The use of under-tree sprinklers for frost protection is an established practice but the specific mechanisms of the practice aren't well understood. This study of sprinkler spacing showed that best protection depends on placement of lines and air movement within the orchard.

The authors thank Robert N. Hennigan of Hennigan Farms, Chico, California, for the interest and cooperation that made this work possible. This work was supported in part by a grant from the Almond Board of California.