The fungus Cercospora beticola Sacc. is the one of the most important pathogens on the sugar beet. The frequent application of fungicides with the same mode of action increase a risk of development of resistant strains of the pathogen. Occurrence of C. beticola resistant strains has been never researched in Slovakia. In this work, C. beticola isolates were collected from 10 localities of Slovakia and analysed for fungicide resistance in laboratory conditions. Nine fungicides with different mode of action were tested – trifloxystrobin + cyproconazole, kresoxim-methyl + epoxiconazole, azoxystrobin + cyproconazole, thiophanate-methyl + tetraconazole, thiophanate-methyl, prochloraz + propiconazole, picoxystrobin, tetraconazole, and difenoconazole. The results confirmed, that occurrence of fungicide resistance in C. beticola population was established in Slovakia. Different criteria of assessment of fungicide resistance (based on EC50 and on growth rate – inhibition percentage) showed slightly different results, but both criteria confirmed resistant C. beticola strains to thiophanate-methyl, picoxystrobin and difenoconazole. Fields with higher frequency of application of these fungicides significantly supported the development of resistant strains. Assessment of any C. beticola strains have not confirmed reduced sensitivity to active ingredients tetraconazole and prochloraz + propiconazole. The lowest level of risk of fungicide resistance was confirmed in the locality Oslany. It is very important to focus on anti-resistant strategy and reduce of using fungicides on localities, where the occurrence of resistant C. beticola strains was confirmed – Dolné Saliby (thiophanate-methyl and picoxystrobin) and Senec (picoxystrobin and difenoconazole).

Roháčik T., Hudec K. (2007): Fungal infection of malt barley kernels in Slovak Republic. Plant Protect. Sci., 43: 86-93.The influence of agro-environmental factors (year, cultivar and climatic factors) on the occurrence of fungi on kernels of malt barley, species spectrum and seedling viability were evaluated during 2004 and 2005. The seeds (asymptomatic, fraction above 2.5 mm) originated from different cultivars and locations of the Slovak Republic. Surface sterilisation of the kernels before isolation of the fungi was the key factor for objective results on the occurrence of Fusarium species. Screening of non-sterilised kernels gave a different spectrum of fungal species and their frequency and may lead to distorted results. The most frequent species isolated from barley kernels were Alternaria spp., cochliobolus sativus, epicoccum nigrum, Fusarium spp. and Pyrenophora teres. The results confirmed that agro-environmental factors (mostly year and microclimatic conditions) had a major influence on infection by and population structure of fungi in malt barley kernels. The total sample infection by Fusarium spp. was significantly higher at localities with higher altitude and in 2005. The infection level varied from 0% to 20%, in some localities in 2005 it exceeded 20%. The widest fungal species spectrum was recorded in the locations with high level of kernel infestation. In localities with lower infection, the species spectrum was narrower.

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