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The PAV strain of barley yellow dwarf virus (BYDV) is one of the causal agents of yellow dwarf disease in cereals. The use of germplasm resistant to BYDV is generally regarded as the most effective means of controlling damage caused by this pathogen. In field trials, response to infection with a barley yellow dwarf virus of selected wheat cultivars registered in the Czech Republic was compared with that of control cultivars. Although a good level of resistance to BYDV-PAV was found in cultivar Athlon and yield loss was low, symptoms were more severe than on the moderately resistant control cultivar Sparta. Several other cultivars, such as Nordika, Julie, and Replik, also had slightly less than a 30% reduction in grain weight per spike, even though symptoms were more severe on Sparta or Athlon. Our results showed that, in the case of approximately 60% of wheat plants with BYDV-PAV symptoms, the yield reductions under optimal agronomic conditions reached approximately 17% for moderately resistant cultivars and 30% for moderately susceptible cultivars. The application of N fertilizer significantly reduced yield losses in BYDV-PAV-infected wheat cultivars, particularly in the moderately resistant cultivars. Even when infected with BYDV-PAV, the yield of moderately resistant cultivars, including those of spring wheat, was still acceptable. However, the re-cultivation costs of spring wheat in replacing damaged winter wheat lead to a total economic loss per hectare that is much greater than that for BYDV-infected wheat cultivars (moderately resistant and/or moderately susceptible ones). Furthermore, the economic loss is much lower when a moderately resistant cultivar is used. Hence, even with a high level of disease symptoms in winter wheat, the re-cultivation of spring wheat is not economically feasible. [ABSTRACT FROM AUTHOR]

A biography of associate professor Jaroslav Polák of Crop Research Institute (CRI) in Prague in Czech Republic is presented. He was born on January 25, 1942 and studied and graduated at the Agricultural University in Prague in agronomy. He worked at the Phytopathological Institute in Aschersleben, Germany wherein he acquired more scientific knowledge and technical experience on plant viruses. Polák is a prominent scientist with international reputation in agriculture.

The bird cherry-oat aphid ( Rhopalosiphum padi (L.)) is one of the most detrimental pests of cereals, causing harm mainly by transmitting Barley yellow dwarf virus (BYDV). R. padi migration has been monitored since 1992 using suction traps at five sites in the Czech Republic. The count data were subjected to the following different analyses: (i) the minimum temperature thresholds for the aphids to take off were determined; (ii) a partial redundancy analysis using the minimum, average, and maximum temperatures, as well as the wind speed, the precipitation total, and past aphid migration descriptors was performed to explain the relationship between aphid occurrences and weather patterns; and (iii) three types of models from the field of machine learning were used to predict aphid occurrences. According to our findings, (i) in Central Europe, 8°C is the temperature threshold for R. padi migration unless insufficient daylight delays the take-off; (ii) weather conditions occurring roughly 9 months before R. padi migration influence the migration size; (iii) the duration of the summer migration influences the autumn migration size; and (iv) the daytime and nighttime temperatures in the autumn determine the summer peak, whereas winter frosts and precipitation influence the autumn peak.