Micronised and non‐micronised sulphur applications control peach scab equally well with negligible differences in fruit quality

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AbstractIn a 2‐year study, micronised (finely ground) and non‐micronised sulphur spray programmes were investigated for peach scab control and influence on peach fruit quality variables including fruit colouration, soluble solids content and flesh firmness. Both sulphur programmes, applied six or 11 times at 15 kg ha−1, controlled scab equally well in both years on cultivars (cvs) Contender and Cresthaven. Six applications of a half dosage of both micronised and non‐micronised sulphur programmes were significantly less effective (P < 0.05) compared with all other programmes when scab incidence was >90% on cv. Contender. None of the sulphur programmes influenced significantly (P < 0.05) colouration and flesh firmness of harvested fruits compared with the industry standard (a chlorothalonil–captan programme). Only soluble solids concentrations showed significant differences among fungicide programmes (P < 0.05), but these differences were not consistent with either particle sizes of sulphur fungicide or reduced application fungicide programmes. In conclusion, our study showed that (a) micronised sulphur did not control peach scab more effectively compared to non‐micronised sulphur; (b) six applications of sulphur were sufficient to control peach scab when disease pressure was low to medium; and (c) neither six nor 11 applications of sulphur‐based products applied at 15 kg ha−1 had commercially relevant negative impacts on important peach fruit quality variables.