A major problem in applying agricultural pesticides is spray drift
which can cause crop protection chemicals to be deposited in undesirable
areas with serious consequences, such as damage to sensitive adjoining
crops and other susceptible, off-target areas, environmental contamination,
health risks to animals and people, a lower dose than intended on the
target field, which can reduce the effectiveness of the pesticide, wasting
pesticide and money (Nuyttens et al., 2007).
Spraying is one of the most efficient methods for pesticide control.
The successful application of pesticides to field crops results from proper
use of equipment while considering the prevailing field conditions, morphology
of the crop, target area and mobility of the pest (Mathews, 2000). Improvement
in the uniformity and efficiency of chemical deposition is frequently
the goal of spray application research. Production of high value fresh
market fruits and vegetables requires diligent pest control practices,
which often involve application of chemical pesticides (Kang et al.,
Generally, air blast sprayers are used on vineyard applications direct
the air from a single axial-flow fan in a radial direction, occasionally
resulting in a large amount of spray just blowing out and over the canopies.
Air blast sprayers are used to apply pesticides, plant regulators and
foliar nutrients to grapevine by applying these materials as liquids carried
in large volumes of air. Air blast sprayers have adjustments the fluid
and air delivery systems that permit tailoring of applications to fit
a wide range of vineyard conditions.
The efficiency and cost effectiveness of pest management programs are
influenced by the skills of managers and sprayer operators who evaluate
vineyard conditions and alter machine settings and operating techniques
to optimize performance, forward velocity and chemical selection is necessary
for optimal results.
Equipment manufacturers have developed a number of approaches to providing
more or less aggressive control of the spray process. Among these, air
assisted spraying has been developed at various levels on boom sprayers.
At one of the spectrum, there is the bi-fluid nozzle, where a low volume
of pressurized air is used to assisted liquid atomization and even control
spray quality, offering some control on drift (Lund, 2000).
Air blast sprayers can be a significant source of spray drift because
they deliver spray horizontally and vertically towards a target area.
Several factors including weather conditions, crop canopy and sprayer
setup can contribute to spray drift. Droplet size is the most important
factor in determining the potential for drift. Smaller droplets improve
coverage but are more likely to be blown through or above a canopy. Large-droplet
air-induction nozzles have been shown as means for reducing drift without
significantly reducing coverage (Derksen et al., 2000).
A recent trend in vineyard spray application is based on the use of non-conventional
sprayers to improve the effectiveness of the treatment and reduce environmental
pollution. Pesticide losses have been shown to relate mainly to poor match
between the conventional air blast sprayer and plant geometry (Cross,
Salyani and Whitney (1990) studied the effect of sprayer ground speed
on spray deposition at different locations within citrus canopy. Deposition
of a copper hydroxide tracer was measured on citrus leaves and cotton
ribbons. Results indicated no effect of ground speed (1.6-6.4 km h-1)
on mean spray deposition. However, there were large differences in deposits
at different canopy locations. Deposition decreased with canopy depth.
The objectives of this study were to characterize spray deposition within
the vineyard operating air blast sprayer and to determine the effect of
sprayer speed on the spray deposition.
MATERIALS AND METHODS
This study was conducted in Thrace region in July 2006. The treatments
were applied to Semillon grape vineyard. The vineyard spacing was 3 m
between rows and 1.5 m in each row. The location of leaves was between
the heights of 80 cm and 1.6 m from ground and average vine width was
The sprayer tested was commercially available rear mounted air assisted
machine with 760 mm diameter axial fan , driven by the power take-off
(p.t.o) (Turbo 400-A, Taral company, Turkey). The two deflectors were
fixed to the upper part of the fan`s frame and had opened up to an angle
of 45°, allowing the airflow to be adjusted to mach the canopy height.
The sprayer had 8 nozzles (hollow cone) arranged circular on the fan.
They were spraying at an operating pressure of 12 bars and the fan speed
was 1950 min-1. The liquid pressure was produced by mean of
diaphragm pump and the liquid output was controlled by a constant pressure
The sprayer was connected to a 46 kW tractor and measured pressure, 12
bars, was constant in all the treatment. The spray flux and the spray
coverage were evaluated on one side of the sprayer, always in the same
sampling position in the treated rows. During the test, three repetitions
were made with the sprayer at different sprayer speed, 2.1-4.9-7.7 km
The grapevine were sprayed a 2 g Tartrazine (a fluorescent tracer) per
1 L water. The filter papers (Schleicher and Schull, 125 mm diameter)
were used to collect the spray deposit at the different distances, 1.5-3-6-9
m. They were located in 1.5 m on leaves and in 3-6-9 m on wooden bar in
the centre of treated rows (Fig. 1).
Grapevine was divided into three zones vertically (A-B-C) (Fig.
1). The filter papers of located on leaves were positioned at three
heights (70-120-170 cm) using three filter papers at each height. Three
of filter papers, placed on the soil (shown as D zone in Fig.
1) near the wooden frame of plants, were also used to collect the
spray deposit on the ground.
||Layout of filter paper collectors for evaluation of
in-canopy spray deposit and off-target spray los
The vertical wooden bar was 2 m high and had 10 height levels at the
intervals (0, 15 m). There are three filter paper on the horizontal bar
(length of 30 cm) at the each height. Vertical bar had 30 filter paper
and 10 different heights (Fig. 1).
The samples were collected and each of them was placed into a separate
plastic snap-seal container within 15 min after spray application. They
were stored in the dark for further processing. The fluorescent tracer
(Tartrazine) was extracted from filter paper collectors with 100 mL pure
water. A tracer concentration in the extract was determined with spectrophotometer
and the actual amount of tracer deposit (mg cm-2) was read.
Prior to analysis the background for clean paper was equal to the one
obtained for washing solution (Holownicki et al., 2000).
Air temperature, air relative humidity and wind speed during the spray
applications were recorded using Lutron AM 4202 anemometer and Testo 605
h 1 in vineyard. All the measurement was performed different point in
vineyard and in height of 2 m.
Analysis of variance followed by Duncan`s Multiple Range Test was applied
to separate mean values of the deposit and spray loss for treatments.
Coefficient of variation (CV) for spray deposit was calculated on the
basis of different sprayer speed. The means for these parameters were
compared at 5% level at significance.
RESULTS AND DISCUSSION
Treatments were applied during sunny day and weather conditions
(Table 1). Ranges of maximum temperature during the test
were 30°C applying 4.9 and 7.7 km h-1. Maximum relative
humidity was 69% applying 2.1 km h-1. Maximum Wind velocity
was measured 3.0 km h-1 and wind direction ranged from 130-310°
(measured clockwise with winds from north = 0°).
The spray depositions on leaves were measured different sprayer speed
and different levels of the height in vineyard. Effect of sprayer speeds
on the spray deposition were found to be very significant (F = 5.94**).
Results showed that the levels of the height in plant had not an important
effect on the spray deposition (Table 2). The deposition
was the highest on the level of A and at sprayer speed of 2.1 km h-1.
The spray deposits on leaves of grapevine in the rows at the different
levels of the height (A:70 cm, B:120 cm, C:170 cm, D: level of the ground)
were measured and analyzed (Fig. 2). When the spray deposits
was examined and their means were calculated, maximum spray deposit was
obtained 66.1 mg cm-2 at sprayer speed of 2.1 km h-1
and minimum deposit was obtained 37.1 mg cm-2 at sprayer speed
of 7.7 km h-1.
||Weather conditions during the treatments
|| Statistics of mean values of the spray deposits
||Spray deposit (mg cm-2) on different level
of height (A: 70 cm, B: 120 cm, C: 170 cm, D: level of the ground)
of plants and at the sprayer speed (2.1-4.9-7.7 km h-1)
Spray deposit were measured minimum of 13.9 mg cm-2 on the
level of the A and maximum of 19.39 mg cm-2 on the level C
at the sprayer speed of 2.1 km h-1. It was measured minimum
of 7.48 mg cm-2 on the level of the A and maximum of 13.85
mg cm-2 on the level B at the sprayer speed of 4.9 km h-1.
Minimum of 7.12 mg cm-2 on the level of the A and maximum
of 11.06 mg cm-2 on the level B at the sprayer speed of 7.7
km h-1. Similar results on effect of height were also reported
by Salyani and Whitney (1990).
According to the results, the spray deposition on the leaf decreased
by increasing sprayer speed. Generally, there was less spray deposit on
the top of the plants than others. However, it was increased at the bottom
part of the vines where were more density of leaves.
Maximum spray deposition (77.1 mg cm-2) was obtained on the
3 m, at the sprayer speed of 2.1 km h-1. It was 48.52 and 39.21
mg cm-2 on 3 m at 4.9 and 7.7 km h-1, respectively
(Fig. 3). Generally total spray deposition were highest
in the 3 m. It decreased to distance from the sprayer. Increasing sprayer
speed, spray deposit increases towards the 9 m. small differences in total
spray deposits were found between 6-9 m.The spray depositions were significantly
affected by sprayer speed (F = 19.79**) and distance (F = 101.79**). Also
there was very significant (F = 49.05**) interaction between the sprayer
speed and distance. Results showed that the levels of the height in wooden
bar had not an important effect on the spray deposition (Table
The amount of the spray deposits was highest on the wooden bar located
distances of 3 m at all sprayer speeds (Fig. 4). The
maximum of the amount of the spray deposit in the distances of 3 m were
9.18 mg cm-2 (on the level of g), 5.8 mg cm-2 (on
the level of d) and 5.25 mg cm-2 (on the level of b) at 2.1,
4.9 and 7.7 km h-1, respectively.
The maximum of the amount of the spray deposit in the distances of 6
m were 3.69 mg cm-2 (on the level of c), 3.7 mg cm-2 (on
the level of g) and 3.33 mg cm-2 (on the level of c) at 2.1,
4.9 and 7.7 km h-1, respectively. The maximum of the amount
of the spray deposit in the distances of 9 m were 3.5 mg cm-2 (on
the level of e), 3.8 mg cm-2 (on the level of b) and 4.0 mg
cm-2 (on the level of m) at 2.1, 4.9 and 7.7 km h-1,
Spray deposit distribution at different sprayer speeds in Fig.
5 show considerable in different point in vineyard. It shows increasing
drift by the sprayer speed. Spray deposit was highest near the sprayer
at the same sprayer speed. However, gone far from sprayer, it was minimum.
In all treatments the spray flux was characterised by a higher deposit
at 2.1 km h-1 and on the first row (at the
||Due to total spray deposit (mg cm-2), spray
distribution at different sprayer speed (2.1-4.9-7.7 km h-1)
and different distances (1.5-3.0-6.0-9.0 m)
||The spray deposition (mg cm-2) at different
sprayer speeds (2.1-4.9-7.7 km h-1) and on the different
distances (3-6-9 m)
||Spray deposition (mg cm-2) pattern on the
vineyard by air blast sprayer
||Statistics of mean values of the spray deposits
|*Significant, **Highly significant
3 m). The grapevine canopies directly exposed to the sprayer speed showed
good uniformity in all tests at different heights.
By increasing the driving speed, the vertical air jet is bent and distorted.
This leads to the smallest droplets escaping from the spray into the atmosphere
downwind of the sprayer, resulting in a higher amount of spray drift (Ghosh
and Hunt, 1998).
Based on the results obtained with the above mentioned equipment,
grapevine and sample locations, the following conclusions may be drawn
from this experiment:
||Sprayer speed had significant effect on spray deposit
||Increasing sprayer speed increased drift
This research was supported by Scientific Research Projects of University
of Trakya (TUBAP 539).