Preparation of some safer insecticidal

materials for common use

Kerosene emulsion

This is a contact insecticide useful against many sucking insects. For preparing this, slice 500 g of ordinary bar soap and dissolve in 4.5 litres of water by boiling. Cool and add 9 litres of kerosene under violent agitation till the oil is fully mulsified. The stock solution may be diluted with 15-20 times of water before spraying.

                                          Tobacco decoction

This is very effective for controlling aphids and other soft-bodied insects infesting vegetable crops. Tobacco decoction can be prepared by steeping 500 g of tobacco waste in 4.5 litres of water for 24 hours. Dissolve 120 g of ordinary bar soap separately in another vessel. The soap solution is added to tobacco decoction under violent agitation. Dilute this stock solution 6-7 times before spraying.

Neem kernel suspension (NKS)

This is very effective as a repellent/deterrent against locusts, grasshoppers and other chewing insects particularly lepidopterans. The kernel should be ground into a coarse powder. The effective concentration of NKS ranges from 0.1 to 0.3%. For obtaining 0.1% concentration, 1g of powered neem seed is required per litre of water. The required quantity of the coarse powder should be put in a small muslin cloth bag and dipped in water for about 12 hours. Thereafter, squeeze the cloth bag repeatedly so that the out-flowing fluid turns light brownish. The NKS is now ready to be sprayed as such on crops.

Neem oil + garlic emulsion (2%)

To prepare 10 litres of 2% neem oil + garlic emulsion, 200 ml neem oil, 200 g garlic and 50 g ordinary bar soap are required. Slice the bar soap and dissolve in 500 ml lukewarm water. Grind 200 g of garlic and take the extract in 300 ml water. Pour the 500 ml soap solution in 200 ml neem oil slowly and stir vigorously to get a good emulsion. Mix the garlic extract in the neem oil + soap emulsion. Dilute this one litre stock solution by adding 9 litres of water to get 10 litres of 2% neem oil + garlic emulsion.

(Source : Kerala Agricultural University)