Cut it out: smaller pistachio trees are healthier and easier to harvest when they capture more sunlight

摘要

Irecently returned from Iran, where the pistachio trees were quite small and moderately productive, judging by nut load. Iranian pistachio trees are generally grown on their own roots, and are irrigated four times a season, usually with saline water. The resulting trees are small, bushlike, and easily hand-harvested. The Iranian trees reminded me of an article Craig Kallsen, Kern County farm adviser, wrote in his February 2001, Pistachio Notes. Kallsen notes that as pistachio orchards age, particularly those at 17-by-21-foot spacings, the result is a densely shaded orchard with large, poorly branching trees, producing few interior leaves and fruit only on the periphery. Large trees are more difficult to shake as the vibration must travel farther and nuts can travel beyond the catch frame. Large, densely-shaded canopies are a better host for potential pests and fungal diseases due to humidity and poor spray penetration. Most importantly, large, densely-shaded trees have more bare, non-productive wood.