Visit our new site Pesticidewise.com for more help on spraying pesticides with a knapsack sprayer including:
- Checking your knapsack sprayer
- Choosing your nozzle size
- Calibrating your knapsack sprayer
- Cleaning your knapsack sprayer
- Advice on personal protective equipment
- Protecting your land
Efficient Knapsack Sprayer Use
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Efficient knapsack sprayer use - overview
• To get the maximum benefits from the use of any crop protection product (pesticide), as well as reducing risks of any potential human or environmental contamination, it is important to apply the product in the optimum way.
• Best maintenance, calibration and use of the knapsack are critical to the success of any application and will ensure that you get maximum value, effect and safety from the products used.
• This guide for efficient knapsack use gives tips on the key points of maintenance, calibration and use of knapsack sprayers.
Best spraying practices - practice using just water if not sure
Four steps to good knapsack spraying
- Check sprayer for leaks with clean water (always before use)
- Calibrate sprayer output (at least once per season)
- Ensure an even and uniform application
- Clean sprayer after each use
Step 1. Check sprayer with clean water
Check, double check and keep sprayer clean
repair leaks immediately
- Fix all leaks before using the sprayer
- Know where leaks are most likely to occur
- Keep spare parts to repair leaks
Step 2. Calibrate sprayer output
- read product label
- follow calibration instructions
- fit appropriate nozzle
- measure swath width
- adjust water volumes (l/ha) within recommended limits to your specific needs, such as stage of crop growth
See "Calibration of Handheld Sprayer Equipment" training module for more detailed information
Step 3. Application
use best field practices
Step 4. Cleaning of sprayer after use
cleaning is critical
Choosing nozzle type
Three main nozzle designs are used on knapsack sprayers. Each nozzle design is available in a range of sizes to optimise use of product to be applied
See "Nozzle Selection for their optimised use" training module for more details
- A range of nozzles are available, to meet the needs of contrasting products, for applying differing water volumes as well as differing droplet sizes and distribution patterns
- Selecting nozzle type and size is critical: for water volume rates (l/ha), drop size and distribution
- Drop size used may affect activity of the product applied and safety; smaller droplets can cause spray drift
- Water volumes used must not be too high to lead to product waste through run off or too low to not adequately cover all target surfaces
Best practices summary
- What are the 4 steps to efficient knapsack use?
- Using the dosing wheel, tell me how much product you would require to add to a 20l knapsack if the calibrated output is 300l/ha and the product rate is 1.5l/ha?
- To calibrate a knapsack, what information is required prior to checking the sprayer output?
- Which is the best way to increase or decrease application volume?
- Demonstrate that you can calibrate a knapsack and determine the application volume.
- Where are leaks most likely to occur on a knapsack sprayer?
- Ensure there are sufficient knapsacks to allow trainees to work in teams of 2 or 3 to calibrate sprayers.
- Check availability of field space to allow for realistic calibration practice.
- Use water sensitive paper, if necessary, to demonstrate swath width. If not, then use dry concrete surfaces.
- Have sufficient laminated sheets, calibration cards and Kalibottles (if used) for each participant.
- Fit knapsacks with different nozzles to demonstrate different flow rates, drop sizes and spray patterns.
- Use water sensitive paper to show different spray patterns from a range of nozzles.