Winter wheat samples infected by eyespot were collected during the years 2015–2017. In total 143 Oculimacula spp. isolates were obtained and determined by PCR. Oculimacula yallundae isolates prevailed (122) over Oculimacula acuformis isolates (12) and 9 mixed isolates of both species. O. acuformis predominated only on one locality. The reaction of 104 Oculimacula spp. isolates to ten different fungicides was evaluated in laboratory tests on Petri dishes. The highest efficacy showed the combination of epoxiconazole + fluxapyroxad + pyraclostrobin and the lowest efficacy was evaluated after application of prothioconazole + trifloxystrobin. The decrease of efficacy of fungicide no. 6 (prothioconazole + trifloxystrobin) has been observed since 2015. The sensitivity of 114 Oculimacula spp. isolates to prochloraz has been tested. More than half of the isolates (58%) showed low to medium resistance. One isolate of O. yallundae from the year 2017 showed high resistance to prochloraz (ED50 ranged 1.7 μg ∙ ml–1). The rest of the isolates (42%) were sensitive to prochloraz.
The aims of the present study were to estimate the general combining ability (GCA) and the specific combining ability (SCA) effects controlling type II FHB resistance across environments in a set of European winter wheat varieties and, for purposes of future selection, to identify potential combinations of parents with suitable levels of FHB resistance. Parental varieties as well as F1 generations were evaluated under both field and greenhouse conditions in two years. The results of the present study indicate that in the F1 generation mean DON content was relatively lowest after crossing of moderately resistant parents (Sakura/Bakfis, Sakura/Federer, Petrus/Bakfis, and Sakura/Petrus), and mean DON content is low also after crossing the moderately resistant Bakfis variety with the susceptible Biscay and Cubus varieties. Evaluation of crosses in the F1 generation was followed by evaluation of selected crosses (derived from the Bakfis and Sakura varieties) in the F2 generation. Correlations between F1 and F2 were highly significant in relation both to their DON content and visual symptom score (VSS), as well as between the individual experiments (and in the different years). The only exception was in the case of the 2014 field experiment, when inoculation was successful but conditions were not optimal for the disease to progress and DON to accumulate. The selection of a suitable parental variety (with a high GCA) can markedly influence the success rate of breeding for resistance to FHB. Detection of high SCA in the F1 generation is important for directing breeders to promising combinations for achieving FHB resistance. It was demonstrated here that low DON content may be achieved even after crossing a moderately resistant variety with susceptible varieties. Another possibility is to make use of heterosis directly for acquiring resistance in hybrid wheat (for decreasing DON content and manifestation of symptoms).