Are there any tips for spraying my crop?

The best knapsack spraying technique for your crop will vary with the type of pesticide that you will be spraying, the shape of the crop and its growing system. Here we offer tips on how to spray some commonly grown crops. More crops will be added.

  • Lettuce

    When growing lettuces, you may need to use different types of pesticide during the life of the crop. Typically, lettuce crops are grown in rows from transplanted young plants. At this early growth stage, the young plants can easily lose out to competition from weeds so you may need to use a herbicide. As the crop matures, the plants produce a center of very dense leaves. You may need to use an insecticide or fungicide to protect this valuable crop center. However, the pest or disease will only be controlled if spray can get past the outer leaves to reach and stay on the inner leaves.

    1. Nozzle type. Choose the type of nozzle that will produce the right drop size. Hollow cone nozzles produce large numbers of small droplets; they are often used for spraying lettuce to get a better and more even coverage of the crop. Also consider a standard flat fan nozzle which produces drops with more momentum to take the spray further and faster.

    2. Swath width. Adjust the height of the nozzle to find the width that you need the nozzle to produce. Where lettuce is grown in rows, the swath spray width should be the same as the width of the row of lettuce. This is so that as much pesticide as possible is sprayed onto the crop, rather than onto the ground.

    3. Foliage. Lettuce has a dense center of waxy leaves. When grown in beds or where the foliage between the rows is touching, consider using a miniboom fitted with hollow cone or standard flat fan nozzles. Keep your nozzles at the advised height (often 50 cm) from the top of the foliage for an even spray coverage.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

  • The coffee crop varies in how it is grown and how large the coffee bushes become as they mature: they can become very tall plants with a complex internal structure and a dense leaf canopy. The main types of pesticide used to protect coffee are fungicides and insecticides and these are used at every stage in the life of the crop. You will need to adjust your spraying method and recalibrate your knapsack sprayer before each application.

    1. Nozzle type. Choose the type of nozzle that will produce the right drop size. Hollow cone nozzles produce large numbers of small droplets that spray from the nozzle at many angles: these are often used for spraying the dense canopy of waxy leaves of coffee. Also consider standard flat fan nozzles, which produce drops with more momentum, spraying further and faster. Angle these nozzles to get more spray on the sloping leaves of the crop.

    2. Swath width. Find the right nozzle swath width to produce an even cover of pesticide drops.

    3. Foliage. Coffee plants have a complex internal structure with dense leaves. It may also be advised to angle the nozzle upwards to get some of the spray under and past the outer waxy hanging leaves and into the center of the canopy. Be careful not to spray too much spray mix to avoid surface run-off.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

    Follow local expert advice: You may be advised to spray from the bottom of the coffee plant and go up to get more pesticide on the developing crop of berries that are within the canopy.

  • When growing onion crops, you may need to use different pesticides during the life of the crop. Often onion crops are grown in beds from seeds or as transplanted young plants or sets (small bulbs around 1 cm in diameter grown from seed the previous season). At early growth stages, vulnerable seedlings can easily lose out to competition for light, water and nutrients from weeds, so you may need to use a herbicide for weed control. As the crops become more mature, you may need to use an insecticide or fungicide for pest and disease control. Because the leaves of onions are often widely space, waxy, thin and upright. It can be difficult to retain pesticide spray drops so consider using wetters, surfactants or stickers to help the drops to stay on the onion leaves better.

    1. Nozzle type. Choose the type of nozzle that will produce the right droplet size. Hollow cone nozzles produce large numbers of small droplets that spray from the nozzle at many angles. They are often used for spraying onion with their upright, waxy leaves. Also consider standard flat fan nozzles, which produce spray drops with more momentum to take the spray further and faster. Angle these nozzles to get more spray on the upright leaves of the crop.

    2. Swath width. Adjust the height of the nozzle to find the swath width that you need the nozzle to produce. Sometimes onions are grown in narrow beds of just a few rows, which are close together. The swath width should be the same as the width of the bed. This is so that all the pesticide is sprayed onto the crop and little reaches the ground on either side. When grown in wider beds consider using a miniboom fitted with the hollow cones or standard flat fan nozzles. Keep your nozzles at a height of 50 cm from the top of the foliage.

    3. Foliage. Follow any label advice on the use of stickers or wetters as onion leaves are very waxy and grow upright – these products will help the pesticide spray drops to stay on the leaves.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

  • When growing potatoes, you may need to use different types of pesticides during the life of the crop. Typically, potato crops are grown in rows from potato tubers. At early growth stages, potato crops can easily lose out to competition from weeds for water, light and nutrients, so you may need to use a herbicide. Potatoes grow very quickly and this makes the control of pests and diseases on young leaves, and those at the center of the crop, more difficult . You may need to spray your insecticide or fungicide at regular intervals. Smaller drops are commonly used as they move more easily through the canopy to reach more of the leaves.

    1. Nozzle type. Choose the type of nozzle that will produce the right drop size. Hollow cone nozzles produce large numbers of small drop so are often used for spraying the dense leaf foliage of potatoes. Also consider standard flat fan and even flat fan nozzles, which produce drops with more momentum to take the spray further and faster. Angle these nozzles to get more spray within the crop.

    2. Swath width. Adjust the height of the nozzle to find the swath width that you need the nozzle to produce. If your potatoes are growing in rows, the swath width should be the same as the width of the potato canopy of that row. This is so that all the pesticide is sprayed onto the crop and little reaches the ground on either side.

    3. Foliage. Potatoes can have denser foliage than many other crops. When the foliage between the potato rows is touching then consider using a miniboom fitted with hollow cones or standard flat fan nozzles. Keep the nozzles at the advised height which is usually a 50 cm from the top of the foliage. For dense canopies, try angling flat fan nozzles so that the spray is projected forwards into the leaf canopy. In addition, potato foliage can grow very quickly so you may need to increase spray mix/water volumes through the season. Take extra care to avoid leaf run-off with increasing volumes of water.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

    As the crops grow, you will need to increase your spray mix/ water volumes to have enough drops to cover the increasing surface area of the leaves. Be careful to avoid leaf run-off when spraying higher spray mix/water volumes.

  • When growing tomatoes, you may need to use different pesticides during the life of the crop. Tomato crops can be grown in various systems. Typically, growing systems (such as cages and stakes) are used to support the crop for better air circulation and to reduce the chance of disease spreading when left on the surface of the ground. Tomato leaves develop very quickly, making it hard to control pests and diseases on the new leaves and those at the center of the crop. You may need to spray your insecticide or fungicide at regular intervals. Smaller drop are often used as they move more easily through the canopy to reach more of the leaves

    1. Nozzle type. Choose the type of nozzle that will produce the right drop size. Hollow cone nozzles produce large numbers of small drops and so are often used for laterally spraying upright tomato plants. Also consider a standard flat fan nozzle, which produce spray drops with more momentum to take the spray further and faster. Angle these nozzles to get more spray within the crop.

    2. Swath width. When tomato plants are growing in rows and are still young, the downward spraying swath width should be the same as the width of the leaf canopy of each tomato plant. This is so that as much pesticide as possible is sprayed onto the crop and little reaches the ground on either side. When laterally spraying, the swath width is usually 50 cm or more.

    3. Foliage. Remember that tomatoes grow quickly so the pesticide label may advise increasing spray mix/water volumes through the season. Take extra care to avoid leaf run-off when increasing volumes of spray mix/ water.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

    As the crops grow, you will need to increase your spray mix/water volumes to have enough drops to cover the increasing surface area of the leaves. Be careful to avoid leaf run-off when spraying higher water volumes.

  • When growing rice, you may need to use different pesticides to control pests. Typically, rice crops are grown in fields directly from seeds or from transplanted young plants which are evenly and closely spaced over the ground. The crop has long, thin upright leaves which makes it difficult for spray drops to remain on the plant. Rice paddies or fields are often flooded with water which makes it difficult to walk and spray at a constant speed. Spraying safely and well may now be more of a challenge as some new varieties can grow up to 2 m tall.

    1. Nozzle type. Choose the type of nozzle that will produce the right drop size. Hollow cone nozzles produce large numbers of small drops and so are often used for spraying rice. Also consider standard flat fan nozzles, which produce spray drops with more momentum to take the spray further and faster.

    2. Swath width. Find the swath width that you need the nozzle to produce. Single hollow cone and flat fan nozzles often produce a swath width of about 50 cm.

    3. Foliage. As rice plants grow close together over larger areas, consider using a miniboom fitted with hollow cone or standard flat fan nozzles. Keep your nozzles at the advised height which is usually 50 cm from the top of the foliage.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

    It will be hard to walk and spray through the rice paddy at a constant speed. When calibrating your sprayer, take care to use a speed that you can maintain.

    Do not swing the nozzle from side-to-side: you will spray too much pesticide in some areas and not enough in most areas.

  • When growing maize, you may need to use different pesticides during the life of the crop. Maize crops are grown in rows and grow very quickly to become tall and wide. These mature crops have long spreading leaves which makes the gaps between the rows very narrow. This can make it difficult for you to spray safely and well.

    1. Nozzle type. Choose the type of nozzle that will produce the right drop size. Hollow cone nozzles produce large numbers of small droplets and so are often used for spraying the upright leaves of maize. Also consider standard flat fan nozzles, which produce spray drops with more momentum to take the drops further and faster. Angle these nozzles to get more spray on the crop.

    2. Swath width. Find the swath width that you need the nozzle to produce. When maize plants are still young and growing in rows, the downward spraying swath width should be the same as the width of the row of maize. This is so that all the pesticide is sprayed onto the crop and little reaches the ground on either side. For the taller, more mature crops, you may need to use an extension lance to get the nozzle to spray from a height, laterally and downwards, over the tops of the crop.

    3. Foliage. The surfaces of maize leaves, stems and cobs are steeply angled and very waxy making spraying more difficult. In addition, when applying¨pesticide, it is very likely that you will need to spray in a small space with small drops, upwards and you may have contact with the sprayed crops. Thus, it is very important to take extra care to wear the correct personal protective equipment (PPE) to fully protect yourself.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

    When spraying tall maize crops, stand upwind so that the spray will not cover you as it falls. Take extra care to wear the correct personal protective equipment (PPE) to fully protect yourself.

  • When growing cabbages, you may need to use different types of pesticide during the life of the crop. Typically, cabbage crops are grown in rows from transplanted young plants. At early growth stages, cabbages can easily lose out to competition from weeds for water, light and nutrients, so you may need to use a herbicide. As the crop grows, you may need to use an insecticide or fungicide for pest control. Pests can attack any part of the plant from the upper or lower side of the leaves, to deep within the center of the crop. The waxy leaves of cabbages make it difficult to spray these crops so that the pesticide reach and stay in the right place.

    1. Nozzle type. Choose the type of nozzle that will produce the right drop size. Hollow cone nozzles produce large numbers of small drops and so are often used for spraying cabbage. Also consider a standard flat fan nozzle, which produce drops with more momentum to take the spray further and faster.

    2. Swath width. Adjust the height of the nozzle to find the swath width that you need the nozzle to produce. Where cabbages are grown in rows, the swath width should be the same as the width of the row of cabbage. This is so that as much pesticide as possible is sprayed onto the crop and little reaches the ground on either side.

    3. Foliage. When grown in beds or where the foliage between the rows is touching, consider using a miniboom fitted with hollow cone or standard flat fan nozzles. Keep your nozzles at the advised height which is usually 50 cm from the top of the foliage.

    4. Nozzle size. Find the size of the nozzle that will spray your chosen spray mix/water volume at your spraying speed, at the calibrated pressure that your knapsack sprayer must maintain; to give the swath width that you need.

    The waxy leaves of cabbages make it difficult to spray these crops and so that the pesticide reaches and remains in the right place. Using wetters as advised and spraying small drops will greatly help the chances of your spray getting to, and staying in, the best position on the cabbage for your pesticide to work well.

Resources

  • Videos

Menu