Features of root rot development in the spring wheat agrophytocenosis under various agricultural technologies in the forest-steppe of Western Siberia

Crop infection is a stress factor for plants. The development and spread of fungal phytopathogens (Fusarium, Bipolaris, Alternaria, etc.) of the root system leads to a significant decrease in both quantitative, and qualitative parameters of grain crop productivity. The current paper has presented the data (2011–2018) on the study of subsoil parts of spring wheat plants when they are damaged by root rots of various etiologies, depending on the forecrops, agricultural technology and plant protection products. In the conditions of the Omsk region, the introduction of rapeseed into field crop rotations is justified. The grain crop has a positive effect on improving the phytosanitary condition of the soil and crops. There has been established that the greatest spread of infection on the root system of plants is identified on wheat sown in fallow (35–46 %), the minimum spread after rapeseed (7–16 %). Seeds of bluegrass weeds during protective tillage are concentrated in an uppermost (0–10 cm) soil layer. The increased weed infestation of agrophytocenosis reduces the competitiveness of cultivated plants and, as a result, the population of B. sorokiniana conidia in soil increases, creating unfavorable conditions for spring wheat development, especially during the initial period of growth. The highest crop productivity, regardless of a forecrop, mean for intensification options, was provided by moldboard tillage with 3.02 t/ha (wheat sown in fallow); 2.60 t/ha (wheat sown after wheat) and 2.15 t/ha (wheat sown\ after rapeseed). With a protective tillage, there was grain productivity decrease on 0.20 t/ha (wheat sown in fallow); 0.22 t/ha (wheat sown after wheat) and 0.12 t/ha (wheat sown after rapeseed) t/ha, respectively, in comparison with a moldboard technology. When fertilizing and herbicidal-fungicidal treatment of sowings during a vegetation period of plants, there is a slight difference between agricultural technologies. The complex use of chemicals reduces the infection of agrophytocenosis on 7–11 % and increases spring wheat productivity upto 4.14 t/ha (on 98 %) relative to extensive agricultural technology.