FIXED SPRAY SYSTEM FOR EFFECTIVE BIOTIC AND AUTOMATED ABIOTIC  STRESS MITIGATION IN MODERN VINEYARDS

Dattatray Bhalekar

Crop loss from the biotic and abiotic stressors poses a significant challenge to Vitis vinifera vineyards typical in the Pacific Northwest. This dissertation focuses on developing precision crop protection technologies to effectively manage these stressors. Specifically, an pneumatic solid-set canopy delivery system (PSD-SSCDS) was optimized to address previous challenges hindering the large-scale adoption. This system was then field-tested for season-long disease control and heat stress management in vineyards. The dissertation work also focused on the development and field evaluation of precision heat stress management technology for vertical shoot position (VSP) trained vineyards. Objective 1 optimized PSD-SSCDS for modern VSP-trained vineyards to address the known limitations such as high cost, high emitter density and their mechanization incompatibility, as well as reduced spray efficacy of the existing SSCDS variant. Three system configurations (C1–C3) were designed using modified low-cost emitters. Configuration C3, with emitters installed in the top and bottom canopy zones, demonstrated optimal spray efficacy while reducing system cost by 54% compared to the existing variant. In objective 2, PSD-SSCDS C3 was further evaluated for biological efficacy to control key disease (i.e., Erysiphe necator) and results were contrasted with airblast sprayer applications. Evaluation was done for two seasons (2023 and 2024) using fungicide spray regime designed per Washington state pest management guide. Despite lower spray coverage, comparable disease control was observed in PSD-SSCDS treatments, indicating it as an emerging alternative in near future. Objective 3 investigated the cooling effectiveness of PSD-SSCDS C3 to mitigate grapevine heat stress compared to under-canopy fogging systems. In 2023, a crop physiology sensing system (CPSS) integrated with thermal-RGB imager and leaf wetness sensor was used to automate under-canopy fogging. Automated heat stress mitigation effectively reduced air, berry, canopy, and soil temperatures compared to no cooling (control). However, intermittent CPSS failures indicated a need for more robust heat stress monitoring for automated cooling. Improvements in 2024 included real-time berry temperature-driven automation of PSD-SSCDS and two under-canopy fogging systems using a low-power wireless sensing network. While maximum cooling was recorded in SSCDS, both under-canopy fogging systems used 70-78% less water and achieved comparable mitigation. Overall, the study highlighted the effectiveness of localized, data-driven automation PSD-SSCDS and under-canopy fogging for precision heat-stress management in vineyards.

FIXED SPRAY SYSTEM FOR EFFECTIVE BIOTIC AND AUTOMATED ABIOTIC STRESS MITIGATION IN MODERN VINEYARDS

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