Publication 360, Fruit Production Recommendations: Calculating Output

Table of Contents

1. Output of the average nozzle
2. Horizontal boom sprayer - total output
3. Horizontal boom sprayer - band spraying output
4. Directed (airblast) sprayer output in an orchard or vineyard
5. Other Information on Pesticide Application
   • Handling and Mixing Pesticides
   • Filling and Agitation
   • Calculating Water Volume and Pesticide Rates
   • Sprayer Calibration and Nozzle Maintenance
   • Calculating Output
   • New Developments in Spraying Technology
   • Other Resources in Application Technology
6. Related Links

Calculating Output

Output of the average nozzle

• Park the sprayer with the PTO engaged and the throttle adjusted to reach the PTO speed (RPMs) set in the test run.
• Adjust the pressure regulator to the desired working pressure with full flow to the boom.
• Collect the output from each nozzle (in milliliters) for the average length of time needed to travel the 50 m in the test run. For airblast sprayers, it is helpful to use a flexible tube to guide the spray from the nozzle to the graduated cylinder.
• Add up all of the nozzle outputs and divide by the number of nozzles. This will give you the average output per nozzle.

If the flow rate of a single nozzle is 5% more or less the average, replace all nozzles, not just those that appear damaged. Do not over-tighten nozzles. For disc-core nozzles, replace the seal gasket around the core and always match the correct orifice disc to the correct core; it is generally best to replace the disc, core and gasket at the same time. Replace nozzles once a year or at the first signs of deterioration. The cost of renewing an entire set of nozzles is a fraction of the potential cost of wastage and potential crop damage. Inevitably, all nozzles will wear out.

Horizontal boom sprayer - total output

• Measure the spacing between nozzles in metres.
• Use the following formula to determine the sprayer output:
  

  Output of an average nozzle (for average amount of time needed to travel 50 m) (A) ÷ Nozzle spacing (m) (B) x Constant (C) = Sprayer output (L/ha) ((A÷B)xC)
  
  eg. 2,000 ml (A) ÷ 0.5 m (B) x 0.2 (C) = 200 L/ha ((A÷B)xC)

• Calculate the actual area sprayed after each tank of spray solution is applied. Recheck the actual sprayer calibration after each tank of spray is applied by dividing the volume sprayed by the actual area sprayed. The nature of some products may slightly alter the calibration from that of clean water.
  

Horizontal boom sprayer - band spraying output

For banded spray applications, measure the width of the spray band (at the soil surface or surface of the crop canopy) and enter this value into the formula instead of the "nozzle spacing".

For example, if the sprayer has 10 nozzles and each nozzle covers a 36 cm (0.36 m) band, the total width of the spray patterns (swath width) is: 10 × 0.36, or 3.6 m.

For band spraying, the area sprayed is not the same as the field area. Unless otherwise stated, herbicide rates in most publications and labels refer to the field area sprayed (i.e. if an insecticide was applied at 1 kg/ha in a 3 m band over rows spaced 10 m apart, the 1 kg would cover 3 hectares of crop).

Directed (airblast) sprayer output in an orchard or vineyard

Information you will need:

• Forward Speed - e.g. 5 kilometres per hour (3.1 miles per hour).
• Target Output - e.g. 2,000 litres per hectare (214 US Gallons per acre).
• Row Spacing - e.g. 3 metres (10 feet).
• Number of Active Nozzles - e.g. 12 per side for a total of 24 nozzles.
  
  

1. Calculate time to spray.
   • Distance to cover 1 hectare in metres.
     Area of a hectare (A) ÷ Row spacing (B) = Travel distance per hectare (A÷B)
     eg. 10,000 metres² (A) x 3 metres (B) = 3,333.3 metres (A÷B)
     
   • Time to Spray 1 hectare (not including turning or refill time)
     (Travel distance per hectare (A) ÷ Speed in Metres per hour (B)) × Minutes per hour (C)
     = Time to spray in min. per hectare ((A÷B) x C)
     eg. 3,333.3 metres (5 km/hr × 1,000) 60 40 min.
     
2. Calculate sprayer output per minute.
   • Output per nozzle per hectare or acre.
     Target output (litres per hectare) (A) ÷ Total number of nozzles (B) = Total nozzle output per hectare (A÷B)
     eg. 2,000 L/ha (A) ÷ 24 (B) = 83.3 L/ha (A÷B)
   • Output per nozzle in litres per minute.
     Total nozzle output per hectare (A) ÷ Time to spray in min. per hectare (B) = Nozzle output in litres per minute (A÷B)
     83.3 L/ha (A) ÷ 40 min. (B) = 2.1 L/min. (A÷B)
3. From manufacturer's nozzle charts, find a nozzle that gives this output at the selected operating pressure. This gives an even distribution of spray rates for each nozzle, but does not reflect the shape of the target tree or vine. When added, the total output should be close to the value calcu-lated. For small trees, block off enough of the top and bottom-most nozzles to prevent waste of spray.
   

Figure 10-1. Distribution of Airblast Output for a Classic Spindle Apple Orchard, and Figure 10-2. Distribution of Airblast Output with Towers for a Classic Spindle Apple Orchard, show the distribution of output for a classic spindle apple orchard. Adjustments in output should reflect the density of the canopy the nozzles are aimed at - in other words, the more canopy, the more output.

Figure 10-1. Distribution of Airblast Output for a Classic Spindle Apple Orchard

Figure 10-2. Distribution of Airblast Output with Towers for a Classic Spindle Apple Orchard

Related Links

• Pesticide Application and Safety
• How Weather Conditions Affect Spray Applications Order No. 09-037w
• Six Elements of Effective Spraying in Orchards and Vineyards Order No. 09-039
• Adjusting, Maintaining and Cleaning Airblast Sprayers Order No. 10-069
• The Hidden Cost of Damaged Nozzles
• OMAFRA Sprayer Calibration Calculator
• Grower Pesticide Safety Course Manual
• Pesticide Companies and Agents
• Search the PMRA website
• Ontario Minor Use Program
• OMAFRA Publication 75: Guide To Weed Control: Tree Fruit