Block-Specific Sprayer Calibration Worksheet*Wesley R. Autio, Kathleen Leahy, and Jon Clements |
1. CALCULATE DILUTE GALLONAGE REQUIREMENT PER ACRE (based on Tree Row Volume, TRV) = Dilute GPAThe formula: (Tree Shape X Tree Width (ft.) X Canopy Height (ft.) X 35) / Row Spacing (ft.) Dilute Gallons Per Acre (GPA) is a fundamental concept of sprayer calibration. It is based Tree Row Volume (TRV), i.e. the total canopy volume (cubic feet) per acre and the fact (for Eastern orchards) it takes 1 gallon of spray material (water plus crop protectant) to cover 1,450 cubic feet of foliage. Dilute GPA should be calculated for every orchard block that differs significantly in tree size, shape, or age; and row spacing. The calculated GPA represents a full dilute (1X concentrate) spray volume of water plus crop protectant. |
2. SPRAYER OUTPUT IF NOZZLED FOR SPECIFIC BLOCK = Sprayer Gallons per Minute (GPM)The formula: Dilute GPA/Concentration (1X, 2X, 3X etc.) = Gallons Per Acre; Gallons Per Acre X Travel Speed (m.p.h.) X Row Spacing (ft.) / 495 = Gallons Per Minute (GPM). Gallons per minute (GPM) is the desired sprayer output (calibration 'target') based on dilute GPA, desired concentration (1X, 2X, 3X, etc.), tractor travel speed, and block row spacing. Dilute GPA and GPM are the two orchard factors essential to calibrate your sprayer to accurately deliver recommended pesticide rates on a block-by-block basis. |
3. ADJUSTING FOR BLOCK DIFFERENCES WITH KNOWN SPRAYER OUTPUTThe formula: Actual output per acre (GPA) = (GPM X 495)/Travel Speed X Row Spacing; Actual concentration = Dilute GPA/GPA Given the known GPM (sprayer output), you can easily calculate GPA for another block with different row spacing and/or travel speed. (Of course, this assumes the same nozzle set-up.) Then divideDilute GPA by GPA to determine the actual concentration (2X, 3X, etc.). Ideally, dilute gallonage requirements per acre (based on TRV) and sprayer output(GPM) should be calculated first for each block. |
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