THE FLOWER THINNING EFFECT OF DIFFERENT COMPOUNDS ON ORGANIC 'GOLDEN SMOOTHEE®' APPLE TREES

The use of different compounds as blossom thinners on organic apple ‘Golden Smoothee®’ was evaluated during 2005 in Lleida (Spain). Ten-year-old ‘Golden Smoothee®’ trees grafted onto ‘Pajam 2®’ were treated with 6 different products and rates, and compared to an unthinned and a hand-thinned treatment in a randomized complete block design with four replicates. The products tested were olive oil, potassium soap, kaolin, mineral oil, sodium salt, and lime sulfur. Two treatments of each compound were applied, first at full bloom and at petal fall thereafter. Overall flower clusters per tree were counted just before flowering, and phenological stages were monitored during flowering. Fruit yield, number of fruits per tree and mean fruit weight were determined with a commercial sorting machine at harvest. Additionally, a sample of fruits was used to determine the incidence of fruit russet in a 12-degree scale. First results show important differences among products, with a certain relationship between their thinning effect and the russet incidence, with olive oil being one of the most effective treatments.