Regulated deficit irrigation is the practice of reducing irrigation to obtain some type of desired stress level. This practice is often used during the initiation of the hull-split period to reduce hull-rot strikes. It also has been utilized during periods of water shortages to save 5-15% of the seasonal water use of almond. Due to the limited effect on yield, as well as the benefits, it has been advocated for application within orchards by the University and industry (including myself!). This practice, however, can have negative impacts when applied incorrectly and should only be used if deemed appropriate. In theory, this practice is easy to apply. Water application rates should be cut to achieve -15 bars stem water potential for two weeks preceding the onset of hullsplit (e.g. Blank split). This stress should be maintained at this level for this period. At the end of the two weeks, regular irrigation resumes and the orchard prepares for harvest. The difficulty in application has everything to do with accurately monitoring plant stress. Every orchard and orchard practice creates a different approach in application. For example, assuming similar irrigation levels, stress levels achieved in a mature orchard planted on sandy soil will occur in a shorter time frame than an orchard on a heavier clay loam. Every orchard site requires careful monitoring to determine when to cut and resume full irrigation. I have observed numerous orchardists apply tree stress only to see a reduction in kernel yield. This is due to ongoing gains in nut weight that occur between the onset of hull-split and harvest. If the tree is significantly stressed during this period, the conversion of carbon to fats is reduced, impacting the final crack out percentage. One closely monitored orchard in which I worked, demonstrated a 10-15% reduction in kernel weights