How is agarwood (oud) formed and how many years before an agar tree gives resin?

Agarwood comes from Aquilaria trees. The tree itself is plain wood. The valuable dark, fragrant resin only forms when the tree is wounded or infected and reacts by producing the resin over time. In commercial cultivation this is done by artificial inoculation, drilling and inserting a fungal or chemical inducer, usually only after the tree is several years old. From planting, you are typically looking at around 6 to 8 years before inoculation and several more years for good resin to build up, so the full cycle is long and the quality of resin varies a lot. Returns depend heavily on inoculation success and resin grade, both of which are uncertain, so any income figure is a wide range, not a fixed number. Assam and the North East have a long agar tradition, so consult the State Forest Department, the agar growers in your area and any government agar institute before investing, and confirm the legal position on Aquilaria felling and trade.