Brassica growers are facing a tough year with sprout and cabbage crops under threat, according to experts.
Growers are being advised to plan programmes for broad-spectrum control when considering this season’s disease threats.
The Allium and Brassica Centre’s Andy Richardson is anticipating that Brussels sprouts and storage cabbage will require protection against white blister and light leaf spot (LLS) in addition to the every-year risk of ringspot.
The four-spray programme Ricahrdson recommends is to start with Nativo followed in sequence by Rudis (prothioconazole), Amistar Top (azoxystrobin + difenoconzole) and Rudis.
Oilseed rape (OSR) is a major source of LLS innoculum spreading to vegetable brassicas and ADAS plant pathologist Dr Peter Gladders says it is now the number one disease problem in OSR. “It has been perceived as a northern disease but this is no longer the case.”
The spring 2011 CropMonitor survey recorded LLS infection in 84 per cent of English OSR crops with an average of 34 per cent plants infected. This is the highest ever proportion of crops found to be infected and continues the rising trend over the last six years: the picture is consistent across all regions. Gladders warns it’s a clear sign there is a problem waiting to happen for vegetable brassicas.
Richardson added; “Last year we saw the first significant LLS infection entering a crop of cabbage in Nottinghamshire surrounded by OSR. Rudis did an excellent job of drying up lesions. We’ve also been seeing some infection in Lincolnshire crops over the last two years but nothing as bad as in the borders yet.
“Genetics clearly has a key role to play in the future and the LLS detection kits being developed by Professor Roy Kennedy at the University of Worcester will enable us to get a much better handle on risk periods.“
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