Ultra-low volume (ULV) application of

pesticides Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampric ...

has been defined as spraying at
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 Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus ''Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor perce ...

farmers in central-southern and western

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. It has also been used in massive aerial spraying campaigns against disease vectors such as the

tse-tse fly Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glos ...

. A major benefit of ULV application is high work rate (i.e. many hectares can be treated in one day). It is a good option if all (or some) of these conditions apply: * large area of land to treat * rapid response required * little or no water for making pesticide tank mixtures * logistical problems for supplies * difficult terrain: poor access to target site

Equipment

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 Electrostatics is a branch of physics that studies electric charges at rest (static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber ...

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 fogging machines

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 30 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.

Parts

Ultra low volume fogging machines consists of a blower, a formulation-holding tank and in some equipment a pump. The machine can have an electric, battery or gasoline engine that drives the blower. The blower creates a low pressure area and forces air through the nozzle of the fog machine. Air pressure can be controlled by adjusting the engine speed. Formulation is delivered by means of either electric, gear, FMI or Diaphragm pump to deliver the formulation to the nozzle of the machine, or in other equipment it is delivered through creating a low air pressure in the formulation tank to force the formulation to the nozzle for easy application. The nozzle of the machine has a very specific shape, which causes a swirling motion of the air stream. The motion is achieved by means of several stationary fins that force the air to rotate. The formulation is delivered to the air by means of a supply tube that is situated in the center of the nozzle. The motion of the air shears the liquid formulation into very small droplets and then disperses it into the atmosphere. MaxiProULV1

ULV fogging machines are the most preferred misting machines as the size of the droplets can be controlled by means of machine calibration.

Advantages and disadvantages

The chemicals used in this type of machine are more concentrated than the chemicals used in other spraying equipment, which also increases the killing efficiency. Other advantages of ULV misting machines includes lower risks of injury due to the fog cloud being nearly invisible, low volumes of carrier chemicals, lower application cost and low noise levels. Unfavorable aspects of these machines may include longer application times, wind drift, high concentrations of active ingredients causing environmental hazards, and the requirement of higher technical skills for calibration of the machines.

Applications

ULV fogging machines can be used in a number of different industries. Some applications includes pest control: mosquito control, bird control, agricultural applications such as grain storage, disinfectant purposes such as hospitals and laboratories, mold control and surface decontamination. A specific application for ULV machines that have been well researched is protecting avocado trees from different diseases. The most common diseases that these trees are prone to suffer from includes

Cercospora ''Cercospora'' is a genus of ascomycete fungi. Most species have no known sexual stage, and when the sexual stage is identified, it is in the genus ''Mycosphaerella''. Most species of this genus cause plant diseases, and form leaf spots. It is a ...

spot,

anthracnose A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticultur ...

and stem-end rot.{{cite journal, last =van Niekerk, first =J.M., author2=Z.S. Mavuso , title =Evaluation of ultra-low volume fungicide applications for the control of diseases on avocado fruit, journal =South African Avocado Growers' Association Yearbook, issue =30, pages = 63–68, publisher = Westfalia Technological Services, location =Tzaneen, year =2012, url = http://www.avocadosource.com/Journals/SAAGA/SAAGA_2011/SAAGA_2011_34_PG_71.pdf, access-date =2013-03-18 The diseases affecting the avocado trees are controlled by applying high volume copper oxychloride fungicides to the trees. The original application techniques included the use of a hand gun sprayer. This technique posed the problem of high run-off of the formulation. The use of ULV machines for the application of the pesticide formulation yielded more than 80 percent healthy fruit that was free from Cercospora spot. These results compared very favorably with the traditional method of using a hand gun sprayer. Another industry that have benefited substantially from the technology provided by ULV fogging machines is the chicken industry. This industry suffers great losses due to the

litter beetle ''Alphitobius diaperinus'' is a species of beetle in the family Tenebrionidae, the darkling beetles. It is known commonly as the lesser mealworm and the litter beetle. It has a cosmopolitan distribution, occurring nearly worldwide. It is known wi ...

and ''

Aspergillus ' () is a genus consisting of several hundred mold species found in various climates worldwide. ''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...

'' fungi. ULV fogging machines offers great solutions to kill both these pests in chicken houses. Another industry that uses fogging equipment is the cleaning industry, in particular the pre-occupation cleaning industry. Where there's construction, there's dust. Dust particles can vary in size, some dust particles are 5 micron and larger, other may be smaller. The dust created as a byproduct of cutting tiles or concrete can be as small as 1 micron. The real world implication of this is that a surface is always at risk of being layered in dust even though the surface has been thoroughly cleaned due to the dust laden air. This causes havoc during the commissioning stages of sensitive equipment that require near perfect conditions in which to do the testing of the equipment that are being commissioned. In these cases, ULV fogging machines are placed in strategic locations throughout a facility prior to the first cleaning phases. The ULV fogging equipment disperses water into the atmosphere that binds to the dust particles ultimately bringing the dust down against the walls and on the floor. This allows the ambient air to be free of dust contamination ensuring the cleaning of the fogged room is more effectively done. When this application is planned, ensure that all electrical outlets have been taken through the correct LOTO (Lock Out Tag Out) procedures ensuring a safe working environment. It is also prudent to enclose all electrical sockets and switches with water resistant material such as plastic bags and tape.

References

External links

ULV spraying equipment
Pesticides