 High friends, in the last class we discussed mode of action of different insecticides particularly the new molecules that have come very recently. In continuing the discussion on chemical control in insect pest management, in this class we will try to understand important considerations that one has to make while using chemical treatment. There are list of considerations to be made the most important one is choosing the right pesticide, purchasing of the insecticide and knowledge that one should know while storing and using insecticides and information on the compatibility of the adjuants and then proper equipment selection and its application technology, measuring and diluting the pesticide concentrates, quality and regulations of these insecticides, phytotoxicity particularly to the plants and then resistance management. We will take up one by one and then discuss in brief. Coming to the first one, choosing the right pesticide. You know specific pest has got a specific insecticide in order to spare or protect the beneficial arthropods that are existing in the ecosystem. For biting and chewing insects in general, any contact insecticides can be used or any microbial insecticides works better for example, lot of commercial microbials are available in the market, dipole and thuricide they can be used, they certainly increase the efficacy by knocking down these biting and chewing insects by sparing the natural enemies. Similarly, the sucking pest can be very effectively controlled with systemic insecticides, thereby even the formulation is also most important. The granular formulation of systemic insecticides in case of paddy ecosystem, you know effectively controls the stem borer as well as the brown plant hopper by sparing the predators and the parasotoids associated in the crop. Then more than one insect is available in a given ecosystem, may be defoliator, may be sucking pest, may be borers, then the use of broad spectrum insecticide is advisable, but on the contrary there may be rapid resurgence of some of these minor pests, the major pest, but the minor pests which are of primary or secondary importance they assume the major status. And in particular, we have seen this case whenever we have used pyrothroid in a paddy ecosystem and not only the resurgence is there, they also bring down the population of many of these parasotoidic wasps. Another information while choosing the pesticide one has to consider is the toxicity level of the pesticides, you know acute LD50 values indicate the toxicity considerations. Again in that acute oral LD50 value and acute dermal 50 value, acute oral LD50 are more toxic than acute dermal toxicity values. If the values indicated say 39 milligrams per kg is more toxic to the higher animals including human beings, whereas higher the value of these LD50 values lesser will be the toxicity to higher animals. The second component that one need to consider is the purchasing of insecticides, you know in the market nowadays large number of pesticides are available in the market to address to our various pest problems. So the question of storing well in advance and keeping it over a long period does not arise at all. One need to purchase into the market or stocked product or freshly labeled products and another factor is one need to understand the generic names or the chemical name of the insecticide. It may so happen that if one purchases on different trade names, we may end up in spraying or in purchasing the same chemical repeatedly. For example monocrotophos in the market is available in 22 brands, monophos, uniphos, noochron all leading to monocrotophos only. So that is why chemical name or the generic name should be very well understood before purchasing any insecticide. Then one need to determine the application of the equipment as well as the required equipment and the adjuvant and their compatibility also with the products before purchasing any insecticide. Then the knowledge in storing and using of insecticides is most important. Any insecticide has got a self-life. Normally unopened insecticide container in the room temperature can be effectively stored without affecting any toxicity for 2 years. That is why very clearly it has been mentioned and the manufacture in the bottling stage itself. The lifespan or the self-life of any pesticide is for 2 years. Then to prevent any damage to equipment, some of these pesticides which are preserved for a long time, if used suddenly they may affect the sprayer itself. So to know any damage it may induce, first mix a small quantity of the pesticide in a jar, find out how it mixes with the water, what happens to the spraying equipment. Then you can go in for large scale preparation and then application. Then if it is an alkaline water or saline water, one need to avoid these water because they have an influence on the efficacy of a particular product. Then particularly when you use water pH of the water should be neutral around 7, otherwise as I said it reduces the efficacy of the active ingredient of the chemical on a particular insect in a particular crop. Then temperature at the time of spraying also influences the efficacy of a particular insecticide. It is normally said OP insecticides works better when the temperature is high in the sense more than 35 degree centigrade. The same thing you know is reverse when you use some of these carbamate insecticides. So one need to know the information on these particular aspects. Then another knowledge that one should have is compatibility of the insecticides with the adjuvants or the additives that we use. Commonly we use adjuvants like spreaders which allow the pesticide to form uniform coating whenever we treat on a leaf surface. Then there are stickers which allow the pesticide to stay on the treated surface for a long time. Then foaming agents by adding this it reduces the drift you know under a field situations. Then we have thickeners which also reduce the drift by increasing the droplet size whenever we spray. Then we have buffers also they allow these insecticides whenever we mix it with acid water or alkaline water. Then another important consideration to be given is the selection of equipment that is the spraying equipment itself for a particular pesticide. You know equipment normally varies according to the site of application where exactly you are applying according to the choice of pesticide. What is the type of insecticide that you are using again based on the formulation it varies and then willingness to work with more complicated application devices that is another factor which induces the selection. Then the pest to be controlled is another important factor for the selection of equipment whether it is a soil insect, whether it is a leaf feeding insect, whether it is a defoliator or whether it is we want to spray to the tree plants. All these things alter the selection of the equipment. Then again within the stage of the crop also is important say in case of cotton. In the first 30 days of cotton planting you know lot of sucking pests come. We need to use knapsack sprayers, high volume knapsack sprayers but the same crop around 70 to 100 days we need to use high volume power operated sprayers. In the same crop the type of sprayer varies according to the stage of the crop. Then formulation of pesticides for controlling most effectively in a given crop for example paddy. In the early stage soil granular insecticides are more preferred because the stem borer and the BPH can be effectively checked by systemic action whereas in the later stage for case worm and for other leaf folder pests you know spray formulations are advisable. So that is why I said formulation of pesticides also decides the type of equipment to be used. Then we need to have thorough understanding of the various types of pesticide applicators. Normally we have two types dusters and sprayers. According to the dusters you know these are usually used for dry dust application of pesticides. You know their coverage is to a large area within a given time and compared to sprayers. There is no question of any corrosion whenever these dust formulations are mixed with the applicators. Normally in the market we have bellow dusters for small scale applications, rotary dusters relatively medium sized applicators, plunger dusters at the specific site of application, knapsack dusters which are commonly used by the farmers for relatively say about 3 to 5 acres. Then if the area is more than 5 acres we go for power operated dusters. Then the other category is sprayers you know sprayers are usually used for dispersing the fluid insecticides in the form of droplets for uniform application over the plants. Depending upon the quantity of the spray fluid required per unit area the different types of sprayers can be used. Normally knapsack sprayers are used for agricultural pest control of small area and also for mosquito control. Wild sprayers are available which are most useful for kitchen garden and glass houses. Rocker sprayers and bucket sprayers are used for tree and tall field crops. Foot sprayers are usually used for small fruit crops even for flower plants. Then power operated pneumatic sprayers are used for an extensive area where we want to cover more than 5 acres in a given day. Then these insecticide spray fluid based on this there is a classification again. There are three types of spraying that we use high volume spraying, low volume spraying and ultra low volume spraying. In case of high volume spraying the spray fluid used per acre varies from 200 to 400 wherein in low volume spray it varies from 40 to 60 whereas in ultra low volume it varies from 2 to 4. The droplet size is significantly varying in the first case it is more than 150 micron is the droplet size wherein in low volume spraying it varies from 70 to 150 it is much lower 20 to 70 in case of ultra low volume spraying. The area coverage per day is again significantly varying in case of high volume hardly we can cover 2.5 acres per day whereas with low volume spraying 5 to 6 acres we can cover whereas with ultra low volume spray we can go as 20 sprayers and the types of spray equipments for each spray also we have indicated. One point we have to remember irrespective of the type of spraying high volume or low volume or ultra low volume quantity of insecticide required remains same only the spray fluid in the form of water the size and the area varies. Other types of specific applications we have for soil injector we have a soil injector particularly at the base of the tall tree plants and we have specific tree trim injectors for injecting insecticide in case of coconut normally we use these things and we have granular applicators wherein granular formulation of insecticides can be applied through tractors and then we have seed dressing machines particularly to the seed itself some of the insecticides can be treated before sowing and similarly slurry seed treatment machines are also available of late for treating to the seed itself. Then we need to follow some safety and regulations one should understand based on the toxicity of a particular pesticide any product a product label has been given along with the bottle one should go through the personal protection equipment details involving all these aspects spray cloths and then safety glasses then respirator and then rubber gloves even the shoes this all helps in avoiding the direct contact of the insecticide to the spraying person. We have to mix pesticides in a well ventilated area or outdoor and then we should avoid contact with the skin and for breathing vapors also one should avoid you know otherwise we have a lot of toxicity problems to the human being itself as I said starting from headache to even carcinogenity also there are various reports and immediately after the spraying is completed one need to take shower immediately after spraying. Then lastly you know phytotoxicity of these pesticides to plants if used on a higher dosage which will happen only when higher dosage than the recommended dosage is used and that typical plant damage symptoms are seen in the form of a burning you know near the tips or the margins as leaf spots or necrosis where in the whole plant is dead chlorosis symptoms appear in the form of spots or tip allowing and then leaf distortion we see various curling crinkling and cupping up of the leaf symptoms and then stunting that is abnormal growth all these leading to poor growth affecting the growth of the plant ultimately affecting the yield of the plant. So, all these considerations what I mentioned so far are very much essential before including any insecticide as a component in IPM thank you.