Various products are for sale of which it is claimed or at least hoped that they can promote fruit set. In 2023, Dutch Proeftuin Randwijk tested some of these products on the Kordia variety (see table). In the most favourable case, 13% more cherries could be picked than on the trees that had remained untreated. The best result was achieved by 4 sprayings with Vidi-Terrum or with 3 sprayings with Vidi-Terrum plus 2 times Kudos. The fruit set boost of the other products varied from 0% (Biopolin) to 8%. “In that same year, by already closing the cover before flowering, we could pick 30% more cherries of Kordia”, stone fruit researcher and consultant Johan Sonneveld stated during the cherry day of StonefruitConsult. Therefore, his conclusion is transparent and clear: “Closing the cover during flowering has more effect on fruit set than spraying products.”
Table. Tested products in fruit set trial Kordia at Proeftuin Randwijk in 2023
untreated
3 x 5 litres Vidi-Terrum
4 x 5 litres Vidi-Terrum
4 x 5 litres Avitar
2 x 7.5 litres Aminosol
Biopolin
4 x Colortect
2 x Kudos
3 x 5 litres Viditerrum + 2 x Kudos
Source: StonefruitConsult and Proeftuin Randwijk