Abstract Radial trunk growth of mature almond trees under 4 irrigation treatments was measured with Verner dendrometers for 4 consecutive years. Trunk growth rates and total seasonal growth were affected primarily by soil water and secondarily by crop density conditions. In early spring, when soil water was abundant (near field capacity in entire root zone), the rate of trunk growth was inversely correlated with crop density. Later on, trunk growth was influenced more by soil moisture conditions. Irrigation early in the season increased trunk growth rates even though 30 to 40% available water remained throughout the root zone at time of irrigation. Irrigations after mid-season merely maintained the prevailing trunk growth rates.