Effect of Preharvest Treatment with Seaweed Products, Kelpak (R) and Goemar BM 86 (R), on Fruit Quality in Apple

The effect of two formulations made from seaweed extracts on apple tree productivity and fruit quality was evaluated in seven experiments conducted during the period 2001-2005 on apple trees 'Gala Must', 'Golden Delicious', 'Jonagold Decosta', and 'Elstar'. One of the formulations, Kelpak (R), contains natural auxins and cytokinins extracted from Ecklonia maxima, while the other one, Goemar BM 86 (R), contains amino acids, vitamins, phytohormones, and poligosaccharides extracted from Ascophyllum nodosum, and the mineral nutrients N, Mg, B. The preparations were used, separately and together in a mixture, by spraying trees at the end of bloom, and subsequently four times at intervals of 4 weeks, the last time being about 4 weeks before harvest. In the other three experiments, Kelpak (R) and Goemar BM 86 (R) were used separately by spraying trees at full bloom only. It was found that Kelpak (R) and Goemar BM 86 (R), applied five times during the period from the end of bloom until up to 4 weeks before harvest, sometimes improved fruit set and the size of apples, to a greater or lesser extent depending on the fruit set, but above all they caused an improvement in the distribution of apples in size classes and somewhat reduced russeting. Depending on the cultivar, the preparations caused a deterioration ('Gala Must') or an improvement ('Jonagold Decosta') in the red coloration of apples. Sometimes, a negative effect of the treatments on the internal quality of apples, expressed mostly by the refraction value after storage, was noticed. The apples treated with the preparations were found to have high levels of total nitrogen. No effect of the two seaweed preparations on the storage quality of apples was found. Both preparations stimulated the growth of shoots and leaves, caused an improvement in flower quality, and prolonged the blooming time, but no effect on the blooming of trees a year after their application was observed. When the preparations were used only once at full bloom, they had a small effect on the size distribution of apples but a distinct effect on the vegetative growth of the trees.