Induction of pumpkin culture seeding’s immunity to powdery mildew as a result of treatment by rhubarb extracts

Abstract

The aim of the research was to determine the fungicidal and immunostimulating action of seedling treatment with rhubarb extracts based compositions in powdery mildew protection. It was necessary to solve the following problems: a) to determine the effect of the time interval (72 and 4 hours) between the treatment of fam. Cucurbitacea seedlings and their artificial infection (S. fuliginea) on the biological effectiveness of rhubarb extract based compositions; b) to determine the effect of microelements and rhubarb leaf extract in combination with rhubarb root extract on the effectiveness of the composition. As a result of research, the optimal concentration of rhubarb root extract (1,0 - 1,5%) was identified, to suppress the development of powdery mildew and to increase the chlorophyll index on pumpkin seedlings in greenhouses, and its biological effectiveness was determined (87,6 - 96,6%). The immunostimulating effect of rhubarb root extract in a concentration of 1,5 - 2,0% has been proven, the biological effectiveness of which, when processing the pumpkin seedlings leaves (4 and 72 hours) before infection, reaches 89,3%, providing reliable and stable protection of seedlings from powdery mildew. The addition of micronutrients (Zn, Fe, Mg, B) microdose increases the immunostimulating properties of the composition. It is proved that the composition of the rhubarb root and leaves extracts has a fungicidal and immunostimulating effect and is the most promising and cost-effective for protecting pumpkin cultures from powdery mildew in greenhouses.