10 July 1998

New strain brown rust?

RAMPANT brown rust in wheat points to a new strain of the disease, says NIAB.

"Brown rust has taken up where yellow rust left off. The disease has rocketed despite apparently cool weather," says cereal pathologist Phil Stigwood. But not all susceptible varieties are equally affected.

"There seems to be a race thing going on. Buster is heavily infected, yet similarly susceptible Soissons and Rialto are showing surprisingly low levels of the disease." A temperature interaction may be to blame.

Brown rust on Buster appears to thrive at lower temperatures than the 20C favoured by strains on other varieties, notes Mr Stigwood. The threshold seems to be closer to yellow rusts favoured temperature range of 10-18C.

Geographical spread is also changing, with the disease increasingly found in East Anglia and Lincs.