PLANT PROTECTION EQUIPMENT
Chemicals are widely used for controlling disease, insects and weeds in the crops. They are able to save a crop from pest attack only when applied in time.
They need to be applied on plants and soil in the form of spray, dust or mist. The chemicals are costly.
Therefore, equipment for uniform and effective application is essential. Dusters and sprayers are generally used for applying chemicals. Dusting, the simpler method of applying chemical, is best suited to portable machinery and it usually requires simple equipment.
But it is less efficient than spraying, because of the low retention of the dust.
High volume spraying is usually effective and reliable but is expensive. Low volume spraying to some extent overcomes the failings of each of the above two methods while retaining the good points of both.
Spraying is employed for a variety of purposes such as application of:
i. Herbicides in order to reduce competition from weeds,
ii. Protective fungicides to minimize the effects of fungal diseases,
iii. Insecticides to control various kinds of insects pests,
iv. Micro-nutrients such as manganese or boron,
The main function of a sprayer is to break the liquid into droplets of effective size and
distribute them uniformly over the surface or space to be protected. Another function is to
regulate the amount of insecticide to avoid excessive application that might prove harmful or
wasteful. A sprayer that delivers droplets large enough to wet the surface readily should be
used for proper application. Extremely fine droplets of less than 100 micron size tend to be
diverted by air currents and get wasted. Crops should, as far as possible, be treated in regular
swaths. By use of a boom, uniform application can be obtained with constant output of the
machine and uniform forward travel.
Classification o~ Spraying Technologies
Spraying techniques are classified as high volume (HV), low volume (LV) and ultra low
volume (UL V), according to the total volume of liquid applied per unit of ground area.
Initially high volume spraying technique was used for pesticide application but with the
advent of new pesticides the trend is to use least amount of carrier or diluent's liquid.
In spraying, the optimum droplet size differs for different types of application. Fine droplets
are required to control insects, pests or diseases and bigger size droplets for application of
herbicides, etc. The greater the number of fine droplets produced by the device better will be
deposition on target area. The size of droplet is important as it affects drift and penetration
distance of droplets towards the target. Hence a compromise is to be made to prevent drift,
achieve wide coverage of plant or target area and more penetration. The optimum droplet
sizes are indicated in below: