'Ethylene is commonly available in the market under the brand names Ethefon and Etheral. It is sprayed on the plant. Fruit colour starts developing nearly 15 to 20 days before attainment of maturity of fruits,' the botanist said.

Singh, however, said: 'We are raising awareness among farmers about the need for adopting organic farming instead of chemical farming in apple orchards. Though use of chemicals stimulates or regulates various plant processes, including the opening of flowers and shedding of leaves, its overuse at this stage (when the fruit is naturally attaining colour and ripening) has a negative impact both on the fruit and the plant.'

'Of course, the fruit ripened with chemicals lacks natural sweetness, colour and succulence. It can also affect the human body's immune system and cause severe stomach complications,' he said.

Kanwar Dayal Krishan Singh, a farmer in Kotkhai in upper Shimla, said: 'Some farmers are frequently using chemicals, and this practice is quite prevalent in the mid-hills where the fruit takes time to ripe in natural conditions.'

Bhardwaj said the use of chemicals is also prevalent in other apple-producing states like Jammu and Kashmir and Uttarakhand.

Himachal Pradesh is one of India's major apple-producing regions, with more than 200,000 families engaged in the cultivation of the fruit.

The apple economy of the state is around Rs.1,500 crore and is flourishing mainly in Shimla, Kullu, Mandi, Lahaul and Spiti, Kinnaur and Chamba districts.