Effect of strobilurin fungicides on disease control and yield in blackcurrants

Strobilurin fungicides have been marketed for use on cereals, apples, grapevine and cucumbers in various countries. These products have a wide spectrum of activity, including the control of powdery mildews and leaf spotting fungi. In a series of experiments, covering the period 1995-2000, examples of these fungicides have been evaluated for the control of the blackcurrant American gooseberry mildew (Sphaerotheca mors-uvae), leaf spot (Drepanopeziza ribis) and grey mould (Botrytis cinerea). The strobilurin fungicides examined as part of these studies have been azoxystrobin, kresoxim-methyl and trifloxystrobin, and all experiments were carried out in commercial plantations of cv. 'Ben Lomond'. Good control of all three diseases was found but, with some products at some timings, phyotoxicity resulted in yield reductions when compared to standard fungicide programmes. The results of experiments, done in 1996 and 2000 are discussed in detail.