Peach thinner may bear fruit
As consumer demand for premium fruit increases, growers are being challenged to bring consistently high-quality fruit to market. And to boost their bottom line, orchard owners are experimenting with new techniques that can increase fruit quality while reducing labor costs.
Thinning by hand, a common practice used by growers to produce larger, healthier fruit, is among the most labor-intensive orchard practices, with significant impact on fruit production overhead, and ultimately, prices paid by consumers. A Penn State research team published the results of new research on a horizontal string thinner used in peach production in a recent issue of HortTechnology. A string thinner prototype for open-center tree canopies was tested in six orchards. Remarkably, fruit size at harvest was increased by the horizontal string thinner in all but one trial.
• New mechanical peach thinner promises savings for producers.
• Product helps create superior peaches, as growers are asked for high-quality fruit.
• Thinning by hand costs California growers $1,000 or more per acre.
Eliminates hand labor
Project leaders Tara Baugher and Jim Schupp noted that higher-quality fruit can result when “blossom thinning” is used. This thinning technique ideally removes 50% to 75% of the excess fruit early in the growing season, and is most often done by hand. But the practice is labor-intensive and can carry an enormous financial burden; a recent survey reported that Eastern peach growers commonly spend $350 to $600 per acre for hand-thinning peaches, while California peach producers spent an average of $1,000 per acre, with extremes of up to $1,500 per acre reported.
Horticultural and economic evaluations of chemical blossom thinners were conducted in 16 commercial orchard trials from 2005 to 2007. The treatments were applied at 80% full bloom and compared to hand thinning postbloom. Chemical efficacy was variable among years and blocks. Chemical thinners cut follow-up hand-thinning time in 33% of the trials and increased fruit diameter in 55% of the trials, resulting in net impacts of $14 to $983 per acre in 78% of the trials.
Similar evaluations of two mechanical thinners were conducted in four commercial peach orchard blocks in 2007. A mechanical blossom thinner designed by a German grower for thinning apple trees in organic orchards was tested on peach trees trained to either a perpendicular V or quad-V system. Thinning was conducted at 20% or 80% full bloom. A USDA spiked-drum shaker, originally designed for harvesting citrus, was included in the orchard tests at 45 days after full bloom.
Mechanical thinners reduced fruit set, decreased follow-up hand-thinning time, and increased the quantity of fruit in the 3-inch-or-greater size distribution in 100% of the trials. Net profit ranged from $71 to $796 per acre. Bloom thinning at 20% full bloom was similar to thinning at 80% full bloom. Detailed flower counts on branches with different orientations indicated that pruning may be adjusted to improve thinner performance. Upshot: Blossom thinning may speed adoption of narrow-canopy systems.
This article published in the February, 2010 edition of CALIFORNIA FARMER.