VIEW ARTICLE

Resistance

A Method for Field Evaluation of Wheats for Low Receptivity to Infection by Puccinia graminis f. sp. tritici. J. B. Rowell, Research plant pathologist, Cereal Rust Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, University of Minnesota, St. Paul, 55108; D. V. McVey, Research plant pathologist, Cereal Rust Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, University of Minnesota, St. Paul, 55108. Phytopathology 69:405-409. Accepted for publication 17 October 1978. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1979. DOI: 10.1094/Phyto-69-405.

Uredospores of Puccinia graminis f. sp. tritici in light mineral oil were applied uniformly with a portable mist blower to a linear arrangement of rows of susceptible wheat accessions. Large differences in amounts of primary infection caused by uniform inoculations with race 15B-2 were consistently detected between the highly receptive wheat line Purdue 5481C1 and the less receptive cultivars Thatcher, Sentry, and Idaed 59. Receptivity changed from high to low with increasing age in Thatcher and Sentry, and from low before anthesis to high afterwards on leaf blades of Idaed 59. Primary uredia were larger on juvenile plants than on older plants of Marquis, Lee, Thatcher, Sentry, and Idaed 59, but were consistently large on Purdue 5481C1. Low receptivity in Idaed 59 appears to be governed by a single dominant gene linked or identical to Sr Tt-1, and in Thatcher by two recessive complementary genes. Lee appears to possess a third recessive gene for low receptivity that reacts cumulatively with the two complementary genes in Thatcher to yield lines of very low receptivity.