Abstract
The adult-plant wheat leaf rust resistance gene Lr 13 was detected in seedlings of wheat (T. aestivum) at 25.5.degree. C but not at 18.1.degree. C when inoculated with Cereal Rust Laboratory culture no. 82-BHL-MD of Puccinia recondita f. sp. tritici. Cultures of P. recondita f. sp. tritici were separated into 2 groups on the basis of their virulence to Lr 13 at 25.5.degree. C.