6 September 1996

Rustratings leave question mark hanging

NEW yellow rust ratings from NIAB highlight the extreme susceptibility of one of the most widely grown winter wheats and the weakness of another, provisionally recommended, variety. Breeder spokesmen, though, are relatively unconcerned.

Brigadier and Reaper get ratings of 2 and 3, respectively, on the 1-9 NIAB resistance scale in the latest issue of Cereals Varplan 97.

Chianti from CPB Twyford also merits a 3, and Zenecas 1997 recommended list candidate Harrier a 4. All others rate 5 or higher.

The latest data, based on inoculated tests with the new YR17 race, leave "a question mark hanging over Brigadier", according to NIAB cereal pathologist Mike Meadway. A rating of 3 for the disease is the minimum permitted for new varieties vying for a slot on the recommended list.

Precisely how the independent Cereal Trial Advisory Committee will make use of the new data on fully recommended Brigadier remains to be seen, he says.

Alan Armstrong, for Brigadier breeder, Zeneca, says it is easy to become emotive about the ratings. But the general Varplan comments about the variety noting its yellow rust susceptibility, its need for prophylactic fungicide, and the likelihood of it remaining popular this autumn, are very fair, he says.

Stephen Smith for Reaper breeder New Farm Crops points out that there were no signs of field infection last season. "There are some excellent fungicides out there."

Mr Meadway concedes that fungicides can contain the disease. "But if it gets away from you it can be very hard to control," he warns. &#42