Crop sprayer and pesticide sprayer types for agriculture: tank-mix, injection, air-directed, backpack and wick
Sprayers use pressure created by a pump to force spray mixture through hoses to nozzles. They may be mounted, pull-type or self-propelled; boom and boomless units match a wide range of applications; electrostatic and air-directed sprayers also exist.
The basic components of a crop sprayer are the tank, pump, agitator, hoses, valves, fittings and nozzles.
Tank-mix sprayer or injection sprayer
A tank-mix sprayer has one large tank in which water and chemicals are mixed. It is less expensive and easy to operate, and the mix needs attention to tank-mix compatibility and the order of mixing for some products.
An injection sprayer has a large tank that contains only water, plus one or more separate tanks for the product. Electronic controls measure the flow of water and inject the proper quantity of chemical into the water stream before it reaches the nozzles. This reduces contamination potential and eliminates the need for tank agitation. The water tank is never contaminated with chemicals, so cleanup is simpler, and you never mix more than needed; the price is a higher purchase cost. Products that are difficult to clean can have dedicated chemical tanks.
On a liquid sprayer, the pump needs a capacity at least 50% larger than the sum of the nozzle outputs and the agitator; pumps are usually attached directly to the tractor PTO.
Closed mixing system for pesticides: the paraquat case
Handlers who mix and load with paraquat closed systems may not reduce or modify handler PPE requirements, and Gramoxone SL 3.0 follows this rule.
If a proposal says “paraquat closed system”, ask for the product and system documentation and find out whether the system covers loading into the sprayer or delivery to the crop; these are separate operations.
Air-directed sprayers: airblast, air boom and air nozzle
Air-directed sprayers fall into three groups: airblast, air boom and air nozzle. Airblast sprayers have been widely used for years in vineyards and orchards; a nozzle or nozzle cluster sprays into the discharge of a high-volume fan, and the airflow spreads the droplets onto the crop. An air boom sprayer is a conventional hydraulic sprayer with an air tube added over the nozzles; the air blast blows the spray down into the crop canopy, improving penetration and reducing drift.
An orchard air blast sprayer applies pesticides, plant growth regulators and foliar nutrients to orchard trees as liquids carried in large volumes of air, with adjustments in the fluid and air delivery systems to fit a wide range of orchard conditions. The fan produces a high-speed airstream that transports the droplets toward the target. Air movement displaces leaves and branches, which aids spray penetration and increases the exposure of surfaces to spray, and the air stream gives the droplets velocity, which increases impingement of very small droplets on the target.
An electrostatic sprayer uses a high-voltage electrical charge to create an electrostatic field between the plant and the spray droplet; the opposite charges attract, and the droplets cling to any exposed plant surface, top or bottom.
Choosing an orchard airblast sprayer
A sprayer must be adequate for the worst of orchard conditions: one that is adequate only under favorable conditions is a liability under adverse conditions, and it should at least meet the demands of spraying large, thick trees under the poorest conditions allowable for spraying. Reliability, maintenance history and the ability to cover the projected acreage are the selection criteria.
Horsepower is very important because fans must move a considerable weight of air and materials. Manufacturers give a recommended horsepower range, and reliability and equipment longevity are often better when you select from the upper end of that range.
Observe sprayers operating in orchards where tree size, row spacing, weather, speed and application volume are challenging, and examine the coverage. Request dealer demonstrations and ask for the names and locations of customers who operate the models of interest. When observing a demonstration, relate its speed, pressure and nozzle output volume to the more challenging conditions you expect.
Ask for the demonstration in the tallest and densest canopy the machine will treat; an empty-yard display shows the controls, but not the coverage. Ask the seller to show how to collect nozzle output, read the operating pressure and measure travel speed, and which method fits the proposed machine. Check serviceability too: ask the dealer to include replacement parts and maintenance support in the quote. If you consider an air-assisted boom sprayer, ask the supplier to explain its air delivery and show the pattern in your crop.
Handheld pesticide sprayer, backpack, portable and wick sprayers
A backpack sprayer consists of a tank, a pump and a spray wand with one or more nozzles. Its small size, portability and ease of use make it a valuable tool, and it is best suited for small acreage, spot spraying and areas where a larger sprayer is impractical. Most chemical backpack sprayers use hand pumps; some have a small battery or engine-powered pumping system, and consistent, uniform pressure control is essential for proper application.
Hand-operated sprayers should have a reversible handle for left- or right-hand use, shoulder straps that distribute the load evenly, removable screens that protect the pump and nozzles and are cleaned regularly, and a stable base that holds the sprayer upright for filling and mixing.
When you choose a backpack or portable sprayer, whether a Stihl, a Cooper Pegler or another brand, give the supplier the product directions, target area and required application method, and compare models by filling, carrying, cleaning and measured delivery.
Product labels can restrict the sprayer type: do not apply Gramoxone SL 3.0 by mechanically pressurized handgun or backpack sprayer; application by manually pressurized handwand is permitted.
A wick applicator, a convenient way to apply contact herbicides, brushes a rope or sponge wick soaked with solution against the plant. It applies chemical only to a selected target, for instance weeds and grasses taller than the crop, and can use less chemical than broadcast spraying.
Spray tank backpack and chemical backpack sprayer
A spray tank backpack is the tank of a backpack sprayer carried on the shoulders; a chemical backpack sprayer is the same unit used with pesticides. Most use hand pumps, and some have a small battery or engine-powered pumping system. Use a unit with a removable screen and a stable base, and dedicate it to chemicals rather than to water or fertilizer.
Keep your spray records in one place. Free to start.
Spray tanks for trucks and drone chemical sprayers
Spray tanks for trucks sit in the truck bed; the choice of tank is covered on the sprayer tank selection page. A drone chemical sprayer or drone insecticide sprayer is an aircraft in law; the FAA rules are on the agricultural spray drone requirements page.
Best pesticide sprayer: commercial, professional and plant pesticide sprayers
There is no single best pesticide sprayer: no one nozzle covers every type of application, and sprayers may be mounted, pull-type or self-propelled, with boom or boomless units for a wide range of applications. A commercial pesticide sprayer, a professional pesticide sprayer, an industrial herbicide sprayer, a portable agricultural sprayer and a sprayer used in farming are compared on the treated area, the application method and measured delivery. A plant pesticide sprayer for a greenhouse or a garden bed is the backpack or handheld end of the same range.
Gas, petrol, motorized and mini sprayers
Most chemical backpack sprayers use hand pumps; some have a small battery or engine-powered pumping system, and consistent, uniform pressure control is essential for proper application. A gas powered pesticide sprayer, a petrol pesticide sprayer, a 4 stroke agriculture sprayer, a motorized pesticide sprayer and a leaf blower pesticide sprayer are engine-driven versions; an agriculture mini sprayer, a mini pesticide sprayer and an agriculture mechanical sprayer are small units for small acreage and spot spraying. A backpack sprayer is best suited for small acreage, spot spraying and areas where a larger sprayer is impractical, and a spray tank backpack carries the mix on the operator's back. The label can still restrict the sprayer type, as the Gramoxone SL 3.0 label does for backpack sprayers and handguns, so read it before choosing the unit.
Self-propelled, smart, solar and paddy field sprayers
Self-propelled farm sprayers are one of the three carrier types of crop sprayers, with mounted and pull-type. A smart pesticide sprayer, a solar operated sprayer for farming and a paddy field sprayer are judged the same way as any other: by the nozzle type and size for the product directions, the pump capacity and the delivery you measure in calibration.
Nozzles: type, size and material
The first step in sprayer calibration is to determine the correct nozzle type and size. Flat-fan nozzles are used for broadcast spraying of most herbicides and some insecticides where a medium droplet size is needed, and for banding herbicides. Flooding and full cone nozzles used for pre-plant herbicides produce drift-resistant large droplets and allow wide nozzle spacing. Hollow cone nozzles produce smaller droplets and are used for insecticides and contact herbicides that need to penetrate the canopy.
Nozzle size depends on the desired application rate, ground speed and nozzle spacing. For each nozzle type and spray angle, the manufacturer recommends spray height and nozzle spacing. No one nozzle covers every type of application, and when a chemical label specifies a particular nozzle, use that nozzle.
Many boom sprayers use quick-change nozzle caps so that tips can be swapped without tools; a Quick TeeJet cap, for example, allows attaching most TeeJet tips to nozzle bodies, and with this cap there is no automatic alignment, so the operator rotates the tip until the spray is in the proper location in relation to the target.
Wear-resistant materials such as tungsten carbide, ceramic and hardened stainless steel help nozzles maintain a constant flow rate after a long period of use. After 50 hours of spraying, a brass nozzle can have a flow rate 10 to 15 percent higher, while a hardened stainless steel nozzle increases only about 2 percent. Erroneous flow rates can result from damaged, worn or plugged nozzles or strainers.
Herbicide spraying methods: broadcast, banded and directed
Before planning herbicide spraying, decide whether the treatment is broadcast, banded or directed, and write it into the job description together with the crop and target, so the adviser, operator and recordkeeper understand the same job. Calibration uses three bases by type of application: broadcast in gallons per acre, band in gallons per acre of band, and row in gallons per acre of row. For a band application, measure the band width. Do not confuse the treated-band width with the distance between rows when you work out the area and rate.
Overlap of flat-fan nozzles is required for broadcast work because the outer edges of the spray patterns are tapered; the most uniform pattern is achieved when the overlap is 50 to 60 percent of the nozzle spacing. Even flat-fan nozzles apply uniform coverage across the entire spray pattern and are used for banding chemicals over the row; the band width is determined by nozzle height, and the recommended pressure is 20 to 30 psi.
A directed foliar spray can be applied in higher volumes through spray wands attached by hoses to vehicle-mounted spraying systems that have much larger herbicide tank capacities. The product label defines where, how, how much and how often the product may be used.
Swath width is the spacing of the applicator's passes through the field, which differs from the width of the spread pattern, the maximum width over which the product is distributed.
Granular applicators are not liquid sprayers
A granular applicator typically consists of a hopper, a metering system, drop tubes and a diffuser. The metering system works by gravity flow or positive displacement. In the gravity flow type, the size of an orifice or opening is adjusted to control how the product flows out of the hopper; an agitator in the bottom of the hopper ensures smooth delivery but likely does not control metering. In the positive displacement type, the metering unit delivers a fixed volume of material for every revolution it makes. The drive is often connected to a ground wheel, and some units are driven by PTO, hydraulic drives or small electric motors. Find out which drive your unit has before you choose a calibration procedure, and do not copy settings from a liquid sprayer.
On a granular unit, check the tubes and diffusers for leaks or blockage; drop tubes or hoses should let the material fall freely without collecting in the tube.
Next step
Calibrate the chosen sprayer with the sprayer calibration guide. Each nozzle should be within 10 percent of the average output; replace nozzles that are not.
If the machine will be shared among products, check the cleanout access before you buy. For a side-by-side or tractor-mounted boom sprayer, check the hitch, lift and load specifications of your vehicle, ask for a demonstration on it, and look at the boom at working width and in transport.