Chemical treatments in "Golden Delicious Spur" fruits in relation to russeting and nutritional status

The impact of chemical products on mineral nutritional status and russeting in 'Golden Delicious Spur' was studied. In addition, we sought to define t he nutrients responsible for russeting in order to avoid imbalances in thei r concentrations in the fruit. Lime-sulphur (lime and sulphur, T1), ProVide (gibberellic acid GA(4+7), T2), calcium nitrate (8.5% N and 11.5% Ca, T3), Microthiol Special (micronized wettable sulphur at 80%, T4), Packhard (8% Ca, 6% carboxylic acid, 0.5%B, T5), and Dithane (ethylene-bis dithiocarbama te of manganese 62%, Mn 16% and Zn 2%, T6) were applied to apple trees at t he onset of flowering, at petal drop, and at the onset of fruit development . The ProVide and Microthiol treatments reduced the damaged fruit area and the percentage of damaged fruits in comparison to control (trees without ap plication, T0). The application of calcium nitrate and Dithane increased th e percentage of damaged area in relation to control, whereas the use of Pac khard increased the percentage of fruits with russeting. In conclusion, our results indicate that russeting is more influenced by the formulation of t he chemical products than by the nutrient content in the fruits, although w e found a highly significant reduction and inversely proportional relations hip between the Mn concentrations and the appearance of russeting.