There are some natural solutions for this purpose and we should understand their basis of operation. If we do so, we will be able to help our crops withstand any pest attack. In organic farming we take the view that every life form helps us in some way.
The following leaves help repel insect pests:
Leaves those cattle don’t eat. Ex – AdAthOdai, nochchi.
Stems that secrete milky sap when broken. Ex – erukku, Umaththai .
Leaves that taste bitter. Ex – neem, aloevera.L
eaves that tastes salty. Ex – kAttAmaNakku
Seeds that tastes bitter or salty. Ex – seeds of neem, custard apple, etti.
Fermented solutions and extracts made with such leaves and seeds act as excellent pest repellents by creating unpleasant odors. When sprayed, these solutions prevent pests from feeding on plants. In general, worms use their sense of smell to identify edible plants. When we spray solutions made with the above plants with dung/urine, we disrupt the sense of smell of the worms and insects. So they avoid crops thus sprayed and either starve to death or, having eaten leaves sprayed with such repellents, die of stomach problems. This considerably lowers the number of egg-laying survivors. Those eggs that do get laid and hatched give rise to handicapped offspring that are easily picked on by predator birds.
Preparation: Take 2 kg each of leaves/seeds (as the case may be) from the five categories mentioned above.
Fermentation method: Add 12-15 liters cattle urine to the above. (Add more if necessary, so that the plant material is completely immersed in cattle urine). Add 3-5 kg dung (mixed with cattle urine) and 100-250 gms turmeric powder (if available). Let it ferment for 7-15 days. Leaves get fermented and the solution is ready for use.
Usage: Mix 500 – 1,000 ml with 10 liters water and spray.
Boiling method: Chop the 10kg leaves/seeds and soak in 25 liters water. Make sure the plant material is fully immersed in water. Boil this under steady heat. Filter this and set apart in a separate container. Add 25 liters of water to the solid matter that is left over after filtering. Boil this. Filter it and add the liquid to the second container (to which the filtered solution was added earlier). Add 100 – 200 gms turmeric powder to this liquid and let ferment for 12 hours.
Usage: Add sufficient water for a total of hundred liters solution and spray.