SEEDLING REACTIONS OF WHEAT VARIETIES TO STEM RUST AND LEAF RUST AND OF OAT VARIETIES TO STEM RUST AND CROWN RUST

Abstract

A study of the rust reactions of wheat varieties to 20 physiologic races of stem rust has shown that several varieties of the vulgare type, namely, McMurachy, Eureka, and several strains from Kenya, East Africa, are immune in the seedling stage at ordinary greenhouse temperatures (55° F. to 80° F. daily). This immunity largely disappears when the plants are kept at a constant high temperature (75° F. to 80° F.). Certain other varieties and hybrid strains were found rather highly resistant to eight physiologic races of leaf rust, but none of the vulgare varieties tested showed immunity or high resistance to both stem rust and leaf rust.Tests to determine the resistance of oat varieties to the physiologic races of oat stem rust and crown rust prevalent in Canada showed that four oat varieties derived from the cross Hajira × Joanette were resistant to all the physiologic races of oat stem rust used in the test, and that certain strains derived from the cross Victoria × (Hajira × Banner Sel. 524) were resistant to all but one of these races. The last mentioned strains and the varieties Victoria and Trispernia proved resistant to the nine races of crown rust to which they were tested.