周围叶组织淡黄色，与健部界限不明，有时病菌可沿叶脉... 相似文献
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2009年,南京中山植物园王莲育苗池中的朗伍德王莲(Victoria‘Longwood Hybrid’)发生了叶片腐烂病。按照柯赫氏法则对其进行了病原物的分离、纯化和致病性测定,并对菌株进行了形态学和分子生物学鉴定。从发病部位稳定分离到形态一致的低等真菌;致病性测定结果表明,回接后发病株产生与自然侵染相同的症状,并重新分离到相同菌株。通过病原菌形态特征和核糖体rDNA ITS序列分析,病株分离物被鉴定为旋柄腐霉(Pythium helicoides)。这是国内外首次报道在王莲上分离出旋柄腐霉并证明其为王莲的致病菌。该病害被定名为王莲腐霉叶腐病。 相似文献
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为有效防控黄瓜绵腐病,本研究对自江西省南昌市南昌县武阳镇和八一乡采集的黄瓜绵腐病病样进行分离,基于致病性测定、形态学特征和分子生物学方法对其进行鉴定,并采用菌丝生长速率法测定甲霜灵、霜霉威、霜脲氰、烯酰吗啉4种常用杀菌剂对该病原菌和辣椒疫霉Phytophthora capsici的抑制效果。结果表明,自武阳镇和八一乡采集的病样经分离、纯化培养后分别获得12株和10株菌株;自武阳镇分离的病原菌的藏卵器柄较直,藏卵器大小为18.1~32.9 μm;自八一乡分离的病原菌的藏卵器柄较弯曲,藏卵器大小为15.1~25.3 μm;结合致病性测定及rDNA-ITS测序结果,将自武阳镇分离的病原菌鉴定为瓜果腐霉Pythium aphanidermatum,将自八一乡分离的病原菌鉴定为德里腐霉Py.deliense。室内毒力测定结果表明,甲霜灵对瓜果腐霉和德里腐霉抑制效果最好,EC50分别为0.71 μg/mL和0.25 μg/mL;霜脲氰次之,EC50分别为3.68 μg/mL和3.36 μg/mL,甲霜灵、霜霉威、霜脲氰3种杀菌剂对瓜果腐霉、德里腐霉和辣椒疫霉的抑制效果差别不大,但烯酰吗啉对瓜果腐霉、德里腐霉和辣椒疫霉抑制效果差异明显,EC50分别为18.06、33.58和0.18 μg/mL,表明防治黄瓜绵腐病优先选择甲霜灵。 相似文献
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Reduced persistence of metalaxyl in soil associated with its failure to control cavity spot of carrots 总被引：3，自引：2，他引：1
Metalaxyl was used to control Pythium diseases of carrots in experiments on farms with a history of cavity spot. The first experiment compared the method of application (sprayed, banded or broadcast) and rate (0, 1.5, 3 or 6 kg a.i. ha−1 ) one week after sowing. Three additional experiments compared the rate (0, 0.75, 1.5 or 3 kg a.i. ha−1 ) and time (sowing, 1- to 2- or 4- to 5-true-leaf stage) of application. In expt 1, the application of metalaxyl, but not the method by which it was applied, increased yield by 20% and significantly reduced the incidence of cavity spot, forking and misshapen carrots. In expts 2, 3 and 4, neither the rate nor time of application affected yield or reduced the incidence of Pythium diseases. Comparison of the sites showed that they differed in past metalaxyl usage. Metalaxyl had not been used on the site of expt 1, but had been used previously at sites 2, 3 and 4. Laboratory experiments were conducted to determine whether these differences in efficacy resulted from reduced sensitivity of Pythium isolates to metalaxyl, or reduced persistence of metalaxyl in soil. ED50 values showed that there was no reduction in metalaxyl sensitivity. The half-life of metalaxyl was 82 days in soil from expt 1, but was 10 days or fewer in soils from expts 2, 3 and 4. Thus the failure of metalaxyl to control Pythium diseases was associated with reduced persistence in soil, not reduced sensitivity of the target fungi. 相似文献
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Koji KAGEYAMA Tomoaki AOYAGI Rumi SUNOUCHI Hirokazu FUKUI 《Journal of General Plant Pathology》2002,68(1):15-20
Miniature roses growing in an ebb-and-flow watering system developed dieback during the summer growing season of 1996 in Gifu
Prefecture. The main diagnostic symptoms were chlorosis of leaf followed by blight, and a brown, water-soaked root rot followed
by dieback. Pythium isolates were recovered from the rotted root. The isolates form proliferous ellipsoidal papillate sporangia, spherical smooth
oogonia, elongate antheridia, and aplerotic oospores. The optimum temperature for hyphal growth was 35°C with a growth rate
of 34 mm/24 hr. Optimum temperature of zoospore formation (25-30°C) was lower than that of mycelial growth, and zoospores
were produced even at 10°C. The isolates were identified as P. helicoides on the basis of these characteristics. In pathogenicity tests disease severity was highest at the highest tested temperature
(35°C) at which the disease naturally occurred in summer. Four days after inoculation, the leaves turned yellow and the roots
had a water-soaked rot, followed by leaf blight and root dieback after 7 days. The disease transmission test showed that diseased
plants were found throughout the bench after 10 days.
Received 4 July 2001/ Accepted in revised form 10 October 2001 相似文献
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A comparison of oomycete diversity in reed stands ( Phragmites australis ) of Lake Constance, Germany, and maize fields close by provided evidence for the occurrence of natural hybridization between Pythium phragmitis , a newly described reed pathogen, and an as-yet unknown Pythium species closely related to P. phragmitis and P. arrhenomanes . Internal transcribed spacer and β-tubulin sequences of a large set of Pythium isolates from reeds showed dimorphic signals at several positions, indicative of a mixture of characters of two parent species. Involvement of P. phragmitis in the putative hybrid species was confirmed after cloning and sequencing of ITS regions and β-tubulin genes of the hybrid isolates. Mitochondrially inherited cox II gene sequences did not show dimorphic sites and suggested that the hybridization event was relatively ancient, or that other species might be involved. Intermediate habitat preferences, morphological characters and aggressiveness towards reeds and other grasses confirmed the suggestion that these isolates comprise a natural hybrid between two Pythium species. Pythium arrhenomanes , likely to be involved in the putative hybrid's evolution, was repeatedly isolated from maize fields adjacent to P. phragmitis -infested reed stands. The interface between natural habitats with established oomycete communities and agricultural fields with potentially introduced pathogens might constitute an evolutionary hot-spot giving rise to new species with as-yet unknown host ranges. As indicated by inoculation tests, the hybrid was significantly more pathogenic towards reed rhizomes than P. phragmitis , which caused no damage to these organs. This is apparently the first report of the occurrence of natural hybridization in Pythium . 相似文献
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Evaluation of fungicides for the control of carrot cavity spot 总被引：2，自引：0，他引：2
Cavity spot is one of the most common and serious diseases of carrot (Daucus carota L). The disease, caused by different species of Pythium, including P. violae Chesters & Hickman, P. sulcatum Pratt & Mitchell and P. sylvaticum Campbell & Hendrix, leads to frequent high rejection rates during grading worldwide. In the area of the city of Québec, the disease is caused mainly by P. sulcatum, P. sylvaticum and P. macrosporum Vaartaja & van der Plaats-Niterink. Cavity spot can be controlled with metalaxyl, but reports are emerging that this treatment show little or no efficacy in many regions. This situation reinforces the need for alternative fungicides. The objectives of the present study were: (1) to determine the sensitivity of 14 pathogenic isolates of P. sulcatum, P. sylvaticum and P. macrosporum collected from carrots produced in the area of the city of Québec to different broad-spectrum and oomycete-specific fungicides (chlorothalonil, etridiazole, fludioxonil, fosetyl-Al, metalaxyl, zoxamide), (2) to evaluate the efficacy of the fungicides in controlling cavity spot, and (3) to evaluate the risk of resistance development of isolates with the best-performing fungicide(s). The determination of EC50 for the fungicides tested showed that most isolates were highly sensitive to both metalaxyl and zoxamide but insensitive to fludioxonil, fosetyl-Al and chlorothalonil. In greenhouse assays, only zoxamide provided significant and consistent disease control as measured by the number of cavity spot lesions caused by P. sulcatum. Investigations into the risk of resistance development to zoxamide showed that, for specific isolates, repeated exposure to the fungicide resulted in a loss of sensitivity. 相似文献
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Molecular characterization and pathogenicity of Pythium species associated with damping-off in greenhouse cucumber (Cucumis sativus) in Oman 总被引：3，自引：1，他引：3
A. M. Al-Sa'di † A. Drenth M. L. Deadman A. W. A. M. de Cock E. A. B. Aitken 《Plant pathology》2007,56(1):140-149
A study was undertaken in 2004 and 2005 to characterize pathogens associated with damping-off of greenhouse-grown cucumber seedlings in 13 districts in Oman. Identification of Pythium to the species level was based on sequences of the internal transcribed spacer (ITS) of the ribosomal DNA. Of the 98 Pythium isolates collected during the survey, Pythium aphanidermatum , P. spinosum , P. splendens and P. oligandrum accounted for 76%, 22%, 1% and 1%, respectively. Pythium aphanidermatum was isolated from all of the districts, while P. spinosum was isolated from seven districts. Pathogenicity tests showed inter- and intraspecific variation in aggressiveness between Pythium species. Pythium aphanidermatum , P. spinosum and P. splendens were found to be highly aggressive at 25°C. However, the aggressiveness of P. spinosum decreased when the temperature was raised to 30°C, which was found to correspond to the lower frequency of isolation of P. spinosum in the warmer seasons, compared to the cooler time of the year. Pythium aphanidermatum exhibited limited intraspecific variation in the sequences of the ITS region of the rDNA and showed 100% similarity to the corresponding P. aphanidermatum sequences from GenBank. The ITS sequence data, as well as morphological characteristics of P. spinosum isolates, showed a high level of similarity within and between P. spinosum and P. kunmingense , and suggested that the two species were synonymous. This study represents the first report of P. spinosum, P. splendens and P. oligandrum in Oman. 相似文献
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Pseudomonas putida 40RNF applied to seed pellets reduced the occurrence of Pythium damping-off of sugar beet. A density of 6 × 107 40RNF per pellet reduced Pythium damping-off from 70 to 26% when seeds were sown in artificially infested soil (250 propagules Pythium ultimum per g dry soil). The efficacy of 40RNF was dependent on its density in the seed pellet (in the range 2 × 104 –6 × 108 per pellet) and on the number of propagules of Pythium in soil. 40RNF declined to or stabilized at approximately 1 × 106 per pellet 3 days after planting, and this was independent of the inoculum density. This indicated that the crucial steps resulting in damping-off of sugar beet caused by Pythium ultimum must occur within 3–4 days of sowing. 40RNF reduced pericarp colonization by P. ultimum by 43% 48 h after planting and caused a 68% decrease in the number of sporangia of P. ultimum in the surrounding soil (0.0–5.0 mm). P. putida 40RNF also reduced pre and post-emergence damping-off (from 69.5 to 37.5%) caused by indigenous populations of Pythium species in an infested soil and this was as effective as the fungicide hymexazol (69.5 to 40%). 相似文献
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从水稻旱育秧病苗上分离到67个菌株 ,经鉴定分属于镰刀菌58个、腐霉菌7个、丝核菌2个。经回接测定其致病性 ,结果表明致病的镰刀菌主要是串珠镰刀菌 (Fusarium moniliforme) ;腐霉菌中主要是盐腐霉 (Pythium salinum)、间生腐霉 (P .interedium)和顶生腐霉 (P .acrogenum) ;丝核菌为立枯丝核菌 (Rhizoctonia solani)。接种试验表明串珠镰刀菌在6～8d龄幼苗的根中部侵染发病率最高 ,腐霉菌和丝核菌在一叶一心期茎基部侵染发病率最高。药剂试验表明以浸种灵(二硫氰基甲烷)、土菌消(hymexazol)、甲霜灵(metalaxyl)等种子处理加土壤处理 ,防效优于单独种子处理或土壤处理。 相似文献
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Summary. Experiments were conducted between 1985 and 1988 to evaluate the effect of duration and time of solarization on the control of two broom rapes ( Orobanche aegyptiaca Pers., O. crenata Forsk.) and other weeds common in the fields of faba bean ( Vicia faba L.) and lentil ( Lens culinaris Medik.) in West Asia. Solarization was performed by applying clear polyethylene sheet to the soil for 0, 10, 20, or 40 days in 1985/86, 0, 30, or 40 days in 1986/87 and 0, 20, 30, 40 or 50 days in 1987/88 during the hot season (July and August) and for 50 days immediately before sowing during milder weather (September and October) in 1986/87. Best control was obtained with solarization for 30–50 days in the hot season. Maximum soil temperature under polyethylene at 5 cm was 55°C in 1985, 48°C in 1986 and 57°C in 1987. Broomrape dry weight decreased in the first experiment by more than 90% in both faba bean and lentil fields. Solarization controlled broom-rape and other weeds in the following two seasons when the soil was left undisturbed during the season of the treatment. 相似文献
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研究了温室条件下45份草地早熟禾材料对腐霉枯萎病的抗病性差异.结果表明,不同接种条件下草地早熟禾的发病率存在显著差异:传统的土壤接种法造成草地早熟禾的发病率最高,可达39.2％;改进的土壤接种法测定的发病率明显低于传统的土壤接种法.相同试验条件下品种间抗病性差异显著,不同的试验条件下同一品种表现出的抗病性不一致,具有相对稳定的特征.温室效果评价获得的高抗品种有:‘公园’、‘午夜’、‘肯塔基,、‘开鲁坦,、‘纳苏’和‘特拉内尔’等,高感品种有:‘莫桑斯克’、‘菲尔京’、‘雪狼’等. 相似文献