Vlasjuk O. Leaf spot of sugar beet and measure of restriction of their development in the conditions of the western Forest-steppe of Ukraine

The dissertation is devoted studying of laws of development Cercospora leaf spot (Cercospora beticola Sacc.), zonate leaf spot (Phoma betae Frank.) and Alternaria spot (Alternaria alternata (Fr.) Keissl.) the sheet device of a sugar beet depending on a number of factors. The equations of mathematical models to spend authentically the occurrence and development forecast Cercospora leaf spot that are based on hydrothermal indicators of May and June are developed. Influence of hydrothermal indicators on distribution zonate leaf spot which has considerable correlation with quantities of deposits in the third decade of July is established. For the first time from a distribution and etiology establishment Alternaria spot of a sugar beet research is carried out a zone of the western Forest-steppe of Ukraine. The pathogenic agent defined as parasitic saprophyte which amazes fabrics of the weakened leaves. The investigate action of solutions fungicides on germination conidium's pathogenic agent Cercospora leaf spot and Alternaria spot depending on term of their storage and concentration of solutions is carried out. For the first time action of solutions fungicides on germination conidium's different isolates fungi Cercospora beticola Sacc is studied and Alternaria alternatа (Fr.) Keissl. in laboratory conditions. The estimation of tolerance of grades and hybrids of a sugar beet concerning its defeat spots leaf the sheet device is given. It is not revealed proof to Cercospora leaf spot grades of a sugar beet that are grown up in Khmelnitskiy area. It is proved, that fоns a food of plants essentially influence defeat of a sugar beet by illnesses of leaves. On improved backgrounds development Cercospora leaf spot increases, and zonate leaf spot that Alternaria spot - decreases. It is established high efficiency of action fungicides against Cercospora leaf spot and also their influence on productivity and sugar content of root crops of a sugar beet in conditions both natural, and artificial infectious backgrounds. It is given the economic estimation fungicides for protection of crops of a sugar beet against illnesses of the sheet device is given.