Inheritance of tomato leaf resistance to Phytophthora infestans - new information based on laboratory tests on seedlings

In her i tance of to mato re sis tance to P. infestans was stud ied in prog e nies of crosses of re sis tant ac ces sions: West Vir ginia 700, Ot tawa 30, PI224675 and the va ri ety New Yorker and also of the va ri ety West Virginia’63 and re sis tant breed ing lines crossed with sus cep ti ble forms. Pop u la tions of F1, F2, par ents and re sis tant stan dards were eval u ated for re sis tance to late blight us ing the test on seed lings grown in liq uid me dium. Re sis tance of the ac ces sions West Vir ginia 700, Ot tawa 30 and PI224675 was found to be iden ti cal and de ter mined by the same genes: Ph-1 and Ph-2. It has not been rec og nized if these ac ces sions carry other genes, nei ther if the va ri ety West Virginia’63 and lines of equal re sis tance pos sess other genes be side Ph-2.