Ultra-low volume

The term Ultra-Low Volume (ULV) (spraying) is used in the context of pesticide application.

Ultra-low volume application of pesticides has been defined as spraying at a Volume Application Rate (VAR) of less than 5 L/ha for field crops or less than 50 L/ha for tree/bush crops. VARs of 0.25 – 2 l/ha are typical for aerial ULV application to forest or migratory pests.

ULV spraying is a well-established spraying technique and remains the standard method of locust control with pesticides and is also widely used by cotton farmers in central-southern and western Africa. It has also been used in massive aerial spraying campaigns against disease vectors such as the tse-tse fly.

A major benefit of ULV application is high work rate (i.e. hectares can be treated in one day). It is a good option if all (or some) of these conditions apply:

ULV equipment is designed to produce very small droplets, thus ensuring even coverage with low volumes. The equipment is based on aerosol, air-shear (mistblowers, exhaust gas sprayers) or better still, rotary nozzle techniques. An electrostatic charge may be applied to the droplets to aid their distribution and impaction (on earthed targets), but commercial equipment is rare at present.

Ultra low volume (ULV) fogging machines are cold fogging machines that use large volumes of air at low pressures to transform liquid into droplets that are dispersed into the atmosphere. This type of fogging machine can produce extremely small droplets with diameters ranging from 1-150 µm. ULV machines are used for applying pesticides, herbicides, fungicides, sterilizers, and disinfectants amongst other chemicals. The size of the droplet is very important as each application has an optimal droplet size. The optimum droplet sizes are between 5 and 20 µm for flying insects, 20 to 40 µm for leaf nematodes and 30 to 50 µm for fungi. Low volume refers to the low volume of carrier fluid that is required with these types of machines. The droplets that are created are of such a small size that less carrier for the formulation is required to cover the required surface area. The best way to understand the concept of using less formulation to cover a larger surface area is to look at the mathematical side of the scenario. In the case where the diameter of a droplet is reduced to half its original size then the amount of droplets that can be formed from the same volume of formulation will increase eightfold. If the droplet diameter is reduced to 10 percent of its original size, then the amount of droplets that can be formed will increase a thousandfold. In this way the droplet diameter determines the amount of droplets that will form.

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Wikipedia