Evaluation of Whitefly Control on Tomato Crop Using Different Nozzle Orientations and Spray Application Volumes

Effective management of greenhouse whiteflies (Trialeurodes vaporariorum) is critical due to their high potential for crop damage and relative susceptibility to insecticidal control. This study was conducted to evaluate the impact of spray nozzle orientation, application volume, droplet size, and insecticide deposition on whitefly mortality and foliar spray coverage in tomato crops. Two insecticidal formulations viz. emamectin benzoate 5% and beta-cyfluthrin 5% EW were applied using three nozzle orientations and two spray volume rates. Results indicated a negative correlation between insect mortality in the upper plant canopy and increased spray application volume. At the same canopy level, spray droplet size was positively correlated with deposition (R² = 0.97), with small droplets depositing significantly less insecticide compared to medium and large droplets. However, droplet size did not have a significant effect on nymphal mortality. Furthermore, increasing the spray volume to 858.4 L · ha^-1 did not enhance insecticide deposition or improve spray coverage. Canopy penetration by spray droplets was also unaffected by application volume but was significantly influenced by nozzle orientation. Overall, increasing spray application volume beyond 858.4 L · ha^-1 is not recommended. Instead, reducing spray droplet size to approximately 128.53 μm may enhance whitefly control efficacy by improving canopy penetration and insecticide coverage within tomato crops..