Drone-Based Blight Diagnostics and Fungicide Application Efficiency: A Cost–Benefit Intervention for Potato Farmers in the Chencha Highlands

{ "background": "Late blight (Phytophthora infestans) is a devastating disease for smallholder potato farmers in the Chencha Highlands, leading to significant yield loss and inefficient fungicide use. Conventional scouting is labour-intensive and often results in untimely or blanket applications.", "purpose and objectives": "This study evaluated the effectiveness of a drone-based multispectral imaging intervention for targeted late blight management. The primary objectives were to assess its impact on fungicide application efficiency and to conduct a detailed cost–benefit analysis from the farmer perspective.", "methodology": "A randomised controlled trial was conducted with 120 smallholder farms assigned to control (conventional practice) or intervention groups. The intervention utilised weekly drone flights to generate Normalised Difference Vegetation Index (NDVI) maps, guiding variable-rate fungicide applications. Application volume, yield, and costs were recorded. A cost–benefit model was constructed, and treatment effects were estimated using a linear regression model: $Yi = \\beta0 + \\beta1 Ti + \\mathbf{X}i\\boldsymbol{\\beta} + \\epsiloni$, where $Yi$ is the outcome for farm $i$, $Ti$ is the treatment indicator, and $\\mathbf{X}_i$ is a vector of covariates. Robust standard errors were used for inference.", "findings": "The intervention reduced fungicide application volume by 32% (95% CI: 26% to 38%) compared to the control, while maintaining equivalent tuber yield. The cost–benefit analysis showed a mean net gain of ETB 4,150 per hectare for intervention farmers, with the benefit-cost ratio exceeding 2.5:1. The probability of a negative net return was less than 0.05.", "conclusion": "Drone-based diagnostics significantly enhance input efficiency and economic returns for potato blight management in this highland smallholder context, proving to be a financially viable precision agriculture technology.", "recommendations": "