ENGINEERING SOLUTIONS FOR IMPROVED SPRAY APPLICATIONS IN PERENNIAL SPECIALTY CROPS

Haitham Yaqout Bahlol

Spray applications for pest management in tree crops have off-target drift potential due to local meteorological conditions, crop characteristics, spraying equipment and properties of the sprayed materials. Despite decades of research, reducing the negative impact of agrochemicals remains challenging. Therefore, the overall goal of this dissertation was to explore new engineering approaches with hypothesis that these could contribute in reducing the negative impacts of spray applications in perennial specialty crops. In first objective, developed was a new tool for rapid and in-field spray pattern assessments in real-time as a decision making basis for adjusting sprayer attributes to reduce the drift during spray applications. Such a tool, smart spray analytical system (SSAS), was tested for its functionality under field conditions. SSAS was then successfully used to quantify air velocity and spray patterns for two commercial orchard sprayers. Pertinent data showed variation between different sides of the sprayers in terms of air assist and spray volume uniformity and symmetry that could be due to the sprayer air delivery design features. The second objective focused on developing a new strategy, i.e. horticultural oil (HO) thermotherapy for pest management. An apparatus was designed for laboratory testing of the HO-thermotherapy for pear psylla control. Psylla bioassays were exposed to HO-thermotherapy to evaluate feasibility of such approach and to find the optimal spraying parameters (heat, nozzle, pressure and concentration of the spray mix). Results showed that HO- thermotherapy applications had significantly higher pear psylla mortality (63.7 ± 2.4 % [mean ±standard error]) than HO only (43.6 ± 1.8 %). Similarly, nozzle and concentration had a role in the way to deliver the HO-thermotherapy effect. Overall, the new engineering solutions, SSAS for spray calibration and assessment as well as HO-thermotherapy, could potentially be the effective solutions to reduce the negative impact of agrochemicals in perennial specialty crops production. Field studies are recommended to develop a clear relationship between the spray/air velocity patterns and canopy attributes for different crops, and to evaluate efficacy of HO-thermotherapy along with pertinent phytotoxicity effects.

ENGINEERING SOLUTIONS FOR IMPROVED SPRAY APPLICATIONS IN PERENNIAL SPECIALTY CROPS

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