Pesticide Application in Vineyards
Sprayer Components
The pesticides used to control weeds, insects, and diseases in the vineyard are applied with sprayers, which can either be tractor-mounted, pull-type, pickup-mounted, and self-propelled. All sprayers have several basic components: tank, pumps, filtration devices, fans, and nozzles.
Tanks
Tanks should be made of a corrosion-resistant material. Suitable materials used in sprayer tanks include stainless steel, polyethylene plastic, and fiberglass because of their rust and corrosion resistance. Stainless steel tanks are the most durable, corrosion-resistant, and the strongest option. Due to their high cost, they make the most sense for high-use spraying situations.
Agitation System
Many spray mixtures must be agitated (stirred up) to keep the pesticide and carrier mixed. For liquid concentrates, soluble powders, and emulsions, the system bypass line is usually adequate to keep the formulation well mixed.
Direct Injection Sprayers
Direct injection sprayers use separate tanks for the water and the pesticide. The pesticide is injected into the water stream at a rate dictated by the forward speed and controller. While more costly to purchase, injection sprayers have the advantage of reducing risk since you never mix more than needed.
Pumps
The pump must deliver the necessary flow to all nozzles at the desired pressure to ensure uniform distribution. When selecting a pump, consider the pressure ranges the pump can handle, the gallons per minute it can supply, its resistance to corrosive damage from pesticides, ease of priming, and power source availability. It’s a good idea to choose a slightly oversized pump. A pump must have sufficient capacity to operate a hydraulic agitation system, as well as supply the necessary volume to the nozzles.
Piston Pumps
Piston pumps are among those most commonly used for applying agricultural chemicals. These are positive displacement pumps that can be used for both corrosive and abrasive materials. There are two types of piston pumps used for different application purposes: high pressure-low volume-high speed, and low pressure-high volume-low speed applications.
Diaphram Pumps
Diaphragm pumps, although often more expensive than other pumps, have some important advantages in use and maintenance. These include: (1) a small number of moving parts; (2) a limited area of exposure of pump components to the injected chemicals; and (3) design which allows for easy adjustment of injection rate.
Centrifugal Pumps
Centrifugal pumps are the most popular type for lowpressure high-volume sprayers. They are durable, simply constructed, and can readily handle wettable powders and abrasive materials.
Roller Pumps
Roller pumps are widely used on low-pressure boom sprayers for herbicide application and run efficiently at low PTO speeds.
Filtration Devices
Proper filtering of the spray mixture not only protects the working parts of the spray system but also avoids misapplication due to nozzle tip clogging. Three types of strainers commonly used on sprayers are tank filter strainers, line strainers, and nozzle strainers. As the mixture moves through the system, strainer openings should be progressively smaller. Tank filter strainers prevent large contaminants (e.g., grass, rocks, labels) from entering the tank upon filling.
Fans
Fans are used to move spray into vines to enhance the uniformity of pesticide deposition on berries, foliage, and wood. Air movement also displaces leaves and branches, which aids spray penetration and increases the exposure of surfaces to spray.
Nozzles
TThe term nozzle is used in a wider sense of any device through which spray liquid is emitted, broken up into droplets, and dispersed over the target. The nozzle regulates the flow rate, atomizes (breaks up) the mixture into droplets, and disperses the droplets in a specific pattern. Nozzle selection is one of the most important decisions to be made related to pesticide applications. The type of nozzle affects not only the amount of spray applied to an area but also the uniformity of the applied spray, the coverage obtained on the sprayed surfaces, and the amount of drift.
Nozzle Materials
Nozzles are made from several materials. The most common are brass, nylon, stainless steel, hardened stainless steel, tungsten carbide, thermoplastic, and ceramic. There are advantages and disadvantages with each type of material. Brass nozzles are relatively inexpensive, but they wear rapidly with abrasive materials, such as wettable powders and liquid fertilizers. Stainless steel and hardened stainless steel are the most resistant to wear, but their expense discourages some users.
Nozzle Nomenclature
There are many types of nozzles available, with each providing different flow rates, spray angles, droplet sizes, and patterns. Some of these spray tip characteristics are indicated with a four- or five-digit number designation on the tip. Remember, when replacing tips, be sure to purchase the same tip number, thereby ensuring your sprayer remains properly calibrated. For example, the TeeJet 11004 nozzle has a 110-degree spray angle and applies 0.4 gallons per minute (GPM) at the rated pressure of 40 PSI (Figure 26.1)..
Other System Components
Pressure Regulators
A pressure regulator is one of the most important parts of a sprayer. It controls the pressure and therefore the quantity of spray material delivered by the nozzles.
Pressure Guages
Pressure gauges monitors spray system operations because a sprayer is set up to operate within a specified pressure range.
Control Valves
Control valves should be located between the pressure regulator and the nozzles in order to regulate the flow to specific boom or manifold sections or even to individual nozzles.
Sensors
Sprayers can be equipped with sensors to detect the presence or absence or vines. Sensor-controlled sprayers are often referred to as smart sprayers.
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