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1.
An association of a begomovirus with leaf curl symptoms on Cleome gynandra was detected using a polymerase chain reaction (PCR) with begomovirus-specific primers. Further, the complete DNA-A of the begomovirus was cloned and sequenced. BLAST analysis of the sequence data revealed 92–99% identities and close relationships with several isolates of Ageratum enation virus (AgEV); therefore, we identified the virus associated with leaf curl symptoms of C. gynandra as an isolate of AgEV. This report is the first on the detection of AgEV in plants of C. gynandra with leaf curl in India.  相似文献   

2.
Leaf blight disease was found on Gloriosa superba L. (Liliaceae), an endangered, herbaceous, perennial, climbing lily that produces colchicine, in West Bengal, India in 2004. Small brownish spots on leaves developed into concentric rings, which eventually darkened and coalesced to blight the entire leaf. The causal fungus was morphologically identified as Alternaria alternata (Fr.) Keissler. This is the first record of A. alternata on G. superba.  相似文献   

3.
Morphology of the nematode Spinitectus minor harboured by Mastacembelus armatus from Burdwan, West Bengal, India was studied by light and scanning electron microscopes. The worms were described, illustrated and discussed taking into consideration of the information available relative to this species. Alate spicules, polar caps on the eggs and prodelphic uteri are clearly seen in the present LM studies and SEM photomicrographs provided detailed information about the microtopography of the worms.  相似文献   

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Yellow vein mosaic disease (YVMD) caused by whitefly‐transmitted begomoviruses is an economically significant viral disease of okra. In this study, a survey of begomoviruses associated with YVMD was carried out in eight states and two union territories of India. A total of 92 full‐length DNA‐A components were sequenced and characterized. Sequence comparisons and population structure analysis revealed the existence of four begomovirus species. Two novel species were detected with several recombinationally derived genome fragments that probably originated from begomoviruses known to infect malvaceous and non‐malvaceous hosts. Among the four species, Bhendi yellow vein Maharastra virus (BYVMaV) and Bhendi yellow vein Madurai virus (BYVMV) were found to be predominant in okra, with BYVMV having a pan‐India distribution. There was evidence for a high degree of genetic variability and subpopulation structure within these four species. Neutrality tests suggested the occurrence of purifying selection acting upon these populations. The results of the current study have uncovered the diversity and genetic structure of okra‐infecting begomoviruses in India and generated potentially useful information for developing management strategies for YVMD.  相似文献   

7.
The occurrence of Asian grey weevil Myllocerus undatus (Curculionidae: Coleoptera) damaging coconut (Cocos nucifera L.) seedlings is reported for the first time from Kerala, India. A mild to moderate level of infestation damaging 5–10% leaf lamina of un-split leaves with a typical notching-like symptom along the leaf margins is noticed on the majority of the coconut seedlings belonging to different coconut varieties, viz., ‘Chowghat Orange Dwarf’, ‘Chowghat Green Dwarf’, ‘Malayan Green Dwarf’, ‘West Coast Tall’ and Dwarf x Tall hybrids. M. undatus has not been reported as a destructive pest on any of the crops from India and is considered to be a pest of quarantine significance. Adult weevils have a characteristic tri-spined hind femur and elytra strongly angled broader than the prothorax.  相似文献   

8.
The nematode, Lappetascaris lutjani, recovered from the fish, Pellona ditchela from West Bengal, India, was studied by light and scanning electron microscopes. Surface features of the head and tail ends of the body as also the distal parts of the spicules were described, illustrated and discussed with regard to the available data relative to this species. Present LM studies provide information concerning the head structure in greater detail and existence of narrow but distinct lateral cervical alae. SEM studies give microtopographic details of the worm. Some of these represent new information and might be useful in the taxonomic evaluation of this interesting nematode. P. ditchela is the recorded new host of L. lutjani.  相似文献   

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Morphology of the nematode Viguiera dicrurusi Gupta, 1960 harboured by Dicrurus macrocercus albirictus (Hodgson) (Passseriformes: Dicruridae) from Baruipara in 24-Pargonas (South) district, West Bengal, India was studied by light and scanning electron microscopy (SEM). This represents the first study of V. dicrurusi using SEM. Scanning electron micrographs provided detailed information about the nature of pseudolabial plates, number and shape of teeth, dentate nature of striae, and the relative position of vulva, anus and phasmid opening in female. A detailed morphometrical comparison of this species with Viguiera viduae Chabaud, 1960 described from Dicrurus forficatus from Madagascar indicates that V. viduae is a junior synonym of V. dicrurusi. Two other species, Viguiera bhujangai Jehan, 1972 and Viguiera adsimilisai Sood et Kalia, 1978 are considered species inquirendae.  相似文献   

11.
In 2007, a rust disease of ohia (Metrosideros polymorpha) was found in Japan. We identified this pathogen as Puccinia psidii based on its morphological characters and the internal transcribed spacer (ITS) sequence of the ribosomal DNA. This pathogen was pathogenic on Eucalyptus amplifolia and E. rudis in addition to previously reported host species. This is the first report in Japan of a rust disease on ohia and the occurrence of its causal fungus, P. psidii.  相似文献   

12.
In June 1989, a survey was made of 733 fields of winter cereals, 627 in England and Wales and 106 in Fife and the Lothian regions of Scotland. The occurrence of Bromus species was noted in three areas of each field: the uncropped field margin, the cropped headland and the field centre. Three arbitrarily defined infestation levels were recorded: severe, light and intermediate. The most common species recorded was Bromus sterilis L., which accounted for almost 87% of all sightings. Most of the other occurrences were almost equally distributed between B. hordeaceus L., and B. commutatus Schrad. Two other species were found, on one field each: B. diandrus Roth and B. × pseudothominii Hard. Surveyors were briefed to recognize B. secalinus L, but none was reported. The brome grasses were widespread throughout the surveyed regions. They were most common in the Lothians (81 % of surveyed fields) and in the South East (60%) and the South West (52%) of England and least common in the English West Midlands, Fife and Wales (17%, 15% and 4% of surveyed fields). Distribution was biased towards the uncropped margins and field headlands. In England and Wales, there were 146 fields where Bromus species occurred in the field margins only, 179 in margins and headlands only and 63 with infestations in all three areas. In contrast, there were only 26 fields where they were restricted to the cropped areas. A similar pattern occurred in Scotland. The correlations between incidence of the Bromus species and management practices were much weaker than had been anticipated. The standard advice for control is to plough rather than use non-inversion tillage systems, to delay sowing and to avoid long runs of winter cereals. The conclusion of this survey is that, although these practices may be reducing or preventing increase of these weeds, they are not effective at eliminating infestations. Incidence des espèces Bromus comme mauvaises herbes des céréales d'hiver en Angleterre, au Pays de Galles et dans certaines parties de I'Écosse En juin 1989 une enquête a été réalisée dans 733 champs de céréales d'hiver, 627 en Angleterre et au Pays de Galles, et 106 dans les régions d'Écosse Fife et Lothian. La présence d'espèces Bromus a été notée sur trois zones de chaque champ: la bordure non-cultivée ('field margin'), la bordure cultivée ('headland') et le centre du champ. Trois niveaux d'infestation arbitraires ont eAté notés: sévère, léger et moyen. Les espèces les plus communément rencontrées étaient Bromus sterilis L. qui représentait presque 87 % de l'ensemble des présences. Dans la plupart des autres relevés, B. hordeaceus L. et B. commutatus Schrad se distribuaient presque également. Deuxautres espèces ont été trouvées, chacune dans un champ: B. diandrus Roth et B. × pseudothominii Hard. On avait appris aux enquêteurs à reconnaître B. secalinus L. mais cette espèce n'a pas été rapportée. Les bromes se rencontraient sur tout le territoire des régions étudiées. Elles étaient les plus communes dans les Lothians (81 % des champs étudiés) ainsi que dans le Sud Est (60 %) et dans le Sud Ouest (52 %) de l'Angleterre; les moins communes dans les West Midlands, en Fife et au Pays de Galles (17, 15 et 4 % des champs examinés). Leur distribution était biaisée en faveur des bordures non-cultivées et des bordures cultivées. En Angleterre et au Pays de Galles, dans 146 champs les bromes ne se rencontraient que dans les bordures non-cultivées, dans 179 ils ne se rencontraient que dans les bordures cultivées et non-cultivées, et dans 63 ils se rencontraient dans les trois secteurs du champ. Inversement, il n'y avait que 26 champs oü ils ne se trouvaient que dans la partie cultivée. Une répartition semblable s'observait en Écosse. Les corrélations entre la présence de bromes et la conduite des cultures étaient plus faibles qu'anticipé. Le conseil habituel est de labourer plutôt que de pratiquer des façons culturales sans renversement de la terre, de retarder le semis et d'éviter les longues successions de céréales d'hiver. La conclusion de cette étude est que, bien que ces pratiques peuvent réduire ou prévenir la prolifération de ces mauvaises herbes, elles ne sont pas efficaces pour les éliminer en cas d'infestations. Verbreitung von Bromus spp. in Wintergetreide in England, Wales und Teilen Schottlands Im Juni 1989 wurde auf 733 Wintergetreidefeldern, 627 in England und Wales und 106 in Fife und in den Lothian-Gebieten in Schottland, das Auftreten von Bromus spp. aufgenommen, getrennt nach dem nichtkultivierten Feldrand, dem Vorgewende und dem Feldinnern. Die Befallsstärke wurde nach schwer, mittel und leicht unterschieden. Die häufigste Trespen-Art war Bromus sterilis L. mit fast 87 % aller Beobachtungen. Die übrigen Vorkommen waren zu fast gleichen Teilen Bromus hordeaceus L. und Bromus commutatus Schrad. Aufje l Feld wurde Bromus diandrus Roth und Bromus × pseudothominii Hard, gefunden. Trotz intensiver Suche wurde kein Bromus secalinus L. festgestellt. Die Trespen traten im Beobachtungsgebiet verb-reitet auf, am häufigsten in den Lothians (81 % der untersuchten Felder) und im Südosten (60 %) und Südwesten (52 %) Englands, am wenigsten in dem englischen West Midland, in Fife und Wales (17, 15 bzw. 4 %). Die Verteilung konzentrierte sich in England und Wales auf 146 Feldern auf die kulturfreien Feldränder, in 179 Fällen auf die Feldränder sowie die Vorgewende, und auf 63 Feldern waren alle 3 Bereiche mit Trespen verunkrautet; nur auf 26 Feldern waren die Arten auf das Feldinnere beschränkt. In Schottland wurde eine ähnliche Verteilung beobachtet. Zwischen der Bewirtschaftung und dem Auftreten der Bromus spp. bestand eine weit schwächere Korrelation als erwartet. Die generelle Bekämpfungsempfehlung ist Pflügen statt nichtwendender Bodenbearbeitung, spätes Säen und Vermeidung von Fruchtfolgen mit hohem Wintergetreideanteil. Aus den Untersuchungsergebnissen folgt, daß diese Bekämp-fungsmaßnahmen Trespen wohl zurückdrängen oder ihre Zunahme verhindern, aber nicht eliminieren können.  相似文献   

13.
中国茶树炭疽菌属病害研究进展及展望   总被引:1,自引:0,他引:1  
茶树是一种重要的经济作物,广泛种植于热带和亚热带地区。随着茶产品经济价值的提高,茶叶生产安全备受关注。炭疽菌是引起茶树病害的病原菌之一,严重影响茶叶产量和茶产品品质,威胁我国茶产业的良性发展。利用抗病品种是防治茶树病害最为经济、有效的措施。目前,茶树炭疽菌种名使用混乱,茶树与炭疽菌的互作研究也较为薄弱,而简单依靠药剂防治病害也对茶叶质量安全造成一定的影响。本文梳理并明确了危害茶树的炭疽菌种类;总结了现有的茶树和炭疽菌互作的研究成果,提出识别免疫(effector triggered immunity,ETI)模式是茶树防御炭疽菌的主要机制;对茶树病理学存在的问题进行了归纳并提出解决办法,并展望了深入开展茶树抗病机理研究的思路,以期为制定茶园绿色防控技术及选育茶树抗病良种提供科学参考。  相似文献   

14.
Rhamphicarpa fistulosa is a facultative hemi‐parasitic plant of the Orobanchaceae family, adapted to wet soils. Apart from tropical Australia, it is only found in sub‐Saharan Africa, where it is considered a minor weed in cereal crops such as rice. Due to this status, the species has received only sporadic attention. Recent field observations and encounters with rice farmers in several African countries showed that R. fistulosa is, however, a more serious and increasing production constraint than previously thought. Results from a systematic literature review and a global herbarium study support this. The species has a broad distribution over Africa (at least 35 countries from Madagascar to Senegal and from Sudan to South Africa) and a wide range in altitude (0–2150 m a.s.l.) and environment (waterlogged swamps to moist free‐draining uplands). Rhamphicarpa fistulosa is relatively independent and persistent because of the presumably wide host range, the facultative nature of its parasitism and its prolific seed (estimated 100 000 seeds m?2 under moderate infestation levels). Finally, R. fistulosa causes severe yield losses (average 60%) and high regional annual economic losses (estimated US $175 million), while effective control options are scant and awareness of the species among important R&D stakeholders is almost absent. An integrated approach is advocated to assist the rice sector to reduce current R. fistulosa‐inflicted losses and to prevent further spread of the species into new areas.  相似文献   

15.
Agonoscena pistaciae is a serious pest of pistachio in the Middle East and the Eastern Mediterranean. In this paper the presence of the species in Spain and Western Europe is confirmed. It is widespread in the regions of Castilla–La Mancha and Extremadura in Central Spain, where it develops mostly on Pistacia terebinthus, in contrast to the Middle East, where its preferred host is Pistacia vera. In the literature and internet sources, A. pistaciae is often confused with other, morphologically similar species, namely A. succincta and A. targionii. Morphological characters are listed and illustrated for the identification of the species found in the West Mediterranean.  相似文献   

16.
Sub‐tropical and tropical plantations of Eucalyptus grandis hybrids in eastern Australia have been severely affected by anamorphs of Teratosphaeria (formerly Kirramyces) causing a serious leaf blight disease. Initially the causal organism in Queensland, Australia, was identified as Teratosphaeria eucalypti, a known leaf parasite of endemic Eucalyptus spp. However, some inconsistencies in symptoms, damage and host range suggested that the pathogen in Queensland may be a new species. Isolates of T. eucalypti from throughout its known endemic range, including Queensland and New Zealand, where it is an exotic pathogen, were compared using multiple gene phylogenies. Phylogenetic studies revealed that the species responsible for leaf blight in Queensland represents a new taxon, described here as Teratosphaeria pseudoeucalypti. While the DNA sequence of T. pseudoeucalypti was more similar to T. eucalypti, the symptoms and cultural characteristics resembled that of T. destructans. The impact of this disease in central Queensland has increased annually and is the major threat to the eucalypt plantation industry in the region.  相似文献   

17.
The papaya mealybug, Paracoccus marginatus Williams and Granara de Willing (Coccomorpha: Pseudococcidae), is a polyphagous pest that damages many tropical crops. It is native to Central America and spread to the Caribbean region and South America in the 1900s. Since then, it has accidentally been introduced to several islands in the Pacific region and some countries in Africa and Asia. The first record of this mealybug in Polynesia was in Hawaii, in 2004. This paper presents the first report of this pest in Tahiti (French Polynesia), where it was found in March 2017 on papaya (Carica papaya) and frangipani trees (Plumeria spp.). Its presence, which is mainly in the inhabited part of the island of Tahiti, suggests the recent introduction of the pest in French Polynesia. Several coccinellid predators have been found feeding on the mealybug in Tahiti: Cryptolaemus montrouzieri, Hyperaspis pantherina and Scymnus spp. None of its parasitoids have been found yet.  相似文献   

18.
In the Circeo National Park (Italy), a survey assessed the occurrence of the ambrosia beetle Xylosandrus germanus in addition to the conspecifics X. compactus and X. crassiusculus. This is the first report in Europe of the co-presence of three Xylosandrus species, in an evergreen Mediterranean maquis dominated by holm oaks (Quercus ilex L.). Although no damage caused by X. germanus has been observed, the richness of plant species in the Circeo National Park may allow the establishment of this highly polyphagous ambrosia beetle, possibly endangering this native ecosystem. The dominance in the associated fungal community of Ambrosiella grosmanniae and Fusarium spp. reflects a stable symbiotic relationship of these taxa with X. germanus.  相似文献   

19.
An overview of the occurrence of species of the genus Bursaphelenchus in Romania is presented. The data is based on recent surveys conducted for the first time throughout the country, to monitor and evaluate the potential entry of the pine wood nematode, Bursaphelenchus xylophilus. Wood samples were collected from declining trees, wood‐processing companies and imported wood packaging material. Of the 895 wood samples examined, 11 contained Bursaphelenchus specimens. Morphological and molecular analyses were carried out to characterize the species detected. With respect to the possible presence of B. xylophilus, all samples were negative, confirming the absence of this quarantine pest in Romania. Nevertheless, five Bursaphelenchus species were found: B. hofmanni, B. poligraphi, B. vallesianus, B. willibaldi, and one putative new species belonging to the sexdentati group, classified here as Bursaphelenchus sp. NR512. These results constitute the first report of the genus Bursaphelenchus in Romania.  相似文献   

20.
In October 2009, vein yellowing disease was observed on the weeds Crassocephalum crepidioides and Ageratum conyzoides in a subtemperate region in northern India. Ageratum enation virus (AEV), along with a nanovirus like satellite DNA 1, was found to be associated with both weeds. The isolates had 99% identity with each other and with an isolate of AEV reported from Zinnia elegans from this region. To the best of our knowledge, this report is the first of any begomovirus infection in C. crepidioides in India and the first on AEV infecting C. crepidioides worldwide and A. conyzoides in India.  相似文献   

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