Hydraulic sprayers

Spray schedules applied on experimental plots at the Yakima, Wash., and Vincennes, Ind., laboratories of the United States Bureau of Entomology and Plant Quarantine were studied to determine the magnitude of parathion and DDT spray residues at harvest. The parathion sprays were prepared from 25% vet table powder and the DDT sprays from 50% wettable powder, except in one series of tests, when a 25% DDT wettable powder was used. All spray treatments were planned and made by members of the Division of Fruit Insect Investigations. Conventional hydraulic sprayers were used in this work. 

Because little agitation of the spray suspension is needed, emulsifiable concentrates are especially suitable for low-pressure, low-volume sprayers and for mist blowers. You can also use them with many other types of application equipment, including dilute hydraulic sprayers, low-volume ground sprayers, mist blowers, and low-volume aerial sprayers. 

Pounds formulation per tank for hydraulic sprayer (24) x Concentration wanted (5X) = Pounds of formulation to add to air blast tank (120)... 

The main types of equipment considered here are the hydraulic sprayers, such as compression (Figure 5.1) and lever-operated knapsack sprayers (Figures 5.2, 5.3) normally used for residual applications to surfaces. Hydraulic sprays may also be applied with motorised pumps on knapsack sprayers, or larger units are carried on a trolley (Figure 5.4) or small vehicle. Pesticides formulated for dilution in water are frequently applied at volumes of around 100-500 litres per hectare. Other types of space treatments and more specialised equipment are considered later. 

Apart from small motorised hydraulic sprayers, similar to the tractor-mounted equipment but on a miniature scale, the majority of small ground-based sprayers are manually carried or, if trolley-mounted with a hose and lance, are manually operated. A common feature of these sprayers is that the actual delivery of a... 

The versatility of hydraulic sprayers enables them to be used in a wide variety of situations. There are BSI standards for the compression and lever-operated knapsack sprayers. The relatively inexpensive compression sprayers have a small air pump to pressurise a container of 0.5-10 litre capacity, which is filled with the spray liquid to about three-quarter capacity. Pumping is not required while... 

Multinational companies have shown interest in the development of application technologies, but commitment has not been sustained where intellectual property rights (IPR) in large markets could not be established. Disappointingly few farmers worldwide are aware of alternatives to conventional hydraulic sprayers, which inefficiently use large volumes of water, but remain by far the most important method of pesticide application. Worse still, recent emphasis in application research has focused on the reduction of spray drift (especially in Europe and North America). The most common solution to be implemented to date has been to increase droplet size spectra (without necessarily improving spray quality) thus spray application has probably become generally more inefficient. 

In-cab electronic sprayer controls Hydraulic boom-folding... 

Exposure control Use engineering/technical means, e.g. Low-level filling bowls Suction probes Closed handling systems Soluble packs In-cab electronic sprayer controls Hydraulic boom-folding (These measures should be used in preference to protective clothing)... 

Field Plots. An apple orchard in Hood River, Ore., in the northern part of the state, has been treated with DDT every year since 1946 for a total application of 388 pounds per acre. Until 1949 the sprays were applied with hand-controlled hydraulic equipment. Since 1949 air carrier sprayers have been used. The orchard is never cultivated, and the soil type is Wind River sandy loam. It is located on the edge of a low plateau about 300 feet above Hood river, a tributary of the Columbia river. 

A pear orchard in Medford, in the southern part of the state, received DDT treatments each year between 1947 and 1959, for a total estimated dosage of 169 pounds per acre. Until 1953 applications were made with hand-controlled hydraulic systems, after which spraying was done with air carrier sprayers. The soil type is Meyer clay adobe, and the orchard is kept free of vegetation by cultivation. 

These sprayers involve a double-action hydraulic pump which is operated with a push-pull motion. The pesticide is sucked into the cylinder and pushed... 

These sprayers are mounted on a two-wheel cart with handles for pushing. Trailer hitches are available for towing the units. Spray material is hydraulically agitated. Some models have 15- to 30-gallon tanks. Pumps deliver 1.5 to 3 gallons per minute at pressures up to 250 psi. 

These sprayers are usually mounted on tractors, trucks, or boats, but some are self-propelled. Roller and centrifugal pumps are most often used and provide outputs from 5 to more than 20 gallons per acre. Tank sizes range from 50 gallons or less to 1,000 gallons. The spray material is usually hydraulically agitated, but mechanical agitation may be used. 

Formulations which make the insecticide readily available and easy to detach from the surface, such as suspensions, wettable powders and microencapsulated preparations, provide the most active residual deposits, although oil solutions or emulsions are effective and frequently used- Application is usually through standard hydraulic pumps or compression sprayers (knapsack sprayers), where a tank pressure of about 20 psi ( 138 kPa) can be maintained. 

Although wide drop-size distributions can sometimes be an advantage (Hislop, 1983) the large numbers of small drops produced in hydraulic nozzle sprays can result in spray drift and inadequate targeting (Miller, 1993). Rotary atomisers (Bals, 1975) can reduce the breadth of drop-size distributions and provide a more targeted size distribution. They have not been widely adopted in broad-acre ground crops, because their spray volumes and drop trajectories often cause control difficulties, but they have found some acceptance in orchard sprayers. 

The most commonly used application systems in arable crops are boom sprayers equipped with equally spaced hydraulic nozzles (Robinson, 1993). The quality of the spray influences the quantity deposited on the crop and spray-drift. The combination of forward speed, nozzle type and pressure defines the sprayed volume. Volume rates have been reducing for several decades. While in the 1950s it was common to spray 10001/ha, nowadays 100-3001/ha is more common. 

---