The effect of model-based fungicide and ozonated water spraying on Botrytis fruit rot in open-field strawberries

Abstract

The aim of the study was to determine whether it is possible to reduce the frequency of spraying fungicides from the usual three times to only one application at more precise time based on the flowering stage or disease prediction model and how effective the spraying with ozonated water is against Botrytis fruit rot (BFR) in open-field strawberry ( Fragaria × ananassa Duch.). The treatments: 1) CTRL – strawberry plants were not sprayed against BFR (control); 2) OW – sprayed with ozonated water twice a week from the beginning of flowering until the end of harvesting; 3) S1F– fungicide 1 (boscalid and pyraclostrobin) application once at 60% flowering (BBCH 65); 4) S1W – fungicide 1 application once based on the predicted BFR risk according to the Bulger model data; and 5) FARM – conventional fungicide spray programme used by strawberry growers: fungicide 2 (cyprodinil, fludioxonil) twice and fungicide 1 once. The number of marketable and BFR-damaged strawberry fruits was determined for each harvest. For analyses, fruits from the 4th harvest were used. In the CTRL treatment, 17% of fruits were infected with BFR. All fungicide treatments significantly reduced infection, and there were no differences between the FARM, S1W, and S1F treatments. The OW applying did not reduce BFR. Fruits sprayed according to S1W and S1F contained residues of boscalid, while fruits sprayed according to FARM contained residues of boscalid, cyprodinil and fludioxonil. All fungicide treatments reduced the total polyphenol content and total antioxidant capacity of fruits, while the FARM and S1W treatments reduced ascorbic acid content. The results of the experiment showed that the frequency of fungicide sprays can be reduced from the usual three times to only one-time application at more precise time without significantly increasing the number of strawberry fruits affected by BFR.