Reducing Labor Costs of Hand Thinning for 'Akko 1' Using an Organosilicone Surfactant

The self-compatible loquat cultivar 'Akko 1' sets fruit in excess, and therefore fruit thinning is necessary to obtain desirable commercial-size fruit. In the Israeli orchard, fruit thinning is done by hand, and usually consists of two steps: at the beginning of the flowering season the upper part of the inflorescences is trimmed, leaving only 2-3 of the lower lobes. The second thinning step is done about 2 months later, when fruitlets are thinned to only 2-3 developed ones per panicle. The aim of this study was to reduce the costs of 'Akko 1' hand thinning by using an organosilicone surfactant as a bloom thinner and/or by omitting the first handthinning step (inflorescence trimming). Application of 0.1-1% of the organosilicone surfactant Silwet L-77 at full bloom, with or without the first thinning step, reduced fruit set significantly. Nevertheless, fruitlet thinning was still needed to obtain commercial-size fruit. In addition, application of Silwet L-77 did not improve total yield or fruit size, despite its fruit-set-thinning effect. However, labor costs for trees that only underwent the second step of fruitlet thinning were much lower. Taken together, it was concluded that the cost of thinning of 'Akko 1' fruit can be reduced by eliminating inflorescence trimming, and reducing the number of fruitlets per panicle in a single, manual fruitlet-thinning step. Applying this economical practice did not impair total yield or fruit size compared to the conventional two-step handthinning procedure.