Why neem oil is the OG pest buster

Safer than chemical pesticide, it works in harmony with nature

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March 6, 2025

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Chemical pesticides may effectively eliminate pests, but their collateral damage is hard to ignore. From links to neurodegenerative disorders like Parkinson’s disease to unintended harm to ecosystems, chemicals have sparked public health concerns.

As the air thickens with warnings about the damage caused by chemical pesticides, a quiet hero emerges from the Indian subcontinent: the neem tree. Often referred to as the “botanical marvel” or the “village pharmacy,” neem has interested scientists, environmentalists, and farmers.

Scientifically known as Azadirachta indica, neem is also popularly known as the “gift of nature”. Its adaptability to poor, degraded soils and its resilience in the harshest environments make it an agricultural favourite. Its uses extend beyond providing just shade or firewood. For centuries, neem has been tapped for its medicinal and insecticidal properties. Therefore, time and again, its potential as a natural pesticide has come into sharp focus, too.

The potency of neem extract is not a new area of interest for researchers. A 1992 report points out that Indian scientists jumped on the bandwagon to study the tree much after the West began to see it as a solution to the problem of modern agriculture. Starting in the 1980s, a patent controversy ensued between the researchers from the West who tried to patent neem and Indian activists who fought to protect traditional knowledge. The latter won in 2005.

Farmers have long battled the fall armyworm, a savage pest species that attacks cereals like maize. As savage as the name, the pests have caused one of the deadliest pest epidemics in the Indian subcontinent in 2018-19. The usual synthetic solutions have proven beneficial but are highly problematic as pests sometimes resist them. On the other hand, neem compounds work on the insect's hormonal system, not on the digestive or nervous systems, and therefore, do not lead to the development of resistance in future generations. Its extracts have been shown to affect nearly 300 insect species, including aphids, whiteflies, leafhoppers, and thrips, known menaces amongst Indian farmers.

Several methods were used to extract the beneficial chemicals from neem seeds and leaves. The chemicals were then tested on various crops, from cardamom to mangoes.

Also read: The 'plant' doctor will see you now

‍A multitasking plant

The plant’s resourcefulness as a natural pesticide is buried in its seeds, specifically the kernel, which bears an oil rich in insecticidal compounds. Neem oil contains sulfur and other bioactive components that work like a charm against pests. It can be transformed into powders, granules, and emulsifiable concentrates, creating a wide range for farmers to choose from. But no matter how you use it, neem oil requires patience. It takes four to seven days to show results, and repeat applications are often needed.

Its strength, however, lies in its versatility. It targets pests and eggs that hide through winter as a dormant spray. Moreover, timing is essential; pick a dry, calm day when the temperature is above 4°C, and avoid using it if a frost is coming.

It can be applied directly to leaves as a foliar spray, keeping pests and diseases away during the growing season. For more stubborn issues, one can try a soil drench. This involves mixing neem oil with water and pouring it into the soil, where the plant’s roots absorb it. Once inside, the neem does its thing, tackling fungus gnats, soil-borne fungi, and pests hiding in the dirt. Whether dealing with houseplants or an outdoor garden, neem oil is a simple way to protect plants.

Distinct from chemical pesticides

Unlike chemicals, which kill indiscriminately, neem oil acts as an “antifeedant,” deterring insects from feeding and ultimately starving them. This modus operandi ensures that neem-based treatments target only pests while sparing beneficial insects such as bees and butterflies when used adequately. Research has consistently highlighted neem’s efficacy. In rice fields, for instance, neem oil sprays and soil amendments have proven effective against pests like the rice leaffolder (Cnaphalocrocis medinalis). The larvae’s growth and development are stunted when incorporated into their food. Neem’s reach extends beyond rice; it protects pulses, cotton, groundnuts, brinjals, okra, and even bananas.

Neem oil is a godsend for organic gardeners. A simple mixture of two teaspoons of neem oil, one teaspoon of mild liquid soap, and almost a litre of water can transform into a potent spray. This concoction repels pests and fights fungal infections like powdery mildew. With neem, gardeners and farmers have an eco-friendly ally that is biodegradable and non-toxic to humans, pets, and wildlife.

But neem’s appeal isn’t just its effectiveness; it’s also its sustainability. Unlike chemical pesticides, neem doesn’t accumulate in the soil or water. Pests don’t develop resistance to their bioactive compounds (i.e., elements found in miniscule amounts that support the fundamental nutritional needs of any living organism), which is a chronic problem with synthetic chemicals. Moreover, neem can be combined with other natural oils for enhanced potency.

But despite its many advantages, neem isn’t a band-aid solution. Its effectiveness is gradual, often requiring repeated applications to achieve significant results. It also struggles to tackle fungal and bacterial infections in plants. Yet, ‘The Wonder Tree’s’ strengths far outweigh its limitations, particularly when viewed through the lens of long-term ecological health.

Discovering neem’s usefulness as a pesticide reminds us that nature often holds the solutions to its own challenges, provided we pay attention and listen.

Also read: Natural vs organic farming: What you need to know