CHANGES IN VIRULENCE GENES FREQUENCY IN B ELORUSSIAN POPULATION OF PUCCINIA-TRITICINA ERIKSS. DURING 1980, 1984, AND 1994

Virulence genes of Puccinia triticina Erikss, population widespread in Belarus were studied using series of isogenic lines of Thatcher varie ty. Variability in effectiveness of wheat resistance genes against the pathogen was found based on the data from 15-years study. Increase in Lr 1 gene effectiveness and decrease in frequency of clones, virulent to Lr 2a and Lr 3d genes were demonstrated. It was also found that th e number of clones that overcame resistance genes Lr 3a, Lr 14b, Lr 17 , Lr 20, and Lr 23 riched 100% in 1994. Lr 10, Lr 15, and Lr 24 genes effectiveness decreased significantly. Frequency of clones virulent to genes Lr 9 and Lr 19 was low.