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  • Author or Editor: J. Komáromi x
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The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is a new pest of corn in Europe. Future management may include the use of natural enemies. Our study focused on the deter­mi­na­tion of density and species composition of spiders in corn fields, as well as in the adjacent corn field margins, during the peak flight period of WCR adults. An additional objective was to test different sampling methods, used for spider collecting, in corn fields and in adjacent corn field margins. The field study was conducted in July and August, 1999, in experimental corn plots, as well as in the adjacent field margins, owned by the Cereal Research Institute, Szeged, in Southern Hungary. Spiders were collected by individual plant search and by sweep nets. Number of spiders /m2 was significantly higher, whereas /m3 was significantly lower in the corn plots compared to the adjacent field margins. Remnants of WCR adults were found in theridiid [Theridion impressum L. Koch, T. pictum (Walckenaer), Enoplognatha latimana Hippa and Oksala] and agelenid (Agelena sp.) webs. We observed that individuals of both families were able to kill 1-5 adult beetles within 90 minutes.

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Since first detected (Ba∞a, 1993), the western corn rootworm has become one of the main pests of maize in Central Europe. CSALOMON® pheromone traps (sticky panel-LEM, cloak-PAL, etc., Plant Protection Institute, Hungarian Academy of Sciences, Budapest, Hungary) are recommended mainly for detection of western corn rootworm (WCR) (Tóth et al., 2003). In the USA at economic WCR population levels, for field risk assessment, visual yellow sticky (Multigard, Pherocon AM) traps are used. In a region where WCR population has been present only for few years yet and the population increase proceeds, both trap types may be suitable. In order to estimate the correlation between the captures of visual and CSALOMON® pheromone traps, experiments were conducted for three years (1998-2000) to find out whether a useful correlation exists between captures on these two traps. Moderately strong and strong (minimum R=0,77; maximum R=0,87) correlation was found between captures on Multigard and CSALOMON® pheromone traps. At this population level no correlation was found between capture on Multigard traps and next year's adult emergence.

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Over the last two centuries the atmospheric CO2 level has exhibited a consistent rise, leading to an increase in the greenhouse effect. This level is now 35% higher than it was before the industrial revolution. On the basis of various scenarios from the Special Report on Emissions it is expected to rise from the present level of 385 ppm to 650–970 ppm by the end of the 21st century.Plant biomass and resistance of winter wheat to various powdery mildew pathotypes were investigated at normal (400 ppm) and enhanced (700 ppm) atmospheric CO2 levels in a greenhouse. Wheat cultivars Ukrainka and Mv Hombár, and 12 lines from the mapping population developed from their cross and exhibiting different level of resistance were tested.The results showed that the atmospheric CO2 level had little influence on the resistance of winter wheat to powdery mildew infections based on the percentage of leaf area covered whole plant percentage severity. In response to higher atmospheric CO2 level there was an increase in the aboveground biomass of the winter wheat genotypes tested in the present work, leading to an increase in plant height and in stem and leaf weight. However, the number of tillers and the grain yield did not increase compared with the values recorded at normal atmospheric CO2 level.

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Fifty Triticum aestivum genotypes, including winter wheat cultivars from Martonvásár, were tested for fusarium head blight (FHB) resistance under artificially inoculated conditions. Field resistance, kernel infection, and the relative yield components (test weight, thousand kernel weight and kernel weight/heads) were examined following infection with Fusarium graminearum and F. culmorum isolates. Using data from two years, a number of Martonvásár varieties with above-average resistance to FHB were identified. On the basis of field infection, AUDPC values close to those of resistance sources were calculated for the variety Mv Emese, while 67.5% of the varieties tested had values which did not differ significantly from those of the control variety Arina. The yield components examined were modified substantially by artificial FHB infection. The thousand kernel weight and test weight of the variety exhibiting the greatest degree of infection were only 21.14% and 25.58%, respectively, of the untreated control. In one case the decline in the kernel weight/head was more than 90%. The results of multivariable statistical analysis indicated that among the Hungarian wheat genotypes, Bánkúti 1201, B9086-95 (a line derived from Bánkúti 1201), Mv Emese, Martonvásári4 and Mv Táltos could be grouped with the best sources of resistance. The experimental data revealed wide genetic variability for FHB resistance in the Martonvásár breeding stock.

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As in the case of other wheat diseases, adult plant resistance (APR) to powdery mildew remains effective longer than monogenic hypersensitive resistance, so the objective was to identify winter wheat genotypes with this type of resistance. Field and greenhouse tests conducted on 41 varieties and breeding lines indicated that 36 were susceptible in the seedling stage, and only five were resistant in all stages of development. It is probable that these latter genotypes contain major resistance genes. The area under the disease progress curve was the same for most of the wheat genotypes as for the APR control variety Massey, but varieties and lines with significantly better resistance were also identified. Among the genotypes in the Martonvásár breeding stock, Mv Táltos and the line Mv07-03 were found to have excellent adult plant resistance.

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Authors: G. Vida, M. Cséplő, G. Gulyás, I. Karsai, T. Kiss, J. Komáromi, E. László, K. Puskás, Z. Wang, C. Pace, Z. Bedő, L. Láng and O. Veisz

Among the factors which determine yield reliability an important role is played by disease resistance. One of the breeding aims in the Martonvásár institute is to develop wheat varieties with resistance to major diseases. The winter wheat varieties bred in Martonvásár are examined in artificially inoculated nurseries and greenhouses for resistance to economically important pathogens. The effectiveness of designated genes for resistance to powdery mildew and leaf rust has been monitored over a period of several decades. None of the designated major resistance genes examined in greenhouse tests is able to provide complete resistance to powdery mildew; however, a number of leaf rust resistance genes provide full protection against pathogen attack (Lr9, Lr19, Lr24, Lr25, Lr28 and Lr35). In the course of marker-assisted selection, efficient resistance genes (Lr9, Lr24, Lr25 and Lr29) have been incorporated into Martonvásár wheat varieties. The presence of Lr1, Lr10, Lr26, Lr34 and Lr37 in the Martonvásár gene pool was identified using molecular markers. New sources carrying alien genetic material have been tested for powdery mildew and leaf rust resistance. Valuable Fusarium head blight resistance sources have been identified in populations of old Hungarian wheat varieties. Species causing leaf spots (Pyrenophora tritici-repentis, Septoria tritici and Stagonospora nodorum) have gradually become more frequent over the last two decades. Tests on the resistance of the host plant were begun in Martonvásár four years ago and regular greenhouse tests on seedlings have also been initiated.

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