Effectiveness of fungicidal protection of spring wheat against powdery mildew and tan spot

Abstract

The results of the study of the effectiveness of plant protection products against powdery mildew (Blumeria graminis) and tan spot (Pyrenophora tritici-repentis) for spring wheat are presented. It has been noted that the probability of mass destruction of crops by phytopathogens is determined by the stock of the infectious beginning of pathogens, the susceptibility of the host plant and the favorable weather conditions for their development and spread. The experiment was carried out using the methods generally accepted in the Russian Federation. During the observation period, the degree of plant damage of more than 20% in the heading phase was noted in 46% of the years of observation (in 2009, 2013, 2014, 2016, 2017). Epiphytotic development of powdery mildew together with brown leaf rust (Puccinia triticina Eriks.) was registered in 2013–2014 and 2016–2017. For 2009–2019 the degree of plant damage of more than 20% in the heading phase was noted in 46% of the years of observation (in 2009, 2013, 2014, 2016, 2017). Effective protection of wheat against powdery mildew (75–87%) was provided by fungicides based on 2–3 active ingredients. The biological effectiveness of the biofungicide (Bacillus subtilis) was manifested only in the years with moderate wheat damage and did not exceed the average level of 58%. It is more expedient to carry out operational control of yellow spotting of wheat leaves with preparations based on such active substances as "azoxystrobin + epoxiconazole", "tebuconazole + propiconazole". The level of statistically significant yield preserved due to fungicidal protection during the years of depression was 5–6%, with a moderate development of leaf diseases due to chemical fungicides - 18%, and the biological product provided an increase in productivity of 9%. During the years of epiphytoties, the chemical protection of crops retained an average of 24% of the wheat yield, polycomponent preparations had the best performance and stability of action, and the biological protection of plants under these conditions was ineffective.