You may have a point. Here in the Périgord, hazelnut trees are reckoned to decline in truffle production when they are around 10 years old. Oaks go on producin

You may have a point. Here in the Périgord, hazelnut trees are reckoned to decline in truffle production when they are around 10 years old. Oaks go on producing for decades. If he's planted solely hazelnut and he's waited nine years, he may have a problem.