S tritici incidence is worst on record
WHEAT growers could have contributed to the worst incidence of Septoria tritici recorded in the crop since the disease came to prominence in 1985.
Levels of the foliar disease in crops this season were twice the ten-year mean and nearly ten times those of last year, provisional results of a DEFRA-funded national survey show.
Weather is the main reason, says Nigel Hardwick of the CSL who conducted the survey. But he believes grower practice also had an influence. "Were wondering whether poor fungicide timing or use of lower doses is contributing to the higher levels found. Growers were lulled into a false sense of security by the dry April. By the time the wet May arrived it was too late to do anything about the disease."
Dr Hardwick is concerned at the amount of the national crop sown to varieties not noted for their resistance to septoria.
A survey of grower practice, which he hopes will shed more light on the problem, is due to be completed before Christmas. *
Disease 10-year mean (1992-2001) 2000 2001 2002*
Mildew 0.3 0.1 0.1 0.2
Septoria tritici 4.7 7.2 1.0 9.7
Septoria nodorum 0.2 0.3 0.1 trace
Brown rust 0.2 0.1 trace trace
Yellow rust trace trace trace trace
Eyespot 13.4 22.9 5.7 6.6
Foliar diseases – % area of leaf two affected. Stem base diseases – % stems with moderate or severe lesions. Trace – 0.05% area affected. * = provisional.