Wheat bane is stem base
The official 1997 cereal
disease survey holds
lessons for all growers.
Andrew Swallow relays the
results and asks what they
mean for 1998
STEM base diseases caused most yield loss in 1997. To reduce that pressure, growers should exploit rotation, advises Nigel Hardwick of the Central Science Laboratory.
Eyespot levels were the highest since 1988 and cost growers an estimated £20.4m. Nationally it cut yield by an average 1.6%. But the figure masks heavier losses where conditions favoured the disease. Second and third wheats and crops sown before October were worst affected.
Take-all was worst after set-aside, a "crop" commonly regarded as a break on farm. "This disease still accounts for most yield loss in cereals every year," says Mr Hardwick. "Clearly there is a message here for set-aside management practices, as well as rotations."
Fusarium levels rose again, most severely in early drillings.
Of the foliar diseases, Septoria tritici was again the most damaging. Nationally it trimmed 1.3% from yields worth an estimated £26.8m.
"In most cases, this is the disease growers must protect the flag leaf from," says Mr Hardwick. "The introduction of strobilurins raises questions on application timings, but septoria remains the target."
Yellow rust was more obvious than at any time since 1990, though still only at trace level nationally. "It is a disease which growers should target only in high risk situations. Assess the variety, location and previous disease incidence," advises Mr Hardwick. Mildew recorded its second lowest appearance since 1970.
There were big differences in disease levels, notably of Septoria tritici, between varieties, even among those with similar NIAB resistance ratings. But this does not undermine the trials system, stresses Mr Hardwick. "It is more a reflection of the growth habit of these crops at the time of infection."
CS survey suggests there is still plenty more scope to tailor inputs.