When working on a job, the pesticide applicator must choose the correct pesticide, formula, application method and equipment to use. These choices are influenced by factors such as the size of the job, the nature and habit of target pests, site characteristics and cost and efficiency of the pesticides and application methods. Below are some common application methods.
- Applying a pesticide in parallel strips (or bands) is called band application.
- Directing herbicides to the bottom of brush or small trees is called basal application.
- Uniformly applying a pesticide to an entire area or field is called broadcast application.
- Applying small amounts of pesticide into cracks or crevices in buildings is called crack and crevice applications.
- Specifically targeting pests to minimize pesticide contact with non-target organisms is called directed-spray application.
- Applying pesticide to the leafy portions of a plant is called foliar application.
- Releasing pesticides onto a device that is wiped onto weeds taller than the crop or onto individual weeds in an ornamental planting bed is called wiper treatments.
- Placing pesticides directly on or in the soil instead of on a growing plant is called a soil application.
- Using tillage, rainfall or irrigation equipment to move pesticide into the soil is called soil incorporation.
- Applying a pesticide under pressure beneath the soil surface is called soil injection.
- Applying a pesticide in an enclosed area is called a space treatment.
- Applying a pesticide to a small, distinct area is called a spot treatment.
- Applying a pesticide under the bark of a tree is called a tree injection.
Application Equipment
The label will always specify the legal application rate and may also include suggested equipment to use with the product. Pesticides may be applied as sprays, dusts, granules, gases, fogs, baits, rubs or dips. Once you have chosen the pesticide and application method needed for a job, you must choose the correct equipment.
With nearly 90% of pesticides formulated for spraying, sprayers are the most common type of pesticide application equipment. The two types of sprayers are hydraulic and air-blast sprayers.
Hydraulic sprayers range from small hand-held and backpack sprayers to large boom and power sprayers to be used for agricultural use. No matter the size, these sprayers work when pressure from a pump, air or compressed gas is used to atomize the spray mix at the nozzle. While large boom sprayers are a big investment and mainly used in agricultural settings, smaller units are affordable, simple to operate and easy to clean and store. They are commonly used for spot treatments with adjustable spray guns for accurate application.
Air-blast sprayers use both water and air as carriers with a pesticide. This sprayer releases droplets that are delivered to the target by an air-stream. This type of sprayer is typically used for disease and insect control on fruit trees, vineyards, vegetables and christmas trees.
When investing in a sprayer, it is important to choose the best components. No matter the sprayer size, a tank will be required to contain the spray mix. The tank should be made of, or coated, with a material that will not corrode and can be easily cleaned. Corroded tanks will not only need to be replaced, they can clog screens and nozzles, which leads to uneven applications. Tank agitation devices may be added on if your formulation requires agitation [e.g., wettable powders (WP) or dry flowables (DF)].
The pump in the sprayers produces the flow of spray materials to the nozzle and powers the agitation device. The pump parts must also resist corrosion and abrasion, especially when abrasive formulations like wettable powders are used. The sprayer pump should never be operated at a speed or pressure above what is recommended by the manufacturer.
The nozzle is one of the most important parts of the sprayer, as it determines the amount of material distributed, the distribution pattern and droplet coverage and drift. Nozzles should be chosen based off a few different factors. First, consider the pesticide you will be using. Nozzles come in brass, aluminum, plastic, stainless steel, and ceramic. Choose the nozzle that is less likely to react to your pesticide of choice. Next, choose your nozzle spray pattern based on the target pest, type of application, coverage needed and drift potential. Bigger droplets minimize off-target drift, while smaller droplets maximize surface coverage of the target.
Granular applicators are used for band and broadcast applications. They can be used as a standalone unit or, to save time, they can be attached to other equipment such as planters or cultivating equipment. Granular applicators, such as rotary spreaders and drop spreaders, are operated by gravity feed with an adjustable opening to regulate the flow of product. The application rate is determined by the ground speed, granule size/shape/density, field terrain and even the relative humidity. These applicators require recalibration after every use to ensure accurate application.
Other common application equipment includes:
- Baits dispensers to control rodents, insect and predators. Commonly used where there is a competing food source.
- Foggers used for indoor pest control and occasionally for outdoor insect control.
- Dusters used for small-scale disease and insect control.
- Rubs used for applying pesticides to livestock.
- Chemigation systems for greenhouses and field crops.
Calibration
Calibration is defined as the process of measuring and adjusting the amount of pesticide your equipment applies or delivers to a specific area.
Calibration ensures that your equipment is applying the correct amount of pesticides uniformly over a given area. While charts and tables on equipment may guide the operator on how to adjust the settings, sprayer calibration procedures are essential to avoiding misapplication. Equipment should be calibrated often through a trial application. Simply measure the output of the equipment on a pre-measured area. For example, spray your test area with water and travel at the speed you would during an application. Now that you know how much water was used, you can calculate the amount of water and pesticide needed for the actual application area.
Taking the time to calibrate your equipment may seem like a nuisance, but it will end up saving you money, provide your customer with more efficient applications and is safer for you and the public.
Calculating the Area and Application Rate
Precise application requires you to calculate the size of the area you are treating. Below are examples of how to find the area in acres of various shapes.
Rectangle
Circle
Triangle
Application Rate
Now that you have performed your calibration test to determine how much pesticide and carrier you will need and calculated the acreage of the application site, it is time to calculate the application rate.
During the calibration test, you found that your sprayer delivered 15 gallons of water over a half (0.5) acre test area. The pesticide you chose recommends adding four (4) ounces of product per gallon of carrier. With this information, find out how much spray mixture and product is needed for the job.
Minimizing Drift During Applications
In this packet, we have gone over different application methods, application equipment and safety measures. The following list is a quick guide for reducing drift while applying pesticides. Following these steps will ensure you are doing the best, safest and most efficient job possible.
- The pesticide label, along with the nozzle manufacturer’s guide, will help you determine the best nozzle and pressure combination.
- Selecting a nozzle that increase the droplet size will provide greater product coverage and decrease chances of drift.
- Lowering the height on a boom sprayer can reduce off-target drift.
- Maintain an appropriate travel speed, as high speeds may cause increased drift potential from an unstable boom.
- Keep the nozzle close to the target when using hand-held equipment.
- Watch the weather – heavy rains and high wind speeds may cause drift and can affect droplet deposition.
- Leave a buffer zone, where so product is applied, around sensitive areas.
- Drift control additives may be used to increase the droplet size in order to reduce drift, but do not make for up poor spraying practices.
Summary
- Specifically targeting pests to minimize pesticide contact with non-target organisms is called directed-spray application.
- Air-blast sprayers use both water and air as carriers with a pesticide. This sprayer releases droplets that are delivered to the target by an air-stream. This type of sprayer is typically used for disease and insect control on fruit trees, vineyards, vegetables and christmas trees.
- The nozzle is one of the most important parts of the sprayer, as it determines the amount of material distributed, the distribution pattern and droplet coverage and drift.
- Choose your nozzle spray pattern based on the target pest, type of application, coverage needed and drift potential. Bigger droplets minimize off-target drift, while smaller droplets maximize surface coverage of the target.
- The application rate of granular applicators is determined by the ground speed, granule size/shape/density, field terrain and even the relative humidity. These applicators require recalibration after every use to ensure accurate application.
- Baits dispensers to control rodents, insect and predators. Commonly used where there is a competing food source
- Calibration is defined as the process of measuring and adjusting the amount of pesticide your equipment applies or delivers to a specific area.
- Taking the time to calibrate your equipment may seem like a nuisance, but it will end up saving you money, provide your customer with more efficient applications and is safer for you and the public.