2.2. Methods
The tests have been carried out in a plain hedgerow
peach orchard (cultivar Star Red Gold) with a row distance
of 4)3 m and trees spaced at 3)3 m apart. The
vegetation was about 4)5 m high, starting at 0)5 m from
the ground and had a uniform thickness of about 1)5 m.
The mechanical trials have been repeated in two vegetative
stages: the "rst after blooming, with a low leaf
area index (LAI: leaf area divided by the relative ground
surface), and the second in full vegetation, at the top leaf
density. The setting of the two sprayers have been
pointed out according to some preliminary test results
and are indicated in Table 1. The great di!erence in
volume rates used with the two types of sprayers is
evident: the higher volume of the traditional one can be
considered usual for that dimension of peach orchard; for
the experimental sprayer the maximum volume with no
observed runo! was chosen.
In every trial, the following parameters have been
measured: unit deposit on the plant at di!erent heights
and depths; and unit deposit on the ground and liquid
recovery.
To measure the deposition, a 2% water solution of
MgSO4 was distributed on the plants where arti"cial
collectors made of circular "lter papers (110 mm diameter)
had been hung on the branches at di!erent locations.
The amount of magnesium was then detected by
atomic absorption. In the "rst trial (10 April), where the
low LAI value was not an obstacle to penetration, the
targets were only placed in the inner part of the plants, on
four levels, spaced at 100 cm. In the second trial (27 May),
at the top vegetation density, they were also located in
the external layers, at about 20 cm from the outside on
both sides, with one more level, where new vegetation
had developed on the tree.
On the ground, rectangular stripes (5 cm by 50 cm) of
"lter paper collectors were positioned perpendicular to
the row, in continuous lines, interrupted in correspondence
to the tracks of the tractor tyres. In these intervals,
the missing data were calculated by interpolation.
The collectors were placed in the same trees and in the
same positions in every experiment and replication; they
were "xed on grids applied inside the canopy and on the
ground.
The volume of the liquid recovered by the equipment
was measured in the collectors at the base of the shields
after spraying over a base of 100 m of a row.
Every experiment was replicated 4 times, positioning
the arti"cial targets in the central row of a 2000 m2 plot
and treating all the rows in order to simulate a real
treatment.
The statistical analysis of the data was made by means
of ANOVA at a probability P)0)05. When ANOVA
indicated a signi"cance, Fisher's least signi"cant di!erence
(LSD) procedure at 95% was used. Thus, in graphs
and tables, di!erent letters mean a signi"cant di!erence.
The data in percent were transformed with the angular
transformation before being treated for statistics.
A further investigation was carried out during the
following year on the same sprayers to control the biological
e$cacy of the tunnel recycling system, using similar
volume rates as for the mechanical trials (900 l ha~1 for
the tunnel and 1600 l ha~1 for the air blast, changing the
concentration of the chemical and keeping the same
dosage per hectare). The control was made on large plots
during all the cycle of treatments (20 May}23 July) on
aphids (Myzus persicae), Cydia molesta, thrips (¹hrips
maior), mildew (Sphaeroteca pennosa). For these experiments
the same statistics as the distribution trials were
applied to a four replications experimental design.
While for the fruits and buds all the elements of the
sample trees were observed, the following method was
adopted for the percentage of leaf surface attacked. Only
5}7 terminal leaves of the leaf buds were considered,
dividing them in classes of attack:
(a) class 0 no infection;
(b) class 1 * 2)5% of the mean leaf area infected;
(c) class 2 * 15% of the mean leaf area infected;
(d) class 3 * 50% of the mean leaf area infected.