Trunk growth studies of almonds at Davis have given new information about the need for spring irrigation. A lever-type dendrometer developed at the University of Idaho was used to follow trunk growth patterns for four consecutive years under widely varying conditions of soil, water, and crop density. The study has shown that the need for early irrigation increases when there is a heavy crop. In the spring, trunk growth rates were increased by irrigation even when as much as 40 per cent available water still remained in the top 4 ft of soil. After mid-season, trunk growth rates were not increased by irrigation unless the soil water content had dropped to the plant wilting percentage before irrigation. These studies also showed that trunk growth rates were reduced as the crop density increased.