Crops or trees can be protected from diseases by carefully timed application of chemicals. As little as a few grams of the chemical may be needed and it has to be formulated to facilitate its distribution over the aerial parts of plants or to treat seeds or other propagating organs (tubers, bulbs, corns, etc.) or the soil in which plants are to grow.
Any chemical may be applied in one or more of four physical states — gas, solid, liquid, or solution. It is, therefore, necessary to use the most efficient equipment for securing a uniform deposit of the chemical on the target substrate without wastage of the material in the minimum time and with the minimum labour.
The types of equipment commonly used in plant protection from diseases may be broadly classified as follows:
Equipment # 1. Sprayer:
Sprayer is equipment in which the spray fluid is broken up into fine droplets and ejected under pressure. Actually, the function of the sprayer is to provide the spray fluid with some energy so that it can be broken into fine droplets through the nozzle and propelled to the target. The energy can be produced manually or with the help of any other source of power.
Droplets smaller than 100 mm in diameter are considered the best for controlling plant diseases. There are a variety of sprayers (e.g., manually operated sprayer, hand-compression sprayer, battery sprayer, hydraulic sprayer, foot sprayer, rocker sprayer, motorized knapsack sprayer, tractor mounted sprayer, power sprayer, etc.), which are used depending upon the volume of spray fluid elected to cover a unit area.
Equipment # 2. Duster:
Duster is such equipment which is used for the distribution of chemical in its finely powdered form. The dusters used in plant disease control operations may be manually operated or power operated, some of the important manually operated dusters are plunger duster, bellows duster, rotatory or fan duster, and wet dusting equipment. Tractor mounted duster, engine operated duster, and motorized knapsack dust-blower are some important power operated dusters.
Equipment # 3. Sprayer-Cum-Duster:
This equipment is called ‘mist blower’ and combines the features of both sprayer and duster. The air-blast produced by a fan fitted in it may be used for blowing the liquid and dust simultaneously so that the dust is wetted and is not easily blown off or washed away. If needed, this equipment can be used as a sprayer or a duster only.
Equipment # 4. Flame Thrower:
Flame thrower is a compressed sprayer filled with kerosene, the lance of which is modified into a burner. When the burner is heated and kerosene allowed to flow through it, the latter bursts into flames which are thrown forward. A hood is provided in some cases to change the direction of the flame as per requirement. Flame thrower is used for burning weeds, disinfecting seed beds, etc.
Equipment # 5. Soil-Injector Gun:
Soil-injector guns are light (3.6-6.75 kg) in weight when empty, with a capacity of about 2.25-3.50 litres. They are used to fumigate soil to a depth of 12-18 cm to control nematodes, soil borne pathogens, etc. The gun possesses a sharp pointed end by which the soil is pierced and the liquid fumigant is injected therein. The injector is calibrated to ensure the application of required doses of the fumigant at regular intervals.
Equipment # 6. Granule Applicator:
Granule applicators are used for scattering chemical granules or for application in furrows or lines before or after planting, or for placing granules in the leaf axils of plants. Most granule applicators are manually operated.
A common granule applicator is made up of plastic (except the calibration unit, which is made of metal). It is light in weight and has a granule capacity of 1.0 – 1.3 kg. Comparatively large-sized granule applicators are also available, which possess a granule capacity of 10 kg.
The essential components of a granule applicator are a hopper to hold the granules, a long flexible discharge tube with a nozzle at the distal end, and a finger-controlled mechanism to regulate the flow of the granules. At each end of a stroke, the exit hole is exposed and a specific quantity of granules is released into the tube. The released granules are flung out from the tube during its movement, to the other end of its stroke.
Equipment # 7. Seed-Dressing Machine:
Seed-dressing machine is used for seed-treatment with chemicals or their solutions. Most of the commonly used such machines are hand-driven. Typically, a seed-dressing machine consists of a drum fitted on a stand. The drum possesses a small door in the middle through which the seeds and chemical are put in and the treated seeds are taken out. For a thorough mixing of the chemical with the seeds, baffles are provided inside the drum.
The baffles comprise small iron plates fixed at right angles to the inner surface of the drum. However, the drum is rotated slowly, 30-40 times, for two minutes. As a result, the seeds are coated with the chemical. The normal capacity of a drum varies from 20-60 kg and it can treat 200-800 kg of seeds per day.
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