Post-bloom thinning of peaches for canning with hand-held mechanical devices

Abstract

Peaches for the canning industry were thinned by hand and with hand-held mechanical devices (one branch brusher and one pneumatic branch shaker) that were used alone and/or combined with hand thinning. Hand thinning was the most time-consuming thinning technique and it was also the most expensive (25 and 30 min tree −1 and 3.43 and 4.11 € tree −1 in 2008 and 2009, respectively). The pneumatic branch shaker together with follow-up hand thinning reduced the time needed to complete the task by 28% at a cost of 2.55 € tree −1 relative to hand thinning (control), but this technique did not remove enough of the green fruit from the trees. A brusher device combined with conventional hand thinning reduced time by 46% with respect to the control at a cost of 1.93 € tree −1. To improve this procedure, workers were instructed to detach only fruits on clusters in follow-up hand thinning and to work directly from the ground without the use of ladders. Accordingly, a time reduction of 82% was achieved at a cost of 0.77 € tree −1 under these conditions. The brusher used alone, without follow-up hand thinning, reduced the time spent by 90% relative to the control at a cost of 0.50 € tree −1. On average, all thinning techniques reduced crop load by 38% and increased fruit size by 47% at harvest relative to non-thinned trees. No significant difference was found in the yield of fruit per tree or in fruit with diameters over 55 mm among the 4 mechanical techniques, but there were differences found between the mechanical techniques and hand thinning. Because all peaches with a calibre over 55 mm receive the same price, excessively large peaches are not desirable and usually require severe thinning and, consequently, a reduction in peach yield. It is better to obtain higher yields while accomplishing the minimum size required. In this study, non-thinning was the technique that resulted in the highest economic impact.