Orlovska G. Monitoring, biological properties of viruses and prevention of viral infections of sunflower.

The thesis is focused on monitoring of viral infections of sunflower in 15 sunflower-growing regions of Ukraine, on diagnostics of 7 virus pathogens infecting this culture (TSWV, AMV, CMV, PVY, PVS, TMV, PVX), and on elaboration of preventive methods of control (heat treatment, use of biological and coordination compounds). TSWV, AMV, CMV, PVY, PVS, TMV, and PVX may cause mixed infection of sunflower, and the relative percentage for plant infection with these pathogens have been revealed. Isolates of TSWV and CMV most common for such mixed infections have been isolated and described. Morpho-structural organization and localization of TSWV, CMV, and PVY have been studied. Edwarson structures typical for PVY have been firstly found in PVY-infected sunflower cells. Heat treatment of seeds has been shown effective against AMV and TSWV. We have experimentally selected efficient concentrations and exposition time(s) for presowing treatment of sunflower seeds with coordination compound P039, 'BOA' and 'Bioecofunge-1' preparations reducing TSWV content. In low doses, these compounds have been also demonstrated to act as growth stimulators.