COIMBATORE: With wild boars' attacks reported on farms in western districts, the State government's initiative to help farmers has put the spotlight on a home-grown herbal solution that has already protected thousands of acres of crops across Tamil Nadu and neighbouring states.
The Tamil Nadu government, in its budget presented on August 6, announced a special wild boar damage prevention scheme under which an eco-friendly bio-repellent developed by Tamil Nadu Agricultural University (TNAU) will be distributed to farmers at a subsidised price to cover 14,000 acres.
Developed by the Agricultural Research Station (ARS) at Virinjipuram in Vellore, the plant-based repellent has emerged as a widely used tool to protect crops from wild boar incursions. Besides farmers in Tamil Nadu, the herbal solution is also being used in Kerala, Karnataka, Andhra Pradesh and Puducherry.
According to Dr V Sendhilvel, associate professor and head of the ARS in Virinjipuram, the bio-repellent has recorded a success rate of about 92 per cent in field studies.
"It couldn't achieve 100 per cent effectiveness because of the odour of certain pesticides used in crops, rain and inadvertent errors in erecting the protective fencing. With the government now announcing subsidised distribution, we are working to increase production to meet the expected demand substantially," he said.
The repellent has been found effective in protecting crops such as paddy, ragi, sugarcane, tapioca and groundnut.
The frequency of application varies depending on the crop cycle. Groundnut farmers, for instance, generally need to use the repellent once, as wild boars tend to raid fields when the pods have filled, and the crop approaches harvest.
Sugarcane, an 11-month crop, requires about three applications, while paddy, with a crop duration of around three months, generally requires two applications.
Vellore, Krishnagiri and Dharmapuri are among the districts with particularly high demand, owing to the large wild boar population and the extent of crop damage reported by farmers.
Approved by the TNAU, the formulation is awaiting patent approval. Developed entirely from plant extracts, the product is biodegradable and is not expected to harm other insects or animals.
The growing demand for the product is reflected in its sales. From its commercial launch in 2016-17 until July 31 this year, a cumulative 109,473 litres of the repellent have been distributed to farmers.
The product recorded sales of 153 litres in 2016-17 and 148 litres in 2017-18. Demand increased to 276.5 litres in 2018-19 and 462 litres in 2019-20, before reaching 1,010 litres in 2020-21 and 1,724.5 litres in 2021-22. Sales stood at 1,010 litres in 2022-23.
The biggest surge came in 2023-24, when 1,00,709.5 litres were sold after the State government placed bulk orders for use in sugarcane fields. The repellent was subsequently supplied to farmers at a subsidised price.
Demand has remained steady since then, with sales of 2,138.5 litres in 2024-25, 1,751 litres in 2025-26 and 89.5 litres up to July 31 this year.
The ARS currently has an installed production capacity of up to 600 litres a day. Around 100 litres of the product is also supplied annually to neighbouring states.
Scientists at the research station are now working on a nano formulation that could enable the repellent's odour to disperse more rapidly and improve ease of application. Researchers are also exploring a formulation similar to household odour-repellent products to make its delivery simpler and more practical for farmers.
"The research is aimed at developing a product that is easier to handle and use. However, the impact of El Niño has affected sales this year," Sendhilvel said.
The current application method involves erecting a fence using wooden stakes about 2.5 feet high, placed at 10-foot gaps. An iron binding wire is tied at a height of about 1.5 feet, from which small plastic containers containing the repellent are suspended.
Each container, about 2 cm in diameter, is filled with five millilitres of the repellent. Around 100 such containers are required for an acre and need to be perforated below the neck to allow the odour to disperse. The repellent is priced at Rs 590 a litre, with about half a litre required to cover an acre.
M Raveendran, Director of Research, TNAU, said the herbal formulation was made from volatile plant extracts whose odour is generally disliked by wild boars.
"Several farmers have benefited from the repellent, and we have decided to scale up production. Wild boars can adapt to a particular deterrent if it is used continuously for a long period. Farmers therefore need to adopt different techniques and alternate their strategies to keep the animals away effectively," he said.