Is drone spraying effective compared to knapsack for pesticides?

Drone spraying covers large areas very fast, uses much less water than ground spraying and avoids walking through and trampling the crop. It is especially useful for tall or dense crops, standing water paddy, and during pest outbreaks when speed matters, and it keeps the operator away from chemical contact. Coverage depends on correct flight height, speed, nozzle and droplet size, and on the chemical being approved and formulated for drone use. It may be less suited to very small or oddly shaped plots, or where fine penetration into the lower canopy is needed. Use only approved chemicals and a trained operator. For many farmers hiring a drone service per acre is the practical route rather than buying.