Many farmers have embraced the use of chemical pesticides to protect their crops from being attacked by insects.
According to research, long-term chronic adverse effects of pesticide exposure are cancers, birth defects, reproductive harm, neurological and developmental toxicity, immunotoxicity and disruption of the endocrine system.
The research further says the main environmental concerns related to pesticides are soil, water or air pollution and damage to non-target organisms including plants, birds, wildlife, fish and crops.
However, Henry Galiwango, a lecturer at the Agricultural Sciences
School of Education, Makerere University says using natural pesticides is the best option today.
He says natural pesticides are comprised of substances that exist naturally in plants and whose main function is to protect the plant from disease and insect attack.
Galiwango says in recent years, the term natural/organic pesticides has become associated with the development of natural resources for sustainable agricultural products.
“These newly-discovered tools have proven especially successful in the realm of organic farming and are now being used to contain and, in some cases, outrightly eliminate some of the pernicious types of insects, nematodes, fungi and even some strands of complex bacteria of pathogenic origin that are present in many of the farmlands of the world. Natural pesticides are relatively non-toxic to mammals,” he explains.
Advantages of using organic fertilisers
Galiwango says no hazardous residues are realised in using organic fertilisers.
“Organic fertiliaers are environmentally friendly, help farmers access profitable export markets, enable harvest flexibility, are an effective tool for resistance management, ensure worker safety, can be used in conventional and organic agriculture and they reduce the amount of conventional pesticides needed,” he says.
Procedure of making the natural pesticides
· Pound/grind about 100g of onions equivalent to 2-3 big onions. You can use a small pestle or blender to ensure uniform pieces.
· Soak the crushed onions in half a litre (1 tumpeco) of water for 24 hours.
· Soak 10g of soap in water and mix with onion. At times we use liquid soap. This soap is necessary in ensuring the solution (concoction) fully dissolves well when mixed in the spraying pump and for efficient fluid flow during spray. This soap also increases the killing/repelling ability of the coaction. It is specifically used to suffocate small, soft-bodied insects and arthropods such as aphids, mealybugs, thrips, whiteflies, spider mites, leaf hoppers, earwigs, and immature scales (crawlers).
· Stir and sieve with cloth to ensure the onion pieces do not clog/block the pump tubes
How to apply the pesticide in the field
· Add water in the mixture at a ratio of 1 liter of the concoction to 20 litres of water and spray.
· If you are to use for your home vegetable garden, use smaller hand sprayers to ensure it is done closely with the plant. Spray uniformly both at the base and upper parts of the leaves.
· It is always good to spray on cool days-preferably in the early morning or towards sunset
Why onions and garlic are used
Onions
Galiwango says onions are effective in controlling aphids, flies, fruit worms, white flies, mites, root knot nematodes as well as early and late blight in plants. Parts of the crop used are bulbs and leaves.
Materials needed: a pestle and motor, onions, water, cup (tumpeco), cloth/sieve, spraying pump.
Garlic
Galiwango further says garlic is used to control nematodes and insects in crops.
“It is stronger than onions and so we use relatively less amounts of it compared to onions. Garlic has good repelling ability to a number of insects and even human enemies such as snakes,” he says.
Materials needed: Take 85g of finely chopped garlic and soak in one litre of water for one day. Add 10 ml soap, stir, then add 1 litre water and stir.
Add water in the mixture at a ratio of 1: 20 and spray to the plants.
Spraying can be done twice a week to offer maximum protection.
Onions or garlic planted directly in the field
Any type of onion when planted and mixed with other vegetable crops they tends to repels some of insects due to its smell. These contain a chemical called allicin which gives them their distinct odor that is useful in repelling many insect pests. When planted, vegetables surrounding these two crops enjoy smooth growth as chances of being attacked by pests are reduced.
Caution
Galiwango says onion taste/flavour can be retained in the vegetable/ product for one month.
He adds that onions intended for use as natural pesticide should not be fertilised because fertiliser reduces the effectiveness of onion against pests.
