Agriculture Reference
In-Depth Information
ber hose to the end of a broomstick or similar pole, or tape a piece of cloth
around the end of a pole to serve as padding. The rubber or cloth softens the
blows and helps prevent damaging the branches. Plastic or rubber-covered
baseball bats also work well for thinning.
Pole thinning is less accurate than hand thinning but much faster, and
with practice, you can obtain good results. Use the padded end of the pole to
knock off individual fruits, but avoid breaking off the fruiting spurs. Also use
the poles to thin out fruit clusters. Strike a cluster once or twice to break it
up and remove some of the fruit.
Mechanical Thinning
Mechanical thinning is used in pome and stone fruit orchards. Early thinning
methods included ropes mounted to rapidly spinning cylinders or disks, or
high-pressure water jets. In these methods, the spinning ropes or water jets
knocked some of the fruits off the trees. They did not produce uniformly
effective results in orchards, however, and have given way to shakers and
string thinners.
Regardless of the mechanical thinning method you use, you will need to
follow up with hand and pole thinning to achieve optimum fruit sets. The ad-
vantage is that mechanical thinning reduces the amount and cost of hand
thinning required.
Shakers.
In fruit thinning trials, researchers found that shaker devices can
be quite effective, and the method is now being adopted by orchardists, par-
ticularly for peaches. These devices also hold promise for apple and plum
orchards. Several versions have been developed by the U.S. Department of
Agriculture and private sources and are being tested across the United
States. Essentially, they are modified citrus and raspberry harvesters with
long rods mounted to oscillating spindles or drums. As the tractor travels
along the alley, the rods reach into the canopy and shake the branches. The
devices are probably best used 40 to 55 days after full bloom to remove
green fruits, although they have been tested during bloom and can effect-
