Agriculture Reference
In-Depth Information
apple and pear trees can work very well. Taller trellises may also be suitable
for new commercial orchards, and they are particularly valuable where space
is limited. Trellises lend themselves well to U-pick orchards.
Because traditional trellises produce lower yields than spindle-trained
trees, they have largely fallen out of favor for new commercial orchards, even
though they are generally less expensive to install than the taller spindle
systems. The lower yields are due to the fact that the trees are kept short
and the crop rows are narrow. Researchers at Pennsylvania State University
determined that, in terms of canopy height and density, trellis systems are
about as productive as the taller vertical axis designs for the first 10 years
after planting. They are now testing tall trellises (about 10 feet in height) for
commercial orchards.
It's important to select a rootstock that will create enough vigor to fill the
canopy but not so much as to require excessive pruning. Trellised trees are
usually spaced about 3 to 6 feet apart in rows that are 10 to 12 feet apart,
and they require 660 to 1,452 trees per acre. The more closely spaced the
trees, the more expensive it is to establish the system and the more intensive
the management becomes.
Spindle Support Systems
These became very popular for high-density apple orchards during the
1980s and 1990s. The slender spindle was one of the first designs and is
simply a post supporting a tree, usually to a height of about 6 feet. Newer
designs can be up to 10 feet tall. No horizontal wires are used and the trees
are typically trained to be the shape of a Christmas tree or pyramid. Vigor-
ous, upright leaders are cut off, and weak shoots are tied up in their places
to form slow-growing leaders as part of an orchard-size control program.
Due to their relatively high cost and low yields, slender spindle systems
have become less popular than newer training systems. The newer super
spindle system is a viable design for commercial apple orchards. While it re-
sembles the earlier slender spindle, the trees are supported on wires without
the use of posts, and the trees are planted about 2 feet apart to quickly form
