The Allium & Brassica Centre's Andy Richardson said: "This will be a big help to growers this year as it's the most difficult crop in which to control fungal diseases."
"Rudis also delivers strobilurin-like physiological benefits including enhanced greening. It's now the strongest contender against all four major leaf spot diseases and powdery mildew."
Richardson added that the first sprays of Nativo 75WG (tebuconazole + trifloxystrobin) were applied to storage cabbage crops to counter the white blister and powdery mildew risk presented by the warm, showery weather. These first sprays were also timed to keep older leaves clear of ring spot.
He said: "While ring spot remains the main threat south of the Humber - light leaf spot is creeping this way. Dry conditions so far are also likely to make powdery mildew more of an issue this year."
Richardson recommended a four-spray programme to get the required broad spectrum control, including two applications of Rudis (prothioconazole) as the second and fourth treatments.