Sustainable Phytosanitary Development of the Host-Parasite System on the Example of Head Blight of Winter Wheat

The territory of Stavropol Krai falls into the category of Fusarium head blight distribution areas. The analyzed period demonstrates that the disease developed on an area of more than 200 thousand ha, indicating the need to establish principles for sustainable phytosanitary functioning of the “winter wheat – Fusarium head blight infectious agent” system. Route surveys in the Kochubeyevsky district (the zone of average disease severity) and laboratory analysis of samples allowed us to establish that the dominant species of Fusarium fungi isolated from winter wheat seeds is Fusarium graminearum Schwabe. Corn agrocenoses, in which the pathogen multiplies annually, causing red rot on the cobs, implement the evolutionary-ecological tactics of the pathogen reproduction (P-tactics). At the same time, plant residues of corn, which do not pass mineralization and biological self-purification, act as the object of phytopathogen transfer to new plants (the so-called survival tactics or S-tactics). Winter wheat varieties susceptible to Fusarium head blight are sources of nutrients and energy for the phytopathogen population. Thus, the phytopathogen implements its evolutionary and ecological tactics of trophic connections (T-tactics). The analysis of internal factors (the so-called driving forces of the epiphytotic process) allows us to identify the adjustable elements of the general technology for winter wheat cultivation, thus reducing the risk of epiphytotic development. The cultivation of resistant varieties is the touchstone of study since the absence of a susceptible host plant disrupts the chain of internal factors stalling the epiphytotic process even with a sufficiently high infectious background under favorable conditions for the development of phytopathogens.