Integrated protection of alfalfa against fungal diseases in the eastern forest steppe of Ukraine

Abstract

The results of studies on the spread, harmfulness, and biological characteristics of the pathogen of fungal diseases of alfalfa in the Eastern Forest Steppe of Ukraine are presented in the article. Monitoring of alfalfa diseases showed that the most harmful were brown spot (the pathogen is Pseudopeziza medicaginis (Lib Sace.)), downy mildew (the pathogen is Reronospora aestivalis Sya.), Ascochyta leaf spot (the pathogen is Ascochyta imperfecta Peck.) and yellow spot (the pathogen is Pseudopeziza Dyonesii Nann.). A reliable connection between the indicators of the maximum spread and development of the diseases and meteorological factors during the growing season of the crop has been established. The conducted screening as for the disease resistance of promising alfalfa varieties showed that the Vlasta and Unitra varieties are characterized by group resistance to fungal diseases. The high efficiency of using summer wide-row sowing in stabilizing the phytosanitary condition, which ensures a reduction in the spread of the main alfalfa diseases by 11,8–17,5% compared to regular sowing has been established. The necessity of early spring stubble combing out has been proven. It contributes to reducing the infection in the crops, the spread of the diseases during the alfalfa growing season by 1,2–2,4%, and their development by 1,6–2,8% compared to the control. The equations for predicting the maximum spread of alfalfa Ascochyta leaf spot Y1= 0,034x9,651 and its maximum development Y2=0,025x+3,9 have been developed. The use of the short-term forecast data as for the development of the alfalfa diseases which we have developed, provides an opportunity for timely spraying of alfalfa in the phase of budding with 25% e.c. of Tilt at the rate 0,5 l/ha and zinc sulfate at the rate 0,02 kg/ha. At the same time, the spread of fungal diseases was reduced by 3,6%, the development of diseases – by 13% compared to the common technology of growing alfalfa