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75 years of the chestnut blight fungus Cryphonectria parasitica (Murr.) Barr in Europe
82-85Views:237The chestnut blight fungus Cryphonectria parasitica is a native pathogen in East Asia and has been introduced into North America and Europe. Historical records and population genetic studies revealed at least three major introduction events from Asia into Europe.
Nowadays, chestnut blight is present in almost the entire distribution range of European chestnut, i.e. from the Iberian Peninsula to the Caucasus. The C. parasitica population in most countries has been studied in respect to the diversity of vegetative compatibility (vc) types and the occurrence of hypovirulence. The vc type diversity of the different populations varied considerably. Typically, a high diversity of vc types has been found in areas with a long history of chestnut blight and where sexual recombination between divergent genotypes commonly has occurred. On the other hand, newly established populations often showed a low diversity with only one, or a few vc types present.
Hypovirulence, i.e. the occurrence of C. parasitica isolates infected by Cryphonectria hypovirus 1 has been found widespread in Europe. Natural dissemination and active biological control applications have lead to a high prevalence of the hypovirus and to the recovery of many chestnut stands. Virulent cankers became hypovirus-infected within a short time and ceased expansion. There is concern that the diversity of vegetative compatibility types could increase in Europe through sexual reproduction between C. parasitica genotypes originating from different introductions. A higher level of vegetative incompatibility would not only hamper hypovirus spread within a population but could also select for lower virulence in CHV-1 and subsequently lead to an erosion of biological control. Recent studies, however, indicate that the vc type barriers are not so restrictive than previously assumed and that so far no evidence for an erosion of biological control system in high diversity populations can be observed.
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Studies of Cryphonectria parasitica (MURR.) BARR subpopulations on Quercus petraea in Ukraine
70-75Views:143Chryphonectria parasitica (Murr.) Barr, the casual agent of chestnut blight disease, which is one of the most important fungal pathogens of chestnut (Castanea sativa). The disease seriously affected the chestnut in Northern-America and in Europe as well. It is important to mention that the pathogen does not only infect the chestnut but oak species (Quercus spp.) also. In the Carpathian-Basin, the chestnut is endemic in the Mecsek mountains, in Zala, in Somogy counties but it also can be found in the Danube-Bend. In the Carpathian-Basin (outside Hungary) the chestnut is found in Slovakia, Ukraine, Romania. In our study bark samples infected by Cryphonectria parasitica were collected from Bobovyshche, Serednje and Rostovjatica (Ukraine). The rate of infected chestnut tree were higher than 90% around Bobovyshche and beside chestnut, the symptoms were detected on oak trees as well. We collected bark samples from chestnut and oak as well and then we isolated the pathogen Cryphonectria parasitica in the lab of University of Debrecen. Symptomatological observations, laboratory examinations on fungus morphology, as well as comparisons of ITS sequency homology were made and approved that the causal agent of new disease was Cryphonectria parasitica. Our results proved that the Cryphonectria. parasitica infects oak trees beside chestnut in the Carpathian-Basin. Further studies are needed to determine the VCG (Vegatative Compatibility Group) group of the Cryphonectria parasitica found on oak trees.
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The occurrence and phenology of moth pests in different granary of Borsod-Abaúj-Zemplén County
70-75Views:100The aims of my studies were the followings: primarily to find correlation between the conditions of granary and the occurrence of moth pests. Secondly I studied the effect of disinfection on individual numbers in the population of moths. My studies were started in May 2009 in six different places of Borsod-Abaúj-Zemplén County. Indianmeal moth (Plodia interpunctella) and Mediterranean Flour Moth (Ephestia kuehniella) traps with pheromone were installed in four repetitions as well as Angoumois Grain Moth (Sitotroga cerealella) traps in also four repetitions. Control traps without attractant were also placed at every place.
From my researches, it became clear that the disinfection alone is not enough to protect cereals from moths. As in the case of crop protection, we need to apply integrated pest management.
We have to make differences between preventive protections from moth pests and the elimination of them by chemicals.
Up to my opinion, the regular checking and cleaning of the granary are important as well as the prognosis of the possible occurrence of moths. The prognosis is considered important because the studied moths do not feed at the adult stage or only at a low level. However, the caterpillars coming from the eggs placed by females can cause a significant damage in the stored cereals.
The studied sex pheromone traps are proved to be useful for the reduction of number of moths since the traps caught lots of them. These traps are relatively cheap because only the temporarily changes of pheromones increase the cost. -
Molecular studies on Cryphonectria parasitica isolates from Carpathian-basin
76-80Views:105Chryphonectria parasitica, the casual agent of chestnut blight, is one of the most important fungal pathogens of chestnut (Castanea spp.) in Europe and Hungary. In this study we analyzed the diversity of 14 Cryphonectria parasitica strains isolated from different location of Carpathian-Basin. For the analyses we used the partial sequences of the translation elongation coding gene, tef1. Our results showed that the tef1 gene, contrary to other fungal species, is not suitable for the molecular analyses of C. parasitica. In the future, for the molecular studies of C. parasitica, we need to use other molecular markers like microsatellites.