Studies documenting pistachio fruiting patterns conclude that this species demonstrates alternate bearing. Across a diverse range of pistachio species and cultivars, I ranges between 0.1 and 0.8 (Esmailpour, 2005). For the widely planted Pistacia vera ‘Kerman’ and ‘Peters’ orchards of California, I ranges between 0.67 and 0.76 (Johnson and Weinbaum, 1987; Ferguson et al., 2002; Kallsen et al., 2007) and yields fluctuate by as much as an order of magnitude between on-years and off-years (NASS, 2003). While these results suggest pistachio is alternate bearing, no study to date has statistically tested alternate bearing in this species.