Survey and Race Analysis of Puccinia triticina Eriks. Causing Leaf Rust Disease in Wheat; Evidence for Secondary Foci of Infection in Puccinia Path

A survey was carried out on leaf rust of wheat in kharif and rabi season during 2010–11 and 2011–12 in Karnataka. Survey in the districts Chikmagaluru and Chitradurga during kharif season of both the years revealed the absence of wheat cultivation in these areas. Survey (roving survey) during rabi, 2010–11 and 2011–12 revealed the difference in disease severity and incidence of leaf rust in different districts. Among seven districts; Belgaum, Bhagalkot, Bijapur, Dharwad, Gadag, Gulbarga and Yadgiri disease was observed only in three potential wheat growing districts viz., Belgaum, Dharwad and Gadag with severity ranges of 10MS-100S, 20MS-100S and 60S-80S, respectively during rabi, 2010–11 and 10MS-100S, 20MS-100S and 5S-100S respectively during rabi, 2011–12. The bread wheat variety DWR162 grown in large area (>50%) showed the highest disease severity and infection type in all surveyed districts. The pathotype 121R63-1 (77-5) was dominant and distributed in 35.71 per cent and 58.90 per cent during rabi 2010–11 and rabi 2011–12, respectively. Occurrence of a diverse population of pathotypes, some of which (12,104,162 group of pathotypes) do not occur in Nilgiri hills reveal that the surveyed areas form a different focus of infection.