Thinning of Organic Apple Production with Potassic Soap and Calcium Polysulfide at the North of Spain.

Summary in the original language of the document

Asturias, in the North West coast of Spain, is a region with old tradition at cultivation of
apple and its transformation to cider. The production of apple is mainly done under
traditional uses and semi-extensive or semi-intensive system and with local cultivars.
Thinning strategy is little practiced and the biennial bearing cycle is one of the main
problems for the farmers. The production of apple under organic techniques in Asturias is
still limited but increasing. Since 2005, experiments have been conducted on several
cultivars (‘Raxao’, ‘Xuanina’ and ‘Gold-Rush’) to evaluate the effects of Potassic Soap
(with or without olive oil) and Calcium Polysulfide as thinning products. We present here
the first promising results of these experiments. With different concentrations of both
products we have increased the apple production of two cultivars for the period 2006-
2007. There were positive effects on the vegetative growth of the trees and on the quality
of apples. In the spring 2007 we initiated new experiments with other cultivars (‘Durona de
Tresali’, ‘Solarina’, ‘Raxao’, ‘Regona’) in order to confirm our results. The new experiments
also include the comparison of their effects with those of commonly used chemical
products and with those of manual thinning techniques.