Knapsack Sprayer: How To Use Different Spraying Techniques
Knapsack spraying techniques

Knapsack spraying techniques…

Are you going to spray herbicides, pesticides etc on smaller or taller plants? Do your plants grow in rows or in beds, or do they cover the entire farmland? Do you need to spray downwards, sideways or upwards? Or are you just spraying some plants?

Here is an explanation on the basics of using knapsack sprayer so that you can choose the right technique for your current spraying task.

How To Use Downward Spraying Technique

Use this spraying technique to spray crops, under 50 cm tall, for example: young tomato plants; cotton; sorghum; potatoes; sweet potatoes; rice; maize; wheat; barley; oats; soybeans; cassava; and sugar beet. While spraying, remove your sleeves from overall over the gloves. This will help prevent the spray mixture from coming in contact with your gloves and hands.

This spraying technique can be used for direct spraying pesticides in a row of crops or between rows of crops.

You have to move at the constant speed you use to calibrate your knapsack sprayer.

Keep the tip of your nozzle at the height used for calibration; usually 50 cm above the ground or the crop or weeds to be sprayed. This will help you spray evenly by keeping the nozzle stable and at the correct height.

Let your spray head do the work of applying the pesticide dose and spray/water mix volume in the desired range and drop size.

Do not move nozzle left or right.

Changing the height of your nozzle while spraying, will result in an uneven swath.

When you lower the height of nozzle, you will achieve a narrower spread. Meaning that too much pesticide will be applied in some places than others.

If you raise the height of the nozzle, you will spray a wider swath, apply too little pesticide and under-dose. Raising the height of the nozzle will also increase the risk of spray drift.

Ensure you’re moving forward in a straight line when spraying.

Do not spray if wind speed is too high. Only spray if wind speed is safe and do not spray or cause spray in an irregular manner.



Walk to the front of the swath and let the breeze blow away from you. Walk around the outside of the swath so you don’t step on the spray surface and don’t spray yourself.

Do not walk where you’ve sprayed.

If you approach the edge of the treatment area, maintain the speed you started with and turn the sprayer off when you reach the edge so that nothing is sprayed outside the treatment area. Do not spray while turning.

Align and adjust your nozzle so you can start the next spray when you reach the edge of the treatment area.

Confirm that spray cover all target surfaces, including those not affected by pests. This is because some products protect the crop for a period after spraying.

Check the nozzle chart for the correct nozzle distance and usage distance. This will ensure you get the correct coverage and apply the correct volume of water per spray in evenly distributed drops.

Make sure that each swath is sprayed side by side, with no gaps between the lines and no overlapping swaths. Use a stick to guide the spray path.

When handling larger areas, the spraying task can be completed more quickly by using 2 or 3 nozzles (same type and size) on a small spray arm.

Spraying Herbicides: Maintain speed even when spraying selective herbicides to control weeds in crops. Don’t take too long if there are too many weeds as this can cause an overdose and damage the crop.

Spray non-selective herbicides between rows, taking care not to spray crops. Use spaying guard.



How To Use Upward Spraying Technique

This spraying technique is used for tall crops of 2m or higher, such as bananas, apples, oranges, dates, pawpaw, orange etc.

By spraying pesticides upward, you’re significantly increasing your risk of contamination. Make sure you use the correct PPE. Wear gloves on the outside of the sleeves to prevent drops from running down your hands and under the sleeves. It’s best you seal the glove and sleeve together.

If you have to spray up, it’s a challenge to spray pesticides safely; drops may fall on you, or droplets may be blown by wind.

Start at the bottom of the canopy. Direct the pesticide up and into the leaves so that the droplets enter under the leaves.

Use the extension lance and tilt toward the crop for taller crops. This means that you will need to keep some distance from the crop.

Spray pesticide sideways or downwards rather than upwards – the less spray is projected directly upwards, the less likely the droplets are to fall.

If you are spraying long rows of tall crops with pesticides or fungicides, move the spray head from top down. Fix the nozzle firmly at the correct distance from the crop and move the nozzle at a calibrated speed. Make sure the spray is evenly distributed over the leaves. Remember, if you move the nozzle too fast, you won’t be able to spray enough pesticides. If you move the nozzle too slowly, you will spray a lot of pesticides.


Read more >>> on all the spraying techniques.

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