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1.
Investigations on the efficacy of various methods of managing root-knot nematodes in microplots and under field conditions revealed that soil solarization, Furadan 5G and Tagetes erecta applied separately or in combination with other control methods, were the most effective in reducing the numbers of three root-knot nematodes, and root gall and egg mass indices. These management methods also resulted in significant increases (P0.05) in number of pods per plant, number of seeds per pod and 100-seed weight, and increased seed yield by up to 96.7 percent. Farmyard manure and Crotalaria ochroleuca were the least effective treatments. The use of T. erecta was the most economical root-knot nematode control method.  相似文献   

2.
The objective was to identify and characterize the causal agent of foliar necrosis and leaf scorch of Eucalyptus spp. in Brazil. Nineteen putative isolates of Rhizoctonia obtained from Eucalyptus plants during clonal propagation were compared with isolates from other hosts and with tester strains of anastomosis groups of Rhizoctonia solani. Features compared were morphological characteristics of anamorphs and teleomorphs, numbers of nuclei per cell in the vegetative hyphae, anastomosis of hyphae, and ability to produce necrotic lesions on cuttings and damping-off of E. grandis×E. urophylla hybrid seedlings. Rhizoctonia solani AG1 (AG1-IB like) was the most frequent causal agent isolated from Eucalyptus plants and cuttings with symptoms of leaf scorch and foliar necrosis respectively. These isolates were highly virulent on Eucalyptus cuttings and presented naturally epiphytic growth on Eucalyptus shoots. Binucleate isolates and isolates of R. solani AG4 were also virulent on cuttings and were most virulent on Eucalyptus seedlings causing pre- and post-emergence damping-off. Virulence on Eucalyptus cuttings and seedlings was not restricted to a single species or anastomosis group of Rhizoctonia.  相似文献   

3.
Foliar sprays and soil drenches with DL--amino-n-butyric acid (BABA) reduced the number of Heterodera avenae and H. latipons cysts on wheat and barley. Foliar sprays of wheat with 8000mgl–1 BABA reduced the number of H. avenae cysts by 90%, whereas 2000mgl–1 BABA was enough to reduce the number of H. latipons cysts by 79%. Multiple spray treatments with 2000mgl–1 BABA at 10-day intervals reduced the number of H. avenae cysts on wheat and barley. A soil drench of wheat with 125mgl–1 BABA reduced the number of H. latipons cysts by 93% and H. avenae cysts by 43%. Second-stage juveniles of these nematodes penetrated and formed syncytia in wheat roots soil-drenched with BABA. More adult males of H. avenae were produced in BABA (<250mg1–1)-treated wheat roots (~76%) than in untreated roots (27%). Soil drenches with higher concentrations of BABA inhibited development of adult males and females. Several chemical elicitors of induced resistance were tested for their ability to reduce the number of H. avenae cysts on wheat. Only BABA was found to be an effective resistance inducer. The number of egg masses of an unidentified Meloidogyne sp. root-knot nematode, which infects only monocots, was also reduced by 95% by a soil drench of wheat with 500mgl–1 BABA. Development of this nematode inside the BABA-treated roots was also inhibited.  相似文献   

4.
为明确云南省紫茎泽兰根结线虫病的病原种类,于2019年2月在云南省澜沧县林下三七种植区采集根部带有明显根结的紫茎泽兰根系进行根结线虫分离,通过观察所分离根结线虫的2龄幼虫、雌成虫、会阴花纹特征对其进行形态学鉴定,并利用序列比对、系统发育树分析、序列特异性扩增区段(sequence characterized amplified region,SCAR)对其进行分子生物学鉴定。结果表明,该病原线虫雌成虫会阴花纹呈圆形至卵圆形,背弓中等高或低平,侧区一侧或两侧延伸形成翼状,尾区有刻点,2龄幼虫、雌成虫形态特征及形态测量指标与北方根结线虫Meloidogyne hapla相似;该病原线虫rDNA的ITS序列和mtDNA的COI序列与NCBI数据库中已登录的北方根结线虫相应序列相似度较高,分别达99.35%和98.05%以上;该病原线虫rDNA的ITS序列、mtDNA的COI序列分别以99%、100%的支持率与北方根结线虫聚为同一分支;利用SCAR特异性引物,该病原线虫均能扩增出大小约1 500 bp的基因特异性条带。综合形态学和分子生物学鉴定结果将云南省紫茎泽兰根结线虫病病原种类鉴定为北方根结线虫。  相似文献   

5.
A comparison of the uptake of simple (C1–C4) aliphatic amines byPenicillium digitatum revealed that the fungitoxicity of (–)sec-butylamine [(–)SBA] was not due to its accumulation by hyphae since (+)SBA was accumulated to the same extent and methylamine, which showed negligible antifungal activity, accumulated to twice the level of SBA. Amines with a secondary alkyl structure were resistant to fungal metabolism, whereas primary amines were degraded to a significant extent byP. digitatum during a 4 h incubation period.(–)SBA accumulated in the fresh hyphae ofP. digitatum to a level 24 times higher than that in the culture medium containing 1 mol ml–1; most of the SBA effluxed from the hyphae when transferred to fresh culture medium minus SBA. SBA did not accumulate when hyphae were incubated in N2 or in the presence of respiratory inhibitors. The absorption and accumulation of SBA is characteristic of active transport.  相似文献   

6.
The nematode species Longidorus attenuatus, L. elongatus, L. macrosoma and Paralongidorus maximusare economically important pests to the viticulture industry due to their ability to vector two nepoviruses (Raspberry Ringspot Virus and Tomato Black Ring Virus) to grapevines. In Germany, these species occur in vineyard soil with other non-vector but morphologically similar longidorid species, L. helveticus, L.profundorum and L. sturhani. Species-specific primers were designed from ribosomal DNA for all seven species to facilitate taxonomic identification for non-specialists. Primers were assessed for their reliability by screening, where possible, a number of populations of each species. Furthermore, their selectivity and sensitivity were determined when challenged with closely related longidorid species and general nematode communities typical of vineyard soil. A multiplex approach using a common forward primer combined with species-specific reverse primers enabled three target nematode species to be detected in the same PCR reaction. All primers were highly specific, detecting all nematode developmental forms from disparate populations and were sufficiently sensitive to detect a single target nematode within a whole nematode community typical of a vineyard soil comprising of a range of non-target species. Given their specificity, sensitivity and reliability, these diagnostic primers should be of great benefit to both phytosanitary/quarantine services related to the viticulture industry and also as a decision management tool for growers.  相似文献   

7.
Organic amendments and green manure are potential alternatives to the harmful chemical control means currently used against plant-parasitic nematodes. In this work, Chrysanthemum coronarium was applied to the soil as a green manure to control the root-knot nematodes Meloidogyne incognita and M. javanica. Chrysanthemum coronarium significantly reduced nematode infection of tomato roots and improved plant-top fresh weight, both in the greenhouse and in microplots. Other green manures, derived from Anthemis pseudocotula, wild chickpea (Cicer pinnatifidum), Geranium spp. and wheat, were not as effective as C. coronarium. Chrysanthemum coronarium, retained its nematicidal activity even when applied as a dried material. Only mature C. coronarium plants, in their flowering stage, exhibited nematode control activity, but the green plant parts were more effective than the flowers. An aqueous extract of C. coronarium exhibited in vitro, nematostatic activity towards M. incognita and M. javanica second-stage juveniles and inhibited their hatching from eggs and egg-masses; its nematostatic activity was expressed also against other phytonematode species such as Heterodera avenae and Pratylenchus mediterraneus, but did not affect the beneficial entomopathogenic nematode Steinernema feltiae.  相似文献   

8.
Graminaceous cyst nematodes form a group of eleven valid species including Heterodera avenae, Heterodera filipjevi and Heterodera latipons and constitute major pests to cereals. They are widely spread in circum-mediterranean areas where they are presumed to cause yield losses on bread and durum wheat. The objective was to document the diversity of these cereal cyst nematodes, in particular samples from Mediterranean regions, in comparison to species which develop on cultivated or wild grasses (H. arenaria, H. hordecalis, H. mani) and on rice or sugarcane (H. sacchari). Studies involved PCR-RFLP of ITS and morphometrics of the juvenile and cyst characters. UPGMA analysis of molecular data showed that the isolates segregated in two main clusters which seem to represent different evolutionary lineages. The H. avenae sensu lato cluster (I) contained H. arenaria, H. avenae, H. filipjevi and H. mani. The second cluster (II) contained isolates of H. hordecalis and H. latipons. Within H. avenae sensu lato, H. filipjevi was separated from the other related species with significant bootstrap value. The differentiation of H. arenaria, recognized for the first time based on molecular data, and H. mani with few restriction enzymes were the least significant. Intraspecific polymorphism allowed differentiation of isolates originating from Australia within H. avenae sensu stricto. The group H. hordecalis–H. latipons showed the greatest genetic variability between and within isolates. Two representatives of Heterodera sacchari, taxonomically included in the schachtiigrave group, were genetically as distant to this group as to the other graminaceous species belonging to either H. avenae sensu lato or H. hordecalis–H. latipons group. Results inferred from multivariate analysis applied on morphometrics of the cysts and juveniles showed agreement between genetic and phenotypic classifications. This study demonstrates the utility of combined molecular and classical methods to enhance our knowledge about the diversity within the complex of graminaceous cyst nematodes and to establish robust techniques to identify a wider set of nematode species.  相似文献   

9.
为探究河南省主要禾谷类作物孢囊线虫的发生分布,明确孢囊线虫对不同作物的危害情况,于2017—2020年对河南省18个市50个县（区）的小麦、玉米和水稻作物的孢囊线虫种类和发生分布进行随机取样调查,采用形态学特征、分子生物学鉴定和rDNA-ITS序列进化树分析技术鉴定不同作物孢囊线虫的种类,并根据土壤中孢囊基数和单孢囊卵数明确不同作物孢囊线虫的发病严重度。结果显示,共采集土壤样品308份,其中224份样品检测到孢囊,孢囊检出率为72.7%。小麦孢囊线虫发生分布范围覆盖40个县（区）,其中15个县（区）为禾谷孢囊线虫Heterodera avenae侵染,23个县（区）为菲利普孢囊线虫H. filipjevi侵染,南阳市西峡县西坪镇和开封市尉氏县张市镇为禾谷孢囊线虫和菲利普孢囊线虫混合侵染发生区;玉米孢囊线虫H. zeae在濮阳市清丰县韩村镇、许昌市长葛市董村镇和禹州市范坡镇检测点首次被发现;旱稻孢囊线虫H. elachista在信阳市潢川县魏岗乡、来龙乡和新乡市获嘉县亢村镇检测点首次被发现。孢囊线虫发病严重度数据表明,小麦田平均孢囊含量高达17.3个/100 mL;玉米田平均孢囊量为11.0个/100 mL;水稻田平均孢囊量为4.4个/100 mL。表明河南省孢囊线虫高发地块主要集中在豫北、豫东和豫中平原区。  相似文献   

10.
The survival of two species of plant parasitic nematodes: the root-lesion nematode Pratylenchus brachyurus, and the root-knot nematode Meloidogyne javanica, was evaluated in saturated atmospheres of 12 natural chemical compounds. The infectivity of two isolates of arbuscular mycorrhizal fungi: Glomus mosseae and Glomus intraradices, under identical experimental conditions, was also determined. All the compounds tested exerted a highly significant control against M. javanica and among them, benzaldehyde, salicilaldehyde, borneol, p-anisaldehyde and cinnamaldehyde caused a mortality rate above 50% over P. brachyurus. The infectivity of G. intraradices was inhibited by cinnamaldehyde, salicilaldehyde, thymol, carvacrol, p-anisaldehyde, and benzaldehyde, while only cinnamaldehyde and thymol significantly inhibited mycorrhizal colonization by G. mosseae.  相似文献   

11.
The coding sequences in RNA2 for the coat proteins (CP) of strawberry latent ringspot virus (SLRSV) were modified and amplified using polymerase chain amplification reactions (PCR) to facilitate their expression inAgrobacterium tumefaciens-transformedNicotiana tabacum Xanthi-nc. The coding sequences for the smaller capsid protein (S, 29kDa) and that for the theoretical precursor of L and S (P, 73kDa) had ATG initiation codon sequences added at the 5-proximal Ser/Gly (S/G) cleavage site in the unmodified sequence. The sequence coding for the larger of the two proteins of mature SLRSV capsids (L, 44kDa) had an ATG codon added at its 5 S/G site and a TAG stop codon sequence added at the 3-proximal S/G site. The P, L and S proteins were expressedin planta to a maximum concentration of 0.01 % of total extractable proteins but did not assemble into virus-like particles. When challenged by mechanical inoculation with virus particles or viral RNA, and compared with control plants, tobacco plants (primary transgenic clones or S1 and S2, kanamycin-resistant seedlings) expressing the virus capsid subunits separately, or their precursor, decreased the accumulation of SLRSV particles in inoculated leaves and fewer plants became invaded systemically. In experiments in which the roots of seedlings were exposed to SLRSV-carrying vector nematodes (Xiphinema diversicaudatum), SLRSV was detected in the roots of non-transformed control tobacco plants (6/20) and in transgenic tobacco expressing the L protein (7/40), but not in any of 25 tobacco plants expressing the S protein or in 35 expressing the P protein. This is the second example of CP-mediated resistance to virus inoculation by nematode vectors.  相似文献   

12.
棉隆与淡紫拟青霉联合防治番茄根结线虫病的效果评价   总被引：4，自引：0，他引：4  
为明确土壤熏蒸与生防微生物对番茄根结线虫病的联合作用效果,采用移栽前棉隆熏蒸处理后穴施淡紫拟青霉Paecilomyces lilacinus YES-2-14生防菌剂的方法在温室大棚开展了联合防治试验。结果表明,棉隆用量为35 g/m~2时,24周拉秧时线虫数量减少90%以上,防效达到85.5%;移栽时穴施浓度10~7~10~8CFU/g的淡紫拟青霉菌剂,24周拉秧时防效为44.4%~59.6%;而当线虫初始密度达到674头/100 g土时,单一菌剂防效只有12.5%,但番茄长势和产量显著提高。棉隆熏蒸后再联合施用淡紫拟青霉菌剂,2个月和5个月时防效比单一棉隆处理分别提高14.1%和21.8%,比单一菌剂处理提高14.3倍和4.1倍,产量较对照、棉隆熏蒸和单一菌剂处理分别提高22.1%、9.5%和2.4%,且该处理地块线虫数量始终最低,与对照差异显著,而淡紫拟青霉数量则高于单一淡紫拟青霉菌剂处理。表明棉隆和淡紫拟青霉菌剂联合使用不仅能显著降低线虫数量,有效防治番茄根结线虫病,还能够促进植株生长并提高产量。  相似文献   

13.
The objective was to study CO2 fixation and photoassimilate partition in coffee (Coffea arabica) seedlings infested with the lesion nematode Pratylenchus coffeae. Seedlings infested with 0, 1000 and 8000 Pratylenchus coffeae nematodes were exposed to 14CO2 and the incorporation and distribution of radioactivity were followed in the roots, stems and leaves. Fresh mass, pigments, soluble sugars, sucrose and specific radioactivity of sucrose in the plant parts were determined. At the highest level of infestation almost all the parameters were significantly changed showing the carbon fixation in the leaves and partitioning to the roots were decreased. Since lesion nematodes are not sedentary and do not form feeding sites that could be characterised as metabolic sinks, it is suggested that their damage is more readily expressed by the leaves, through a reduction in photosynthesis and phloem transport.  相似文献   

14.
甘肃定西地区马铃薯线虫病病原的分离鉴定   总被引：3，自引：1，他引：2  
为明确甘肃省定西市马铃薯线虫病的病原种群分类地位,采用形态学结合分子生物学的方法对该地区马铃薯上的4个线虫群体进行了鉴定,观察和测量其形态特征值,基于r DNA-ITS序列以UPGMA法构建线虫群体的系统发育树,并按照柯赫氏法则进行了致病性测定。结果表明,4个线虫群体在形态学上与马铃薯腐烂茎线虫Ditylenchus destructor一致,但群体DX27与群体DX11、DX16、DX19雌虫的体长、体长/食道长、体长/尾长值存在极显著差异。利用通用引物TW81/AB28扩增r DNA-ITS序列均获得长度为915 bp的片段;序列比对分析表明,群体DX27与其它3个群体相比在ITS1区的第96~255 bp片段内有25个碱基的差异;系统发育树显示,群体DX27与C型群体聚为1支,群体DX11、DX16、DX19与B型群体聚为1支。根据形态学特征及r DNA-ITS序列分析结果确定该病原线虫为马铃薯腐烂茎线虫,其中群体DX27属于C型,群体DX11、DX16、DX19属于B型。  相似文献   

15.
Experiments were designed to analyze the relationships between the root-knot nematodeMeloidogyne incognita and resistant tomato and pepper genotypes. From a natural avirulent isolate, near-isogenic nematode lineages were selected with virulence either against the tomatoMi resistance gene or the pepperMe3 resistance gene. Despite the drastic selection pressure used, nematodes appeared unable to overcome the pepperMe1 gene, therefore suggesting some differences in the resistance conferred byMe1 andMe3 in this species. Nematodes virulent onMi-resistant tomatoes were not able to reproduce onMe1-resistant nor onMe3-resistant peppers, and nematodes virulent onMe3-resistant peppers were not able to reproduce onMi-resistant tomatoes nor onMe1-resistant peppers. These results clearly demonstrate the specificity ofM. incognita virulence against resistance genes from both tomato and pepper, and indirectly suggest that gene-for-gene relationships could occur between these two solanaceous crops and the nematode.  相似文献   

16.
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17.
Leptosphaeria maculans,a fungal pathogen of Brassica napus, secretes large amounts of a 28kDa protein (SP2) in liquid culture. This protein shows high sequence similarity to secreted serine proteases from other ascomycetes and is the major component of culture filtrate with protease activity, as analysed on casein zymogels. The sp2 gene is expressed during infection of B.napuscotyledons when L. maculans hyphae are growing between mesophyll cells, as well as at later stages when the fungus invades the vascular tissue.  相似文献   

18.
A study was conducted in two greenhouses with a history of Fusarium crown and root rot (Fusarium oxysporum f.sp.radicis-lycopersici, Forl) and root-knot nematodes (Meloidogyne javanica andM. incognita). During the 2005–06 growing season, the effectiveness of soil disinfestation by solarization in combination with low doses of metham-sodium (500, 750, 1000 and 1250l ha−1) or dazomet (400 g ha−1), was tested against soilborne pathogens and nematodes in an attempt to find a suitable alternative to methyl bromide, which is soon to be phased out. Solarization alone was not effective in the greenhouse with a high incidence ofForl. In the greenhouse with a low level ofForl, all the treatments tested reduced disease incidence, and were therefore considered to be applicable for soil disinfestation. In addition, root-knot nematode density decreased with all the treatments tested in both of the greenhouses.  相似文献   

19.
In July 1998, a sudden wilt of Star Ruby grapefruit (Citrus paradisi Macf.) occurred in Israel in a region with a warm Mediterranean climate. The wilt of the middle and upper canopy of main limbs was accompanied by gum oozing from the affected branches. The bark of these branches attained a dark colour and the epidermis sloughed off easily revealing a mass of black powder, resulting from copious sporulation of dark conidia. Both the bark and the xylem were intensively colonized with mycelium. The fungus was identified as Scytalidium lignicola Pesante, based on the characteristic mixture of some colourless and dark conidia, produced in branched chains by conversion of the vegetative hyphae. Artificial inoculations induced typical disease symptoms and the fungus was reisolated, thus confirming Koch's postulates. Similar symptoms appeared in Star Ruby interim segments which had been cut and top grafted with various citrus cultivars. This is the first detailed report of pathogenicity of S. lignicola to citrus trees. It is postulated that the disease developed after predisposition of Star Ruby grapefruit trees by comprehensive pruning followed by extremely hot conditions.  相似文献   

20.
The entomopathogenic nematodes Steinernema weiseri, S. feltiae, S. carpocapsae and two strains of Heterorhabditis bacteriophora, isolated from Turkish soils, were evaluated against larvae of the Mediterranean fruit fly (medfly) Ceratitis capitata in plastic cups under laboratory conditions with sandy loam soil and 10% moisture level. At a rate of 100 infective juveniles (IJs)/cm2, the last instar larvae of C. capitata were susceptible to the entomopathogenic nematodes: the S. feltiae 09-31 strain recovered from Aydin provided 78% mortality, whereas S. weiseri and S. carpocapsae killed 50% and 56% of the larvae, respectively. Both strains of H. bacteriophora species caused less than 50% mortality. Except for S. feltiae, the majority of infected medflies died as prepupae or pupae within the puparia. More than 90% larval mortality was recorded at 200 and 400 IJs/cm2 for S. feltiae. None of the nematode isolates infected the medfly pupae within the puparia. In pot experiments containing soil, S. feltiae caused 96% and 97% mortality at 100 and 200 IJs/cm2, respectively. In pot experiments with grass present, more than 94% mortality was obtained in the presence of grass roots.  相似文献   

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