THE OCCURRENCE OF LOOSE SMUT RESISTANCE IN 42, 28 AND 14 CHROMOSOME WHEATS

A total of 865 spring wheat varieties, and selections from the 14, 28 and 42 chromosome groups, were inoculated in 3 successive years with a mixture of Canadian collections of loose smut, Ustilago tritici (Pers.) Rostr. At the end of the first year, 231 were rated immune; after the second inoculation, 188; and after the third, 162. These included 116 from the 42 chromosome group, 43 from the 28, and 3 from the 14. Although some of the reduction in immune or resistant types after the first year may have resulted from escapes, it is probable that most of these showed susceptibility to new collections added in the second and third years.