Effectiveness of fungicide-free approaches to the protection of potato and tomato against late blight

The article describes fungicide-free ecologically tolerant technologies for the protection of potato and tomato against Phytophthora infestans (Mont.) de Bary, agent of late blight of these crops. It has been proved that potato cultivars with field resistance (Lugovskoy) provide a protection level comparable to the effectiveness of modern fungicides. Plant extracts from Southern plants can be used as biopesticides in order to additionally suppress the development of late blight. For example, extracts of four species from Yemen (fam. Asteraceae: Psiadia arabica Jaup and Spach; fam. Lamiaceae: Lawsonia inermis L ; Dodonea viscos L ; Euryops arabicus Steud. ex Jaub and Spach ) were capable of suppressing late blight development on potato. On the contrary, plant growth regulators, Novosil (active compound triterpene acids), Larixin (active compound dihydroquerticin), and Terpenol (active compound triterpene acids), in spite of the periods of high efficiency against late blight, do not provide satisfying effect since these substances could sometimes even promote a pathogen development. Also, vaccination of tomato with attenuated strain of tobacco mosaic virus (TMV) could improve viability and immune status of plants under normal conditions, and in the case of stress situation it promoted weakness of plants and P. infestans infection. In Eastern Europe, fungicide-free technologies for the protection of potato and tomato against late blight, corresponding to the ecological criterion, should be additionally elaborated and tested for potato and tomato cropping.