The officials said they came to know about ganja plants being cultivated in a Karnataka businessman's estate when they were dousing forest fires in some areas.
They said the security guard at a small farm had raised the crop in the estate, taking advantage of the absentee owner.
The officials said they first noticed three persons hiding behind a bush when they were dousing fires. The trio tried to escape, but were arrested and dry ganja plants seized from them.
Forest ranger Saravanan told reporters initial estimates revealed they had smuggled ganja worth Rs 50 lakh.