Effect of loose smut (Ustilago segetum f sp tritici) infection in the enhancement of susceptibility to stem rust (Puccinia graminis f sp tritici) of wheat (Triticum aestivum)

Abstract

A total of 132 bread wheat (Triticum aesfivum L. emend. Fiori & Paol.) lines showing loose-smut [Ustilago segetum (Bull.) Rousel f sp tritici) infection, were studied over 2 crop seasons during 1997-99 to compare the intensity of stem rust (Puccinia graminis f sp tritci) infection between the smutted and non-smutted tillers in each line. The smutted tillers showed higher levels of stem-rust infection than their non-smutted counterparts in more than 94% lines. One-third of the wheat lines studied (45/132) could be rated susceptible (average coefficient of infection> 10.0) to stem rust, when rust reaction of only the smutted tillers was considered for the computation of average coefficient of infection. Stem-rust infection of the smutted tillers was not considered for determining the field response of a wheat line to stem rust, to avoid over-rating.