Agriculture Reference
In-Depth Information
will cause and how they will affect the long-term health of the tree. The
design of the canopy also influences the effectiveness of thinning techniques
and their damage to the trees. Pennsylvania peach growers have found that
branches that project into the alleys suffer greater damage from string thin-
ning than those within the crop rows. Trials in West Virginia have shown
that large, rigid limbs are more susceptible to damage than thinner, more
flexible branches.
Growers with high labor costs for thinning should consider testing mech-
anical thinning. Do your homework and evaluate the devices that are avail-
able. At present, the string thinner approach seems to be somewhat more
popular with commercial orchardists than the shakers, but both designs con-
tinue to evolve. The most effective approach will probably be to use a com-
bination of the two methods: string thinning to remove flowers, followed by
shaker thinning to remove green fruits. This technique reduces hand thin-
ning more than either thinning method alone, and it allows you to judge how
many fruits to remove in mid-season after the fruits have set.
Test the devices on small blocks within your orchard. Compare fruit size,
yields, quality, and tree health over several years before adopting the ap-
proach throughout your entire orchard. You may find that you need to adjust
your training methods and canopy designs to optimize thinning and reduce
tree damage.
Chemical Thinning
Chemical thinning has a greater impact on pome fruit size and fruit bud
formation than does hand or pole thinning and is a standard practice in
conventional apple orchards. Unfortunately, despite decades of research, no
effective and reliable chemical thinners have been found for organic stone
fruits. Chemical thinning is discussed under specific fruits, below.
