Zaima O. Resistance of winter wheat varieties against major leaf diseases and justification of protective measures in the Forest-Steppe of Ukraine

In the thesis, the features of the development of leaf diseases are determined depending on the hydrothermal conditions of the medium on varieties belonging to different groups of resistance. The results of the evaluation of the resistance of collection samples and varieties of winter wheat against basic leaf diseases are presented. 83 samples and 18 varieties of winter wheat with group resistance against powdery mildew, septoria leaf and brown rust were isolated. The pathological changes in sick plants of new varieties of winter wheat under the influence of pathogens were studied. Thus, with a strong lesion of leaves with powdery mildew, their respiratory rate decreases by 0.20–0.36 % compared with healthy ones, with septoria damage by – 0.18–0.39 %. In this case, the electrical conductivity of cell membranes increases by 11.2–30.0 % and 8.5–17.8 %, respectively; The plant height, productive bushiness, the length of the ear, the number of grains in the ear, the sedimentation index and the content of «raw» gluten, respectively, by 2.1–4.7 cm, 0.5–0.7 pcs., 0.6–0.9 cm, 4.5–5.7 pcs., 1–5 ml and 0.2–3.1 %. Positive results were obtained in studying the role of agrotechnical measures in limiting the development of leaf diseases. It was revealed that less damage to plants with powdery mildew occurs after the corn precursor for silage, septoria – after the predecessor of winter rapeseed. Both predecessors restrain the development of brown rust. It is proved that less damage to plants with powdery mildew and septoria occurs at the optimum time of sowing (the second and third decades of September), and brown rust – at a late period (first decade of October). The elements of chemical protection technology for the Podolyanka and Myrlena varieties have been developed. Optimization of spraying of winter wheat crops against leaf diseases with fungicides in various phases of vegetation of plants is proved expedient.