to the type of air circulation which determines the functional
asymmetry of the machine. This asymmetry is also
evident in the greater amount of liquid found in one of
the two collectors, the left one (Fig. 4).
The highest values of losses to the ground were found
with the air-blast sprayer: 57% in the "rst treatment and
31% in the second. The cross distribution pro"le of these
losses is rather uniform in the "rst treatment, while more
concentrated in the second (Fig. 5).
In contrast to the traditional sprayer, the losses to the
ground of the tunnel were 31% with low leaf density and
10% in full vegetation.
In Table 3, the result of the biological controls made
on four major pests present in the Italian peach orchards
is reported. As a general consideration, both sprayers
showed a similar and satisfactory control of the four
pests. Only small di!erences can be observed between the
two systems for S. pennosa and ¹. maior.
Against ¹. maior, the lower infection percentage with
the tunnel sprayer is in accordance with the fact that this
pest a!ects mainly the higher levels of the trees, where the
prototype provides a better coverage. The infection of
S. pennosa (mildew) was very low with both treatments,
but a little higher with the tunnel sprayer, may be due to
the lower volume applied with this equipment.
4. 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 e$cacy 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