Years of experience allow buyers to identify mature fruit from the sound it makes when tapped, supported by visual checks of its colour, shape and stem.
For nearly a decade, To Xuan Anh has travelled from Dak Lak to neighbouring Gia Lai each harvest season, climbing trees and tapping durians to judge their ripeness.
"When the flesh reaches physiological maturity, it shrinks slightly and creates a gap inside the shell, producing a hollow sound," Anh said. "That's one of the clearest signs the fruit is ready."
After selecting ripe fruit, Anh negotiates with orchard owners before selling the harvest to traders. During the peak season, he buys 700-800 kilogrammes of durians a day, earning VND 200,000-300,000 for every 100 kilogrammes, or more than VND 1 million a day.
The job, however, comes with risks.
"When I first started, I harvested fruit too early," Anh said. "The flesh was underdeveloped and I lost tens of millions of dong."'
According to Hoang To Hien, another experienced buyer in Gia Lai, sound alone is not enough. "We also check the shell and the stem. A darker stem, a slightly yellow shell and a hollow sound usually mean the fruit is ready," he added.
A wrong assessment can leave buyers with immature fruit that traders reject or buy only at heavily discounted prices.
Despite the risks, the seasonal work remains attractive because experienced buyers can earn significantly more than many other agricultural workers during the harvest.
Vietnam's durian industry has expanded rapidly in recent years. Durian exports reached about USD 4 billion in 2025, making the fruit one of the country's most valuable agricultural exports.