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Pridannikov M.V.,RAS Severtsov Institute of Ecology | Suprunova T.P.,Russian Research Institute of Vegetable Breeding and Seed Production | Shumilina D.V.,Russian Research Institute of Vegetable Breeding and Seed Production | Limantseva L.A.,Russian Research Institute of Phytopathology | And 3 more authors.
Russian Journal of Nematology | Year: 2015

During 2010-2012, a survey was conducted to determine the distribution and diversity of the cereal cyst nematodes (CCN), including Heterodera filipjevi, within the middle Volga River and South Ural regions of the Russian Federation. A total of 270 soil samples were collected. Seven populations of CCN were found in the rhizosphere area of various cereal plants that showed symptoms of nematode disease in Saratov and Chelyabinsk regions. The highest nematode population density was found in Chelyabinsk Region, with a mean density of 100 cysts (100 g soil)-1. The morphological and morphometric characteristics of these populations are presented showing variations in cyst body width, underbridge and vulval slit length, and in the vulva-anus distance. The morphometrics of second-stage juveniles showed minor differences between Saratov and Chelyabinsk populations compared with those of the paratypes and the population from the Republic of Bashkortostan (Bashkiria). The body lengths of the Saratov and Chelyabinsk populations were smaller than those of Bashkiria and longer than those of the paratypes. The pharynx lengths of the Saratov and Chelyabinsk populations were shorter than the paratypes. For molecular characterisation, DNA was extracted from cysts of each population. Speciesspecific primers for H. avenae, H. filipjevi and H. latipons were developed for conventional PCR amplification of the internal transcribed spacer region of ribosomal RNA (ITSl-rRNA). Primer pairs developed for H. filipjevi and H. latipons amplified PCR products only from the target species, whereas primers for H. avenae amplified H. pratensis in addition to the target species. Molecular data confirmed the identity of the seven populations as H. filipjevi.

Girsova N.V.,Russian Research Institute of Phytopathology | Bottner-Parker K.D.,U.S. Department of Agriculture | Bogoutdinov D.Z.,Samara State Agricultural Academy | Meshkov Y.I.,Russian Research Institute of Phytopathology | And 3 more authors.
European Journal of Plant Pathology | Year: 2015

A large scale survey on diseased potato plants that exhibited symptoms similar to those of stolbur, potato purple top wilt, potato witches’-broom, and potato round-leaf in eight Economical Regions of Russia was conducted from 2006 to 2012. A total of 1228 potatoes were collected and the associated phytoplasmas were identified. Phytoplasmas belonging to five 16S rRNA (16Sr) phytoplasma groups (16SrI, 16SrII, 16SrIII, 16SrVI, and 16SrXII) and at least eight subgroups (16SrI-B, 16SrI-C, 16SrI-P, 16SrII-A, 16SrIII-B, 16SrVI-A, 16SrVI-C, and 16SrXII-A) were identified. To our knowledge, subgroup 16SrIII-B and 16SrVI-C phytoplasmas have not been reported to infect potatoes. Based on the results of the survey, the percentages of infection caused by various phytoplasmas were: 40.2 % (16SrXII), 25.5 % (16SrIII), 20.9 % (16SrI), 12.4 % (16SrVI), and 1.2 % (16SrII). The results also indicated potato diseases exhibiting stolbur or similar symptoms could be caused by stolbur phytoplasma (16SrXII-A) alone or by other phytoplasma groups (e.g., 16SrI and 16SrIII). A survey on potential insect vectors was conducted from 2009 to 2012 in the Moscow oblast of the Central Region. A total of 23 different species of Hemiptera insects were screened for the presence of phytoplasmas. Eight leafhopper and three froghopper species carried phytoplasmas. Euscelis incisus and Macrosteles laevis were the most prevalent. The other species were present in very low populations. © 2015 KNPV

Dzhavakhiya V.,Russian Research Institute of Phytopathology | Shcherbakova L.,Russian Research Institute of Phytopathology | Semina Y.,Russian Research Institute of Phytopathology | Zhemchuzhina N.,Russian Research Institute of Phytopathology | Campbell B.,Albany Research Center
Frontiers in Microbiology | Year: 2012

A common consequence of using agricultural fungicides is the development of resistance by fungal pathogens, which undermines reliability of fungicidal effectiveness. A potentially new strategy to aid in overcoming or minimizing this problem is enhancement of pathogen sensitivity to fungicides, or "chemosensitization." Chemosensitization can be accomplished by combining a commercial fungicide with a certain non- or marginally fungicidal substance at levels where, alone, neither compound would be effective. Chemosensitization decreases the probability of the pathogen developing resistance, reduces the toxic impact on the environment by lowering effective dosage levels of toxic fungicides, and improves efficacy of antif ungal agents. The present study shows that the antifungal activity of azole and strobilurin fungicides can be significantly enhanced through their co-application with certain natural or synthetic products against several economically important plant pathogenic fungi. Quadris (azoxystrobin) combined with thymol at a non-fungitoxic concentration produced much higher growth inhibition of Bipolaris sorokiniana, Phoma glomerata, Alternaria sp. and Stagonospora nodorum than the fungicide alone. The effect of Dividend (difenoconazole) applied with thymol significantly enhanced antifungal activity against B. sorokiniana and S. nodorum. Folicur (tebuconazole) combined with 4-hydroxybenzaldehyde (4-HBA), 2,3-dihydroxybenzaldehyde or thymol significantly inhibited growth of Alternaria alternata, at a much greater level than the fungicide alone. In addition, co-application of Folicur and 4-HBA resulted in a similar enhancement of antifungal activity against Fusarium culmorum. Lastly, we discovered that metabolites in the culture liquid of Fusarium sam-bucinum biocontrol isolate FS-94 also had chemosensitizing activity, increasing S. nodorum sensitivity to Folicur and Dividend. © 2012 Dzhavakhiya, Shcherbakova, Semina, Zhemchuzhina and Campbell.

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