Success in pest control depends not only on the use of proper chemicals at the correct time, but also upon their proper and uniform application by judicious selection of plant protection appliances. Pesticides are generally applied to the plants as dusts, sprays, concentrates, fumigants, aerosols, granules, mist and used for seed dressing. These formulations are used on the crop foliage or to the soils with the help of plant protection appliances or equipments. The foliar applications are done by means of sprayers of dusters and soil applications are made by sprayers, dry chemical applicators, injectors, smoke generators, fumigators, seed dressers, aerosol projectors, rat trappers and bait containers. Treatment of cash crops by using aircraft is also commonly practiced in some countries, but rarely in India where the fields are usually smaller in size.
Plant protection devices can broadly be classified into following. three categories: (i) sprayers, (ii) dusters, and (iii) fumigators. They are either hand operated or power operated.
Sprayers are further classified as :
A) Hand operated
In this article, we will talk about hand operated Sprayers. The liquid formulations of insecticides are applied to the crops with the help of a sprayer. The desired qualities of a sprayer are :
The spraying is caused by atomization of the liquid which is brought about by the injection of the liquid into a gas at high velocity or the passage of the gas through the liquid at a high velocity. The various hand operated sprayers are as follows. The sprayers are used depending on various factors like crop, land area etc. Find your best fit from these :
It is generally used to kill mosquitoes, flies or other insects on the individual plant basis. This type of atomizer docs not give a continuous spray, but spray fluid comes out only when it is pumped like a spring.
This sprayer is used to spray the field crops and trees. It is a medium sized machine which is operated by a single man. As in stove and petromax, it also gives out the spray due to the air pressure. This sprayer is available in 2 gallons, 3 gallons and 4 gallons capacity. It may be divided into three main parts : (a) pump (b) tank and (c) spraying parts.
This type of sprayer is more suitable for the field crops and particularly the trees which are 20 ft high. An iron stand is provided as a base to this prayer. This machine is the assembly of plunger, a stand suction hose, delivery hose, and an extension rod having a spray nozzle at its free end. Since this is a foot operated sprayer, a paddle is attached to the plunger rod to make its up and down movement which ultimately operates the sprayer.
It has a flat or bean shaped tank (2-5 gallons capacity) which fits comfortably on to the back of the operator. There is an agitator inside the tank. The pump handle extends over the shoulder or under the arm and is worked constantly with one hand while the lance is held with the other for spraying. It is useful for operating over small trees, shrubs, low crops, vegetables or nursery stocks.
This consists of a single or double acting pump, which may be clamped or set into a bucket. The single acting pump has one cylinder and exerts pressure only on the down stroke, while the double acting pump has two cylinders, pressure being exerted in once cylinder on the uptake and in the other on the down stroke, thus maintaining an equal pressure. This is useful for spraying shrubs, hedges and low crops.
It is provided with a pump or pressure chamber, fitted on a wooden board and operated by a long handle connected with the pump. The pump may be a single or double barrel one. The rocking movement helps in building up pressure in the pressure vessel which forces out the liquid through the nozzle. There is no tank and the suction hose is dipped in a separate spray tank. The principle of working of rocker sprayer is the same as that of foot or paddle sprayer The only difference is that the rocker sprayer is operated by hand, while the paddle is a foot operated one. It is capable of spraying medium sized fruit trees, plantation crops and field crops
In the next post, we will talk about the power operated sprayers.