Comparison between standard and drift reducing nozzles for pesticide application in citrus: Part I. Effects on wind tunnel and field spray drift

The objective of this study was to evaluate and to compare spray drift potential and field spray drift from pesticide application in citrus orchards carried out mainly comparing standard nozzles with drift reducing nozzles. Two different standard nozzles (hollow cone and full cone) and one Venturi drift reducing nozzle (hollow cone) were tested. Spray drift potential was measured by means of wind tunnel experiments (ISO 22856:2008 method). To estimate field airborne and sedimenting spray drift, two trials with 5 replicates each were carried out (ISO 22866:2005 method) in two different commercial orchards of Clementine mandarins. Results showed that Venturi nozzles significantly reduced drift with the two methodologies. Moreover, the wind tunnel method showed the same trend as the field results. Additionally, spray drift deposition variability was lower for the Venturi nozzles. Therefore, it could be concluded that Venturi nozzles can be recommended to be used in citrus orchards to prevent human and environmental risks and their use could be appropriate for different scenarios where spray drift risk must be mitigated.Authors would like to thank to Cítrics Terres de l’Ebre, S.A.T. and Manantiales Entrepinos, S.L. for allowing the use of their fields and sprayers. Also, Agrícola la Realense Coop.V. for allowing the use of their fields and Pulverizadores Fede S.A. for the use of equipments. Besides, Universitat de Lleida is also thanked for Mr. X. Torrent's pre-doctoral fellowship

Experimental study of factors influencing the risk of drift from field sprayers Part 2: Spray application technique.

Recently, spray drift and its effects have become an important aspect of risk assessment in the registration process of pesticides in Belgium. In this regulation, drift reducing spray application techniques can be used to reduce buffer zones. The purpose of this research is to measure and compare the amount of drift sediment for different spray application techniques under field conditions. A drift prediction equation for the reference spraying was used to compare other spraying techniques with the reference spraying, under different weather conditions. Drift measurements were performed for several combinations of nozzle type (flat fan, low-drift, air injection) and size (ISO 02, 03, 04 and 06), spray pressure (2, 3 and 4 bar), driving speed (4, 6, 8 and 10 km.h-1) and spray boom height (0.3, 0.5 and 0.75 m). Nozzle type as well as spray pressure, driving speed and spray boom height, have an important effect on the amount of spray drift. Larger nozzle sizes, lower spray pressures and driving speeds and lower spray boom heights generally reduce spray drift. Concerning nozzle types, air injection nozzles have the highest drift reduction potential followed by the low-drift nozzles and the standard flat fan nozzles

Nozzle Classification for Drift Reduction in Orchard Spraying: Identification of Drift Reduction Class Threshold Nozzles

In fruit growing high values of spray drift are found compared to arable field applications. In arable spraying drift reducing nozzles are certified for use as drift reducing measures. The nozzles which may potentially reduce drift in fruit growing are not jet classified as drift reducing nozzles, although they are available on the market. The development of a nozzle classification system to identify the drift reduction potential of spray nozzles used in fruit crop spraying would open this market. The results of the initial setup of a nozzle classification system for spray drift reduction in orchard spraying based on drop size measurements is described. An evaluation was made of measured drop size characteristics of a series of nozzles in reference to performed field measurements of two characteristic nozzles; Albuz lilac and Lechler ID9001. Based on these anchor points the ranking of the volume fraction of drops smaller than 100 ¿m (V100) of the nozzle to be classified could be scaled to yield a potential drift reduction, assuming a linear relationship between V100 and spray drift deposition. Within this system, the determination of threshold nozzles for the drift reduction classes 50%, 75%, 90% and 95% drift reduction are described. Identified threshold nozzles for these classes are TeeJet DG8002, Albuz AVI 80015, Lechler ID9001 and Albuz TVI80025 all at 7 bar spray pressure, except for the Lechler ID 9001 which is used at 5 bar pressure. These nozzles will be used in field drift measurements to validate the mode

Predicting off-site deposition of spray drift from horticultural spraying through porous barriers on soil and plant surfaces

New Zealand is a recognised leader in horticultural practices which include the use of boundary shelterbelts around orchards. These shelterbelts were primarily established to provide protection to the crop but are also an effective means of ameliorating agrichemical spray drift that may arise from the crop production area. Shelterbelt structure ranges from large trees (ranging from broad leaf to needle in structure) to hedgerows and artificial netting. The efficiency of the shelterbelt in capturing spray drift is known to depend on factors such as spray drift droplet size, wind velocity and the vegetation structure. However more specific information and models are required to define the capture efficiency to form part of a comprehensive spray drift management system

Advances in developing a new test method to assess spray drift potential from air blast sprayers

Drift is one of the most important issues to consider for realising sustainable pesticide sprays. This study proposes and tests an alternative methodology for quantifying the drift potential (DP) of air blast sprayers, trying to avoid the difficulties faced in conducting field trials according to the standard protocol (ISO 22866:2005). For this purpose, an ad hoc test bench designed for DP comparative measurements was used. The proposed methodology was evaluated in terms of robustness, repetitiveness and coherence by arranging a series of trials at two laboratories. Representative orchard and vineyard air blast sprayers in eight configurations (combination of two forward speeds, two air fan flow rates, and two nozzle types) were tested. The test bench was placed perpendicular to the spray track to collect the fraction of spray liquid remaining in the air after the spray process and potentially susceptible to drift out of the treated area. Downwind spray deposition curves were obtained and a new approach was proposed to calculate an index value of the DP estimation that could allow the differences among the tested configurations to be described. Results indicated that forward speed of 1.67 m/s allows better discrimination among configurations tested. Highest DP reduction, over 87.5%, was achieved using the TVI nozzles in combination with low air fan flow rate in both laboratories; conversely, the highest DP value was obtained with the ATR nozzles in combination with high air fan flow rate. Although the proposed method shows a promising potential to evaluate drift potential of different sprayer types and nozzles types used for bush and tree crops further research and tests are necessary to improve and validate this method.Postprint (published version

Performance of selected agricultural spray nozzles using particle image velocimetry

The aim of the present study was to investigate the influence of nozzle configurations on spray drift and explain the influences using several atomization characteristics (length of spray sheet, spray angle, velocity distribution of flow field, fluctuation of velocity, and droplet size). Nozzles manufactured by one company (Lechler GmbH, Germany) were tested by spraying local tap water in a wind tunnel at an operating pressure of 0.3 MPa and under room temperature. The nozzles tested were compact air-induction flat fan nozzles (IDK120-02, IDK120-03), standard flat fan nozzles (ST110-02, ST110-03), and hollow-cone swirl nozzles (TR80-02, TR80-03). The atomization process was recorded using a Particle Image Velocimetry (PIV) system, droplet size was measured by a Sympatec Helos laser-diffraction particle-size analyzer, and spray drift was evaluated in a wind tunnel with deposition measured using a calibrated fluorometer (Turner-Sequoia model 450). Results showed that spray drift was significantly different among nozzle types (

Development of a Crop Adapted Spray Application (CASA) sprayer for orchards

In the EU-FP6 ISAFRUIT project a Crop Adapted Spray Application system (CASA) for precision crop protection was developed (Doruchowski et al., 2009). The system ensures efficient and safe spray application in orchards according to actual needs and with respect to the environment. The developed CASA system consist of three sub-systems: Crop Health Sensor (CHS) - identifying the health status of fruit crops to apply chemicals only when necessary; Crop Identification System (CIS) - identifying the tree canopy size and density to apply spray precisely at relevant doses; Environmentally Dependent Application Systems (EDAS) - identifying environmental circumstances and navigating the sprayer to adjust application parameters accordingly so that spray drift is minimised and direct water contamination is avoided

Mathematical modelling and experimental assessment of agrochemical drift using a wind tunnel

With the aim to gain a better understanding of the phenomenon of drift occurring during spray application of agrochemicals to agricultural crops, a laboratory testing was carried out using a wind tunnel under controlled environmental conditions (wind, temperature and relative humidity RH). Spray drift was measured with wind velocity of 1, 3 and 5 m/s and RH of 30, 50 and 70%. Under medium to high wind velocities the effect of RH was negligible. These results suggested to work out a simplified mathematical modelling by assuming the absence of droplets evaporation by means of closed solutions of the equations of the droplets motion. The main result of the mathematical model is the removal of the droplets smaller than about 80 \u3bcm from the spray produced by the nozzles

Evaluation of the AGDISP ground boom spray drift model

AGDISP is a well-established spray drift model that has been validated for aerial spraying of forests. Recently a prototypical ground boom option has been added to AGDISP. This was evaluated in the current study by collecting data from spray trials over a grass sward using a ground boom sprayer and representative application parameters. Spray solutions were made up of water, sticker adjuvant and a metal cation, which was changed for each spray application. Deposition from spray drift was measured by analyses of the cation deposits on artificial targets (plastic tapes) placed on the grass surface. Measured deposition was compared with profiles calculated using AGDISP. AGDISP overpredicted deposition from spray drift by a factor of 3.5-100 outside the spray block. Possible reasons for these discrepancies are given. Options are to improve measured deposition and the algorithms for the deposition on the downwind swath of the spray block and evaporation of droplets