Orchard Airblast Sprayer Row Calculator
Size an airblast sprayer pass for orchards and vineyards from tree-row spacing, travel speed and a target dilute or concentrate gallons-per-acre rate.
How This Calculation Works
Airblast rates are often expressed per acre of orchard floor, so the effective swath is the tree-row spacing rather than a boom width. Gallons per acre equals nozzle flow in gpm times 5,940, divided by speed in mph times row spacing in inches. Concentrate spraying reduces the dilute volume by the concentration factor, so a 4X concentrate uses one quarter of the dilute gallons per acre.
Field Calibration & Rate Reference Chart
| Ground speed | Nozzle pressure | Typical GPA | Droplet class |
|---|---|---|---|
| 4 mph | 20 psi | 12 | Coarse |
| 5 mph | 25 psi | 14 | Coarse |
| 6 mph | 30 psi | 15 | Medium |
| 7 mph | 35 psi | 16 | Medium |
| 8 mph | 40 psi | 18 | Medium |
| 9 mph | 45 psi | 19 | Fine |
| 10 mph | 50 psi | 20 | Fine |
| 12 mph | 55 psi | 22 | Fine |
| 14 mph | 60 psi | 24 | Very fine |
| 16 mph | 65 psi | 26 | Very fine |
Common Questions
What is the difference between dilute and concentrate airblast spraying?
Dilute spraying applies the full label volume, often 100 to 400 gallons per acre, while concentrate spraying reduces the carrier and increases the product concentration. A 4X concentrate uses one quarter the dilute volume with the same product per acre. Concentrate saves water and refills but demands accurate calibration.
How do I calculate gallons per acre for an airblast sprayer?
Use the same GPA relationship with the tree-row spacing as the swath width: nozzle flow times 5,940, divided by speed times row spacing in inches. Sum the flow of all nozzles on one side for a single-sided pass. Confirm with a catch test in the canopy.
What travel speed should I use in an orchard?
Most airblast passes run 2 to 3 mph so the air can carry spray through the canopy. Faster speeds reduce coverage on the far side and top. Adjust speed to canopy density rather than holding one figure all season.
How do I check airblast coverage?
Staple water-sensitive cards at the top, middle and bottom of the canopy on both the near and far sides, then spray a pass and read the droplet density. Even coverage across all cards means the air and volume are matched. Adjust nozzle selection and air deflectors until the cards agree.