20 complex interspecific crosses were applied .   Tomato plants grown in plastic green - houses were artificial inoculated in their period of fruitage in July . During inoculations plants were sprayed with a population of Oidium lycopersicum collected from infected commercial tomato plants grown in greenhouses in the Moscow region . In addition to adult plant inoculation we’ve tested resistance of detached leaves in Petri dishes and detached lateral shoots under conditions of artificial inoculation (Tereshonkova et al . 1999) . Resistance of plants was estimated using a scale 0 - 4 , where 0 - 1 . 5   characterize resistant plants and 2 - 4 characterize susceptible plants . Results and discussion During 1997 - 1999 selected resistant lines were derived from a row of crosses . Table1 . Reaction of different accessions of tomato interspecific crosses to powdery mildew ( Oidium lycopersicum) . Combination Generation Resistant accessions disease severity limits (scale 0 - 4) % L . esc x L . pimp . Red Currant BP 10815 S5BC1 - S9BC1 0 - 1 . 5 71 L . esc x L . hir . glab VIR 4175 S4BC1 - S6BC1 0 - 1 . 5 50 L . esc x L . humboldtii VIR 2884 S4BC1 - S6BC1 0 . 5 - 1 . 5 75 L . esc x L . cheesmanii K3889 F5 - F8 0 - 1 . 5 52 L . esc x (L . chees . f . minor VIR 3969 x L . esc v . cerasiforme) F3 - F6 0 . 5 - 1 . 5 - 2 . 0 42 . 8 (L . esc x L . humb . ) x [L . esc x (L . chees .           f . minor x L . esc v . erasiforme )] F1 - F3 0 . 5 - 1 . 5 - 2 . 0 9 L . esc (susceptible check )   - 3 . 5 - 4 . 0 0 To obtain a wider spectrum of forms the F1 hybrids of known genotypes, such Krasnaja Strela F1,   Grein F1 and   Lastochka F1 were used as culture parents in all crosses with wild species . As a result of 7 years breeding with using different breeding methods we have received interesting lines of the above - mentioned combinations with various features . The resistance in the majority of combinations was stabilised in F7 - 9 generations, in some combinations further segregation was found . The lines differ in fruit features (shape, taste, size, colour, density), cluster forming, number of fruit in a cluster, and plant growth: determinant, indeterminant (sp/sp+) . It is necessary to note that the resistance of the various donors has individual features that can be explained by the probable presence of gene - modifiers .   The earliest stability of resistance was established in a combination L . esculentum x L . pimpinellifolium (Red Currant BP 10815) . Milotay (1997) noted L . pimpinellifolium Red Currant as a possible source of resistance . In our case, the