Tilletia species on winter wheat grain

Abstract

Goal. To determine the species composition of the complex of pathogens of bunt diseases of the genus Tilletia on winter wheat grain. Methods. The research was conducted during 2017—2020. 315 samples of winter wheat grain from different soil and climatic zones were analyzed. Seed contamination was determined by washing the grains and centrifuging the spore suspension, followed by counting their number in the Goryaev chamber. Identification of the pathogen was performed in the laboratory by microscopic examination, taking into account the morphological features of teliospores. Results. In 2017 and 2018, the presence of spores of fungi of the genus Tilletia was detected in 23.5 and 28.6% of the analyzed wheat grain samples, respectively. The number of spores per grain varied between 11—388.9 and 2.8—214.8 and averaged 72.5 and 33.7 correspondingly. The largest number of infected samples was observed in 2019 — 47.4%. In the same period, the highest level of seed contamination was observed — up to 1089 spores per grain, in average — 124.6 spores per grain. The lowest level of grain contamination was detected in 2020 — 6.3% of samples with an average of 3.7 spores per grain. Mostly spores of bunt pathogens were found in grain samples from Ternopil, Kyiv, Chernihiv, Lviv, Vinnytsia regions. The following species have been identified: Tilletia caries, T. controversa, T. laevis. Pathogen T. caries was detected annually. It dominated in 2020 and ranked second in detection rate in 2017—2019. T. controversa was found on grain in 2017—2019 and prevailed among other species. Its part in the complex of pathogens varied from 77.1 to 87.5%. In 2018, T. laevis was also detected. Conclusions. In most samples, spores of fungi of the genus Tilletia were not detected. On average, according to the years of research, grain contamination by bunt fungi were detected in 6.3—47.4% of samples with an average spore load of 3.7—124.6 of grain. The highest number of infected samples and the level of contamination were observed in 2019, the lowest — in 2020. The complex of pathogens is represented by three species: T. caries, T. laevis, T. controversa. T. controversa dominated in 2017—2019 and T. caries — in 2020. T. laevis occurred sporadically.