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Pretoria, South Africa

Akyazi R.,Ordu University | Ueckermann E.A.,ARC PPRI | Ueckermann E.A.,North West University South Africa | Soysal M.,Ordu University
Acarologia | Year: 2016

Amblyseius herbicolus Chant, 1959 (Mesostigmata: Phytoseiidae) is reported for the first time in Ordu province (Sea side, Black Sea Region), Turkey. The specimens were collected from persimmon trees (Diospyros kaki Thunb., Diospyros lotus L.) infested with tenuipalpid and tydeid mites in Altınordu and Perşembe, Ordu Province, Turkey. © Akyazi R. et al. Source

Bagheri M.,Islamic Azad University at Maragheh | Mohajer S.S.,Gorgan University of Agricultural Sciences and Natural Resources | Saboori A.,University of Tehran | Asadeh G.,Gorgan University of Agricultural Sciences and Natural Resources | And 2 more authors.
Acarologia | Year: 2011

A new species of Storchia Oudemans (Acari: Stigmaeidae) is described and illustrated based on specimens collected from moss and soil in Golestan Province, Iran. A key to all species of Storchia (female) is also provided. Source

Bahramisharif A.,Stellenbosch University | Lamprecht S.C.,Agricultural Research Council Plant Protection Research Institute | Spies C.F.J.,Stellenbosch University | Spies C.F.J.,Agriculture and Agri Food Canada | And 2 more authors.
Mycologia | Year: 2013

The genus Pythium consists of more than 120 species and is subdivided into 11 phylogenetic clades (A-K) based on internal transcribed spacer (ITS) region sequence data. Pythium clade G contains only seven known species, with most not being well described. Our study characterized 12 Pythium isolates from Aspalathus linearis (rooibos) that fit into clade G. Phylogenetic analyses of the ITS region and a combined phylogeny of four gene regions (ITS, b-tubulin, COX1 and COX2 [cytochrome c oxidase subunits I, II]) identified five clade G subclades. The rooibos isolates formed two groups, Pythium Rooibos I (RB I) and II (RB II), that clustered into two separate clades within subclade 1. The nine Pythium RB I isolates formed a distinct clade from P. iwayamai and is described here as a new species, Pythium cederbergense sp. nov. The three Pythium RB II isolates had P. canariense and P. violae as their closest relatives and were genetically diverse, suggesting the presence of several new species or a species complex that cannot be resolved with the current data, thus precluding a species description of this group. Morphological analyses showed that P. cederbergense and Pythium RB II were indistinguishable from each other but distinct from known clade G species. Clade G studies are being hampered by imprecise morphological descriptions of P. violae, P. canariense and P. iwayamai and each species being represented by only one isolate. The P. cederbergense and Pythium RB II isolates all were nonpathogenic toward rooibos, lupin and oats seedlings. One oligonucleotide was developed for each of P. cederbergense and Pythium RB II, which was able to differentiate the isolates with DNA macro-array analyses. © 2013 by The Mycological Society of America. Source

Tecoma stans var. stans, a tree originating from the Americas, is emerging as an invasive weed in South Africa. A microcyclic gall inducing rust fungus, Prospodium transformans, has been investigated as a biological control agent against this plant. Development of germinating teliospores and symptoms on host plants are described, and the optimum temperature for teliospore germination was found to be 18-22°C. Inoculations of plants grown from seed originating from South Africa and various localities in Mexico and Texas (USA) indicate that there are likely races specific to morphological variants of this widespread and highly variable plant species. Despite readily inducing galls on plants grown under quarantine glasshouse conditions in South Africa, this rust fungus failed to establish in the field upon release. It is suggested that the origin of the form of this plant, which has become invasive in South Africa, needs to be identified to source the correct race of P. transformans for release in South Africa. © Brazilian Phytopathological Society. Source

Spies C.F.J.,Stellenbosch University | Mazzola M.,U.S. Department of Agriculture | Botha W.J.,ARC PPRI | Langenhoven S.D.,Stellenbosch University | And 2 more authors.
Fungal Biology | Year: 2011

The Pythium irregulare species complex is the most common and widespread Pythium spp. associated with grapevines in South Africa. This species complex has been subdivided into several morphological and phylogenetic species that are all highly similar at the sequence level [internal transcribed spacer (ITS) and cytochrome c oxidase (cox) regions]. The complex includes Pythium regulare and Pythium cylindrosporum, which are morphologically distinct, and P. irregulare sensu stricto (s.s.) and Pythium cryptoirregulare, which are morphologically similar. The aim of the current study was to determine whether 50 South African grapevine P. irregulare isolates represented more than one phylogenetically distinct species. The isolates were characterised using nuclear (ITS and β-tubulin) and mitochondrial (cox1 and cox2) gene region phylogenies and two isozyme loci [glucose-6-phosphate isomerase (Gpi) and malate dehydrogenase (Mdh-1)]. Some of the gene sequence data were difficult to interpret phylogenetically, since some isolates contained two or more polymorphic ITS copies within the same isolate (intra-isolate variation) that clustered into different ITS sub-clades, i.e. the P. irregulare s.s. and P. cryptoirregulare sub-clades. The molecular data furthermore only revealed the presence of one phylogenetic species, P. irregulare. Morphological analyses of a subset of the isolates confirmed that the isolates were P. irregulare, and further showed that the P. cylindrosporum ex-type strain formed typical P. irregulare oogonia, and not the previously reported distinct elongated oogonia. Some of the molecular analyses suggested the occurrence of outcrossing events and possibly the formation of aneuploids or polyploids since (i) the nuclear and mitochondrial gene data sets were incongruent, (ii) polymorphic ITS copies were present within the same isolate, (iii) heterozygosities were observed in the β-tubulin gene and Gpi and Mdh-1 loci in some isolates and (iv) more than two β-tubulin alleles were detected in some isolates. Altogether, the data suggest that P. irregulare, P. cryptoirregulare, P. cylindrosporum, and possibly P. regulare should be synonimised under the name P. irregulare. © 2011 The British Mycological Society. Source

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