Terrain.detailObjectDensity

Description

Density of detail objects.

This number goes from 0.0 to 1.0, with 1.0 being the original density, and lower numbers resulting in less detail objects being rendered.

Additional resources: detailObjectDistance.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Start()
    {
        Terrain.activeTerrain.detailObjectDensity = 0.5f;
    }
}