A complex of Fusarium spp. causes Fusarium head blight (FHB) on wheat and also on barley. Infection with FHB results not only in yield loss, but also causes depreciation of the harvested product due to the accumulation of toxins such as deoxynivalenol produced by Fusarium spp. The flowering time is a very susceptible period for primary infection. One reason might be that during this period spores can get into the opened wheat florets where they may later cause infection. Initial symptoms of infection of a wheat ear are visible whitening and drying of individual spikelets or entire parts of the ear. If the florets became infected shortly after blooming, grains are often not formed, while other infected spikelets have grains with various deformities, shrunken and with pink-white coloration (Klem & Tvarůžek 2005). The main aim of experiments was detection of Fusarium species on wheat grains by using of the PCR methods. Abstract Nedělník J., Moravcová H., Hajšlová J., Lancová K., Váňová M., Salava J. (2007): Fusarium spp. in wheat grain in the Czech Republic analysed by PCR method. Plant Protect. Sci., 43: 135-137. The frequency of occurrence of four Fusarium spp. on wheat in the Moravia region, Czech Republic, was determined by polymerase chain reaction (PCR). Grain samples were collected during 2003-2006 at grain purchase centres. The dominant species was F. graminearum, which was recorded in all samples of the first 3 years of the study and in 88% of them in 2006. The previously more frequent F. culmorum was detected in 100% of the samples only in 2005; in the preceding two years the frequency of its detection was lower, 84% and 60%, and in 2006 it was detected in 55% of the samples. Fusarium avenaceum had a very low occurrence in the years 2003-2004, but in 2005 it was recorded in 100% of the samples. In 2006 it was the opposite-total absence of this species. A quite different situation was found in the occurrence of the fourth species-F. poae. In the years 2005 and 2006 it was only detected in 10%, resp. 2% of the samples, compared to markedly higher occurrences in the previous years. A comparison of the current weather development with the long-term mean at the Troubsko locality suggests that years with a relatively long, wet and cold start of the growing season and warmer end of vegetation (late May-July) will favour F. graminearum.

Mycotoxin content in 244 samples of wheat ears randomly collected during 2014 and 2015 from various localities in the Czech Republic was analysed using liquid chromatography coupled to mass spectrometry (LC-MS). Mean mycotoxin concentration in 2014 was highest for deoxynivalenol (DON; 760 μg/kg), followed by zearalenone (ZEA; 115 μg/kg), 3-acetyldeoxynivalenol (3-ADON; 88 μg/kg), deoxynivalenol-3-glucoside (83 μg/kg), and enniatins (ENNs; 102 μg/kg). In 2015, DON (66 μg/kg) also had the highest concentration level, followed by ENNs (35 μg/kg), nivalenol (2 μg/kg), and beauvericin (2 μg/kg). The maximum limit for DON in the European Union (1,250 μg/kg) was exceeded in 2% of samples, and the maximum limit for ZEA (100 μg/kg) was exceeded in 0.8% of samples. Fusarium species causing head blight were identified using PCR assays. During 2014-2015, Fusarium poae considerably dominated (48.7% average value of occurrence in the samples). Other species were detected in much lower frequencies in both years: Fusarium graminearum (average frequency of occurrence 13.7%), Fusarium avenaceum (11.9%), Fusarium culmorum (4.2%), and Fusarium equiseti (2.9%). Fusarium langsethiae was identified only in 2015, at a frequency of 10.2%, and Fusarium sporotrichioides was present only sporadically in 2014.

Dumalasová V., Palicová J., Hanzalová A., Bížová I., Leišová-Svobodová L. (2015): Eyespot resistance gene Pch1 and methods of study of its effectiveness in wheat cultivars. Czech J. Genet. Plant Breed., 51: 166-173.The scientific report presents results of our studies on the gene Pch1, conferring resistance to eyespot disease in wheat, caused by the fungus Occulimacula spp. The presence of the gene Pch1 in wheat cultivars was analysed using the molecular marker Xorw1. In total 106 wheat cultivars registered in the Czech Republic and 54 breeding lines were tested. The gene Pch1 was found in the cultivars Annie, Beduin, Hermann, Iridium, Manager and Princeps and in three breeding lines. Some of these cultivars were tested for eyespot resistance in field trials and showed a high level of resistance. Cv. Hermann was the most resistant winter wheat cultivar in our experiments in the last two years. The method of artificial infection by Oculimacula spp. was optimized.

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.

VEVERKA K., PALICOVÁ J., KŘÍŽKOVÁ I. (2008): . Plant Protect. Sci., 44: 127–137. The warm climate pathogen <i>Macrophomina phaseolina</i> (Tassi) Goid., which causes charcoal disease, has been reported in the Czech Republic since 1999. The aim of our work was to study the incidence of disease between 2000–2007 in the main sunflower growing regions and analyse the relationship between weather conditions and the occurrence of the pathogen. The first and highest incidence of disease was in the Žatec region. However, in the region south of Brno there was no disease in 2000, 2001 and 2003, and only individual low incidence in other years until 2007, when the disease was found in nine localities. The incidence of the disease is increasing year by year indicating a spread of the pathogen. The warm and dry periods throughout the end of July and August have promoted the disease. However in some years where weather conditions were favourable for the pathogen, in several cases no disease was found. It is assumed, that the pathogen was not yet present in these localities. Soil conditions are critical. Diseased plants are usually distributed in several dispersed groups in the stand, especially on higher and drier parts of the field. Disease is also often found on plants suffering from compressed roots. Diseased plants had poorly developed heads and seeds.