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
1. Hand Atomizer
2. Hand Compression Sprayer
3. Paddle Pump Sprayer
4. Knapsack Sprayer Pump
5. Stirrup Sprayer, Sprayer
B. Power-operated
1. Hydraulic Sprayer
2. Mist Sprayer
3. Fog or Smoke Sprayer
4. Aerial Spraying
In this article, we will talk about the 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 :
1. It should discharge a uniform spray on the material being treated.
2. The metal used for the construction of a sprayer should not react chemically with thc insecticides or any pesticides used and should be strong.
3. The construction should be simple so that it can be easily cleaned.
4. It should be efficient i.e. maximum area should be covered with minimum time.
5. The solution must be broken down into very fine uniform droplets before it reaches the materials to be treated.
6. The spray should reach the desired distance and height
7. There should not be any wastage of chemical either through leakage or spilling from the sprayer while using in the field.
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 :
1. Hand Atomizer
It is generally used to kill mosquitoes, flies or other insects on the individual plant basis. This type of atomizer docs did not give a continuous spray, but spray fluid comes out only when it is pumped like a spring.
2. Hand Compression Sprayer
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.
3. Paddle Pump Sprayer
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 the 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.
4. Knapsack 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.
5. Stirrup Sprayer
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 downstroke, while the double-acting pump has two cylinders, pressure being exerted in once cylinder on the uptake and in the other on the downstroke, thus maintaining an equal pressure. This is useful for spraying shrubs, hedges and low crops
6. Rocker Sprayer
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
