Fungicide insensitivity in yellow rust of wheat and barley


Cereals & Oilseeds
Project code:
01 September 1987 - 31 August 1990
AHDB Cereals & Oilseeds.
AHDB sector cost:
£67,514 From HGCA (Project No. 0038/6/87)
Project leader:
E G Barnard NIAB



About this project


An in vivo bioassay was developed for screening isolates of yellow rust (Puccinia striiformis) for sensitivity to the fungicides triadimenol and fenpropimorph. In total, 303 isolates, collected between the early 1960's and 1990, were tested. There was no indication that fungicide sensitivity had declined generally over this period. However, a single isolate collected in 1990 showed a marked decrease in sensitivity to both fungicides and was able to make limited growth on seedlings treated with fungicide equivalent to 2/3 field rate.

Isolates varied in their sensitivity to low rates of fungicide. There was evidence that this variation was associated both with the specific virulence of isolates and with their geographical origin. Isolates possessing the virulence combination WYV 6,9 and those originating from Scotland and Northumberland tended to be more sensitive than isolates without virulence WYV 6,9 and those originating from the south of the UK.

There was no relationship between the sensitivity of isolates and the intensity of fungicide application to the crops from which they had been collected.