Аннотация:Late blight, caused by oomycete Phytophthora infestans (Mont.) de Bary, is one of the most dangerous disease of potato and tomato. In private gardens potato cultivation is characterized with slow rate of fungicide applications, only a few artificial techniques, high diversity of cultivars and sporadic control of seed material. “Garden” populations of P. infestans has a high genotypic diversity, with both mating types. They are different in resistance to fungicides. Oospores are often formed in the blighted samples. “Garden” populations predominate in most regions of Russia, as in private gardens are grown almost 90% of the potato harvest. High genotypic diversity and sexual process in the “garden” populations allow us not to afraid of abroad dangerous clonal lines from imported seed potato because of sexual recombination with “garden” genotypes resulting in less dangerous gene combination. Thus, private gardens play a buffer role, not allowing developing highly aggressive and resistant to fungicides strains that cause severe destruction of commercial potatoes planting.
