Roberto Beltrán‐Martí, Cruz Garcerá, Patricia Chueca
Abstract BACKGROUND Hydraulic spraying is the main method for applying entomopathogenic fungi (EPF). Negative effects of nozzle and spray pressure on conidial viability have been reported, and appropriate droplet size ranges have been proposed to mitigate them. However, information integrating nozzle–pressure interactions with both physical and biological parameters to identify configurations that maximize pest‐control efficacy remains limited. RESULTS Conventional flat‐fan XR110 nozzles and hollow‐cone nozzles, including conventional ATR80 and air‐induction TVI80, covering a range of orifice sizes, were initially evaluated for clogging at a spray pressure of 1.0 MPa. Only small‐orifice flat‐fan nozzles showed clogging. Droplet size distribution of non‐clogging nozzles with ISO 01 and 02 orifice sizes was assessed at spray pressures between 1.0 and 2 MPa, together with their effects on conidial spray efficiency (conidia μL −1 ), conidial viability (%), and conidial infectivity (%) during application of a Beauveria bassiana ‐based product for the control of Ceratitis capitata . Nozzles showed different relationships between spray pressure and both conidial spray efficiency and viability loss. Small‐droplet nozzles (XR110 and ATR80) achieved the highest efficiency. The XR110 nozzle showed the greatest viability loss across all pressures. Despite this, the ISO 02 XR110 nozzle resulted in the highest pest‐control efficacy and EPF‐confirmed mortality, comparable to those obtained with conventional and air‐induction ISO 02 hollow‐cone nozzles. The new parameter ‘spray effectiveness’ normalizes the biological outcome by the actual viable dose and provides insight into resource use efficiency, cost savings, and environmental impact. CONCLUSION Optimizing B. bassiana applications requires balancing clogging risk, droplet and deposition characteristics, conidial viability, and biological efficacy. © 2026 Society of Chemical Industry.