Conclusions
The aim of this investigation was to evaluate one of the
techniques for recycling on tunnel sprayers and it was
made on a prototype which shows a fair margin of
improvement. This technique was compared with a traditional
system consisting of a commercial sprayer, properly
calibrated and set, according to the actual operative
conditions, without introducing a large number of variables.
However, the results make it possible to draw some
general interesting conclusions.
The most interesting result is that this sprayer has the
peculiar characteristic of a tunnel spraying system and
some others typical of the air-blast system. In fact, compared
to the previous research on tunnel sprayers, a great
improvement was obtained as to penetration of the foliage.
This important result, that largely overcomes the
inadequately the traditional equipment, was reached by
means of the high power of the axial fans and of the
intense air circulation between the shields.
Notwithstanding this complex management of the air-
#ow, the sprayer showed a good reduction of losses and
a good efficacy of recycling: the amount of recycling
represents most of the product o!-target. This is important
for reducing the active ingredient sprayed, the risk of
contamination, and the damage to orchards and "elds
adjacent to the treatment area.
Another relevant peculiarity that distinguishes it from
other tunnel sprayers is the dimension, that allows the
treatment of trees up to 4)5 m high. In spite of this, if the
forward speed adopted in the test is not exceeded,
the stability and the control are satisfactory.
The biological tests, even for only 1 year, show that the
prototype at a medium volume can o!er the same protection
as a traditional sprayer at high volume and performance
could be even better when the protection required
at the higher parts of the trees is more important.
The main defects of the prototype are the high concentration
of the losses under the trees and the asymmetry
of deposit on the outer sides of the canopy. While the
first is common to all the tunnel sprayers and
hardly improvable, the second could be corrected by
changing the number of the fans and the geometry of the
air#ow.